May 27, 2008

In this issue

Tree fruit news

§ Early season codling moth management decision-making

§ TNRC trapline data: Codling Moth

Small fruit news

§ Tussock moth monitoring and control in blueberries

§ Altacor insecticide registered for use in grapes

§ Is it a virus disease or something else? A few pointers

§ Monitor for orange rust in brambles

§ Northwest grape IPM “First Friday” meetings

Other news

§ High tunnel tour of England, October 5-9

§ Agricultural labor statistics for spring 2008

§ Pesticide residue testing

§ New core manuals available

§ Regional reports

§ Weather news

Early season codling moth management decision-making

Larry Gut, Entomology, Dave Epstein, MSU IPM Program, Peter McGhee, Entomology, John Wise, Entomology

Putting together a sound codling moth pest management program requires that the practitioner understand several decision-making criteria: moth population pressure as measured with pheromone-baited traps in each farm block, the relative effectiveness of the control tactics available, the mode of action (how they work) of the various options, the life stages each is active on, the optimum time to apply them, and what other pests are controlled if the product is applied at that time. A summary of this information is provided in Tables 1-3.

Another cool spring season in 2008 has provided us with a good lesson in how variable codling moth catches can be from one farm to another, and from one block to another on the same farm. This is not surprising considering that the extent of early season codling moth activity in an orchard is typically associated with how well the pest was controlled in the previous season. Regional information is a part of understanding codling moth activity, but the use of monitoring traps in individual orchard blocks is the only accurate way to know what is happening on your farm and to make economically sound codling moth management decisions. Growers need to weigh the evidence of moth activity as measured by monitoring traps to decide if treatment is justified in terms of cost and time, and to assist them in determining the appropriate time to treat. To get the most benefit from a codling moth control measure, growers should treat a block after moths have been captured and the accumulation of growing degree days required for a particular action as indicated in Table 1 has taken place after the catches were recorded.

Table 1. Codling Moth GDD Model and insecticide timings

DD° Base 50 (Post Biofix)	Event	Action
Pink bud	Development of overwintering larvae	Set traps
0 DD° = Biofix (~200 DD° after Jan 1)	1^st sustained moth captures	Set DD° = 0
100 DD°	Start of 1^st generation egg laying	Timing for 1^st treatment for egg targeted materials
250 DD°	Start of 1^st generation egg hatch	Timing for 1^st treatment if over threshold (for larva targeted materials)
350 DD°	1^st generation egg laying & hatch	Delayed timing for 1^st treatment if pest pressure is low, or for 2nd treatment if an ovicide was applied at 100 DD°)
500-650 DD°	Peak of 1^st generation egg hatch	Timing for additional larvacide if monitoring of CODLING MOTH activity indicates a treatment is needed
1000 DD°	Expected end of 1^st generation activity
1200-1250 DD°	Start of 2^nd generation egg hatch	Timing for treatment if over threshold (for larva targeted materials)
2100 DD°	Expected end of 2^nd generation activity

Targeting the adult lifestage using mating disruption.

The first opportunity to control this troublesome pest is to target the adult stage using pheromone-based mating disruption. Pheromone products for this season should already be in the orchard, as they need to be operating when the first moths emerge from overwintering sites. Mating disruption works by inhibiting male moths from finding female moths, thus interrupting the reproductive part of their life cycle. With less mating, there are fewer eggs and ultimately fewer larvae to infest fruit. It also means that the population that needs to be controlled with insecticides will be smaller. Apple growers participating in the Michigan area-wide mating disruption project for multiple years have been able to reduce the number of insecticide applications needed to achieve codling moth control by an average of 60 percent. With mating disruption as the foundation for managing codling moth, apple growers can more comfortably employ the reduced-spray programs discussed subsequently in this article. Ours and the experience of many Michigan growers is that programs combining the use of mating disruption and insecticides as needed provide better control than insecticide-only programs.

Targeting eggs

The first option for controlling codling moth once mating has taken place is to target the egg stage of the life cycle. Among the newer insecticides for codling moth control registered over the past few years are the insect growth regulators Esteem and Rimon. Both act by suppressing development within the egg, as well as larvae that consume it. Hatching of eggs laid by treated adults will also be inhibited. Eggs are particularly susceptible to these products when laid on top of sprayed residue, thus sprays are timed earlier than most other codling moth control materials. Suggested timing for the first application is biofix plus 100-150 GDD. At this timing, Rimon will provide good to excellent control of Oriental fruit moth, obliquebanded leafroller and spotted tentiform leafminer, while Esteem will be highly active on rosy apple aphid and San Jose scale.

Larval control

The vast majority of insecticides used for codling moth control are aimed at killing larvae. This is not an easy task as young larvae feed and enter the fruit within a few hours of hatching. Options for controlling larvae include conventional contact poisons, like the organophosphate (OP) compounds, Guthion and Imidan, and a number of pyrethroid insecticides. These materials kill larvae that crawl across or consume the lethal residues. They primarily target newly emerging larvae at egg hatch, and thus are typically applied beginning at 250 GDD post biofix. Pyrethroid insecticides appear to be more effective in the spring for first generation codling moth, than summer and have a broad activity spectrum. Pyrethroids are highly toxic to mite predators and should be used carefully to avoid outbreaks of phytophagous mites. Apple growers should be aware that resistance to the OP compounds has been detected in Michigan orchards throughout the state, most extensively in the Fruit Ridge and Southwest production areas. The levels of resistance detected were high enough in those orchards that sole reliance on OP's for CODLING MOTH control is not likely to provide sufficient control. In addition, populations resistant to OP compounds may also be resistant to pyrethroids.

Several new materials have become available for codling moth larval control and growers are encouraged to include these new products in their codling moth management programs. Integrating them into codling moth management programs will not only improve control in orchards experiencing problems, but also will help delay the development of codling moth resistance to OP’s in locations not yet experiencing control failures. The newest options for codling moth control are two compounds that received their U.S. EPA registration within the past few months, Delegate and Altacor. Although tested extensively over the past few years by MSU and other university researchers, Delegate and Altacor will be commercially available for the first time in 2008.

Delegate (spinetoram) is a new compound in the same insecticide class as SpinTor (spinosad). The active ingredients of both Spinosyn compounds are similar in that they are waste metabolites produced during the growth of a bacterium. A major difference between the two AI's, however, is that spinetoram is much more lethal to codling moth larvae. In small-plot trials at TNRC, Delegate has provided excellent control of both first and second generation codling moth. It kills larvae as they hatch and begin feeding, thus should be applied at the larvicidal timings indicated in Table 1. Delegate has very good activity against obliquebanded leafroller. Although also active against apple maggot, results of small-plot trials have been mixed and more research is needed to determine the level of AM control Delegate will provide.

Altacor (rynaxypyr) is a new compound that is the first product developed in a newly emerging class of insecticides. In small-plot trials at Trevor Nichols Research Complex (TNRC), Altacor has provided excellent control of both first and second generation codling moth. Our research at TNRC has focused on the larvicidal activity of Altacor, however Dr. Jay Brunner and colleagues at Washington State University have found that Altacor has substantial ovicidal activity as well. We will be conducting research in 2008 to determine if Altacor is effective at both ovicidal and larvicidal timings. For the 2008 growing season, we suggest Michigan apple growers apply this product at the larvicidal timings. Altacor provides excellent obliquebanded leafroller control. It has limited activity on apple maggot, and thus probably has a better fit in Michgan apple IPM programs for first rather than second generation codling moth control.

