Christmas trees
Field crops
Fruit
Home and yard
Nursery and landscape
Turfgrass
Vegetable
Diagnostic Services
Soil/Plant Nutrient Lab
Enviro-weather
Regional IPM Center
Pesticide safety
Organic: New Ag Network
Invasive species
Sustainable ag & food systems
MSU ANR departments
MSU Extension
Site index
Contacts/permissions
| Fruit Crop Advisory Team Alert newsletter | ||||
|
||||
 |
||||
| Vol. 22, No. 6, May 15, 2007 |
||||
| In this issue Tree fruit news  Plum curculio management and spray timing Fungicide cover spray considerations for cherry leaf spot control TNRC trapline data: Oriental fruit moth Small fruit news Fruitworm management in blueberries Be on the look-out for Phomopsis twig blight in blueberries Mummy berry update in blueberriesOther news Regional reports Weather news |
|
|||
|
||||
| Plum curculio management and spray timing Plum curculio overwinter as adults in the soil, litter and ground cover trash in orchards and in surrounding areas. As soon as daytime and evening temperatures exceed 60°F, plum curculio will begin to move, especially when a light, misty rain or humid night co-occurs with early spring warming trends. The weevils move into orchards and begin to feed as leaves begin to emerge. Their feeding activity expands to blossoms, stems and fruit as they become available. Monitoring Pyramid traps are the most efficient means of monitoring plum curculio activity early in the season. These traps outperform in-tree screen traps in adult capture about two to one in many seasons. Baiting traps with lures (plum essence or benzaldehyde) significantly increases trap catch, but the addition of pheromone baits only slightly increase (1.2:1) plum curculio captures in either trap. Traps are a good indicator of likely plum curculio pressure in the area, and should be placed on the borders of orchards where producers or scouts have observed damage in past years. Often these locations have woods, unsprayed orchards, feral trees or other sources of overwintering plum curculio populations. Table 1. provides a guide for evaluating plum curculio population pressure in three fruit crops. |
||||
Table 1. Population pressure rating: general trap catch/week bloom to 370 dd50 plum curculio
Management In low pressure situations in apples and peaches, growers may want to consider only one insecticide between 200 and 250 DD50. In cherries, it is advisable to cover spray trees from shuck split to 400 DD50, and, if plum curculio are still being trapped, include a third cover beyond 400 DD. Four key factors should be considered when deciding when, how often and with what to manage plum curculio populations in the spring. Note that some growers may want to consider summer generation control of plum curculio in moderate, high or extreme pressured cherry orchards. In these situations, Guthion and Esteem work well. Normally, mid-season controls suppress plum curculio populations in apple and peach orchards, and no summer generation controls are warranted for plum curculio. An exception may occur, when pome and stone fruit management targeting codling moth and leafrollers in mid-season is primarily pheromone disruption or virus (from 1250 DD50 to harvest). First, historical damage in previous years should be considered. The greater the plum curculio pressure in the previous one or two seasons, the greater the care and focus on plum curculio in the current season. Second, the best timing (Table 2.) depends to a great extent on accumulated degree-days and insecticide(s) chosen. Third, understanding and identifying the chosen insecticide’s performance characteristics is important in evaluating control measures taken. For instance, it helps to know whether or not the insecticide selected has curative activity (kills larvae in fruit), and the length of its residual action window. It is also important to consider the modes of insecticidal activity that each compound has, some relying solely on lethal activity versus those that have repellent, antifeedant and oviposition deterrent effects. Lastly, a number of weather related factors can dictate re-treatment to control plum curculio; especially in processed cherries. Therefore, degree-day accumulation (for timing sprays), rain events (residue wash off), and other seasonal characteristics (like cool and cloudy versus warm and sunny) can affect breakdown of sprays and the need for additional coverage. All of these factors contribute to plum curculio control timing, insecticide selection and re-treatment. Table 2. Labeled control materials for plum curculio
MSU is pursuing a post FQPA USEPA defined reduced risk and OP-alternative spray program, to control plum curculio in apples, cherries and peach. For apples, we are recommending an application of the oxadiazine Avaunt at petalfall to kill mated females before they oviposit. In cherries and peaches, Actara can be used at shuck-off to effectively control plum curculio. If plum curculio populations are low, growers may choose to delay applications for up to a week or two, knowing that Actara and the other neonicotinoids have strong curative activity on larvae. If new oviposition scars are observed, or a larval infestation, or plum curculio trap catch remains high, we are recommending a “bail out” Guthion application between 300-350 DD50 up until the PHI of 15 days in cherries. Guthion has also been shown to have curative activity on PC in cherries, killing larvae that have already begun to develop in the fruit. In the case of infested apples, larvae will not survive in developing fruit unless the infested fruit falls off the tree, usually during June drop. As Rimon is already being used for codling moth control in the latter part of the plum curculio control window, we are currently developing a protocol for use of Rimon as a control for plum curculio in apple. We are evaluating the effect and timing of codling moth Rimon sprays on reducing plum curculio’s egg laying success. In our pursuit of more effective plum curculio controls in both organic and conventional crop management, we have been building a plum curculio degree-day phenology model. These efforts link growing degree-days with key plum curculio control periods and registered USEPA defined reduced-risk and OP- alternative insecticides, to bracket ideal spray timings. The accompanying figure early season degree-days with critical plum curculio control periods on both tart cherry and apples. |
