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| Fruit Crop Advisory Team Alert newsletter | ||||
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| Vol. 22, No. 12, June 26, 2007 |
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| In this issue Tree fruit news  Controlling Japanese beetles in fruit crops TNRC trapline data: Japanese beetle When to prune out fire blight: To prune or not to prune Controlling flyspeck on apples USDA cherry production estimatesSmall fruit news Get a head start on management of bunch rot diseases in grapesOther news Regional reports Weather newsNext issue July 10 |
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| Controlling Japanese beetles in fruit crops Japanese beetles have only one generation per year, but these beetles emerge over a long period in July and August, and they live for over 30 days. They feed on the foliage and fruit of various fruit crops grown in Michigan, causing damage to the plant and increasing the risk of fungal disease in fruit. Their emergence during mid-summer can also result in their presence during harvest, creating a risk of contamination. They are also highly mobile insects and can fly into fields from surrounding areas. This article provides information on insecticide options based on tests over the past few years conducted at the Trevor Nichols Research Complex and at grower’s farms. Broad-spectrum options The carbamates Sevin and Lannate provide immediate kill of beetles present during the spray. They are also stomach poisons, so if beetles eat treated foliage they will also receive a higher dose. This can be a good property for control of Japanese beetles, since they eat so much that a strong dose of insecticide is taken up. Lannate has a short residual activity of a few days, whereas Sevin provides a week or more of protection. Sevin has a three or seven day PHI depending on the crop, and Lannate ranges from 3-14 days. The organophosphates Guthion and Imidan (buffer to pH 6.0) provide excellent lethal activity on adult beetles, although it can take a few days for their effects on Japanese beetles to be seen as the beetles take up the insecticide. They provide 10-14 days of activity, with 3-21 day PHI, depending on the crop. The pyrethroids Danitol, Warrior, Asana, Brigade, Baythroid, Mustang Max and Capture give instant knockdown and mortality of adult beetles, with 7-10 days of activity. It is important to remember that the pyrethroid class of insecticides is quite sensitive to hot and sunny conditions, so performance in mid-summer will be less than that expected in the spring. Beetles that do not receive a lethal dose of pyrethroid may also be repelled from treated fields, providing an additional mode for reducing infestation of crops. PHI’s for pyrethroid insecticides may vary widely across crops, so check the label before using this class of materials. |
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| Selective insecticides The labeling of Provado for use in some fruit crops after bloom provides a selective option for Japanese beetle management. Provado provides two to three days of lethal activity from the surface residues before it is absorbed into the foliage. Thereafter, beetles must eat treated foliage to get a dose of the insecticide. Once inside the foliage, Provado is rainfast and provides significant sub-lethal effects of repellency and knockdown activity, but with much less direct mortality from the residues. This neonicotinoid will also control aphids and leafhoppers. It has a zero to seven day PHI depending on the fruit crop. Another member of this chemical class, Assail, can provide some protection of foliage from feeding by Japanese beetles, though the level of beetle mortality may be lower than expected from the broad-spectrum options. The rate allowed in different crops will have a big impact on the effectiveness of Assail. Other neonicotinoids labeled in fruit crops include Actara, Calypso, Clutch and Venom. Short PHI and organic options For growers looking for beetle control immediately before harvest or in organically grown fruit crops, some selective insecticides with zero day PHI’s can provide a tool to repel beetles and help achieve beetle-free fruit during harvest. Compounds containing neem (Azadirect, Ecozin, Neemix etc.) have a zero day PHI and pyrethrum (Pyganic) has a 12 hour PHI. These compounds are labeled for organic use, and have a short but effective impact on adult Japanese beetles, with some mortality, some knockdown off the crop and some repellent activity. Typically, there is only one to two days of activity against beetles because the residues do not remain active for long. The non-organic form of Pyganic, called Evergreen, also has a 12 hour PHI, and is much more effective against Japanese beetle than Pyganic due to the addition of a chemical that inhibits the beetle’s ability to break down the insecticide. Soil-applied insecticides Japanese beetles typically lay their eggs in moist grassy areas and many fruit farms have a large amount of this suitable habitat. An additional approach to managing Japanese beetle populations is to target the grub stage of this pest in these areas to reduce the abundance of beetles in the following year. If the location of high grub densities near fruit fields is known, these areas could be treated with a soil insecticide to get maximum return on this treatment. Our experience in Michigan blueberry fields has been that application of Admire (16 oz/acre) to grassy field perimeters reduced the abundance of beetles on bushes for the first few weeks of their flight period. After that, beetles flying into the area from outside swamped out this effect, so there is only a short-lived benefit from targeting the grubs in fields that are surrounded by infested grassy areas. |
