May 8, 2007

In this issue

Tree fruit news

§      Early season codling moth management decision-making

§      Vegetative growth control on crop loss apple tree

Small fruit news

§      Monitor for mummy berry in blueberries

§      Prowl H2O and Outlook labeled for strawberries

Other news

§      Control options for mites in fruit crops

§      TNRC trapline data: Green fruitworm

§      Regional reports

§      Weather news

Early season codling moth management decision-making

Larry Gut, John Wise and David Epstein
Entomology

Putting together a sound codling moth pest management program requires that the user understand how the various options at their disposal work (mode of action), what life stage each is active on, when is 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.

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)

1st sustained moth captures

Set DD° = 0

100 DD°

Start of 1st generation egg laying

Timing for 1st treatment for egg targeted materials

250 DD°

Start of 1st generation egg hatch

Timing for 1st treatment if over threshold (for larva targeted materials)

1000 DD°

Expected end of 1st generation activity

 

1200-1250 DD°

Start of 2nd generation egg hatch

Timing for 1st treatment if over threshold (for larva targeted materials)

2100 DD°

Expected end of 2nd generation activity

 

 

Targeting the adult life stage 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. Our experience, and that of many Michigan growers, is that programs combining the use of mating disruption and insecticides as needed provide better control than insecticide-only programs.

Michigan apple growers treated over 5,000 acres with codling moth pheromone in 2006 and we estimate have surpassed this usage in 2007. Areawide, or whole-farm codling moth disruption, projects are now on-going in Kent, Ottawa, Van Buren, Berrien and Grand Traverse counties. The areawide, or whole-farm, approach deploys mating disruption over large, contiguous plantings, rather than in small plots surrounded by other orchards. This tactic makes it more difficult for male moths to move to pheromone-free air and locate mates, while minimizing the movement of mated females from orchards not treated with pheromone into the pheromone treated blocks. The results of a Michigan codling moth areawide project initiated in 2004 have been very positive and quite encouraging for the participating growers. On the original eight farms in Kent County, codling moth catch decreased by 74 percent from 2004-2006. Orchards within the project saw an overall 70 percent reduction in fruit injury from start to finish and 96 percent less injured fruit in comparison to non-disrupted orchards. Growers also were rewarded with a reduction in the overall number of insecticide applications needed to achieve codling moth control. The overall number of pesticide applications on areawide farms deploying pheromone disruption for three years declined from 10.1 to 6.3.

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 75-150 GDD. At this timing, Rimon will provide good to excellent control of Oriental fruit moth (OFM), obliquebanded leafroller (OBLR) and spotted tentiform leafminer (STLM), while Esteem will be highly active on rosy apple aphid (RAA) and San Jose scale (SJS).

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 codling moth 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 codling moth 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 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. Thus, the best results have generally been achieved when the first application is made just prior to the start of egg hatch (ca. biofix plus 200-250 GDD). Assail 30SG 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 (PC), OFM and STLM.

Clutch, a new neonicotinoid registered for use in pome fruits, is a broad-spectrum material targeting codling moth as well as aphids, leafhoppers, PC, STLM, OFM and pear psylla. Research trials have indicated that Clutch is not as effective as Assail or Calypso, especially for second generation codling moth control. 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 control of first generation codling moth in trials at the Trevor Nichols Research Complex and on-farm in 2006. Last season the label only claimed suppression of codling moth, but for the 2007 season control of first generation larvae is supported on the label. Proclaim has very good activity against OBLR.

