First generation codling moth (CM) adult emergence began in some of the apple growing regions of the state early last week, but the appearance of cold, wet weather, starting last Wednesday (May 10) impeded subsequent moth flight. Temperatures generally dropped below 50°F during evening twilight hours when adult moths are known to be most active, and rain showers were common. These conditions severely limit CM flight, thus it is likely that very little mating and egg laying occurred during this period. As soon as evening temperatures warm up to around 60 degrees F, though, growers should be regularly checking CM traps in their orchards to establish biofix. Biofix, the first date at which moths are captured in traps, provided that moths are trapped on two successive trapping dates, is the point from which one begins accumulating degree days (GDD50) to predict CM biological development for targeting insecticide applications.

Options for controlling CM once activity is underway include conventional contact poisons, like the organophosphate (OP) compounds, Guthion and Imidan, and a number of pyrethroid insecticides. These materials primarily target newly emerging larvae at CM egg hatch, beginning at 250 GDD post biofix. 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 CM control is not likely to provide sufficient control.

Several new materials have become available for CM control and growers are encouraged to include these new products in their CM management programs. Integrating them into CM management programs will not only improve CM control in orchards experiencing problems, but also will help delay the development of CM resistance to OP’s in locations not yet experiencing control failures. One of the best CM resistance management strategies is to use pheromone-based mating disruption. Recognizing this, Michigan apple growers have treated over 5000 acres with CM pheromone over the past few weeks. Area-wide or whole-farm CM disruption projects are now on-going in Kent, Ottawa, Van Buren and Grand Traverse counties. The area-wide 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.

Among the newer insecticides for CM control registered over the past few years are the insect growth regulators Esteem, Rimon and Intrepid. Esteem and Rimon 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 CM control materials. Suggested timing for the first application is biofix plus 100 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). This is the second season that Rimon has been available for commercial use. Last year Rimon generally provided CM control at least equivalent to the best standard material used by growers, and where used as an early first generation CM material, also provided excellent OBLR control.

Intrepid provides good control of CM with a residual action of about 10 to 14 days. This product is an insect growth regulator that primarily affects CM larvae, but also has some activity on eggs and has sublethal effects on adults. The best results have been achieved by taking advantage of the sublethal effects and applying the first spray at biofix plus 150-200 GDD. 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.

The neonicotinoids, Assail, Calypso and Clutch are another group of compounds that have recently become available for CM control. Assail and Calypso will provide very good control of CM with a residual action of 10 to 14 days. Proper timing and coverage is required to achieve control. 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 is labeled for CM control at the rate of 2.5 to 3.4 ounces per acre, but the high rate has shown better performance, especially for second generation CM. Application rates near the high end of the label rate are also recommended for Calypso, especially where CM 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 CM 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 CM as well as aphids, leafhoppers, PC, STLM, OFM and pear psylla. Trials conducted at the TNRC in 2004 showed Clutch to be most effective against first generation CM applied at the egg hatch timing of 250 GDD and at the high rate of 6-oz/ac rate. Even at the high rate, Clutch has not provided adequate control of second generation CM.

Avaunt, an oxidiazine insecticide registered in apples, is labeled for use against CM, leafhoppers, plum curculio, leafrollers and Oriental fruit moth. It has excellent activity on plum curculio and early season applications in non-OP resistance areas should also suppress codling moth.

Proclaim, a new CM control material (Avermectin class) available for the 2006 season, provided good suppression of first generation CM in trials at the Trevor Nichols Research Complex and has also shown very good activity against OBLR.

Warrior, Baythroid XL, Asana, Danitol and Decis are synthetic pyrethroid insecticides that can provide good control of CM. Pyrethroid insecticides, appear to be more effective in the spring for first generation CM, 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.

Finally, growers should not overlook including granulosis virus in their CM management program. This is a naturally occurring virus that goes by the scientific name of Cydia pomonella granulovirus (CpGV). Two CpGv products were available for use last year, Cyd-X and Virosoft. This year, a third CpGv product, Carpovirusine, will also be available. 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 CM larvae will ingest the virus as they consume their eggshells.

There are many options for incorporating virus into your CM 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 CM 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 CM control program. Rotating it with chemical insecticides is a good means of combating resistance. We suggest the following approaches to incorporating CM 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.

With the continuing onslaught of rain, growers are wondering about the best options for cherry leaf spot control. Because the rain has provided so few windows for fungicide applications, there have been varying amounts of fungicide applied to tart and sweet cherry blocks. As rain is expected to continue for the remainder of the week, growers need to make quick decisions about the chemistry to apply when the rain actually stops for a while and the wind dies down enough to apply a spray. The following scenarios are meant to help growers decide the best product for their orchard.

Scenario 1
Growers that applied a full cover of Bravo on Tuesday or Wednesday last week (May 9-10) and had relatively good coverage can assume they were protected, but they will have to make an educated guess as to “how protected.” There will be no way to know how long the Bravo lasted or if it is still there, but for the most part, growers with a full rate of Bravo can assume some level of comfort. If this is the case for a particular farm, a grower should go back in with another full rate of Bravo as soon as possible. This scenario assumes a good degree of protection from the cherry leaf spot (CLS) pathogen, and Bravo is the choice for continued protection into the future, up to shuck split. The one thing to keep in mind with this program is that the grower should shorten the interval between sprays if the rain continues as the material will remain on the trees for a shorter amount of time.