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| When to prune out fire blight: To prune or not to prune The question of pruning out fire blight strikes during the growing season, or leaving them until the winter is debated whenever we have wide spread fire blight. The answer to this question depends upon the number of strikes and the weather conditions suitable for infection. Generally, pruning out fire blight strikes only makes sense in young orchards and when there are a relatively small number of strikes that are easy to get to. If you decide to prune out strikes in a young orchard, the strikes should be pruned out as soon as they appear. Failure to do so increases the likelihood that blight will continue to spread both to adjacent trees and into the rootstocks of affected trees. Pruning out infections in mature trees may not be practical, but mature trees with a full crop will set terminal shoot buds earlier than young trees. When trees set terminal buds, blight stops spreading both between trees and within the affected trees. Remove strikes before the cankers extend into the tree. Trees must be examined at least two or three times weekly until the epidemic slows as tree growth slows. In sections where trees are severely affected, it may be more cost-effective to immediately remove entire trees, especially if trees are a susceptible cultivar like Gala. Pulling out badly affected trees will allow blight removal crews to focus their efforts on trees that can be salvaged. Blight removal crews should be trained to recognize the early symptoms of blight on terminal shoots. The first or second fully expanded leaf will droop and closer examination will show blackening along the mid-vein at the base of the leaf blade. The entire shoot tip may appear to be slightly yellowed. Remove such shoots by cutting back into two-year-old wood at least 8-12 inches below the last visible symptoms. If a spur or shoot on the central leader shows signs of blight, immediately remove the central leader down to 8-12 inches below the last visible symptom. Immediate and aggressive removals reduce the need for repeated pruning in the same tree and may result in fewer trees lost to root stock blight. Makecuts into at least 2-year-old wood where bacteria will be less able to multiply. Also, leave "ugly stubs" by cutting branches between nodes and several inches away from the central leader or other branch union. Small cankers that form on these stubs can then be removed during winter pruning whereas a canker that forms at a flush cut on the central leader will be missed during winter pruning. Prune during dry weather. An extension specialist in California reported that he failed to transmit fire blight with pruning tools when he purposely made cuts through active cankers in dry weather. However, he succeeded in transmitting blight on pruning tools when pruning was done in wet weather. Blight removal operations should be suspended in wet weather. If wet weather persists, the risk of spreading the disease during pruning is too great and it may be better to leave the fire blight strikes in the orchard until dry weather arrives. Should prunings be removed from the orchard? My recommendation is to toss prunings in the row middles and allow them to thoroughly dry before mowing them. Dry, dead prunings on the orchard floor do not present a danger to spreading the disease. Dry means that the bark no longer slips on the cut branches, and the cambium is brown. With today's tightly spaced orchards, I am concerned that carrying prunings out of the orchard may spread more blight than occurs when prunings are left to dry in the row middles. I normally do not recommend disinfecting the pruning tolls because you need to soak them for several minutes to do a good job and most will not take the time. Avoid hand thinning, bud pinching and other manipulation activities until after terminal bud set. Delaying hand thinning may result in some loss of fruit size, but risks of spreading blight out-weigh the benefits of early hand thinning. You can spread blight on your fingers while pinching buds (or hand-thinning). Under dry conditions when only a few strikes occur, immediately pruning down to non-infected 3-year-old wood reduces the potential of the disease spreading. This strategy works where infections are located in only an isolated area of the orchard. This strategy works best with old trees. |
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| Controlling flyspeck on apples Editor’s note: This article was originally published in Scaffolds Fruit Journal Volume 15. No. 15 on June 26, 2007. This publication is made possible by Cornell Univerisity – NYS Agricultural Experiment Station and Cornell Cooperative Extension. Flyspeck has caused more commercial losses in New York and New England over the past few years than during most of the previous decade. What has contributed to those losses? How can we prevent them from re-occurring this year? Let's start by enumerating what we know about flyspeck biology: Flyspeck infects a wide range of host plants. That means that the flyspeck fungi can grow on the waxy cuticle of most bushes and trees in orchard perimeters, and these hosts can produce inoculum that blows into orchards. (Recent work in Iowa suggests multiple species may be involved in causing flyspeck, so in this article I will refer to the causal organisms as flyspeck "fungi.") After a spore from one of the flyspeck fungi lands on an apple, the apple must be exposed to 270 hours of accumulated wetting before the flyspeck colonies become visible on the fruit. Brown and Sutton in North Carolina were the first to identify the incubation period for flyspeck, and they found the best correlations when they ignored wetting periods of less than a three hour duration. I have since found good correlations with