The neonicotinoids, Assail and Calypso, will provide very good control of codling moth with a residual action of 10-14 days. Proper timing and coverage is required to achieve control. These compounds are primarily larvicidal, but also have some ovicidal activity when applied over the top of the egg. Assail is labeled for codling moth control at the rate of 6-8 ounces per acre, but the high rate has shown better performance, especially for second generation codling moth. Application rates near the high end of the label rate are also recommended for Calypso, especially where codling moth densities are high or for prolonged control. Field trials have indicated that use of Assail in combination with pyrethroids or carbaryl can result in outbreaks of phytophagous mites. Assail and Calypso are fairly broad-spectrum materials. In contrast to the insect growth regulators, the major secondary targets of these neonicotinoids are the sucking insects, specifically aphids and leafhoppers. The initial application of Assail or Calypso targeting first generation codling moth will also provide control of plum curculio, Oriental fruit moth and spotted tentiform leafminer.

Clutch, another neonicotinoid registered for use in pome fruits, is a broad-spectrum material targeting codling moth as well as aphids, leafhoppers, plum curculio, spotted tentiform leafminer, Oriental fruit moth and pear psylla. Research trials have indicated that Clutch is not as effective as Assail or Calypso. The best results have been achieved when it is used against first generation codling moth larvae applied at the egg hatch timing of 250 GDD and at the high 6-oz/ac rate. Even at the high rate, Clutch has not provided adequate control of second generation codling moth.

Proclaim, a new codling moth control material (Avermectin class) available at the start of the last season, provided good suppression of first generation codling moth in trials at the Trevor Nichols Research Complex and in on-farm demonstration trials. Last season the label only claimed suppression of codling moth, but beginning in the 2007 season control of first generation larvae is supported on the label. Proclaim has very good activity against obliquebanded leafroller.

Intrepid is an insect growth regulator that provides good control of codling moth with a residual action of about 10-14 days. This product is an insect growth regulator that primarily affects codling moth larvae, but also has substantial activity on eggs, and has sublethal effects on adults. The best results have been achieved by taking advantage of the ovicidal and sublethal effects. For example, applying an early spray at biofix plus 150-200 GDD or a delayed timing of 350 GDD. At the early timing, Intrepid will also control obliquebanded leafroller larvae that are still present in orchards harboring high numbers of this troublesome pest. The addition of an agricultural adjuvant is recommended to improve initial spray deposition. As a cautionary note, growers should be aware that populations resistant to OP compounds might also be resistant to Intrepid.

Table 2. Chemical class, activity and timing of insecticides used for CODLING MOTH control.

Compound Trade Name	Chemical Class	Life-stage Activity	Optimal Spray Timing for CODLING MOTH	Mite Flaring Potential
Guthion, Imidan	Organophosphates	Eggs, Larvae, Adults	Biofix + 250 DD	L - M
Asana, Warrior, Danitol, Decis, Baythroid XL	Pyrethroids	Eggs, Larvae, Adults	Biofix + 250 DD	H
Rimon	IGR (chitin inhibitor)	Eggs, Larvae	Biofix + 100 DD Residue under eggs	M*
Delegate	Spinosyn	Larvae	Biofix + 250 DD
Altacor	Anthranilic Diamide	Eggs, Larvae	Biofix + 250 DD
Assail, Calypso, Clutch	Neonicotinoid	Eggs, Larvae, Adults (limited)	Biofix + 200-250DD Residue over eggs	M*
Intrepid	IGR (MAC)	Eggs, Larvae, Adults(sublethal)	Biofix + 150-200DD Residue over eggs	L
Avaunt	Oxidiazine	Larvae	Biofix + 250 DD	L
Esteem	IGR (juvenoid)	Eggs, Larvae	Biofix + 100 DD Residue under eggs	L
Proclaim	Avermectin	Larvae	Biofix + 250 DD	L
Granulovirus	Biopesticide	Eggs, Larvae	Biofix + 250 DD Residue over eggs	L

* May cause mite flaring in combination with carbaryl or pythrethroids that kill predacious mites.

Codling moth granulosis virus

Growers should not overlook including granulosis virus in their codling moth management program. This is a naturally occurring virus that goes by the scientific name of Cydia pomonella granulovirus (CpGV). Each of the three commercially available products, Cyd-X, Virosoft and Carpovirusine, are effective. Optimal use of the virus is against young larvae before they penetrate the fruit. The best way to target young larvae is to have the virus present on the surface of the eggs when they begin to hatch. Hatching larvae will ingest the virus as they consume their eggshells.

There are many options for incorporating virus into your codling moth management program. Deciding how much, when, and how often to apply product, can be quite confusing. Keep in mind the following factors when trying to sort things out: 1) CpGV must be ingested by the larva and may not kill it immediately, 2) the virus breaks down in the environment, thus a spray may only be effective for a week or so, and 3) the virus is highly lethal, a few OB's are all that are required to cause death. Our overall experience is that frequent application of a low rate of product is the best approach for using this biopesticide.

Growers can opt to use the virus as part of a multi-tactic codling moth control program. Rotating it with chemical insecticides is a good means of combating resistance. We suggest the following approaches to incorporating codling moth virus into a management program. If you want to restrict your use to a single generation, target the first generation. Some virus-infected larvae will not die immediately, allowing them to cause fruit damage and even complete larval development. Fortunately, stings or deeper entries in small fruits attacked by first generation larvae often fall off the tree or are removed by thinning. Additionally, research conducted in 2003 revealed that less than four percent of the individuals that managed to complete larval development survived to pupate and emerge as summer generation adults. Thus, applications against the first generation can greatly reduce the size of the summer generation that will need to be controlled.

Regardless of the generation targeted, it is best to make at least two applications. If you want to rotate a CpGV product with other controls, try applying a chemical insecticide as the first spray at the start of egg hatch (250 GDD) and the virus as the second spray. This is because more eggs will be present and covered by the virus spray at the later timing. The insecticide and virus could then be rotated again, or the virus could be applied weekly at a low rate for the remainder of the egg hatch period.

Combined use of an ovicide and larvicide

Over the past few years, colleagues in Washington State have been evaluating two novel codling moth programs that take advantage of the ovicidal or larvicidal properties of various compounds. In one program, an ovicidal material is applied at the start of egg laying and a larvicidal material is applied at a delayed timing of 350-400 GDD. The second program is a delayed timing at 350 GDD of a tank mix of an ovicidal insecticide, such as Rimon, and a larvicidal insecticide, such as Delegate. Growers can learn more about these programs at http://entomology.tfrec.wsu.edu/op-alternative/.

Taking the lead from our Washington colleagues, we have evaluated the early ovicide followed by a delayed larvicide program using Rimon as the ovicide and either Assail, Calypso or Altacor as the larvicide. All programs proved highly effective in controlling first generation codling moth. The delayed larvicidal treatment is possible because the early ovicide treatment kills eggs that would have hatched in the period starting at 250 DD. Another nice feature of this program is that the delayed application of the larvacide is a more efficient timing than the standard first cover timing of 250 DD. Only a small portion of the first generation egg hatch occurs between 250-350 DD, ca 15 percent, while more than 50 percent of the hatch occurs over a two to three week period beginning at 350 DD. The combined strategy also shortens the period of time that larval control is necessary, presenting an opportunity to reduce the number of sprays needed to achieve control.

Table 3. Relative activity spectrum of compounds against spring and early summer apple pests

Primary pests Secondary pests

Insecticide CODLING MOTH OFM OBLR PC AM STLM GAA RAA WALH SJS

Avaunt ** ** * *** * * *

Intrepid *** *** *** **

Spintor ** ** *** ** ** *

Delegate *** *** *** * ** ** *

Esteem ** * * ** ** ***

Rimon *** *** *** **

Altacor *** *** *** * **

Proclaim ** ** *** ***

Actara * * *** *** *** *** *** *** **

Calypso *** *** *** *** *** *** *** *** **

Assail

Clutch ** ** *** ** *** *** *** ***

Guthion *** *** *** *** *

Imidan

Pyrethroids ** ** ** ** ** ** * * * **

Codling moth-codling moth, OFM-oriental fruitmoth, OBLR-obliquebanded leafroller, PC-Plum curculio, STLM-spotted tentiform leafminer, GAA / RAA -green / rosy apple aphid, WALH-white apple and potato leafhoppers, SJS-San Jose scale, TPB-tarnished plant bug, AM-apple maggot.

some activity, ** better activity, *** best activity relative to other insecticides

TNRC trapline data: Codling Moth

For emergence graphs of other common fruit pests refer to our web site at http://www.maes.msu.edu/tnrc/07traplinecover.htm

Tussock moth monitoring and control in blueberries

Rufus Isaacs and Steve Van Timmeran
Entomology

The whitemarked tussock moth (Orgyia leucostigma) is distributed throughout eastern North America and can be a pest of blueberry fields in Michigan. This species feeds on hardwood and ornamental trees and is found in native habitats. When this insect moves into blueberry fields, growers may experience damaging levels of leaf loss on young bushes and contamination of fruit at harvest can cause economic hardship in mature fields. The larvae also have irritating hairs that can cause dermatitis in hand pickers, so it is important to control this insect before harvest. Early detection of this insect is the key to preventing economic loss.