Intrepid is an insect growth regulator that provides good control of codling moth with a residual action of about 10-14d. This product is an insect growth regulator that primarily affects codling moth larvae, but also has some activity on eggs, and has sublethal effects on adults. Taking advantage of the sublethal effects and applying the first spray at biofix plus 150-200 GDD have achieved the best results. At this timing, Intrepid will also control OBLR 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 CM

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*

Assail, Calypso, Clutch

Neonicotinoid

Eggs, Larvae,

Adults (limited)

Biofix + 200-250 DD

Residue over eggs

M*

Intrepid

IGR (MAC)

Eggs, Larvae,

Adults (sublethal)

Biofix + 150-200 DD

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 codling moth 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 codling moth 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 4 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

Taking the lead from colleagues in Washington State, we have been evaluating a program that combines the very different modes of action of Rimon and Calypso or Assail, to allow for an extended interval between sprays without losing efficacy. Rimon applied at around 100 DD kills eggs that would have hatched in the period starting at 250 DD allowing growers an opportunity to delay the first larvicide application until 350-400 DD. One of the nice features of this program is that the delayed application of the neonicotinoid 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, about 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. In a trial at TNRC in 2006, codling moth control using a Rimon and a delayed Calypso or Assail application (two sprays) was equivalent to programs that required three insecticide sprays per generation.

 

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

                          Primary pests                                      Secondary pests

Insecticide      CM         OFM       OBLR    PC          AM         STLM    GAA       RAA       WALH   SJS       

 


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

 

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

 

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

 

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

 

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

 

Proclaim           **           **           ***                                         ***                        

 

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

 

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

Assail

 

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

 

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

Imidan

 

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


CM-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

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

Vegetative growth control on crop loss apple trees

Philip Schwallier
Clarksville Horticultural Experiment Station

In those years when the crop is lost due to freeze or frost, Apogee and Ethrel can be used to reduce growth. Apogee is an effective vegetative growth control material. It must be applied in water with a buffering agent and a surfactant. It is not compatible with some materials such as calcium fertilizer. The full seasonal rate is 12 oz/100 (48 oz/acre on full size trees). It is mostly used on full bearing cropping trees at 2/3 the full rate and adjusted for TRV (Tree Row Volume) size trees. Ethrel can reduce vegetative growth and will increase return bloom. It is applied at 5, 7, and 9 weeks after full bloom at 1 pt/acre. Unfortunately, bearing apple trees that have lost their crop will generally come back with an abundant bloom and don’t need the Ethrel enhancing bloom effect.

To help control the excessive vegetative growth that occurs after crop loss consider applying Apogee split into four sprays at near full seasonal rate. For example, on 75% TRV size trees, the full seasonal rate would be 36 oz/acre split into four sprays (12 + 8 + 8 + 8, 1st spray at 12 oz/acre, then followed by 8 oz/acre, etc.). These sprays would be applied starting at petal fall with the first spray and applied every two weeks. Growers have found that lower seasonal rates will work fine at 24 to 30 oz/acre (example: 8 + 6 + 6 + 6). Ethrel can be added to the lower rates at 1 pt/acre with the third and forth spray. This will provide additional vegetative control. On 75%TRV trees, the following program will provide good vegetative control, but also increase return bloom. The first spray should be applied at KBPF of 8 to 12 oz/acre of Apogee, second spray two weeks later of 6 to 8 oz/acre Apogee, third spray two weeks later of 6 to 8 oz/acre Apogee + 1 pt/acre Ethrel, and the fourth spray two weeks later the same as the third.

If temperatures are above 85oF, do not apply the Ethrel – wait for cooler conditions. Apples on lightly cropped trees will be advanced in maturity. Ethrel will also hasten apple maturity of any fruit on the trees. It is often the early season varieties that are most affected (varieties that ripen before Empire). If that is not desired, do not treat with Ethrel.

Monitor for mummy berry in blueberries

Annemiek Schilder
Plant Pathology

What to look for

It’s mummy berry season again. The mummy berry fungus enjoyed the snow cover this winter, which provided sufficient moisture for many mummies to germinate this year. In some sites at least 30 percent of the mummies were found to have the trumpet-like mushrooms, also called apothecia. Germination also started relatively early this year. In fact, some cups had opened before there was any green tissue showing on the bushes (in which case infection could not have taken place). If cool, wet conditions return, there may be more waves of germinating mummies ahead. However, if it turns warm and dry, this may be it for the season.