Scenario 2
Growers that applied only a half cover of Bravo should assume they were not protected and need to go back into the orchard with something other than Bravo, as Bravo is only a protectant and does not have the ability to eradicate. As we have little knowledge of after-infection activity of some of our options (strobilurins and Pristine), we have to assume that these products will provide some eradication potential. First, there are no fungicides that will eradicate a spore that has germinated five to seven days ago. Sterol inhibitors (SI’s) used to provide some back action; however, those days are gone as CLS has developed resistance to these products throughout Michigan. Syllit (dodine), another product with some back action, can provide back action up to 36 hours; however, we do not know the current extent of dodine resistance in the CLS pathogen. These two products are an option if an orchard does not have SI or dodine resistance, but the likelihood of having an orchard without SI resistance is very low. Using SI’s to control CLS is not recommended, and a total control failure is probable with these products. Dodine may be more efficacious against CLS, but we have no recent data to verify this assumption; if dodine is used, the flowable rate is 27 oz per acre.

The remaining products are the strobilurins and the strobilurin/boscalid compound Pristine. One tactic for growers that have applied a half side is to come in with a full rate of Pristine at 14.5 oz/acre, Flint at 4 oz/acre, or the new product Gem at 6 oz/acre (See new product write-up for more information.). The full rate is essential to get the best control now and slow a possible CLS epidemic. If a grower applies one of these chemistries at a higher rate, he or she can follow up that spray with another Bravo spray at shuck split timing, about seven days from now. This strategy does not recommend tank mixing at this time for best efficacy against CLS as well as costs. Bravo is better used as the next spray at the shuck split timing. We should also not be cutting back on the rates of the strobilurins and Pristine if orchards have gone without protection during this wet weather.

Cherry leaf spot (CLS) is the most important fungal disease of tart cherry in Michigan. The leaf spot fungus Blumeriella jaapii infects leaves with symptoms first appearing on upper leaf surfaces as small purple spots. As spots accumulate on leaves, the leaves turn yellow and fall. The amount of lesions required to cause leaf yellowing and drop is variable. Sweet cherries can tolerate quite a few lesions before leaf drop occurs, but Montmorency tart cherries will drop with only a few lesions, signifying the importance of proper leaf spot management. Balaton® trees can tolerate more lesions that Montmorency, but they, too, drop their leaves more readily than sweet cherries.

The optimum conditions for lesion development are temperatures of 60°-68°F with rainfall or fog. After lesions appear on upper leaf surfaces, examination of the underside of leaves reveals a proliferation of white spore masses. These spores are dispersed by rain and wind within trees and to adjacent trees; such secondary cycles can continue repeatedly under favorable conditions through autumn.

Preharvest defoliation can result in a crop that does not mature adequately to be marketable, plus cause serious tree damage. Even late summer (August, early September) defoliation reduces the ability of trees to store photosynthate in roots leading to an overall loss of vigor and leaving trees more susceptible to killing by winter injury. Early-defoliated trees typically exhibit reduced flower bud formation and often set less fruit the following season.

Ascospores (primary inoculum) of the leaf spot fungus are released from leaves on the orchard floor by rainfall from early bloom to about six weeks after petal fall. Infection takes place through natural openings (stomata) located on leaf undersides. Once leaves are unfolded, they are susceptible to the CLS pathogen and remain so throughout the season.

Management of cherry leaf spot should be initiated around petal fall or sooner if susceptible leaf tissue is present. The use of chlorothalonil (Bravo) is not allowed after shuck split (except post-harvest). As resistance development to this product is unlikely, Bravo should be used pre-shuck split, as both a protectant and a resistance management tool.

Growers should also consider timing and compounds to control the other important tart cherry fungal diseases. For example, the first cover spray timing after shuck split is a good timing for Pristine or a strobilurin, because these fungicides are also effective in powdery mildew control. Currently, the SI's remain an important tool for brown rot control, particularly if we experience warm and humid or wet weather three to four weeks before harvest. Any use of SI's in Michigan should be in a tank mix with 3 to 4 lbs. of Captan per acre.

The strobulirin/boscalid (Pristine) and strobilurin (Flint or Gem) fungicides are our best tools for multiple disease control. However, both are single-site fungicides with the potential for resistance development. Do not apply these fungicides more than twice consecutively or more than four times per season. Our recommendation is that these fungicides not be used more than twice per season. The risk of resistance is high with these fungicides and loss of a class of fungicide means fewer tools for future disease control.