Life-stages

The egg mass is white-cream colored with numerous 1-2 mm diameter eggs nested within white foam. This is usually wrapped inside a blueberry leaf and attached to a stem, or it may fall to the ground. Over 100 larvae can hatch from one egg mass, and these change from a light brown color when newly-hatched to multicolored as they grow. Full grown larvae have a bright red head with a yellowish body, a pair of upright pencil tufts of black hairs on the prothorax, and four white to yellowish brushlike tufts of hairs on the top of the body toward the head. After the first instar, larvae have a conspicuous red dot on segments six and seven. The adult moths vary considerably between the sexes: the female moth is a ¼-inch long white furry moth without wings, usually found inside a leaf surrounded by the hairs from her pupal case. The male is ¾-inch across its wings that are mottled brown, and it has feathery antennae.

Timing of development

A recently-completed study has revealed the phenology of whitemarked tussock moth in Michigan blueberry fields. This insect has two generations in southern Michigan with peaks of larvae on bushes in June and again in August, and peaks of moth activity in late June and late August. The whitemarked tussock moth overwinters in the egg stage within a large mass of eggs nestled in a hard foam that is wrapped inside a dry leaf. These are usually found on stems and are visible during pruning. The eggs hatch during bloom and larvae stay close to the egg mass at first, dispersing in the plant canopy after a few days. Larvae feed in the shady parts of the canopy until full grown in late June/early July. At this point, they pupate on the bush and emerge in July as adult moths. The female moth is flightless and stays on the leaf she pupated in, mating and laying eggs in this same position. The foamy egg mass hardens and young larvae emerge in late July through August to feed on the mature foliage, growing during the period of blueberry harvest. These larvae are the ones that cause the conflict with pickers and harvest.

Development of whitemarked tussock moth can be predicted using growing degree days. During a two-year project that included laboratory and field studies, we found that development of this pest was best predicted using a base temperature of 55^oF. Egg hatch of the first generation was found to start at 208 DD base 55 (from March 1) while egg hatch of the second generation was found to occur at about 1100 DD base 55. In both years, egg hatch of the second generation in early July was found to start at 300-350 DD base 55 after the first male moths were trapped in pheromone monitoring traps. We are currently working with the Enviroweather team at MSU to integrate the findings of this project into their degree day prediction capability.

Monitoring

Early detection is important for management of whitemarked tussock moth so that the larvae are not full grown when attempting control. Using monitoring traps and bush scouting can help ensure that management actions are made at the best time to ensure a high level of control.

Using pheromone traps

Fields with a history of whitemarked tussock moth infestation should be monitored with two pheromone-baited traps, placed at the field edge and interior, and with regular scouting of bushes. This will allow growers to know where, when, and if a pesticide application is needed. To monitor, place traps in the region(s) of the farm with previous whitemarked tussock moth infestation during early June. Traps should be placed toward the wooded edge of a field if present and in the field center, and checked weekly. One pheromone lure can last all season, so no lure replacements are needed. Weekly catches of moths in the trap can be used to identify whether the infestation was controlled by the post-bloom insect management program, or whether there is still a population with the potential to cause problems during harvest. If high numbers of moths are still being trapped, fields should be carefully scouted for larvae during the pre-harvest period to determine whether chemical control is needed.

Scouting for larvae

To scout for larvae, look on the underside of leaves by turning over leaves with feeding damage and by looking in the center of the bush where the larvae prefer to hide. The large larvae are conspicuous due to their yellow, red, black and white coloration, but the smaller brown larvae may be more difficult to locate. Beware of the allergenic hairs and approach with caution!

Control

Because the first generation of larvae hatches during bloom, application of an effective fruitworm spray program during the early part of the season provides growers with good control of whitemarked tussock moth. Problems with whitemarked tussock moth tend to be worse in fields where no fruitworm sprays are applied, where they are applied without good coverage, or where the fields are weedy. Because larvae prefer the more dense and shady part of the bush, they can escape contact with insecticides if the fields are not effectively treated at the post-bloom timing.

Whitemarked tussock moths are naturally controlled by a complex of parasitic wasps that attack the larvae and by diseases. These natural enemies cycle through the pest population and help to cause the typical increases and crashes seen in whitemarked tussock moth populations. In years where the pest population is amplified, these wasps and diseases cannot suppress the pest population and intervention is needed to prevent larvae contaminating the bushes and fruit during harvest. Selection of a moth-specific insecticide such as Confirm or Intrepid can help conserve the beneficial insects.

Insecticides that are active on other moth larvae are generally effective against whitemarked tussock moth larvae (Confirm, Guthion, Sevin, Lannate, Asana, Danitol, Mustang Max). We also expect the new insecticides Delegate, Intrepid, and Assail to be effective insecticides against this insect. Broad-spectrum insecticides such as Guthion, Lannate, Asana, Danitol, and Sevin will provide fast control of this pest, killing young larvae in one to two days. The growth regulators Confirm and Intrepid take a little longer since they disrupt the molting of the larvae, providing control of young larvae in four to five days. We expect Assail and Delegate to be intermediate in their speed of control.

Because the larvae are sensitive to a broad range of insecticides, applications made for other pests such as fruitworms, blueberry maggot, or Japanese beetle are often able to control whitemarked tussock moth. However, the coverage of the bushes and the spray timing must be sufficient to bring the larvae into contact with the residue. It is important to understand that the larger the larvae become, the more difficult they are to control. This is another good reason to make sure the first generation is controlled in fields with whitemarked tussock moth infestation. This avoids having to attempt control at harvest time when bushes are bigger and laden with fruit, pickers are in the field, and re-entry and pre-harvest intervals make control much more challenging.

We thank MBG Marketing and the Michigan Agricultural Experiment Station for support of our tussock moth research

Tussock moth IPM program

1) If the field had tussock moth problems last year, remove and destroy egg masses during winter pruning. Treat with a bee-safe insecticide at 300-500 DD base 55^oF (mid-late bloom).

2) Monitor tussock moth with a pheromone-baited traps placed in the field by early June. Check weekly and count tussock moths.

3) If high numbers of male moths trapped, especially in interior field traps, treat field at 400-500 base 55 after first consistent moth catch (early-mid July). Beware of PHI and REI restrictions.

4) Monitor bushes weekly from early July to harvest, to detect larvae while small (usually inside canopy).

5) If larvae detected near to harvest, apply an effective insecticide with short PHI and with good coverage of the whole bush.

Altacor insecticide registered for use in grapes

Rufus Isaacs and John Wise
MSU Entomology

Altacor is a new insecticide from DuPont that is now registered at 2-4.5 oz/acre in vineyards, with activity on grape berry moth and cutworms. This is a new chemical class called the anthranilic diamides which act by affecting insect muscle function. As such, it provides growers with an additional insecticide option for resistance management. Altacor is most effective if the insecticide is eaten by the larvae, so excellent cluster coverage is required to get the greatest activity from Altacor. Our 2007 research trials using Altacor applied in 50 gallons of water per acre showed excellent performance against grape berry moth. When tested at 2 or 4 oz/acre, both rates provided over 95 percent control of cluster infestation by this pest, with less than 2 percent infested in the treated plots compared with 43% in the untreated plots. The product is formulated as a WDG formulation, has a 4-hour REI and a 14-day PHI.