Blueberry growers should be monitoring for mummies with trumpet-shaped mushrooms (see pictures). Mummy berry occurs primarily at wetter sites and in poorly drained areas; therefore scouting should target those sites. Dry, sandy sites may not have any mummies at all. The mummy berry fungus shoots ascospores out of the cup as soon as the cup opening is about 1/8 inch wide. Ascospore release continues until the cup collapses. Longevity of the mushrooms is affected by temperature, e.g., at 70şF, the mushrooms may live for less than a week, whereas at 50şF, they can last two to three weeks, and at 40şF up to four weeks. At higher temperatures, the mushrooms expand more quickly (they can almost become dime-sized) and release more spores per day than at lower temperatures. A severe freeze may damage the cups, but evidence shows that they can partially recover their ability to shoot ascospores after exposure to temperatures of 22şF and above. The ascospores are windborne and can travel fairly long distances (up to a mile). So even if you don’t have any mummy berry in your field, there is a chance that ascospores drift in from other fields or nearby woods with wild or escaped blueberries.

Stages of infection

There are two stages of infection. First the developing shoots are infected by the ascopores from the mummy berry cups. Shoot strike symptoms appear approximately two weeks after infection. Shoots are susceptible from bud break until they are about 2 inches in length. Sometimes flower clusters may also become blighted; these are called flower strikes. Both shoot and flower strikes are characterized by drooping/wilting symptoms and a layer of gray spores (conidia) on the surface. These conidia are spread by insects (primarily bees), wind and rain. Bees are attracted to the shoot and flower strikes due to their UV light pattern (a nifty trick of the pathogen) and pick up the conidia on their legs and bodies. Bees then inadvertently deliver the conidia to the flowers where infection takes place. The conidia infect the flower stigma followed by colonization of the developing fruit, which eventually mummifies and drops to the ground. Flowers are susceptible for about four days after they open. The more shoot strikes there are and the better the weather for pollination, the greater the risk of flower and fruit infection. Cultivars such as Berkeley, Bluetta, Blueray, Earliblue, Jersey, Nelson, Patriot and Weymouth are susceptible whereas Bluecrop, Duke and Elliott are moderately resistant to the disease. Some cultivars are more susceptible to shoot strikes and less susceptible to fruit infection, whereas others are just the opposite.

Control

While there are multiple fungicides registered for mummy berry control, Indar consistently has outperformed other fungicides for both the primary and secondary phases of the disease in Michigan. Indar is a sterol inhibitor fungicide and therefore prone to resistance development in target fungi. It is recommended to limit the number of sprays of Indar to two or three per season (five are allowed per the label) and alternate with fungicides in other chemical classes. Options are Bravo (fair to moderate efficacy), Captevate (moderate to good efficacy) Topsin M + Captan or Ziram (moderate efficacy) and Serenade (good efficacy).

Systemic fungicides such as Indar and Topsin will likely provide better coverage of the flower parts (the stigma specifically). Cabrio and Abound have shown poor to fair efficacy in past trials in Michigan. While Pristine did not perform particularly well for control of mummy berry shoot strikes in trials in Michigan, it improved when sprayed for control of fruit infection. We suspect that the activity of Pristine is better at higher temperatures; it therefore may be a decent option during bloom as it also controls anthracnose, Botrytis and Phomopsis twig blight and canker. Orbit (propiconazole), which is in the same chemical class as Indar, now has a supplemental label for blueberries also. It also has a 30-day PHI. In small plot trials in Michigan, we found that Orbit was similar to Indar in the control of shoot strikes, but did not perform as well as Indar for control of fruit infection.

Prowl H2O and Outlook labeled for strawberries

Bernard Zandstra
Horticulture

Prowl H2O was recently labeled for use on carrots, peppers, tomatoes and strawberries. The labels are supplemental labels, which expire at the end of 2008. Hopefully, they will be incorporated into the Section 3 label before that date, and become part of the permanent label.