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| back to top |
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Fungicide cover spray considerations for cherry leaf spot control Cherry leaf spot 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, however, Montmorency tart cherries will drop with only a few lesions, signifying the importance of proper leaf spot management. As soon as leaves unfold in the spring, they are susceptible to leaf spot infection. Similar to apple scab, the leaf spot fungus overwinters in infected leaves on the orchard floor, and produces ascospores that serve as the primary inoculum. Ascospore discharge occurs during and shortly after rainfall from early bloom to about six weeks after petal fall. Ascospore discharge is highest over a wide temperature range (60 to 85°F) and lowest at 41 to 46°F. Conditions in Michigan during 2007, have been favorable for leaf spot spore discharge. 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 can 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, also typically exhibit reduced flower bud formation and often set less fruit the following season. Management of cherry leaf spot should be initiated around petal fall or sooner if susceptible leaf tissue is present. The best fungicide for early season leaf spot management is chlorothalonil (Bravo). This is a broad spectrum fungicide (not subject to fungicide resistance concerns) that provides excellent leaf spot control. Full covers are particularly important early in the season, as infections that occur early can lead to significant buildup of lesions and more inoculum resulting in epidemic potential if sufficient rain occurs. The use of chlorothalonil (Bravo) is not allowed after shuck split (except post-harvest). There are five major classes of fungicides registered for leaf spot control that could be used as cover sprays (Table 1). Resistance to SI fungicides in the cherry leaf spot fungus, occurs universally throughout Michigan orchards. SI resistance is quantitative, meaning that leaf spot populations exhibit a wide range of susceptibilities to these fungicides. However, use of SI's will continually shift orchard populations such that they contain more and more highly resistant individuals. These shifts result in significant control failures and we have observed such control failures in several orchards over the last few years. Table 1. Class of chemistry and fungicides registered for cherry leaf spot control.
Likewise Syllit (dodine) resistance has been reported in Michigan previously. However, Syllit FL at 27 fl oz per acre is an excellent leaf spot material if strains are not resistant. If Syllit has not been used for many years in a particular orchard, then this is a good candidate for use in 2007. Syllit should be tank-mixed with Captan as a resistance management strategy to prevent any buildup of dodine resistance. After shuck split, the use of the strobilurin Gem (3.0 to 3.8 oz / A) or the strobilurin/boscalid Pristine (10.5 to 14.7 oz / A) at the first cover timing is an excellent choice, because both of these materials are also excellent powdery mildew materials. Remember that both Gem and Pristine are excellent fungicides that are at risk long-term for the development of fungicide resistance. Growers need to think about long-term protection of these materials such that they remain effective over a significant number of years. Overuse of these fungicides now could compromise this effectiveness. We suggest that both Gem and Pristine are not used more than two times per season. Copper has proven to remain a highly effective fungicide for cherry leaf spot control. Results from several experiments, consistently show that cherry leaf spot treatments utilizing one, two, or three cover sprays of copper sulfate (1.2 lbs metallic Cu per acre) provided excellent cherry leaf spot control equivalent to or better than standard programs using conventional fungicides such as strobilurins. Successful efficacy of copper compounds, aids both conventional growers, as copper extends the life of traditional fungicides, and organic growers because copper is the only viable option for disease control in tart cherry. The only detriment to copper use is the potential for phytotoxicity effects to tart cherry trees. When copper compounds are applied to tart cherry trees in advance of hot, dry weather, the trees can exhibit phytotoxicity symptoms such as bronzing on the undersides of leaves, large yellow and brown blotches on the upper surface of a few leaves, or blackening of veins on the undersides of leaves. In severe cases, copper phytotoxicity can also cause leaf defoliation. Thus, the second and third cover timings are good for copper use if temperatures are not projected to remain above 80°F for several days. |
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| back to top |