We envision that copper compounds will become more and more important for leaf spot control as other fungicides are lost due to resistance. Copper is highly effective in leaf spot control with the only downside being the potential for phytotoxicity. We are currently recommending a rate of 1.2 lbs per acre of metallic copper with hydrated lime added at 6-9 lbs per acre to reduce phytotoxicity. Do not apply copper compounds prior to periods of warm, dry conditions (temps at or above 80°F). Scout orchards for phytotoxicity symptoms on leaves (bronzing on leaf undersides, conspicuous large yellow blotches on a few leaves, and/or blackening of leaf veins) prior to the next copper application. Do not apply a second copper application if trees are exhibiting phytotoxicity symptoms.

It is time for apple growers to be registered with the Michigan Department of Agriculture if their fruit from the 2006 crop may be shipped to Brazil or Arizona. Although it is the exporting firms’ responsibility to make certain that growers are registered, all parties involved should make sure it gets done. The certification process allows growers' fruit to be shipped to Brazil or Arizona without cold treatment to kill apple maggot. The completed required forms, available from the MDA Pesticide and Plant Pest Management Division, should be received by their office by June 2, 2006.

MDA will be providing certification of all scouts setting and monitoring apple maggot traps as part of the certification process.

In the past week, monitoring traps in commercial blueberry farms in Van Buren County have caught their first cranberry fruitworm (CBFW), but only single moths have been seen in a few traps. Cherry fruitworm (CFW) moths have been trapped for a few weeks in the same region, but also at very low numbers (one or two moths per traps per week). These first captures indicate the flights of these important early-season insects are just beginning, but this is a little too early and the number of moths is too low to warrant any insecticide sprays in response. We have another series of cool, wet days ahead with predicted night-time lows in the 40s through the coming weekend. Under these conditions, temperature-based development of insects is slowed and moths are unlikely to fly when it is cold, windy and wet. This means that mating and egg-laying are also unlikely.

Monitoring traps should be checked again this week and again when it warms up next week. We should then expect the rest of the CBFW and CFW flights to start. Once a consistently increasing number of moths of either species are being caught in monitoring traps and early varieties are entering the susceptible stage when blooms start dropping and fruit set begins, these fields should be considered for protection against fruitworm larvae. Monitoring for the presence of fruitworm eggs on fruit can be used to better indicate the time when fruit protection is needed, though these are small and difficult to see.

Growers typically can manage both fruitworm pests together, but in recent years when there has been a cool period during blueberry bloom, the timing of CBFW and CFW have not overlapped. Instead, the earlier cherry fruitworm went unnoticed and the larvae were already inside fruit when CBFW control programs started. Monitoring for both insects in hotspots on the farm is a good idea, as insurance against missing one of these early pests. This is particularly important in early varieties where it is most likely that the fruit will be picked when CFW larvae are still developing inside the fruit.

There is an array of insecticides available for control of fruitworms, but their performance characteristics are not all the same, and only some of them can be used during bloom. During bloom, options for control are limited due to the need to protect bees. Two products registered for use during bloom and/or in the presence of pollinators have provided consistent control of fruitworms in trials at the Trevor Nichols Research Complex and at grower fields. These are the B.t. products (such as Dipel ® and Javelin ®) and the insect growth regulator Confirm ®. These products must be actively eaten by the larva to be effective, so they are best applied when daily temperatures are likely to reach 70 °F. This may be difficult during the predicted weather this year, so take note of this limitation when selecting when to use these products. B.t. products have short residual activity, providing up to five days active residue depending on the weather conditions. Confirm is more resistant to breakdown, giving between seven and 14 days activity, and it is quite rainfast, which can be a useful property in Michigan spring weather. These products are most effective when applied on top of fruitworm eggs (see table), before larvae hatch, so they are eaten as the larvae emerge from the egg. Another option for control of cranberry fruitworm is the growth regulator Esteem ®. This insecticide disrupts the adult moth's ability to make eggs and disrupts hatching of eggs and molting of larvae and is most effective when applied just before egg-laying. When thinking about application timing during bloom, getting the most out of your insecticides will require close scouting of fields with high fruitworm pressure. As with all fruitworm control applications, excellent coverage of fruit clusters is required to ensure that eggs and/or larvae come in contact with the insecticide.

After bloom, the range of options for fruitworm control increases with Guthion ®, Imidan ®, Asana ® and Sevin ® being the most effective of the broad-spectrum insecticide options. With all these products, maintaining good coverage is still important to get residue to the parts of the berry where fruitworms are found. Recent research trials in Michigan have demonstrated that Confirm ® and SpinTor TMapplied after bloom to fields with low or moderate fruitworm pressure can also achieve control of fruitworms with minimal negative impact on natural enemies such as parasitic wasps, ladybeetles and lacewings.

Correct timing and coverage are critically important, so regular scouting of fields, use of sufficient spray volume to get good fruit coverage and selecting appropriate spreader-stickers can increase activity of most insecticides applied for fruitworm control.

The accompanying table and figure are designed to summarize several key factors that can help you select an insecticide for your Integrated Pest Management program. (view image)

Botrytis gray mold, caused by the fungus Botrytis cinerea, is one of the most important fruit rot diseases affecting strawberries. Typical symptoms include a spreading brown rot and fuzzy gray mold on ripening berries. Wet weather and moderate temperatures are conducive to development of this disease. The bloom period is the most important time for control of gray mold, since primary infections take place almost exclusively through the blossoms. The infections then remain dormant until the berries start to ripen. As gray mold develops on infected berries, these become sources of inoculum secondary infections of adjacent berries. Ripe and overripe berries in particular are very susceptible and gray mold can spread rapidly at that time.