For strawberries, apply 1.5-3 pt of Prowl H2O to the soil surface before transplanting. A second application may be made as a directed spray between rows. Do not exceed 3 pt per application and 6 pt per acre per year. Observe a 35 day PHI. Prowl H2O may cause stunting in strawberry plants, so avoid contact with the plants. The label does not include application on established strawberry.

Control options for mites in fruit crops

John Wise, Rufus Isaacs and Larry Gut
MSU Trevor Nichols Research Complex

Mites can be significant pests of fruit crops. There is an array of miticides available for control of the European red mite (ERM), two-spotted spider mite (TSSM) and rust mites (RM) (apple and pear rust mites, pear blister mite, plum nursery mite, blueberry bud mite), but their performance characteristics are not all alike. The accompanying table is designed to summarize several key variables that can help you determine which miticides are optimal for your integrated pest management program. View pdf of the chart here.

Regional reports

1 – Southwest Michigan

Mark Longstroth, Bill Shane, Greg Vlaming

Weather

Last week was windy. It was pleasant with lows in the mid 40s and highs in the upper 60s and 70s. Cool dry windy conditions have dried the soils. This week’s forecast is for warm weather with lows in the 50s and highs in the 70s. Thunderstorms are possible for the rest of the week. Any rain over the next few days could result in a fire blight infection. Cooler temperatures are forecast for the weekend.

 

Southwest Michigan Growing Degree Days (GDD) Totals
March 1 through May 6, 2007

Grapes from April 1

Location

GDD 42

GDD 45

GDD 50

GDD 50

SWMREC

533

423

276

188

Lawton

600

487

329

209

Fennville

460

358

226

166

 

Tree fruit

Plants are leafing out rapidly and insects are active. As stone fruit emerge from the shuck , growers should scout for plum curculio.

Peaches are near shuck split. The peach crop looks better and better. Large numbers of Oriental fruit moth adults are still being caught in pheromone traps. Biofix was Saturday, April 21 at 230 GDD at SWMREC. Pesticide sprays are targeted for egg hatch at 200 GDD base 45 after Biofix; which was Saturday. The first generation of tarnished plant bug adults are in the trees.

Tart cherries are in the shuck. There is still late bloom opening and most of these flowers look good. Overall the crop looks light, but is very variable across the region, with some growers reporting a good crop. With fruit approaching shuck split, we are near the end of the application window for Chlorothanil. Copper is an effective cherry leaf spot material.

Sweet cherries are in the shuck. Early varieties and those on dwarfing rootstocks are emerging from the shuck. Some growers report a good crop of cherries. Sweet cherries should be protected from brown rot from bloom until harvest and the possibility of warm wet rains exist this week. Copper should not be used on sweet cherries. .

Plums are in the shuck. Growers should be protecting against black knot and brown rot.

Apples are blooming. Early blooming varieties are in petal fall but Winesap and Rome are in full bloom. Thunderstorms this week will likely cause fire blight blossom infections of open flowers. We are updating our Code-A-Phones daily with fire blight conditions. The quality of bloom varies quite a bit and growers should assess their crop in preparation for thinning sprays next week. Apple scab symptoms should appear this week from the April 26 infection. Now is the time to apply Apogee sprays to reduce fire blight and vegetative growth. Growers can also check for apple scab and fire blight at the Enviroweather website. http://www.enviroweather.msu.edu/. Oriental fruit moth is being caught in good numbers in pheromone traps. Biofix was Saturday, April 21 at 230 GDD at SWMREC. Codling moths were trapped on Saturday, May 5 in some locations. Obilquebanded leafroller larvae are feeding in shoot tips. European red mites are out and growers should be scouting for aphids.

Pears are at petal fall. Very little bloom remains, but growers should protect against fire blight. Pear scab is similar to apple scab and pear scab symptoms should appear this week as with apple scab.