Is it a virus disease or something else? A few pointers

Annemiek Schilder, Plant Pathology

This is the time of year that virus symptoms become apparent, particularly in blueberries. A cool spring and slow growth also brings out symptoms more than warm weather. Virus and virus-like diseases in plants manifest themselves in several ways and can be easily confused with abiotic disorders like nutrient deficiencies and herbicide injury. Viruses are tiny pathogens that are only visible with an electron microscope. Their simple make-up, a strand of genetic material covered by a protein coat, belies the damage they can cause. Think of viruses as miniscule hijackers of plant cells. Once they enter a plant cell, they force that cell to multiply the virus particles and thereby derail the cell’s normal functions. Once a plant becomes infected, the virus spreads throughout the plant tissues including the roots. This is called a systemic infection, and the plant is infected for life. This also means that you cannot cut out the symptomatic plant parts and expect the plant to be cured.

Symptoms that may indicate a virus disease include: yellowing or reddening of leaves, mosaic or mottling, crinkling or malformation of leaves and other plant organs, stunting, poor fruit set, generally poor growth, and plant death. Some of these symptoms can also occur when the plants are malnourished or the root system is compromised (e.g., by root rot or nematode damage). The recent cold weather has also induced some reddening in plants due to limitations on nutrient uptake. Symptoms caused by herbicides, such as Round-Up or 2,4-D may also include stunting and malformation of leaves: 2,4-D is especially tricky because it can volatilize and affect plants some distance away from the application site. Herbicide drift from another crop (e.g., Dicamba from corn or soybeans) can also affect nearby non-target crops. Here are a few pointers that may help you decide whether symptoms that you are seeing may be due to a virus or another cause:

1) Are the symptoms present in a few scattered plants or in many plants over a large area? If present uniformly over a large area and also affecting weeds, it is more likely to be caused by herbicide injury, some nutritional disorder or soil condition. Have soil and plant tissue analyzed for nutrients. Some herbicide residues can be detected if samples are taken soon after the application or drift occurred but this is rather expensive.

2) Did the symptoms show up suddenly or have they been worsening over the season or the past couple of years? If the symptoms showed up suddenly in an otherwise normal year, herbicide injury is a possibility, especially if many plants are affected. Symptoms caused by virus diseases usually worsen over time.

3) Does the disease seem to be spreading? If so, it may be a virus disease. Virus diseases vectored by nematodes usually spread in a more-or-less circular pattern in a field, whereas viruses vectored by aphids spread more readily down the row.

4) Did you apply Round-Up last fall? This herbicide may get transported into the roots and may not show symptoms until the following spring.

5) Are symptoms showing here and there in a newly planted field? Consider your source of plants. Did you buy virus-tested planting stock? If not, you may have imported a virus disease with the planting material.

6) If you suspect a virus disease, send a plant sample to the MSU Plant Diagnostic Lab. The best time to send samples in is in the spring, when young plant tissues (leaves or flowers) are most likely to contain virus particles. Samples have to be fresh for virus indexing, so send them on ice in express mail or hand-deliver the cooled sample.

Just as in people, virus diseases in plants are difficult if not impossible to cure, so prevention is the best method of control. Buy virus-tested planting stock whenever possible: it is definitely worth the investment, especially when planting a perennial crop. If you see suspicious symptoms, rogue out and destroy affected plants quickly before they become a source of inoculum and practice good insect control. When planting into a field that had a nematode-transmitted virus disease previously, fumigate the soil before replanting or grow non-host cover crops (e.g., rye or mustard) for a couple of years.

Monitor for orange rust in brambles

Annemiek Schilder, Plant Pathology

This is a good time to check blackberry and black raspberry plantings for orange rust. Red raspberries are immune. Characteristic symptoms are spindly shoots with clustered, misshapen, pale green to yellowish leaves, as well as bright orange, powdery blisters on the undersides of leaves. Before the blisters burst open, they look waxy or shiny, as if covered with lacquer. On black raspberries, the rusted leaves start to wither and drop in late spring to early summer. New leaves produced towards the tips of canes may appear normal, giving the impression that the plant has “grown out” of the disease. However, such canes will remain infected and will produce a mass of spindly shoots with no blossoms the following spring. The plant becomes systemically infected and remains so for the rest of its life. Orange rust does not usually kill plants, but it can significantly reduce vegetative growth and yield. The disease can be caused by either of two closely related fungi, Arthuriomyces peckianus or Gymnoconia nitens. The orange spores are spread by wind and can infect leaves of healthy plants with long periods of leaf wetness provided by rain or dew. Orange rust is favored by relatively low temperatures (50-70ºF). The fungus overwinters in the crown and roots of infected plants, leading to the production of new infected canes every year.

Cultural control

While there were no chemical control options for this disease in the past, we now have several excellent fungicide options. This does not mean that we should abandon cultural practices, such as establishing new plantings from disease-free nursery stock, which will also help in avoiding virus diseases. If any plants show signs of the disease during the spring in which they were planted, this means there were already infected at the time of planting. Upon inspection of plants each spring, any infected plants, which are economically worthless, should be dug up and destroyed promptly before rust pustules mature and spores are liberated. The location of those plants should be clearly marked, and any new suckers arising from root pieces left in the ground should be removed and sprayed with an approved systemic herbicide. It is also prudent to remove infected wild brambles in nearby wooded areas and fence rows. Management practices that improve air circulation, such as thinning out canes within the row, pruning out floricanes immediately after harvest, and effective weed control aid in disease control by reducing build-up of moisture in the planting. Some blackberry cultivars (e.g., Eldorado, Raven, and Ebony King) are reported to be resistant to orange rust, but no black raspberry cultivars are known to be resistant.

Fungicide options

The best fungicide options are Nova (myclobutanil), Pristine (pyraclostrobin + boscalid), and Cabrio (pyraclostrobin). While Abound (azoxystrobin) is labeled for use on brambles, it does not have orange rust (or any other rust for that matter) on the label. Nova may have a bit better curative activity than the others because of its greater systemicity, which would make it the material of choice during or after a rainy period with inoculum already being present. Each of the earlier-mentioned fungicides will also control various other cane, leaf, and fruit diseases. Since Pristine has two active ingredients, it has the broadest spectrum of activity. None of these fungicides will cure an already infected plant. However, they can prevent healthy plants from becoming infected. Since infected plants will continue to be sources of inoculum over their lifetime, it is best to remove and destroy them altogether and replace them with healthy plant material from a reputable nursery. Apply fungicides upon first discovery of the blisters, preferably before they burst open and release spores. If the field has a history of the disease, sprays should be initiated before blisters appear. Since infections can also originate from wild brambles near the field, one should keep an eye on these as well if possible.

Northwest grape IPM “First Friday” meetings

The meeting will take place June 6 from 3:00 to 5:00 PM at Shady Lane. Rufus Isaacs will discuss insects and grapes. For more information, please contact: Erin Lizotte, Nikki Rothwell (Northwest Michigan Horticultural Research Station (231) 946-1510), Duke Elsner or Paul Jenkins.

High tunnel tour of England, October 5-9

Eric Hanson
Horticulture

We are organizing a five-day bus tour of high tunnel culture in England for growers, extension folks, or any other interested people. Cost is $800 per person ($700 double), which includes most meals and all lodging (flight to London not included). Ralph Kramer, the Haygrove High Tunnels representative for the Eastern United States., developed the itinerary. We will tour cherries, raspberries, strawberries and possibly other crops under tunnels, and see the latest developments in tunnel structures, poly, management demos, packing sheds, strawberry harvesting rigs, etc. We will also visit Warwick Castle. Lodging will be in mid-level hotels on the outskirts of the cities. Deadline for registration is August 22, but you may want to register and purchase your air ticket earlier. Full details and registration forms are posted at: http://www.hrt.msu.edu/TUNNELTOUR/. Contact Eric Hanson at MSU (517-355-5191 x1386, hansone@msu.edu) with any questions.