The gray mold fungus overwinters on old leaves and plant debris and can sporulate profusely on dead and decaying plant material. The spores are airborne and are usually plentiful in strawberry fields. If the bloom period is dry and/or good fungicide coverage is maintained, incidence of gray mold at harvest will be low. However, if primary infections get established, it will be harder to control the disease both before and after harvest. Where possible, remove sporulating berries from the field and destroy them to limit inoculum availability. During picking, avoid handling infected berries, since spores can be transferred on hands to healthy berries. Timely harvesting and rapid post-harvest cooling may also help to reduce losses to Botrytis gray mold.

There are a number of excellent fungicide choices for gray mold control in strawberries: Switch (cyprodinil and fludioxonil) and Pristine (pyraclostrobin and boscalid) provide excellent control; both have two different active ingredients – one is systemic, which broadens their spectrum of activity. Pristine in particular also provides outstanding control of fungal leaf spots and anthracnose fruit rot. Elevate (fenhexamid) is a locally systemic fungicide with good to excellent activity against gray mold. Captevate is a pre-mix of captan and fenhexamid and has a broader spectrum of activity than Elevate alone as it also protects against anthracnose and leaf spots. Scala (pyrimethanil) is a newer fungicide labeled for Botrytis gray mold control in strawberries and is similar to one of the active ingredients in Switch. With respect to older fungicides, a tank-mix of Topsin M (thiophate-methyl) and Captan (captan) has good activity against a broad spectrum of fungi, including gray mold. Thiram (thiram) is a broad-spectrum fungicide with fairly good efficacy against gray mold as well but is strictly a protectant.

A number of small fruit crops are affected by fungi belonging to the genus Phomopsis. For instance, Phomopsis vaccinii causes twig blight and cane canker on blueberries as well as twig dieback and fruit rot on cranberries; Phomopsis viticola causes cane and leaf spot and rachis infections and fruit rot on grapes; Phomopsis obscurans causes leaf blight and fruit rot in strawberries. Yet other Phomopsis species cause tree fruit diseases, demonstrating that this fungal genus is versatile and well adapted to fruit crops. In particular, Phomopsis species like cool, rainy weather, such as we have been experiencing for the past week. I therefore would like to pay special attention to Phomopsis diseases at this time, espcieally since Phomopsis twig blight symptoms have already been reported in blueberriesin Ohio and may be appearing in Michigan soon. In grapes, small brown spots surrounded by yellow halos indicative of Phomopsis have been seen on young leaves.

All Phomopsis species are “cousins” and tend to behave rather similarly. As a general rule, they:

• Overwinter in infected perennial plant parts, particularly canes and twigs. In herbaceous perennials, they overwinter in old leaves and fruit remnants. Old wood may be a source of spores for several years.
• Are often introduced in a field on the planting material (dead twigs and lesions may be visible on young plants).
• Produce pear-shaped fruiting bodies (visible as brown to black pimples in infected plant parts) with tiny spores that are exuded in gelatinous masses and dispersed by rain splash and irrigation water.
• Don’t have a sexual stage or the sexual stage is rare, resulting in few or no airborne spores.
• Spore dispersal is local (usually within 3 feet from the source, maybe a bit further in case of wind-driven rain)
• Rain contributes significantly to spore production, dispersal, and infection. Longer wetness durations (24-72 hours) are ideal for infection. Frost injury and wounds may predispose tissues to infection.
• Are active during most of the growing season. Phomopsis species on grape and blueberry are known to release most of their spores in spring and early summer, which is an important time for disease control.
• Have one or more infection cycles per season. Phomopsis on grape does not generally produce spores on newly infected tissues so that overwintering inoculum is all that is available. However, the Phomopsis species on blueberry, cranberry, and strawberry do, leading to multiple infection cycles in these crops.
• Prefer cool to moderate temperatures (59-75ºF).
• Young tissues are most susceptible to infection.
• Cold weather may slow down growth of young tissues and increase drying time if wet, therefore prolonging the susceptible period.
• Infection may be latent for some time, particularly in fruit. Even on vegetative tissues, the infection may not become visible until 2-4 weeks after infection.

Control of Phomopsis diseases is best accomplished by a combination of sanitation (removal and destruction of diseased plant parts) and use of effective fungicides. Do not underestimate the importance of selective pruning in blueberries and grapes and removal of old leaves and fruit in strawberries and cranberries, even though these may be labor intensive. After a heavy outbreak of disease, it will be the main thing that you can do to regain control of the disease. As far as fungicides are concerned, availability varies by crop. In general, good protectants are Dithane/Penncozeb (grapes and cranberries), Bravo (blueberries and cranberries), Ziram (grapes, blueberries), and Captan (blueberries, strawberries, grapes [where not restricted]). Other fungicides that have performed very well against Phomopsis diseases have been Indar, Topsin M (+ Captan or Ziram), and Pristine in blueberries; Abound, Sovran, Pristine, and ProPhyt in grapes; and Topsin M (+ Captan), Cabrio, Nova, and Pristine in strawberries. Dormant sprays of Lime sulfur, sulfur (e.g. Sulfur 6L), and copper (e.g., Cuprofix), are useful in reducing the amount of overwintering inoculum in grapes and blueberries and thereby disease pressure during the growing season.