Small fruit

Blueberries are blooming. Mummyberry shoot strikes are appearing from the April 25-26 infection period. Growers should check the new Blueberry IPM Newsletter at the MSU Blueberry Site. Both cranberry and cherry fruitworms were reported caught in pheromone traps. Obilquebanded leafroller larvae are feeding on fruit buds.

In grapes, Concord shoots are about 3 to 4 inches long with several leaves out. Vinifera grapes are from leaves opening to late swell. Growers have been applying early season disease control materials. This first fungicide spray is especially important for phomopsis control. Growers should apply protectants before the next rain. Be sure and check the MSU Grape website for scouting updates.

Strawberries are at first bloom. Many plantings look rough and growers have been fertilizing and irrigating.

Summer raspberry flower buds are visible in some varieties. Some varieties were severely affected by winter cold snap (i.e. Prelude). Fall raspberry shoots are about 6 inches high. Blackberries were severely damaged by winter cold (early February) and the Easter freeze. Advanced shoots were damaged or killed, but new growth is emerging.

Cranberry buds are beginning to swell.

Miscellaneous

Soils are dry and growers should irrigate if they can. Some fruit plantings from last year look stressed this may be a result of the winter cold snaps. Herbicides applied to dry soils or drought stressed weeds are less effective.

The next Monday Fruit Update meeting will be Monday May 14, at 5 pm, at the Fruit Acres Farm in Berrien County. We will discuss apple thinning. The next Grape IPM meeting is Thursday, May 24. The morning meeting will be from 10 AM to noon at the Cronenwett Farm Shop at 70123 28th Street east of Lawton. The afternoon meeting will be at 2 PM in the Berrien County MSU Extension Office at the Southwest Michigan Research & Extension Center. These meeting are co-sponsored by National Grape Cooperative and MSU Extension and are open to all grape growers. There are RUP credits available for both the Monday Fruit Updates and the Grape IPM meetings.

2 – Southeast

Bob Tritten

Weather

Our season has progressed along quite nicely over the last week, even catching up a bit. It is running just a few days ahead of normal in terms of degree days, and in terms of phenology (or flowering stages), we are also about back to normal. Most of the northern parts of the region received about a half inch of rainfall over the last week, which resulted in an apple scab wetting period.

 

Southeast Michigan growing degree day totals for March 1 to March 21.

Location

GDD42

GDD45

GDD50

Commerce (Oakland)

444

336

202

Emmett (St Clair)

388

291

172

Flint (Genesee)

433

331

203

Lapeer (Lapeer)

428

325

199

Petersburg (Monroe)

495

383

240

Romeo (Macomb)

419

322

196

Tree fruit

Apples are at early petal fall in the south for a few varieties, and full bloom in Ann Arbor and to the north. We also have 1 to 2 inches of new terminal growth over the last week. An astute fruit grower noted last week that our phenology of flowering and leaf growth are not quite in-sync this year. We have had earlier and more abundant leaf growth than normal for this stage of flowering. This may result in a bit of a different thinning strategy down the road, but time will tell. Oriental fruit moth flight continues across the region, with many growers having trap catches in the range of 4 to 5 per trap. Codling moth trap catch is expected at any time now. Redbanded leafroller trap catch is lower this week, however, no larvae have been seen. Spotted tentiform leafminer trap catches have remained low over the entire spring, indicating a much lower than normal population base this year. European red mite egg hatch occurred last week, however, European red mite eggs are hard to find in apples this year as their numbers are low. Rosy apple aphid and apple grain aphid were found for the first time mid-last week. We are also starting to see a few woolly apple aphids beginning to move a bit. There are a number of larvae being seen, including tufted apple bud moth, oblique banded leafroller, green fruit worm, and Eastern tent caterpillar. All of these numbers are very low at this time.