the 270 hours of accumulated wetting over several years in the Hudson Valley when we included all measurable wetting periods. Variability among types and locations of wetness sensors is so great that quibbling about the details of whether to include or dismiss short wetting periods is probably meaningless. In Massachusetts, Cooley and Lerner showed that ascospores for flyspeck are released around petal fall. Therefore, flyspeck colonies initiated by ascospores may begin appearing on unsprayed fruit at 270 hours of accumulated wetting after petal fall. However, scab sprays usually control the ascospores, so ascosporic infections are not common in commercial orchards. Infections initiated by ascospores in wild hosts begin releasing conidia as soon as those infections become visible (after 270 hours of accumulated wetting after petal fall). Once those infections produce conidia, orchards in the northeast are exposed to a continuous supply of conidia blowing throughout the remainder of the summer and fall. If fungicide residues on fruit drop below effective levels, then the conidia will initiate flyspeck infections on fruit. Where trees are left unsprayed after second cover (i.e., they are protected from flyspeck ascospores but not from conidia), flyspeck incidence and severity on fruit increases dramatically around 540 hours of accumulated wetting after petal fall. Thus, flyspeck requires 270 hours of accumulated wetting after petal fall to produce conidia on wild hosts and another 270 hours of accumulated wetting after petal fall to infect and produce visible colonies on apples. Results of two recent trials that indicate limitations of current fungicides Two inches of heavy rain may be enough to eliminate fungicide residues. In an experiment at the Hudson Valley Lab in 2004, we applied all of the common summer fungicides to test plots on August 17. We received 2.15 inches of rain on August 20-22. We had 270 hours of accumulated wetting between August 22 and September 26. Incidence of flyspeck on Golden Delicious fruit on September 27 was 64, 50, 31, 27 and 8 percent, respectively, for plots treated with Captan alone (30 oz of 80W/A), Flint, Sovran, Topsin-plus-Captan and Pristine. Pristine had the best residual activity, but none of the fungicides had adequate residue to completely protect against flyspeck after 2.15 inches rain. Fungicides applied after flyspeck infections have been initiated can arrest growth of the flyspeck fungus temporarily, but they do NOT eradicate the infections. In a 2005 experiment, summer fungicide sprays were initiated at either 337 or 450 hours of accumulated wetting after petal fall to determine if these fungicides could provide post-infection activity that would reach back through either 67 hours of accumulated wetting (i.e., 337 hours minus the 270 hour threshold for conidial infections) or through 180 hours of accumulated wetting from the start of infections. None of the postinfection treatments provided satisfactory disease control. By September 26, flyspeck incidence exceeded 19 percent in all treatments, even though we maintained fungicide coverage up until harvest (i.e., less than 2 inches of rain between sprays and between the last spray and harvest). Sovran was significantly better than Pristine or Flint for suppressing infections, but it was not significantly better than the Topsin-plus-Captan standard. Thus, Pristine provides the best residual protection, but Sovran and Topsin M provide the best post-infection activity, even though the post-infection suppression is less than we had hoped for. Results from these recent trials have caused me to re-evaluate earlier hypotheses. The long incubation period required for flyspeck coupled with our inability to accurately predict or monitor fungicide residues on fruits makes it difficult to interpret results of fungicide trials in dry years. Did fungicides applied in July or August really eradicate earlier infections, or did they just slow fungal growth enough to allow fruit to be harvested before flyspeck appeared on fruit? Wet years such as we have had in the Hudson Valley in 2004 and 2005, provided more definitive evidence concerning the limitations of our fungicides. Combining all that we know about flyspeck along with some working hypotheses, I've compiled the following statements to help formulate options for controlling flyspeck. The period of least risk for significant flyspeck infection occurs between petal fall and 270 hours of accumulated wetting after petal fall for reasons noted above. After 270 hours of accumulated wetting after petal fall, fruit should be continuously protected with fungicides. Any gaps in protection after 270 hours of accumulated wetting after petal fall may allow flyspeck infections to be initiated. Two inches of rain can remove virtually all fungicide protection. Fungicides applied after infections are initiated do not eradicate all infections. Post-infection sprays will arrest incubating infections for varying (and at this point, unpredictable) periods of time. When the fungicide residues drop below inhibitory levels, the surviving flyspeck infections begin growing again. Predicting when suppressed lesions resume growth is difficult because we can't accurately predict when fungicide residues are exhausted. The 270 hours of accumulated wetting after petal fall incubation period for flyspeck can perhaps be viewed as a "grace period" for lapses in fungicide coverage. If apples are consistently protected from infection during summer and fungicide residues are removed by heavy rains on September 1, then flyspeck will not appear on fruit so long as fruit are harvested and cooled before they are exposed to 270 hours of accumulated wettingl. However, if apples are left unprotected through 90 hours of wetting in July or August after conidia