Compared to most fruit crops, a high percentage of blueberry flowers normally produce fruit. When bees are numerous and weather is warm and calm, 80 to 95% of flowers may set fruit. However, cold, rainy weather restricts honeybee activity. When extended periods of poor pollination weather occurs during bloom (such as this year), berry numbers or berry size can be substantially reduced. Flowers not pollinated within three to five days after opening are unlikely to set fruit. After normal pollination, berry growth is dependent on the production of gibberellin and perhaps other growth promoters in the ovary tissues and viable seeds. If flowers are not pollinated, they will abort. If only a few ovules are fertilized, the fruit may set but not contain enough seeds to grow to full size.

When pollination is limited by cold, rainy or windy weather during bloom, gibberellin (GA) applications sometimes improve blueberry set and berry size. GA appears to supplement gibberellin that is lacking due to too few seeds. Several GA products (ProGibb, GibGro) are labeled for highbush blueberries. GA may result in retention of some seedless (parthenocarpic) fruit that normally drop and increases the size of berries with low seed numbers. GA can be applied in a single spray during bloom (80 gram active ingredient per acre) or two 40 g sprays, one during bloom and the second 10 to 14 days later. Higher spray volumes (40 to 100 gallons per acre) may improve coverage and effects. Slow-drying conditions also increase absorption. Also make sure your spray water pH is not above 7.5.

Since the cost of 80 g of GA is over $100, it is important to know when to use GA. If weather has been reasonably good for bee activity and the white corollas fall easily from the bushes, pollination is probably adequate. Keep in mind that blueberries can bloom over a long time, and often only a few days on good conditions is enough to provide adequate pollination. Consistently cold, rainy or windy weather through bloom causes pollination problems. If the corollas stay on the bushes longer than usual and turn red/purple before eventually dropping, pollination may have been inadequate. The corollas of pollinated flowers drop readily while still white. Varieties with fruit set problems (Jersey, Coville, Earliblue, Berkeley, Blueray) are most likely to benefit from GA. Jersey, for example, is relatively unattractive to honeybees, and berry numbers and size are often limited by inadequate pollination. GA does not always provide a benefit, and effects can be subtle. A key to learning about GA benefits is to leave non-treated check rows. This is the only way to tell if your money was well spent.

Regional reports
1 -- Southwest
Mark Longstroth
Bill Shane
Al Gaus

Apricots are scarce.

Peaches are at shuck split. Growers are thinning the fruit. Oriental fruit moth trap catches have fallen. We should be at peak adult emergence, but cool temperatures have kept the flight down. We set biofix for Oriental fruit moth as April 16 with a GDD45 of 180 at SWMREC. Chemical controls are focused on egg hatch, which begins at about 150-170 GDD45 after biofix and continues to about 650 GDD after biofix. We are about 280 GDD past biofix. Tarnished plant bug and green peach aphid have been found in peach orchards.

Sweet cherries are 12-14 mm and at pit hardening. These wet conditions are good for bacterial canker. It is too late to use copper on sweet cherries, but phosphorus acid products are also effective. Plum curculio will be a problem when it warms up.

Tart cherries are at shuck split. There is a wide range in size. The largest fruit are 8 mm and there are still a lot of fruit in the shuck. Growers need to protect against cherry leaf spot.

Plums are out of the shuck and the fruit is starting to sort out by size. We will not have a good estimate of the crop for several weeks. Growers need to maintain protection for black knot.

Apple bloom is ending. Wednesday’s rain was an apple scab infection. Scab symptoms from earlier rains have been found. A lot of scab spores were released Wednesday, and spore release has continued at low levels. Cool, wet conditions this week means that growers need to maintain scab protection. Growers also need to protect against this powdery mildew. There was a fire blight infection in the eastern areas of the district Wednesday, but the cool weather following this event will probably keep this disease down. The cool forecast this week means there is little danger of fire blight. This disease should only be a problem if we get severe weather or orchards have oozing cankers. Canker margin symptoms have not yet appeared. Growers can monitor wetting periods for scab and fire blight infections at the Enviro-weather site. Cool weather dropped insect trap counts to zero for most of last week. Oriental fruit moth and codling moths trap catches are low. A regional biofix for codling moth has not been set. We expect the flight to begin again with warm dry weather next week. See the article on pesticides for codling moth in this week’s Fruit CAT Alert. Leafroller larvae about 20 mm long can be found in apples. They are probably obliquebanded leafroller. The first obliquebanded leafroller adults should be out soon and traps should be out. Aphids can also be found in apples. Growers have been applying petal fall sprays to control rosy apple aphid and spotted tentiform leafminer. This week will be too cool for thinning. The largest apple fruit are about 8 mm. The cool, wet cloudy weather has set up the trees for a good thinning window when warm weather returns . Grower should be prepared to thin apples when temperatures rise into the 70s. Long-range forecasts indicate that this will be about May 22.