Agricultural labor statistics for spring 2008

Vera Bitsch; Agriculture, Food and Resource Economics

This April, the hourly wage for agricultural workers in the United States stood at $10.60, up 40 cents from a year ago. Field workers received $9.65, up 30 cents from a year ago. Livestock workers made $10.32, up 63 cents from a year ago. This wage rate includes supervisors and other workers, such as bookkeepers and pilots. Wage rates do not include the value of benefits. Total hired workers are estimated at 919,000 individuals, down by 7 percent compared to last year. The number of hours worked is up only slightly at 41 precent

Michigan, Minnesota and Wisconsin make up the Lake region. For the three states, the number of hours worked stood at 39.0 hours during this April. The total number of workers, excluding agricultural service workers, is estimated at 52,000 individuals, compared to 56,000 during last April. The average wage rate for all hired workers was $11.25 per hour, up 17 cents from a year ago. Only, Hawaii with $13.28, the Cornbelt I region (Illinois, Indiana, and Ohio) with $11.43, and the Cornbelt II region (Iowa, Missouri) region with $11.88 paid higher wages. Field workers in the Lake region earned $10.57 per hour, up 46 cents. Livestock workers earned $10.78 per hour, up 79 cents.

In addition to analyzing wage rates by type of worker, NASS provides wage data by type of farm with slightly different results. These data combine field workers and livestock workers, but exclude other typically higher paid groups. The average hourly wage rates in 48 states, excluding Alaska and Hawaii, during this April were $9.87 overall, $9.84 for field crop farms, $9.66 for other crop farms, and $10.20 for livestock and poultry farms. Last year those rates were $9.41, $9.36, $9.39, and $9.47, respectively, indicating notable wage increases.

The hourly wage rates in the Lake region were $10.70 for all farms, $10.08 for other crops, and $10.78 for livestock and poultry farms. There was insufficient data to calculate the wages for field crop farms. Last year the wages in the Lake region were $10.05 for all farms, $10.82 for field crop farms, $9.72 for other crop farms, and $10.13 for livestock and poultry farms. Overall, the Lake region has seen considerable wage increases.

To read Dr. Bitsch’s complete newsletter go to her website at http://www.msu.edu/user/bitsch. Under “News” click on “U.S. Agricultural Labor Statistics for Spring 2008” or click on “Agricultural Labor Issues in Michigan” for a list of available newsletters.

For more details, the NASS release is available at http://www.usda.gov/nass/. Select “Publications” and then “Reports Calendar” or “Publications” and then “Search,” by “Title” or “Subject” (Farm Labor).

Pesticide residue testing

Steven Gower, MSU Diagnostic Services

Herbicides can injure desirable, non-target plants in a variety of ways, including drift, volatilization, carryover, tank contamination, misapplication or simply accidental or intentional exposure. In addition to diagnosing plant pathogens, nematodes and insect-related pests, all plant samples submitted to MSU Diagnostic Services – the multi-disciplinary plant health and pest diagnostic facility on campus – are visually inspected for pesticide injury. If warranted, samples can be tested for the presence of pesticide residue using appropriate analytical instruments and techniques.

Sampling

We urge clients that are interested in pesticide residue testing to contact the laboratory before collecting and submitting samples. Samples should be collected immediately if pesticide injury is suspected. If you suspect a drift event has occurred but are not positive, it may be wise to collect a tissue sample that day or the next and place the sample in the freezer. Glyphosate and 2,4-D, for example, can be very difficult to detect and quantify in the tissue once injury symptoms develop. Therefore, a little foresight in sampling may really help if injury symptoms do develop 7 to 10 days later. Collect enough plant tissue to fill a quart-size plastic bag; collect enough soil to fill a pint-size plastic bag. In general, samples should be frozen immediately and kept frozen until arrival at the laboratory.

Fees

Plant samples are visually inspected for pesticide injury for $20. Samples can be tested for pesticide residue on an individual basis or, if available, in multi-pesticide screens. Fees may vary depending upon number of samples, clientele location and numerous other special circumstances. Fees for individual pesticide residue screens are generally $90, $100 and $125 in water, tissue and soil, respectively. Fees for multi-pesticide residue screens are generally $125, $150 and $175 in water, tissue and soil, respectively. Questions regarding pesticide injury or pesticide residue testing should be directed to Steven Gower by phone at 517-432-9693 or email at sgower@msu.edu.

New core manuals available

Carolyn Randall, PSEP Coordinator

Completely rewritten commercial and private certification core manuals are now available from Michigan State University (MSU) Extension.

The manual for private pesticide applicators (Extension Bulletin E3007) includes the National Pesticide Applicator Certification Core Manual and the Michigan Private Core Manual Addendum.

The commercial manual (Extension Bulletin E3008) consists of the National Pesticide Applicator Certification Core Manual and the Michigan Commercial Core Manual Addendum. 

Including the National Pesticide Applicator Certification Core Manual facilitates reciprocity between states, making it more likely that state regulatory agencies will recognize the credentials of certified applicators working in other states. The national core manual discusses federal pesticide laws and the Michigan-specific addendums add the state of Michigan pesticide laws and regulations. The private applicator addendum also includes private applicator equipment and calibration information.

The new manuals are better organized, illustrated, easier to read and more comprehensive than past editions. They also contain more recent information on regulations and pesticide safety recommendations.

These manuals are used to study for the initial and renewal certification exams offered by the Michigan Department of Agriculture. After passing the exams, an individual becomes a certified applicator and can purchase restricted-use pesticides. Applicators must renew their certification every three years by retaking the exams or by attending enough MDA-approved seminars to earn credits toward renewal.

Each manual is available for $30 from MSU Bulletin Distribution Center or any county MSU Extension office. To find an office near you, visit www.msue.msu.edu.

Regional reports

1 – Southwest

Mark Longstroth
Bill Shane

Weather

Last week’s temperatures were cool with highs in the 60s and lows near 40°F. Warmer temperatures finally arrived Sunday, May 25, with highs near 80°F Sunday and Monday. Monday morning lows were about 60°F. This was our first warm night of the season. Rain showers fell Monday morning. Rainfall totals were a tenth to a third of an inch with a wetting period of about six hours with temperatures around 60°F. Soils are beginning to dry out. We expect cool temperatures for the next couple of days and then back into the mid-70s by the weekend. There is a chance of frost Wednesday morning. There is a chance of rain this weekend. Our GDD totals are about ten days behind normal.

Southwest Michigan growing degree day totals March 1 through May 25				Grapes, from April 1
Location	GDD 42	GDD 45	GDD 50	GDD 50
SWMREC:	605	475	302	296
Lawton:	673	536	348	343
Fennville:	559	435	274	270

Tree fruit

Insect activity remained generally low last week. We are now in the treatment window for Oriental fruit moth. Codling moth biofix was set as May 26 for the stations that did not biofix before Monday. We expect codling moth egg hatch to occur at 250 GDD past biofix. Fresh plum curculio egg laying scars have been found. Leaf roller larvae are getting bigger.

Apricots fruits are about an inch in diameter.

Peach fruit are about 10 mm in diameter. The peach crop varies by variety, and generally looks lighter than last year. Now is the time to apply Oriental fruit moth controls. Oriental fruit moth was biofixed on May 4 at SWMREC. Treatment is timed for 200 GDD45 after biofix and with the warm temperatures Sunday and Monday, we reached that mark on Monday. Green peach aphids are curling peach leaves.

Sweet cherries are about 14 to 16 mm in diameter, and the pits are hard. Fresh plum curculio egg laying scars have been found. The rain event Monday was too short and cool for brown rot, but some areas were wet long enough for cherry leaf spot.