are being released, then part of the grace period will have been used in July-August and flyspeck may appear on fruit more quickly than otherwise expected in September. In real life, the total grace period for lack of fungicide protection during the growing season is probably less than 270 hours of accumulated wetting because flyspeck can continue to grow on wet fruit surfaces after harvest until fruit are cooled below roughly 45°F. Fluctuations in air temperatures as storage rooms are filled can cause condensation on surfaces of cold fruit already in the room, and that moisture can allow continued growth of flyspeck. I don't know how much of a 270 hour incubation period can be completed after harvest, but I suspect that up to 70 hours of the required 270 hour incubation period could occur after harvest if fruit are not cooled rapidly. Application of a postharvest fungicide drench might suppress growth during the cool-down period after harvest, but I am not aware of any data that addresses this question. Given all of the above, the safest approach for controlling flyspeck will be to maintain fungicide coverage throughout summer after the 270- hours of accumulated wetting after petal fall threshold has been reached. If extended rainy periods preclude timely respraying of blocks after heavy rains, then that lapse in coverage may use up part of the preharvest "grace period." Wet autumn weather, such as we have had in recent years, may be contributing to elevated inoculum levels in hedgerows and woodlots. Thus, extra caution (i.e., extra sprays in September and perhaps even in early October for late varieties) may be warranted until we get a dry summer-fall combination to break the current high inoculum cycle. Late summer sprays for flyspeck can be compromised by incomplete coverage of fruit surfaces. Including a surfactant with the fungicide during late summer may be helpful, but an excess of surfactant will only cause excessive run-off, thereby leaving less residue on fruit than a spray applied with no surfactant. Probably the best way to improve coverage in late summer sprays is to reduce tractor speed and increase the volume of water applied per acre. |
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| USDA cherry production estimates National Agriculture Statistics Service, 6/21/07. For the full length version please visit: http://www.ipm.msu.edu/cat07fruit/pdf/6-26cherryproduction.pdf United States tart cherry production is forecast at 294 million pounds, 11 percent above the 2006 production and 9 percent above production in 2005. Michigan, the largest producing state, expects a crop of 230 million pounds, up 21 percent from the 2006 crop and 11 percent above 2005. A severe freeze on April 7-8 destroyed the majority of the tart cherry flower buds in the southwest portion of the State, while there was less damage in west central Michigan. Conditions in the northwest were excellent during bloom and pollination, leading to high yield potential. United States sweet cherry production is forecast at 317 thousand tons, up 8 percent from 2006 and 27 percent above 2005. If realized, this will be the highest production on record. The Michigan crop is forecast at 26.0 thousand tons, 21 percent above the 2006 production, but 4 percent lower than the 2005 crop. Michigan growers reported that sweet cherry crop potential is very good. The Washington forecast of 155 thousand tons is unchanged from the June Crop Production report. The forecast is 9 percent below 2006 but 13 percent above the production in 2005. If realized, this will be the second highest sweet cherry production on record. Eastern Washington experienced some damaging frosts in early spring, but growing conditions during June have been good. Fruit size and quality are expected to be very good. Production in California is forecast at 92.0 thousand tons, 119 percent higher than 2006 and 75 percent above 2005. The California forecast is carried forward from the June 1 forecast. Favorable spring weather with no extended rain was ideal for pollination. Acreage increases and good-sized fruit have increased California’s sweet cherry production potential. Oregon production is forecast at 40.0 thousand tons, unchanged from the June Crop Production report. The forecast is 20 percent below 2006, but 40 percent above the production in 2005. Many growers along the Columbia River and in the Willamette Valley experienced a damaging late frost. |
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| Get a head start on management of bunch rot diseases in grapes There are several late-season bunch rots that can affect wine grapes in Michigan. The most common of these is Botrytis bunch rot caused by Botrytis cinerea, the same fungus that causes gray mold in a number of other crops. Tight-clustered varieties such as ‘Pinot gris’, ‘Pinot noir’, and ‘Vignoles’ are particularly susceptible to Botrytis bunch rot. Another, more sporadic bunch rot disease is sour rot, which smells distinctly of vinegar due to the presence of acetic acid bacteria. Often other organisms are also involved in sour rot, including various fungi and yeasts. Damage can be extensive because infections that begin in a single berry can rapidly spread to adjacent berries and destroy most or all of a cluster. While under cool, dry conditions, Botrytis bunch rot sometimes can be beneficial for wine quality (“noble rot”), sour rot is very undesirable. Disease symptoms Bunch rot often begins in one or a few berries, usually at the site of an injury, and then spreads rapidly throughout the cluster. Generally, rotting berries turn brown and become soft, collapse or shrivel up. Specific pathogens are sometimes identifiable by their appearance. Botrytis produces gray spores,whereas Penicillium produces green spores, and Aspergillus and Rhizopus have