Pears are at 8 mm. Growers need to protect against pear scab. Pear psylla nymphs are common in some orchards. Pear blister mite was reported for several small growers.

In grapes, freeze killed areas are very easy to identify. Surviving primary shoots are visible a long way off. Damage from the April 26, 2006 freeze is becoming easier to assess. The new buds out there now look as if they started after the freeze. Tertiary buds are starting to appear at the base of shoots, arms and trunks. A few secondary buds have also appeared but generally in areas where some primary buds also survived. In areas that do not show growth from a distance both primary and secondary buds are killed. There are reports of scattered damage to wine grapes. This appears to be more site-specific since vinifera grapes were less developed than lambrusca grapes. Late growing varieties such as Seyval, Vignoles and Vidal escaped damage because they were just starting growth. This freeze was similar to one in April 2002. In areas with numerous shoots, an accurate estimate can be made in about a month when the flower clusters in new replacement shoots are apparent. Growers should continue their disease control programs in areas that show growth. See the note below on the May 25 Grape Management meetings.

Strawberries are blooming. Growers should consider fungicide applications to control Botrytis at bloom under these wet conditions. See the article on strawberry fungicide selection in this week’s Fruit CAT Alert. Angular leaf spot is other cold wet weather disease. This disease is caused by a bacteria so copper sprays are helpful.

Raspberries flower clusters are emerging. Prelude and Nova are at first bloom. Fall raspberry shoots are about 6 inches tall. Growers should be scouting for leafrollers.

Cranberry buds are beginning to burst.

The next Monday Fruit Update meeting will be, Monday May 23, at the Fruit Acres Farm in Berrien County, at 5:00 PM . The format for the Grape IPM meetings in Berrien and Van Buren counties on Thursday, May 25, has been changed to a discussion on management options for freeze-damaged vineyards. The morning meeting will be from 10:00 AM to noon at the Cronenwett Farm Shop at 70123 28th Street east of Lawton. The afternoon meeting will be at the Southwest Michigan Research & Extension Center from 2:00 to 4:00 PM.

2 -- Southeast
Bob Tritten

GDD totals are still running about five to six days ahead of normal despite the cold weather events of the last week. GDD totals are also well ahead of last year’s relatively early growing season. Soils are now saturated to a point where little to no field work will be done over the next week. Growers have rutted their orchards during the many spraying operations. Obviously, irrigation systems that had been fired up due to drier than normal soils prior to last Wednesday’s start of the rain have now been turned off.

Remember, there is a new web site available: Enviro-weather. Many growers are accessing it to receive real time data generated from seven automated weather stations located across the southeast and Thumb regions. Those weather stations help to predict very specific data for apple scab, fire blight and other tree fruit diseases. I encourage you to visit the web site at: http://www.enviroweather.msu.edu

An older web site, also maintained by Jeff Andresen, contains a great deal of information. That web site, MSU Agricultural Weather Office is: http://www.agweather.geo.msu.edu

Tree fruit
Apples are mostly at 6 to 7 mm in the Flint area with Red Delicious being a little smaller at 5 to 6 mm. In the southern part of the region, apples are mostly at 8 to 9 mm in size. It wouldn’t surprise me to see apple growth continue at a fairly rapid pace despite the cold weather. There appears to be a very good crop. Apple growers will need to turn their attention to thinning sprays fairly quickly. The window of thinning applications may be opening rather quickly late this week as the weather dries out and temperatures begin to warm up into the high 70s. In last week’s report, I reported the first catch of codling moth. With the exception of one or two farms, due to all the cold, wet weather, codling moth trap catches have dropped down to nearly zero. So, in conversations with David Epstein regarding biofixing for codling moth, I think he is recommending that growers start that model over again this week as trap catch will take off when nighttime temperatures are a bit higher. Refer to his article for more information. Oriental fruit moth populations have dropped back dramatically over the last week. Several farms had trap catches last week in the hundreds. Those numbers are now down to the teens to lower twenties. It is hard to say whether Oriental fruit moth trap catches have dropped so dramatically because of the weather or the natural downturn in the end of the first generation flight. It will require a few more days of warmer temperatures to tell where we are headed with trap catches and populations. I tend to think the reason is due to the cold weather that Oriental fruit moth trap catches have dropped off so much. I have seen plum curculio at a few farms, and this started to happen last Tuesday and Wednesday when temperatures were still warm and weather was dry. I have not seen any stings, and sightings of plum curculio have dropped to near zero because of the cold temperatures. Once the weather warms up, I expect to see a pretty good population. Apple curculio was also seen last week, however, numbers were fairly low. Potato leafhoppers were seen at low levels for the first time this morning. Redbanded leafroller trap catches are down; however I am starting to see a few larvae. Spotted tentiform leafminer populations were dropping last week and continue to drop lower this week. I am seeing just a few eggs from the first generation of spotted tentiform leafminer. Tarnished plant bug adults were seen early last week in apples and peaches; however none were seen in yesterday’s scouting. Other larvae I am seeing include green fruitworm, obliquebanded leafroller and Eastern tent caterpillar. In most cases, all these populations are low. I have seen a few orchards with high populations of rosy apple aphid. For the most part, I’m just seeing a few single adults around. European red mite egg hatch has been ongoing over the last three weeks. Over the last week I started seeing egg laying. Generally numbers are fairly low with only one orchard being reported at above threshold levels. Two-spotted spider mite adults have been seen for several weeks now, and last week I started to see just a few eggs being laid. There are a number of predators being seen over the last week. These include Stethorus punctum, fallacis mites and velvet mites. Ladybug populations are now high, and I am starting to see a few minute pirate bugs. Brown lacewing populations continue to build.