Tart cherries are 10 to 12 mm in diameter. The tart cherry crop looks pretty good. The crop is throughout the tree, not just on the outer shell. Fresh plum curculio egg laying scars were found in tart cherries also. Monday’s rain was a light cherry leaf spot infection period in some areas. Many growers applied protectant materials before the rain.

Japanese plums are about 12 to 14 mm. European plums are about 8 to 10 mm. Plum curculio egg laying scars were found in Japanese plums. Growers still need to protect against black knot before rains.

Apples still have scattered bloom. Fruit size is generally in the 8 to 12 mm range. Apple scab symptoms have been found in sprayed orchards. These are probably from the May 4 infection period. Monday’s rain was not an apple scab infection period, and it occurred at night so there was little spore discharge. We are nearing the end of primary scab season. Almost all the scab spores are mature and about 80 percent of the spores have been released. Scab protection will be necessary at least through the next rain event. Last week’s cool weather kept bacterial populations low until Monday when warm temperatures and rain precipitated a fire blight infection. Some growers with open bloom have applied controls Monday. No symptoms of systemic fireblight were visible in apples on Monday. We do not expect to see blossom blight symptoms for at least a week with the cool temperatures forecast.

Southern Berrien County biofixed for codling moth on May 14 at 278 GDD50, some other orchards in the region biofixed May 23 at 284. With the cool week and warm weekend, we are at about 70 and 40 GDD50 Tuesday, May 26. We expect most of the region to biofix Monday, May 26, during the warm evening. The application timing of control materials varies greatly (see the article on codling moth in this week’s Fruit CAT Alert. Spotted tentiform leafminer sap feeders should be out and will leaf mines soon. European red mites are moving about. Expect to see San Jose scale crawlers at 500 GDD50 soon.

Apple fruitlets are 8 to 12 mm in diameter, and we can now see initial fruit set. Some growers applied thinning spray during the weekend. The cool weather forecast means that we will not have another good apple thinning window until Thursday or Friday when the temperature will be in the 70s. A warming trend with temperatures climbing above 70°F for several days offers the best thinning windows. I am recommending a moderate thinning strategy, if set looks light or there are good size differences between fruits in the cluster. There are wide differences in fruit set between varieties and sites. Some blocks have a heavy set, and I recommend aggressive use of combination sprays of Sevin and either NAA (Naphthalenacetic acid) or BA (Benzladenine)

Pears fruit are 10 to 12 mm in diameter. The crop is variable. Pear psylla adults and nymphs can be found in unsprayed trees. Growers should continue to protect against pear scab.

Small fruit

Blueberry bloom continues. Bluecrop is past full bloom; Jersey and Elliot are at full bloom. Leaves are greening up with the warm weather. Cranberry fruitworm biofix was expected Sunday or Monday. Growers should scout for eggs in the calyx cup of fruit. Sprays of bee safe materials are planned when the weather warms up.

Grape growth varies widely. Many vineyards look pretty ragged. Concord and Niagara shoots fall into three distinct groups; 9-11 inches, 6-8 inches and secondary shoots of 4 inches from the base of primaries. There are also new shoots. Tertiary shoots and bud burst about an inch long. Most primary shoots have three clusters. Shoots in mechanically pruned vineyards with many shoots are shorter and generally only have two clusters. Secondary and tertiary shoots have four-inch long shoots with one or two flower clusters. Flower clusters on primary shoots are beginning to elongate. The conditions generally have been too cool for powdery mildew and downy mildew. Monday’s rain was marginal for black rot but was probably a good phomopsis infection. Phomopsis lesions have been reported at the base of this year’s shoots.

Strawberries are at past full bloom. Most of the primaries have thimble-sized fruit. Avoid using insecticides during bloom. Spittlebug is easy to find. Fungicides are applied at bloom to reduce gray mold, anthracnose, leaf spot diseases and leather rot.

Raspberry and blackberry flower bud clusters have emerged.

Cranberry buds are elongating. Growers may need to frost protect Wednesday morning. When the shoots begin active growth before bloom is time for a protectant fungicide spray to protect new foliar and reduce fruit rots.

Miscellaneous

The next Monday Fruit Update meeting will be Monday, June 2 at the Fruit Acres Farm in Berrien County.

2 – Southeast

Bob Tritten

Weather

With the exception of warm temperatures on Memorial Day, May 26, the weather over the last week has remained cool, thus continuing to slow the growth of our fruit crops. Our season is running about five to six days behind normal in terms of degree day totals and some pests, but just one to two days behind normal when I look at the typical phonology of our fruit crops.

Dry soils are a continuing concern at many fruit farms across the region. The southern tier of counties has seen moderate amounts of rainfall this spring, and some limited areas of the thumb had a nice set of rain showers last night. Dry soils are slowing the development of newly planted tree and small fruits. Rain showers over the last week have not resulted in any apple scab wetting events for any of our weather stations across the region. Many strawberry growers have had to frost protect one to two times over the last week, however most growers have been up several more nights checking temperatures as we were very close to frost events. Most strawberry growers have had to frost protect three or four times this season, and many report being up and ready to frost protect another four to six times.

Southeast Michigan growing degree day totals for March 1 to May 26
Location	GDD42	GDD45	GDD50
Commerce (Oakland)	612	481	305
Emmett (St Clair)	571	454	285
Flint (Genesee)	635	508	331
Lapeer (Lapeer)	622	496	326
Petersburg (Monroe)	666	527	341
Romeo (Macomb)	606	475	295

Tree fruits

Apples are mostly at 9 mm to 11 mm, with Red’s being 8 mm to 9 mm. Late this weekend and yesterday, many apple growers made their first thinning application to apples. We have a significant amount of new growth for the season with about 8-inches average. In the past week, it has become evident as to which fruit will be dropped and which will be remaining on the tree. It appears at this point in time that we have a nice crop of apples coming along; however thinning is going to be a bit difficult because in some blocks there is only side bloom left. There are some blocks, mostly on poor sites, that don’t have any crop at all.

Codling moth adult emergence began in earnest last week, with a few farms reaching biofix on May 22 and May 23. However, most farms had just a few moths in traps. I would expect after yesterday’s warm temperatures to see higher numbers, and to see whether or not they are fully into this first generation adult flight. I continue to see plum curculio and had the first reports of fruit stings this morning. Apple curculio was seen for the first time last week, I am only finding adults in trees with no fruit stinging. Mullein bug numbers have been high in a few blocks, and fairly easy to find in many others. Remember that mullein bug typically is a fruit feeding pest very early in the season and then quickly turns into a predator. Although this change over from fruit feeder to predator is difficult to pinpoint for certain, I feel we are most likely at that point in time right now. Oriental fruit moth trap catches are generally low or down across the region, however we still have a couple of farms that report high numbers. Late this week will begin control strategies for growers who biofixed in early May. There continues to be a number of larvae being seen in apples, with red-banded and obliquebanded leafroller being the most plentiful. Larvae in both of these cases is very large and doing a fair amount of leaf folding in some blocks. I am seeing lesser amounts of tree fruit leafroller, climbing cutworm, green fruit worm and eastern tent caterpillar. There continues to be a few tarnished plant bug in apples and other tree fruits, however their numbers are fairly low. San Jose scale females appear to be ready to release their young crawlers at any time, stay tuned for further details in next week’s report. Oyster shell scale crawlers continue to be seen where they are a problem. European red mites are heavy at just a few blocks, however the numbers are building. I am bit concerned about possible mite numbers in a year like this where we have had a distinct lack of rainfall. Fortunately, the cooler than normal temperatures have tended to suppress mite numbers and build ups. I am starting to see a few rust mites. I am seeing a good number of predators and several new ones this week as I move about in apples. Lacewings are most notable in the mix over the last week, and I continue to see thrips, velvet mites, solider bugs, rove beetles, chinch bugs and others.