dark brown or black spores. Sour rot often has a wet look to it, with berries collapsing and leaking juice and no visible mold growth. It also results in the typical vinegar smell from which the name sour rot is derived. Botrytis bunch rot can sometimes be confused with Phomopsis fruit rot; however, Phomopsis usually does not produce visible mold (only small black pycnidia) on berries, does not smell, and is characterized by a black or dark brown necrosis on the rachis and a browning and shriveling of the berries, much like a balloon that is being deflated. Phomopsis-infected berries are not usually leaky and tend to drop off when the berry stem is killed. Factors that favor disease development Injury to the berries is the primary factor influencing bunch rot development. As berries ripen and sugar content increases, injured fruit becomes increasingly susceptible to bunch rot pathogens. Other than Botrytis cinerea, which can directly penetrate intact berry skins under conditions of prolonged moisture or very high humidity, most other bunch rot organisms are opportunistic pathogens that live in the soil or on plant surfaces and can only cause infections if they gain entry to the berry through wounds. Examples are injuries from bird and insect feeding, hail, rain splitting and mechanical cracks or fruit abscission (separation from the pedicel) caused by growth pressure in tight-clustered grape varieties. Entry holes created by grape berry moth larvae are a common cause of bunch rot as well. Similarly, early-season feeding injury from thrips can cause scarring on fruit skin that reduces its elasticity, resulting in small cracks as the berry grows. Fruit flies that are attracted to rotting or overripe fruit may also play a role in development and spread of sour rot. In addition, infection by the powdery mildew fungus creates small dead spots on the berry skin, which can lead to cracking of the berry and possible invasion by bunch rot pathogens. Even inconspicuous powdery mildew colonies resulting from late-season infections can increase the severity of bunch rot. We have to remember that these microorganisms operate on a very small scale, so that even microscopic wounds that are invisible to the naked eye can lead to infection. Bunch rot is more common in grape varieties with tight clusters that may experience fruit abscission or splitting from growth pressure. Any juice leakage from cracked or abscised berries also boosts growth of fungi, yeasts and bacteria. In addition, wet weather during fruit ripening also favors bunch rot, and the longer the wet period, the greater the amount of rot. Therefore, grapevines with dense canopies that dry slowly and maintain high humidity have an increased risk of bunch rot. Disease management strategy One of the main goals in managing bunch rot diseases is to minimize injuries to berries that enable bunch rot pathogens to get established. For instance, effective management of grape berry moth and powdery mildew will greatly reduce the risk of bunch rot in many vineyards. In addition, promoting good air circulation within the grapevine canopy also reduces the risk of bunch rot. Canopy management methods aimed at improving air circulation and reduce humidity include leaf removal in the fruit zone (do this soon after fruit set if possible – late and excessive leaf removal can result in sun scald), shoot positioning, shoot thinning and hedging. Limit excessive vegetative growth by balance-pruning and avoiding excess nitrogen fertilization. There are a number of fungicide options for control of Botrytis bunch rot, including Rovral, Vangard, Scala, Endura and Elevate. However, these are generally ineffective against sour rot and other bunch rot fungi. Captan, as a general broad-spectrum fungicide, is sometimes used to control a variety of bunch rot fungi, but does not have activity against bacteria. While we have no experience testing products in Michigan for control of sour rot, there are two products that have sour rot listed on the label: BlightBan A506 (Pseudomonas fluorescens A506) and Serenade Max (Bacillus subtilis QST 713). There are several formulations of Serenade available, but Serenade Max is an improved, concentrated version. We cannot comment on their efficacy, but they may be worth a try since there is not much else available. Both BlightBan A506 and Serenade are biological control products containing bacteria that are antagonistic to a variety of other microorganisms. In fact, BlightBan A506 is used for reduction of frost damage and russetting on tree fruit and small fruit crops. It works by suppressing the growth of frost-forming and fire-blight inducing bacteria on plant surfaces. Both are strictly protectants, so thorough coverage is important. It would be important to start sprays well before veraison. BlightBan A506 is recommended at bloom and again prior to bunch closure (5.3 oz per acre). Serenade Max is recommended at bloom, before bunch closure, at veraison and pre-harvest (1-3 lb per acre). Both have a 0-day PHI. Serenade is OMRI-listed. |
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| Regional reports 1 -- Southwest Mark Longstroth Bill Shane Greg Vlaming Weather Last week was warm with highs in the 80s and lows around 60°F. The last few days have been hot with highs over 90°F. A cold front on June 19 scattered about a quarter inch of rain across the region. Another cold front this week has a slight chance of rain. Soils are dry and soil moisture reserves are low. Annual crops such as corn and soybeans are wilting in the field and growers, who can, are irrigating. Under these conditions, crops can use up to a quarter of an inch of water a day. The forecast is for continued warm weather with little chance of rain. We are about 10 to 14 days ahead of normal and fruit are ripening early.