As reported in the weather section, several of our weather stations report a continuous apple scab wetting event starting on May 10. I’m not certain if records have ever been kept as to the duration of wetting events, but it’s highly unusual to see a number of 123 hours of continuous wetting, as reported this morning at the Petersburg weather station. I’m starting to see a few apple scab lesions on the bottom of leaves. However, with all the wet weather over the last week, I would expect to see a good number of lesions starting around May 25. I continue to catch apple scab spores with many of the heavier rain events. I would predict an early end to primary apple scab season. Please stay tuned for details over the next several weeks for that information. Let me state clearly that I am not calling an end to primary apple scab season, even though several of the models report that most of the spores should have been discharged. Remember, these are models and not actual figures. No fire blight has been seen.

Pears are mostly around 8 to 10 mm in size. There is a wide range of fruit sizes. Pear psylla populations seem to be under control. At farms where no control measures have been made, egg laying is taking place at a fairly low level.

Peaches are beginning early shuck split. Most blocks are looking as if they have a full crop of peaches. If all this bloom turns into peaches, we will have a tremendous job of thinning to do in June. Oriental fruit moth populations are down this week in the range of 15 to 25 per trap, as opposed to hundreds in traps last week. Most growers will be applying an insecticide pretty quickly here for control. I am seeing a few tarnished plant bugs as well as a few green peach aphids.

Sweet cherries have sized very well over the last week despite the cold weather. Most are now in the 11 to 12 mm range. Pit hardening has not begun. In some blocks I am seeing a fair amount of fruit drop. Perennial cankers are now oozing quite heavily.

Tart cherries are currently at 9 to 10 mm in size with some fruit drop occurring. There is not as much fruit drop as in sweet cherries.

Plums are mostly at shuck split. I have not seen any plum curculio stings, however I am finding a few adults on scattered trees.

Raspberries are growing fairly well through all the rain events. There is some tip death from winterkill that is now being seen in some of the more sensitive black, red and purple raspberry varieties. Flower blossoms are now clearly visible. I expect to see some bloom in the next week or so. Fall red raspberrycanes are about 6 inches in length. No major problems to report.

Blueberries are at early bloom on some of the midseason varieties and full bloom on the early season varieties. There appears to be a fairly good bloom. I am a bit concerned about pollination due to cold weather and this early bloom time. Refer to Dr. Eric Hanson’s article in this edition concerning the use of gibberellic acid as an enhancement to bloom.

Tree fruit
Early apple varieties are in the petalfall stage and mid- to late season varieties are moving out of bloom. Sweet cherry and peach bloom is over, and small fruits are becoming easier to see. The stone fruit crops are looking like there’s a good set.

According to 30-year averages from the Sparta weather station, GDD totals continue to run about seven days ahead for GDD42 and six days ahead for GDD50.

There is still time to apply Apogee for apple growth control, but there is significant tissue growth in some varieties. Be sure to add AMS with Apogee to take care of any calcium in the water that could tie up the Apogee and make it ineffective.

There is very little risk for blossom blight infections from the rains over the weekend because of the cooler temperatures. Looking ahead, we could be at risk again for blossom and or trauma blight near the end of the week if it warms up again. For those with known Streptomycin resistance, you’ll have to watch the weather closely so that you can be covered ahead of a trauma event. For those with no resistance, you can use streptomycin after a trauma event, but it’s still best to use it ahead of time.

Since the rain began late on May 10, this wetting event has been one long infection period for apple scab with well over 100 hours of wetting at 46 to 47 degrees average temperature for all stations. Currently, this wetting event is still on-going for all stations except Belding. For the other stations, we have not had eight hours of continuous dry time – and that means RH below 90% and no leaf wetness or additional rain. Spore numbers have been moderate from this rain event. We are currently just about at 97% mature spores. With the forecasted temperatures, it’s expected that we’ll reach 100% mature spores over the coming weekend. The highest number of spores were caught at the beginning of the wetting event, but have continued to be released every day since this wetting event began. More rain is in the near forecast as well, so be sure to have a good cover on ahead of it. Even though many of the ascospores are mature, they are not all discharged yet.