Apple scab lesions have not been found, but I would expect to see some developing throughout the week. I continue to catch apple scab spores with each of these little rain events. With the dry weather this year, we may have an extended primary apple scab season. Time will only tell. We had an extended bloom period this year in apples, which was a bit unusual. We did not have any fireblight infection periods this year, so I think that we are pretty much out of the woods.

Pears are mostly at 11 mm to 13 mm in size. Pear psylla nymphs are being found in all stages from very young to those with mature wing pads. I continue to see a good number of adults at a few farms.

Peaches are at shuck split with fruit size of about 6 mm to 7 mm. Some blocks and varieties have heavy amounts of fruit, and others are very light. Green peach aphids continue to be seen in many blocks.

Sweet cherries are mostly at 14 mm to 16 mm in size, which is an excellent size for this time of year. Many varieties of cherries only have single fruit left, which would contribute to this large fruit size. I am starting to see some bacterial spot symptoms show up on foliage, as well as some two-spotted spider mites on the bottom centers of some sweet cherry trees.

Tart cherries are 9 mm to 11 mm in size. There has been a fair amount of drop over the last week. There continues to be a fair amount of winter damage showing up on the twigs of tart cherries.

Plums are mostly at 6 mm to 7 mm in size with a fair amount of fruit drop over the last week. We have a fair amount of variability of crop between blocks and varieties.

Small fruits

Strawberries are mostly at full bloom with a few thimble size fruit at many farms. I continue to see tarnished plant bug around the edges of fields, however they appear to be fairly light. I also am starting to see some two-spotted spider mites.

Raspberries are nearing first bloom on some of the early fruiting types, and fall red raspberries have about 12-inches of new growth. There are limited reports of orange rust disease on some varieties of summer fruiting raspberries.

Blueberries are at early petal fall for Blueray and full bloom on Jersey. A few mummyberry strikes have been seen at several farms, however they are scattered. Blueberry stem gall wasps continue to emerge from galls.

3 – Grand Rapids Area

Phil Schwallier
Amy Irish Brown
Carlos Garcia-Salazar

Weather

Degree day accumulations at the Sparta weather station are right at or slightly below average now, due to the cooler weather pattern the last couple of weeks. It’s been dry for the last two weeks with no significant rainfall since May 1.

Tree fruit

Most apples are in the full petal fall stage, but there is some bloom out there on one-year-old wood of some varieties. Early setting apples are gaining size and are at about 8 to 10 mm. Fruit set in apples appears to be strong, but we are still evaluating the need for thinning in many blocks. It looks like there will be a significant thinning window at the end of this week if temperatures increase. Try to leave check trees for your various thinning treatments to get a good idea of how they worked or didn’t work – it’s the best way to learn.

Our last apple scab infection for the greater Grand Rapids area was on May 14. Lesions from that infection could start to show up at any time. According to degree days for apple scab spore development, we should be at 100 percent spore maturity at the end of today. However, since we’ve had little rain, it might take a couple of decent rain events to discharge all the spores. Primary scab fungicide rates are still important to maintain for the next few rains and it’s a good time to do some careful scouting for primary scab before fungicide rates are reduced to summer-time rates. In the past, dry Mays sometimes have lead to late spore releases into June. Also, we sometimes see more problems with powdery mildew in years where apple scab is less of an issue because of reduced fungicide use for scab.

MaryBlyt was calling for high risk of infection for the holiday weekend if we got rain. The Sparta and Belding weather stations recorded 0.02-inch of rain Monday, May 26 in the morning, and fire blight blossom blight infections should have been covered for on any susceptible varieties with recently opened bloom on them – especially in problem blocks with a history of fire blight. Newly planted trees were also in bloom in some blocks and should have been covered up as well. The temperatures have cooled to where blossom blight should not be a problem for the next day or so, but the weekend is calling for more rain and higher temps, so you’ll have to pay attention to any remaining bloom that might be at risk for blossom blight infections over the coming weekend too.

A few egg laying scars from plum curculio have been observed in apples over the weekend, but damage doesn’t seem unusual at this time. Growers will want to continue to scout closely for any damage in small apple fruits.

European red mite eggs should have hatched. No new eggs have been seen yet, but could be reported at any time. Monitor mites closely to determine if early controls are needed.

Aphids are still very active. Both apple grain aphids and rosy apple aphids can still be found. Predators seem to be a little easier to find in aphid colonies over the past week. Green peach aphids can be found more readily than last week. A few black cherry aphids are being reported.

Codling moth flight has been reported in high pressure blocks for about two weeks now. The warmer weather over the holiday weekend has caused a push of codling moth flight in other blocks. A regional biofix has been set for the Grand Rapids area for May 24. We’ve collected 30 degree days base 50 since that biofix. It looks like base 50 degree days will be very slow to accumulate over the next few days, and we might hit 100 DD50 post biofix for egg material timings around June 1 or 2.

Oblique-banded leafroller larvae are getting large and should be pupating, so controls will probably give little help at this time.

Oriental fruit moth is flying, with numbers still sporadic in some locations. A regional biofix has been set on May 8. We have accumulated 160 degree days base 45 since that biofix so early egg hatch is probably underway, and it’s the time to apply control materials in stone fruits for early larvae.

Small fruit

As of May 27, most blueberry varieties north of Allegan County are in 50 percent to full bloom. Although some frost damage was reported in Van Buren County, so far no frost damage has been reported in the west central region. Because of the prevailing low temperatures during the past days, the growing degree day accumulation in Allegan and Ottawa counties has remained low with an accumulation of one to five GDD per day. Thus, up until now, the GDD accumulation varies from 386 in South Allegan to 298 in Ottawa County.

Regarding pest and disease problems, there a few cases of mummy berry shoot strike in Ottawa County. This has been observed in fields that had a problem with mummy berry during the past harvest season. Most growers already applied the second application against mummy berry and some are starting with the third application.

Insect pest activity has been low due to the prevailing low temperatures. However, cherry fruitworm moth activity continues in all counties at low intensity. Cranberry fruitworm has been reported only in the southern part of Van Buren County. The time of emergence of the first male moths in Van Buren County (380 GDD Base 50) coincided with the timing predicted by the newly developed CBFW Degree Day Model (375 ± 20 GDD). However, the moth emergence still is not considered as sustained moth catch, and at this time, no pest control action is needed against fruitworms.

So far, blueberries are in full harvest at Georgia, North Carolina and Florida. There are also blueberries from Guatemala and Mexico but in very small quantities. Prices for fresh blueberries in Chicago and Detroit terminal markets during May 21 and 26 remained at $14 to $16 for a 12 4.4 oz flat, while the 12 1-pt cups with lid was sold for $26 to $28.

4 – West Central

Mira Danilovich

Weather and crop development

The weather conditions were cooler than normal. Generally, the temperatures were in the 60s for highs and in the 30s and 40s for lows until Saturday, May 24. From Saturday on, we finally had temperatures that would be considered normal for this time of the year with highs in the 70s and lows in the 50s. The rain that was predicted for Sunday night and Monday skipped over Oceana and Mason counties and just touched Manistee dropping only 0.01-inch of precipitation. The whole area is getting quite dry. For the whole month of May, we have received less than 0.5-inch in Oceana County, less than an 1.0 inch in Mason County and only 1.8-inch in the Manistee and Bear Lake area. These amounts are from one to two inches below normal for the month.

Tree fruit

Apples are in petal fall with some rag-tale bloom in Idared, Honeycrisp, McIntosh, Jonagold, Jonathan and a few others.

Pears are showing fruit swell, though there are still a few open blooms.

Sweet cherries are out of shuck with the fruit from 8-12.5 mm.

Tart cherries are in shuck with less than five percent starting to break through.

Plums are in the shuck.

Peaches are in shuck showing early fruit swell.