Many fruit growers had an apple scab wetting event last Tuesday, most reporting a high infection. We continue to see spore release with each rain event, however, no lesions have been seen as of yet. I would expect to see lesions from last week’s infection to begin to be visible late this week or over the weekend. With apples in bloom, fireblight becomes a major concern. Several of the models are showing a high EIP index for the rest of the week, indicating that if we get a rain event that the first applications of a bactericide will be going on to control fireblight.

Pears are at full bloom with a nice crop of pears coming this season. Pear psylla egg hatch continues to be seen over the last week.

Peaches are mostly at early petal fall where they have a crop of peaches. Bloom was abundant at a few farms, however many farms report little to no peach crop this year. We are seeing some European red mites in peaches, more so than in apples this season. I am beginning to detect a bit of bacterial spot on foliage of peaches. Peach pruning is now underway at many farms.

Sweet cherries are mostly at petal fall. The crop appears to be thin at this time. Many of the blossoms damaged during the Easter freeze event have dropped to the ground.

Tart cherries are at early petal fall to late bloom. There is quite a bit of scattered bloom being seen in tart cherries this year. There is a fair amount of dead wood starting to show up in many blocks of tart cherries.

Plums are mostly at petal fall. I have not seen any plum curculio egg laying damage in any tree fruits.

Small fruit

Strawberries look much better than they did last week at this time. The flower trusses have emerged from the crowns. I have not seen any strawberry clipper or tarnished plant bugs. There has been a fair amount of volunteer wheat germinated at many farms over the last week to 10 days.

Raspberries have about 1 inch of new short growth for summer red raspberries, with the flower buds just starting to become visible. Fall red raspberries are at about 4 to 6 inches of new growth.

Blueberries are nearing bloom in early varieties. I expect to see some open bloom in the next day or so. Blueberries don’t seem to have much of leaf growth, which is a bit unusual. Many of the early leaves were damaged during the Easter freeze event.

Grapes are at bud break to early short growth.

3 – Grand Rapids Area

Phil Schwallier
Amy Irish Brown
Carlos Garcia-Salazar

Tree fruit

Growth over the last week has continued to be at a normal pace for all tree fruit crops. Apples are mostly at full bloom with some late varieties still at pink, but there isn’t much differentiation in bloom stages of the different apple varieties at this time. Where you notice the difference is from the top of the hill to the bottoms, not so much with the varieties. There seems to be more green shoot growth this year in apples than normal. Bee activity has been really great the past couple of days despite some rather windy conditions. Sweet cherry bloom is ending. There is some bloom in late peaches, but most are past blooming.

As we move through bloom, freeze damage to apples still doesn’t appear to be extensive. There are some trees that have poor return bloom, but that is most likely due to a heavy crop in 2006 and not due to winter cold. Overall, the apple crop from the Grand Rapids area still appears to be at a full crop potential.

Apple scab should be near 80 percent of spore maturity now and the next few rains should give us some rather high spore discharges, since it’s been a week or more with no rain in the area. No lesions from the April 1 rains have been found. Lesions from the infection in late April should begin to show up at anytime.

With the rather warm weather, growers will need to think about adding a mildewcide in the tank for powdery mildew in the next week or so for those varieties that are susceptible to it.

The first few adults of oriental fruit moth were caught in the Grand Rapids area late last week, but flight has not been widespread yet, so a biofix has not been set.

Apple grain aphid can be found a little easier than last week, but they are still in relatively low numbers for this time of year. Rosy apple aphids are being found as individuals in low to normal numbers in commercial apple blocks. Green fruitworm larvae can be found. European red mites are beginning to hatch more uniformly across the region now – hatch in known hot spots began about two weeks ago. Spotted tentiform leafminer adults are flying and sap feeders will most likely be present by the end of next week. No codling moth trap catch reported yet, but it could begin soon in high pressure blocks and known early emergence sites. Plum curculio will most likely be very active with the warmer that usual nighttime temperatures – watch for their activity in early fruited tree species like plum, cherry and peaches.