Japanese beetles are easy to find. We are catching blueberry maggot and cherry fruit fly. San Jose scale crawlers are settling on the fruit. Aphid numbers are building. We are catching peach tree borer. Tree fruitPeaches are 1.5 to 2 inches in diameter. Oriental fruit moths trap catches are rising. The second generation of Oriental fruit moth was biofixed for June 18. Control sprays are targeted for 200 GDD past Biofix, the beginning of egg hatch. We have already accumulated this amount and growers need to protect their fruit. Peach tree borer trunk sprays should be applied soon. Tart cherry harvest is underway. Fruit size and quality look good. There is little sign of cherry leaf spot. Sweet cherry harvest continues. Eastern cherry fruit fly maggots and cherry fruit worm larvae have been found in fruit. Growers should maintain brown rot protection. Apples are 1.25 to 1.5 inches in diameter. Codling moth trap catches are down. Obilquebanded leafrollers are past peak egg hatch. A spike in Oriental fruit moths indicates that the second-generation flight is starting and egg hatch has begun. European red mites numbers are building in some orchards and hard to find in others. Aphids are common on actively growing shoots. Leafhopper burn from potato leafhopper is easy to find. At this point in time, growers are typically applying an insecticide treatment every other week, due to multiple pest emergence. Growers should include a fungicide in their next cover spray to control sooty blotch and flyspeck. Bill Shane has calculated that we have accumulated 200 hours of wetness since petal fall and disease symptoms begin to appear at 250 hours. We can pick up four to six hours of wetness when we have heavy dews even if we have no rain. Small fruit Blueberry harvest is well underway for early varieties. Growers who can irrigate should be applying water now to maintain fruit size. Sprinkler irrigation is conducive to fruit rot development and fungicide protection is very important in these fields. Blueberry maggot is flying. In Grapes, Concords are nearing berry touch and vinifera are at buckshot berry. Berry growth has been rapid. Berries are about half of the final berry weight at about 1200 GDD base 50 after April 1. We are now around 1000 and should be close to 1200 next week. Grape berry moth larvae are moving into the fruit. Given the dry conditions, powdery mildew is the primary disease concern, but growers should apply fungicides to control black rot, phomopsis and downy mildew. All these diseases have been found in sprayed vineyards. We expect to see more Japanese and grape leafhopper numbers beginning to build. Strawberry harvest is over. Growers are renovating fields. Growers should consider Admire treatment to control Potato leafhopper on renovated plants. In raspberries, growers are harvesting both red raspberry and black raspberries. Japanese beetles and potato leafhopper are easy to find. Early treatment will discourage feeding. Cranberries are pinhead fruitm and a post bloom fungicide treatment should be applied. Upcoming meetings The next Monday Fruit Update meeting will be Monday July 3, 5:00 PM, at the Fruit Acres Farm in Berrien County. There are RUP credits available for the Monday Fruit Update meetings. The next grape IPM scouting meeting will be July 12 at Bob Dongvillo's farm, south of Scottdale. These meetings start at 6:00 PM. For more information on these meetings, call Mark Longstroth at (269) 675-8313. |
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| 2 -- Southeast Bob Tritten Weather Continued warm temperatures have resulted in earlier than expected sweet and tart cherry harvest, and summer red raspberries are following rather quickly. Our season is still running several days ahead of normal in terms of degree day totals, but two weeks ahead of normal if we look at phenology of fruit ripening and first harvest of sweet and tart cherries. Soil moisture supplies are much below normal for most of our reporting stations across the region. It was hoped that last week’s rain event on Tuesday, June 19 would have brought more precipitation. Most farms received around 0.20 inch of rain, while a few lucky folks received about a 1 inch. Irrigation systems have been operating around the clock at many farms across the region. Southeast Michigan growing degree day totals for March 1 to June 25
Tree fruits Apples are mostly at a 1.625 inch in diameter in the Flint area, and 1.75 to almost 2 inches in the southern part of the region. We saw a fair amount of apple drop last week. It is a bit difficult to say if that apple drop was caused by thinners or just a normal June drop. I suspect that it is a result of the thinning applications that were made. San Jose crawlers have been seen at many farms across the region. Now is a prime time to control this recently rejuvenated pest problem. Codling moth trap catches are on the rise again. We are most likely seeing the “B” peak at this time. Oriental fruit moth trap catch is on the rise for the start of the second generation flight. For the most part, we still have rather low numbers, but I expect them to jump dramatically throughout the week. Obliquebanded leafroller adult flight has dropped down to near zero, with no larvae being seen. Green apple aphid populations have exploded at many farms across the region. I am starting to see aphids on the fruit, which is a point of concern. Wooly apple aphids continue to move into new wood and suckers. Potato leafhopper nymph numbers are quite high at a few farms, however most are under control. Spotted tentiform leafminer adult flight started as second generation is now underway. European red mite adult numbers continue to build, with a few blocks now over threshold. Two-spotted