West Central Michigan growing degree day totals from March 1

Location	DD42	DD45	DD50	Rainfall in Last week	Rainfall since 4/1
Hart	504	389	239	0.01	4.35
Ludington	484	373	226	0.03	4.89
Manistee	510	398	252	0.05	5.39

The wetting event earlier in the week did not last long enough to cause an apple scab infection. We did have spore release of 14 spores per rod. The apple scab maturation model shows that we have 90 percent mature spores. It will take a few more rain events to flush them all out. It is important to keep the blocks covered until we are out of primary. First scab lesions were found in abandoned and, a few commercial orchards from the infection on May 1-2.

The rain events at the beginning of the week did not present any threat for a fireblight infection in apples and pears due to the cold temperatures. Manistee and Bear Lake area had some light rain yesterday that resulted in high potential for infection but the EIP numbers (87) never reached the threshold (100).

There have been no cherry leaf spot infection periods this week.

For the most of the week the insect activity has been quite low. Over the weekend that trend was reversed. Codling moth has been very active in the last two to three days. Trap catches have been significant with the reports of five to over 60 moths per trap. The regional biofix was set for Saturday, May 24. Growing degree day accumulation on that day was 229 for Hart, 217 for Ludington and 242 for Manistee/Bear Lake area. Scouts are reporting an increase in American plum borer trap catches. It appears that they are approaching peak emergence. There has been a report of a first catch of lesser peachtree borer. Greater peachtree borer larvae have been actively feeding on the trunks of peaches, cherries and increasingly on Balatons. It is important to check trees showing signs of distress (lacking in development, slow to leaf out, smaller leaves, generally “wilted” look, etc.) around the base of the trunk well below the soil line (two to three inches) looking for tan-colored, approximately one-inch long worms that would be feeding on the wood. They become active as soon as the soil temperature reaches 50°F. Their presence necessitates trunk spray application. With the warmer temperatures over the weekend, there have been an increased number of European red mites and two spotted mites throughout the area. Scouts are reporting finding green fruit worm larvae, obliquebanded leafroller larvae, and some green peach and rosy apple aphids throughout the area.

5 – Northwest

Nikki Rothwell
Duke Elsner, Erin Lizotte, Rob Sirrine

Growing degree day accumulations at NWMHRS

GDD42 476

GDD50 217

Growth stages at NWMHRS from May 27 at 8:00 AM.

Apples are at early petal fall.

Bartlett pears are at petal fall.

Sweet cherries: Hedelfingen have 8 mm fruit. Napoleon have 9 mm fruit. Gold are in shuck split.

Tart cherries: Montmorency and Balaton are in shuck.

Apricots have 11 mm fruit.

Plums are in shuck.

Grapes have one to three inch shoots.

Weather

We finally had a taste of spring, even summer, over the holiday weekend. However, temperatures cooled down again last evening where we dropped from 77°F at 5:00PM down to approximately 40°F four hours later. There are predicted freezing temperatures for tonight, May 27. Prior to the weekend, our temperatures were still cool, and we received 0.31-inches of rain on May 23. For growing degree days, we are at 476 base 42 (643 base 42 in 2007) and 217 GDD base 50 (323 base 50 in 2007).

Crop report

Balaton and Montmorency cherries are at petal fall, and most sweet cherry varieties are at shuck split here at the NWMHRS. Apples are in bloom in most regions of the northwest, all at varying degrees depending on variety. Here at the NWMHRS, McIntosh and Galas are at early petal fall. If growers intend to apply Apogee, the first application needs to go on at king bloom petal fall. Apricots are at 11 mm fruit, and plums are in late petal fall. Strawberries are in bloom.

Plum curculio are out and stings are showing up on native hosts in the region. Sweet cherries are vulnerable and should be the main concern this early in the season. We continue to catch American plum borer and green fruitworm larvae in tart orchards. Only one weather station in Northport is reporting a high infection potential for both cherry leaf spot and apple scab. The fire blight model EIP is ranging from 41 to 83 throughout the northwest, but the forecast calls for temperatures to dip below freezing on Tuesday night and Wednesday morning, effectively restarting the EIP accumulation at zero.

Weather news

Jeff Andresen
Agricultural Meteorology
Geography

A strong area of high pressure across southern Manitoba on the morning of Tuesday, May 27, will drift slowly south and eastward across the Great Lakes region during the next few days, leading to a fair and cool weather pattern for Michigan. Given cold temperatures aloft, low dew point temperatures, mostly clear skies, and calm winds, frost and freezing temperatures will be a possibility overnight Tuesday night and Wednesday morning. The greatest threat for sub-freezing temperatures will be across inland sections of upper and northern Lower Michigan, where readings are expected to dip into the upper 20s and low 30s. Low temperatures in northern lakeshore areas and southern sections of the state should remain a few degrees warmer in the low to mid-30s. Some scattered light fronts will be possible once again on Thursday morning, although areal coverage should be much less than on Wednesday morning. Fair and cool weather is expected Thursday, followed by increasing clouds and warmer temperatures on Friday, as an area of low pressure approaches from the west. Showers and thunderstorms are a good bet overnight Friday and Saturday as the system moves through the state.

At this point, widespread rainfall is expected, especially across central and southern sections of the state. The latest model-generated precipitation forecasts suggest totals in the 0.5-1.00-inch range through Saturday evening across almost all of Lower Michigan. Temperatures during the next few days will gradually warm from highs in the upper 50s north to mid-60s south Wednesday, to the upper 60s north to mid-70s south by Friday. Lows will increase from the 30s to low 40s Thursday morning to the low or mid-50s by Saturday. Following the passage of the low pressure area Saturday, fair weather with seasonable temperatures is expected in most areas of the state Sunday through next Tuesday.

In the medium‑range forecast period, a broad upper air ridge is expected to persist across central sections of the United States with troughs on both west and east coasts. The National Weather Service 6‑10 day outlook covering June 1 through June 5 calls for an active weather pattern with below normal temperatures and above normal precipitation totals across Michigan and the Great Lakes region. The 8-14 day outlook for June 3 through June 9 calls for some moderation with near normal temperatures and precipitation totals expected.

NOAA long lead outlooks

In our discussion of the new long lead outlooks, it is worth taking note of the recent series of tornadoes and severe weather across the Midwest and other sections of the country. As of May 23, NOAA=s Storm Prediction Center had tallied 930 tornadoes across the United States so far this year, which is more than 400 above normal for the date. Given at least 50 more tornadoes during the past holiday weekend, approaching the normal annual total of 1270. If this unusual frequency and pace of accumulation were to continue throughout the entire 2008 severe weather season into the fall, which is very unlikely, this year=s total would easily shatter the all time record of 1424 tornadoes set in 1998. Causes of the unusually active season are not completely clear at this point. One important issue was the abnormally early start of the severe weather season in January across sections of the south. Another is the presence of a La Niña event in the equatorial Pacific, which in turn was linked with an abnormally active jet stream storm track from the southwestern United States into the Midwest, and to record heavy seasonal snowfall totals in portions of the upper Midwest. Tornado outbreaks in the central United States are typically linked with an upper air trough in the western United States and a ridge across the east, a strong southwesterly jet stream, and to a warm and humid air mass (Gulf of Mexico origin) on the surface. These key ingredients have unfortunately been present together much more frequently than usual so far this year.

Looking further ahead, La Niña conditions in the Pacific are expected to gradually diminish by mid-or late summer, which is reflected in the new NOAA long lead outlooks. For June, the outlook is linked to recent weather patterns and to medium-range forecast guidance suggesting cooler and wetter than normal weather for nearly all of Michigan and other adjacent sections of the Great Lakes region. For the 3-month June through August period, the outlook for mean temperatures and precipitation totals remains in the climatology scenario of near equal odds of below-, near- and above normal levels. The outlook generally calls for Michigan to remain between areas of cooler and wetter than normal weather across southern sections of the country and warmer and drier than normal to our west (see http://ipm.msu.edu/cat08fruit/pdf/5-27weather.pdf). Finally, this type of pattern also suggests a gradual decrease in the frequency of severe weather over central sections of the country.