Small fruit

Blueberries in west central Michigan are entering the bloom period, and at this moment early varieties are at 25 percent bloom and late season varieties are in the late pink stage. So far, the bloom period has proceeded without problems. As of May 8, growing degree days (GDD, base 50°F) accumulation in west central Michigan is around 215 ± 10 with an average daily accumulation of 7 GDD. Cumulated rainfall for the last seven days ranges from 0.25 to 0.30 inches.

At this time, fruitworm activity is none existent, but traps for cherry fruit worm (CFW) and cranberry fruit worm (CBFW) should be out. It is possible that we may see some CFW activity very soon triggered by the warm weather occurring during the last five days.

Once the traps are installed, it is critical to monitor them twice a week to be able to detect the beginning of the moth flight and to time our pest scouting activities. Typically, CFW moths emerge one or two weeks earlier than CBFW adults. However, because the size of the fruit is not suitable yet for fruitworm oviposition and larval development, no pest control actions are recommended specifically against the CFW before petal fall. Regarding, the cranberry fruitworm, in the past we have observed that CBFW eggs appeared 120-130 GDD (base 50°F) after the beginning of the moth flight. Therefore, if we are using GDD to predict fruit worm activity detection, the beginning of moth flight is critical.

4 – West Central

Mira Danilovich

Weather and crop development

Over the last week, the weather was nice and warm. There was only one wetting period that occurred at the beginning of the week (May,1) that brought various amounts of rainfall ranging from 0.28” (Manistee) to 1.11” (Hart). Crop continues to develop rapidly.

Pollination conditions have been excellent, particularly in the morning hours before the wind would develop. The wind was quite strong in the mid-day to afternoon hours.

Apples are in various stages from full pink (most varieties) to full king bloom with some sides starting to opening up (Idareds and other early blooming varieties).

Pears are in full bloom with signs of early petal fall.

Peaches are in petal fall.

Plums are in full bloom to early petal fall.

Tart cherries are in full bloom.

Sweet cherries are in petal fall.

These phonological stages are true for the central areas of the district. Blocks closer to the lakeshore and further north are delayed in their development for a few days.

West Central Michigan growing degree day totals – March 1 to May 6.

Location

GDD42

GDD45

GDD50

Rainfall last week

Rainfall since 4/1

Hart

378

303

175

0

3.63

Ludington

 368

280

168

1.01

3.59

Manistee

 364

279

169

0.28

2.56

Tree fruit

With blooms present on the apple trees, there is an elevated danger of fireblight/blossom blight infections. Once we add wetting component into the Maryblyt model, prediction is that there is high risk of infection for the next two to three days requiring spray applications. Dr. George Sundin and his group have discovered Streptomycin-resistance in the area, particularly in Oceana County in apples and pears. Under the circumstances, the first step in protection strategies was spraying with copper early in a season. Bloom spray-strategies necessitate a combination of Streptomycin and Mycoshield at full rate in order to optimize suppression of bacteria. In cases with low to moderate disease pressure, Serenade might be used. In all situations, use of Apogee is recommended for suppression of the new shoot growth and development of the shoot blight.

A wetting event early in the week did result in high apple scab infection in Ludington and moderate infection period in Manistee/Bear Lake areas. There was heavy scab spore discharge. Rain forecasted for the reminder of the week is likely to be an infection event.

The last wetting event of May 1-2 produced a moderate cherry leaf spot infection in Ludington and a low infection in the Manistee/Bear Lake area. The Hart area had low infection as a result of rainfall on April 30- May 1. There is heavy inoculum presence in many blocks throughout the area. Aggressive protection approach is recommended.

Other stone fruit is susceptible to leaf spot infections under favorable weather conditions and should be protected. Some of the spray options include, but are not limited to, Elevate, Bravo, Rovral, Vangard, Orbit, Pristine, Captan and Topsin-M.