spider mites are being found here and there, with none at threshold at this time. We have a good number of predators across the region, especially now that we have a good population of green apple aphids. As a result of rainfall last Tuesday morning, I called an end to primary apple scab season at that time. Looking back at the apple scab season, most farms have a touch of scab. I continue to see new fireblight strikes, however far fewer than last week. Pear fruit size appears to be about the same as last week. Many growers have now pruned out suckers that will help to lower the pear psylla population and make control much more effective. Peaches continue to size well with most being around 1.75 inches for Red Haven. I continue to see some high levels of green peach aphids, as well as leaf drop caused by bacterial leaf spot infection earlier in the season. Thinning is now complete at most farms. Sweet cherry harvest is under way at all farms across the region. With the lack of a good crop of sweet cherries, some farms are looking to finish harvest over the weekend or early next week. As I indicated in last week’s Fruit CAT Alert report, this is the earliest start that I’ve seen in sweet cherries. The fruit has sized rather well, with excellent flavor. No cherry fruit flies have been caught. Across the district, birds continue to be a serious problem this week in sweet as well as tart cherries. Tart cherries are being harvested at many farms across the region, with the rest opening late this week or over the weekend. Again, this is an early start of tart cherry harvest. The fruit took on a final swell last week prior to the beginning of harvest. Plums are now around one inch, with no new pest problems. Small fruits Strawberry harvest has been wrapped up at most farms across the region. The remaining farms are thinking that they will be closing rather quickly as a result of heat with the last few days. Most growers reported a good yield, with the exception of some that did not have adequate rainfall or irrigation. So, many farms have now started their renovation process. Raspberry harvest is beginning for summer red raspberries. Berry size is fairly good. Black raspberry harvest will begin later this week. I am seeing a fair amount of cane collapse in black raspberries this last week. Fall red raspberries continue to grow new canes with most being about 3 inches in length. Potato leafhopper populations are high in many fields of fall red raspberries. I am starting to see bud development on many of the shorter canes. Blueberries have not sized much over the last week; however they have developed a fair amount of color. No blueberry maggots have been caught. |
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| 3 -- Grand Rapids Area Phil Schwallier Amy Irish-Brown Carol Garcia-Salazar Tree fruit growth stages Hand thinning of apples and peaches continues where needed. Strawberry harvest is just about over with only some late varieties left. Sweet cherry harvest began over the past weekend. Irrigation is being done where it is available in small fruits and tree fruits. It will be especially important to irrigate strawberries after renovation this year. The general Grand Rapids area has been without significant rainfall for the last three weeks and plant stress is of concern, especially in newly planted trees. The rule of thumb for newly planted trees is 10 gallons of water per tree per week. Tree fruit Fire blight symptoms from the trauma events in early June should be present now, but many blocks are still very clean of blight this year, despite the high risks for blossom blight and the couple of trauma blight situations we had. Growers should still be concerned about potential trauma blight until terminal bud set. We have satisfied enough hours for summer diseases to be a concern, and fungicides for this disease complex should be added to cover sprays over the next several weeks. A regional biofix for Oriental fruit moth was set for Grand Rapids area on May 10, and 950 DD45 have been accumulated since then indicating that first generation Oriental fruit moth should be winding down and cover sprays are not as critical right now. Trap numbers should begin to increase soon, as second generation flight should begin at any time in the Grand Rapids area. Lures should be changed right away to get the best trap numbers. Early egg hatch for second generation is probably a week or so away yet. A regional biofix for codling moth was set for May 20. We have accumulated 630 DD50 since May 20 and 665 DD50 since May 15. Egg hatch should be declining, but cover sprays for first generation codling moth need to be maintained for at least another week or so to avoid stings, especially in blocks with significant trap catches. European red mites continue to be a problem in some blocks, but there are many blocks without any mites in them as well. Numbers of mites per leaf range from 0 to over 20, depending on site. Five mites per leaf is the threshold for June, and it goes up to 5 to 10 mites for July. Predators are still difficult to find in European red mite populations. Green apple aphids continue to be found. In most blocks, the number of aphids has been at a standstill over the last two weeks, but they are starting to build in a few blocks. Predators continue to be found in aphid colonies. Growers in the Grand Rapids area should be ready to deal with Japanese beetle at any time. The very first reports are being made of them in the area. There are other chafer beetles present. |