Powdery mildew should be covered up for as well. It is beginning to show up in abandoned apples already.

A regional biofix for codling moth was set for May 10, and we’ve accumulated 10 GDD50 since then. It’s anticipated that we’ll reach the 100 GDD50 post biofix for early egg materials sometime late next week – probably Thursday or Friday. If we get more normal temperatures over the next four or five days, we could reach that target a bit earlier.

Oriental fruit moth adult numbers have been down a bit in traps. A regional biofix was set for May 1, and we’ve accumulated 121 GDD45 since. Spotted tentiform leafminer continue to fly and sap feeders should be found at any time. Rosy apple aphids continue to be found and numbers are building. European red mites continue to hatch. Plum curculio damage still has not been seen yet, but they should start being active at any time in early fruiting tree fruits such as plum and apricots.

4 -- West Central
Mira Danilovich

This weather pattern created very favorable conditions for many fungal (scab, leaf spot) and bacterial diseases (leaf spot and canker).

This has been very unusual and one of the longest wetting events ever, resulting in high apple scab infection period. Prior to this event, the recommendation has been to provide full coverage by using the full label recommended rates. Even with that, there has been a need to use every available chance to get back into the blocks and respray with the combination of protectant fungicides (such as Captan or EBDC’s) and materials that would have a long-reaching curative action (Nova) to stop the infections in progress. Apple scab spores continue to mature. There are about 95% mature spores. With each rain there has been a spore discharge with the most massive at tight cluster (10,824 per rod). During this most recent rain event between May 9 and May 15 the average spore discharge was 71 per rod. Leaf lesions have been found in the abandoned block from the infection occurred April 23. None have been reported in the commercial blocks. The 6-10 day forecast is not looking encouraging. It appears that there is another massive disturbance moving our way that will bring more of the same – cooler than normal temperatures and normal precipitations. Again, when the first opportunity presents itself, growers need to get in and spray again to keep the blocks covered. Full cover and full rates!

Apples are in full bloom to petal fall with quite a bit of secondary bloom yet. Maryblight model is predicting moderate blossom infection potential for the next three days assuming it rains and the temperatures stay at 60°F or above. This is true for both apples and pears. Pears, too, have quite a few secondary blooms still open. Old cankers are expected to start oozing any day now.

5 -- Northwest
Nikki Rothwell
Jim Nugent
Duke Elsner

Tree fruit
In apples, we had a close call for fire blight infection on May 10 and 11. Some growers sprayed varieties that are especially susceptible. Temperatures then cooled too much for the rest of the week for fire blight to be of concern. Moisture and temperature conditions have been favorable for apple scab infection. No codling moths have been trapped at the NWMHRS, but two consultants each had a site in the region where codling moth were trapped this week. Sites were in areas of high populations last year or next to stored apple bins. We expect more widespread flight activity when warmer evening temperatures return. The first adult generation of spotted tentiform leafminer is declining.

The low pressure system that has persisted across the eastern United States since last Tuesday (May 9) was centered over the mid-Atlantic Tuesday morning (May 16). This system brought 2 to 5 inches of rain to much of Michigan and more than 10 inches of rain and severe flooding to portions of New England. Rain associated with the system fell on an almost daily basis during the past week, leading to extended wetting events in many productions areas (As of Tuesday morning, wetting duration at some MAWN monitoring sites exceeded 120 hours.). On the positive side, rainfall with the system ended the drier than normal conditions that have persisted since late mid-March, and seasonal precipitation totals (since April 1) are back to near normal levels over most of the state.

Looking ahead, the low pressure system is expected to finally move northeastward into the North Atlantic during the next 24 to 48 hours. Unfortunately, another upper air disturbance moving southeastward from Canada will take its place over the Great Lakes region for much of the latter half of the week, leading to more showery and cooler than normal weather.

In the short term, showers and a few thunderstorms will be possible late Wednesday afternoon and evening. Showers are a good bet both statewide Thursday with the chance for scattered showers once again Friday into early Saturday. Dry conditions are expected to finally materialize by Sunday. Precipitation totals during the next five days are forecast to approach to range from near 0.25 inches in western sections of the state to 1.0 inch or more across the eastern Lower Peninsula. Temperatures will fall back from highs in the 60s to near 70 on Wednesday and lows near 50 to highs in the 50s and lows in the upper 30s to low 40s by Thursday and Friday. Cooler than normal temperatures are a good bet through the weekend with mean temperatures remaining 3 to 6 degrees below the climatological norms. Forecast guidance suggests moderation in temperatures by early next week with high temperatures possibly returning to the 70s by midweek.

Medium‑range forecast guidance is suggesting that the upper air troughing pattern across the eastern United States and ridging across the west will gradually shift eastward, leading to an eventual moderation in temperatures. The NOAA 6-10 day outlook (covering May 21-25) still calls for below normal temperatures statewide with precipitation totals ranging from near normal in northeastern sections of Michigan to below normal in the southwest. During the 8-14 day time frame (covering May 23-29), the outlook calls for temperatures to warm back to near normal levels statewide. Precipitation totals during this period are also forecast to be near normal statewide.