First reports of oriental fruit moth came in this week. Our first catch was May 6 at 375 GDD base 42. Scouts are finding a few European red mites, very few rosy apple aphids, oblique red-banded leafroller larvae, a few cutworms and green fruitworms. Pear psylla is active in relatively high numbers. No reports of codling moth emergence. It is still relatively quiet.

5 – Northwest

Nikki Rothwell
Duke Elsner

Growing Degree Day Accumulations at NWMHRS

GDD42

343

GDD50

147

 

Growth Stages at NWMHRS (5/7/07—8:00AM)

Apples are in pink.

Pears: Bartlett are at 90 percent bloom.

Sweet cherries: Hedelfingen and Gold are at full bloom; Napoleon are at early petal fall.

Tart cherries: Montmorency is at 10 percent bloom; Balaton are at 60 percent bloom.

Apricots are in the shuck.

Plums are at 80 percent bloom.

Grapes: Chardonnay are at Late bud swell.

Weather

The weather has been unseasonably warm and dry for this time of year. All crops seem to be moving along quickly with these conditions. Bartlett pears are at 90 percent bloom, and most apples are in pink. We could be in apple bloom by the weekend if temperatures stay warm. Montmorency is at 10 percent bloom, while Balatons are at 60 percent bloom. All sweet cherries are in full bloom.

Tree fruit

With the dry weather, we have not reported an apple scab infection period since May 1. We have not seen any scab lesions from previous infection periods. Since apples are only in pink, we do not need to control for fire blight yet. For insects, we have seen lots of rosy apple aphids, some obliquebanded leafroller larvae, and European red mite nymphs.

Not much moisture for cherry leaf spot infection, but very few leaves are out at this point for the pathogen to infect. Most sweet cherries are in bloom in the region, so it is too late for copper applications to reduce bacterial canker infection.

American plum borers are flying here at the station, and we have picked up an average of 5 moths per trap. Obliquebanded leafroller larvae are also moving around, and we have seen a few green fruitworm larvae.

Small fruit

Many varieties of grapes are now in late bud swell or early bud break. At the research station vineyard and other sites (in both vineyards and other habitats), numerous dead climbing cutworms have been seen showing symptoms of virus infections. Climbing cutworm injury has not been reported at significant levels. Flea beetles should be active now, but these are rarely a problem in commercial orchards.

Weather news

Jeff Andresen
Agricultural Meteorology
Geography

On the morning of Tuesday, May 8, a cool front stretched from Texas northeastward to the Lake Superior. This front is part of the same weather system associated with the major outbreak of severe weather across much of the central United States last weekend. Fortunately for us, this system is now much weaker than it was earlier and is expected to bring only the chance for showers and possibly a few thundershowers beginning late Tuesday continuing into Wednesday and early Thursday. Best chances for rain will be across central and southern sections of the Lower Peninsula, where scattered 0.25-0.50 inch amounts are possible by Thursday morning. Lighter amounts and lesser real coverage are expected across northern sections of the state, with some areas remaining dry. A second cool front is forecast to move through the state on Friday, bringing the chance for a few isolated showers lingering into Saturday (most locations in the state will remain dry). Fair and dry weather is expected statewide on Sunday. Temperatures will fall back from daytime readings in the upper 70's and low 80's Tuesday, to more normal levels in the upper 60's to low 70's by Saturday. Low temperatures will generally range from the low to mid 50's south Wednesday morning, falling back a few degrees to the mid 40's to low 50's by Saturday.

Medium range forecast guidance is suggesting a more west to east zonal upper air pattern across the lower 48 states, which should result in fairly seasonable weather across Michigan and the Great Lakes region. The official NOAA 6‑10 day outlook (covering May 13-17) calls for mean temperatures to range from near normal across Upper Michigan to above normal over the Lower Peninsula. Precipitation totals during this period are expected to remain at near normal levels. During the 8-14 day time frame, the forecast calls for near normal temperatures statewide, with precipitation expected to range from near normal levels across the Lower Peninsula to above normal levels in Upper Michigan.