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| 4 -- West Central Mira Danilovich Weather and crop development The early part of the week brought us some much needed rain and cooler temperatures. The rest of the week couldn’t have been better; cool nights and not-so-hot days with plenty of sunshine. Crops are continuing to develop nicely. Early varieties of sweet cherries are being harvested. Tart cherries are not far behind. Harvest is expected to begin by the end of the week or early next week. It looks like we will have a nice crop; the prediction is 60 million pounds. Strawberries are just about done. It looks like we might start harvesting early Japanese plum varieties by the end of next week. West Central Michigan growing degree day totals since March 1- June 25
Tree fruit In apple scab, there are no new infections. Scouts are reporting seeing lesions from previous infections throughout the area, though it does not appear to be at alarming levels. Fireblight is present in many blocks throughout the area. Cherry leaf spot had a low infection period last week following up the rain event on Monday-Tuesday, June 20-21. Overall, cherries are looking very good with a few lesions being reported. Powdery mildew is still showing up in all fruit. Codling moth numbers are starting to go up. The average number has gone from 0.7 to 1.5 moths per trap. In a few blocks, there is significant pressure, and the trap catches have consistently been high. American plum borer is starting to gain in numbers. It has gone from 2 to 13 moths per trap this week. There is a slight drop in both greater peachtree borer and lesser peachtree borer numbers. Obliquebanded leafroller have exploded. They have doubled their numbers since last week. For the first time in three weeks, we have found a few red banded leafrollers in a couple of traps. Tentiform leafminer numbers have significantly gone up, an increase of 75 percent. First catch of cherry fruit fly was reported June 19 in Mason and Oceana counties. Flies have been identified as black cherry fruit flies. Rose chafers and Japanese beetles are easily found throughout the area. There are quite a few potato leaf hoppers. European red mites and two spotted mites are present in a few blocks, but in isolated pockets. That is true for apples and cherries. |
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| 5 -- Northwest Nikki Rothwell Duke Elsner Growing degree day accumulations at NWMHRS Growth stages at NWMHRS (6/26/07—8:00am) The weather continues to be warm and dry in northwest Michigan. We had rain on June 20, but nothing more recently. The weather is predicted to cool down in the coming days. Crop report Growers are reporting a lot of cherry drop in the past few weeks. Many growers are concerned about the fruit on the ground, but we still have lots of cherries on the tree. The USDA estimate for tart cherries is around 230 million pounds for Michigan, and the United States prediction is estimated at 293 million pounds. The breakdown for Michigan from the CIAB is 160 million pounds, West Central 59 million and the southwest part of the state is predicted to be 11 million pounds. Cherries are ripening quickly, and many growers are starting to apply ethephon. In apples, no wetting events are causing disease infection, and we have not observed scab lesions from past infections. Spotted tentiform leaf miner numbers are climbing, but codling moth trap catches are down to less than 1 moth/trap. Obliquebanded leaf roller numbers are also down this week. Again, no diseases to report in cherry. Insect numbers have remained constant, except for obliquebanded leaf rollers, which have declined from last week. We are still catching cherry fruit flies in the unsprayed entomology block, approximately 15 per trap. |
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| Weather news Following almost another entire week without significant rain, a weak- and slow-moving cool front will move west to east across Michigan Wednesday, June 27, bringing the next chance for showers and thunderstorms. Given that dynamics with the system are weak, rainfall totals will be limited in most areas to 0.25-0.50 inch or less, and some areas may remain dry. After the front clears the state, cooler and drier weather is likely by late Thursday continuing through the upcoming weekend as Canadian-origin high pressure moves into the region from the north. Temperatures through Wednesday will remain at above normal levels with highs in the 80's and lows in the 60's, gradually falling back to normal or slightly below normal levels by Friday. Look for highs ranging from the upper 60's or low 70's far north to near 80 south and low temperatures from the upper 40's or low 50's north to low 60's south through Sunday. Earlier this year, sea surface temperatures in the equatorial Pacific region were falling, and the development of an El Niño event looked possible. That surface temperatures trend unexpectedly stabilized during the spring season and has remained steady since, reducing the chance of an El Niño anytime soon. ENSO factors thus play little if any role in the new series of NOAA long lead outlooks for the upcoming months. For the month of July, the outlooks are directionless for Michigan and the Upper Midwest, with near equal chances for below-, near-, and above normal mean temperatures and precipitation. During July, warmer than normal temperatures are expected across eastern and western sections of the United States. Cooler and wetter than normal weather is expected to continue (due to abnormally wet soils) from the central Cornbelt region south- and westwards to Texas. During the three-month (July-September) period, the outlooks suggests warmer than normal temperatures in Michigan, with the equal odds scenario for precipitation. Warmer than normal temperatures are also forecast for the upcoming fall season as well. |
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