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Fruitworm management in blueberries Pheromone traps should already be out in Michigan blueberry fields for monitoring of adult cherry fruitworm (CFW) and cranberry fruitworm (CBFW). CFW flight is well underway in most areas of southwest Michigan and yesterday, May 14, we received the first report of CFW larvae entering fruit in a Bluejay field. We have also trapped the first CBFW moths in the past few days, one in Grand Junction, and one in Fennville. These were only single moths, but this does indicate the fruitworm management season is upon us. Once a consistent number of moths of either species is caught in monitoring traps and blueberries reach the early fruit set stage (as some of the earliest varieties are now doing), these fields should be considered for protection against fruitworm larvae. Scouting for the presence of fruitworm eggs on fruit is the best way to determine when control actions should begin. 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, especially in early varieties where it is more likely that CFW infested fruit could be harvested. 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. It is important to refrain from using compounds that are toxic to pollinators when these insects are in your fields. Two products registered for use during bloom or in the presence of pollinators have provided consistent control of fruitworms in trials at the Trevor Nichols Research Complex and in grower fields. These are the B.t. products such as Dipel® and Javelin®, and the insect growth regulator Confirm®. These products must be consumed by fruitworm larvae to be effective, so they are best applied over the top of fruitworm eggs, so they are eaten as the larvae emerge. B.t. products have short residual activity, typically around five days, so are best applied when daily temperatures reach 70°F. 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. 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. Because of its activity, it is most effective when applied just before egg-laying, so timing is critical. 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 or larvae come in contact with the insecticide. After 100 percent petal fall, the range of options for fruitworm control increases, with Guthion®, Imidan®, Asana®, Danitol®, Lannate® and Sevin® being the most effective of the broad-spectrum insecticides available. 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 SpinTorTM applied after petal fall 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 table and figure are designed to summarize several key factors that can help you select an insecticide for your integrated pest management program for fruitworm control in blueberries. Table 1. Details of insecticide options and timing for fruitworm control in blueberry
|
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| back to top |
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Be on the look-out for Phomopsis twig blight in blueberries Phomopsis twig blight is caused by the fungus Phomopsis vaccinii. This disease occurs in most blueberry-growing regions and is present at low levels in most fields. In some years and locations, twig blight can be severe, with over 100 blighted twigs per bush. The reasons for the outbreaks are not clear, but appear to be correlated with frequent or prolonged rains or irrigation events during bloom. Cultivars Jersey and Berkeley are particularly susceptible to Phomopsis twig blight. Bluecrop appears more susceptible to Phomopsis infection of newly developing canes. Symptoms of twig blight include dark brown lesions and death of young twigs (Figure 1, 2) and collapse of flower and fruit clusters on diseased twigs (Figure 3). The lesions may extend up to several inches from the tip of the twig and there may be more than one lesion per twig. The lesions initially grow fairly rapidly (up to an inch per week), then eventually stop expanding. In some cases, lesions can be seen surrounding dead buds (Figure 4). These buds may have been infected the previous summer or fall. In the spring, the fungus colonizes and kills the infected bud and then grows into the stem tissues. Phomopsis twig blight may be difficult to distinguish from other diseases that can kill flower clusters, such as mummy berry, Botrytis, and anthracnose. The presence of a spreading dark brown lesion is indicative of Phomopsis, but may also be anthracnose. If in doubt, apply a fungicide that is effective against anthracnose as well as Phomopsis. Phomopsis vaccinii overwinters in dead twigs and canes infected during the previous year(s) (Figure 5). Fungal fruiting bodies may be seen with the naked eye with a hand lens in bleached areas as small pimples on the surface of the bark (Figure 6). Once the weather warms in the spring and the twigs are sufficiently wetted by rain or irrigation water, spores are released from these fruiting bodies and are dispersed by rain and irrigation water. The majority of Phomopsis spores are released between bud break and bloom and infect young twigs and the tips of young green canes as they develop. Young, succulent tissues are most susceptible to infection. Older canes may be infected through wounds. Bloom is an important time to protect blueberry twigs and young canes from new infections. (If most twig lesions are surrounding dead buds, these may be from fall infections which cannot be cured at this point.) The most effective fungicides against Phomopsis are Indar, Topsin M + Ziram (or Captan), Pristine, and Cabrio. The protectant fungicides Bravo and Ziram (4 lb) are also effective, but may need to be re-applied after heavy rain. Bravo should not be applied after the start of bloom to avoid phytotoxicity to blossoms. |
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| back to top |
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Mummy berry update in blueberries
This past week most mummy berry apothecia in four blueberry fields that are being scouted in Allegan and Ottawa counties appeared dried up. However, shoot strikes were found in all of the scouted plots and ranged from three to 29 per bush. The number of shoot strikes increased with the number of mummy berry apothecia found at the site. Since it takes about two weeks for symptoms to show from the actual time of infection, shoot strike incidence will likely still increase in the next week or two. In addition, a few flower strikes were also found. Both shoot and flower strikes are sources of infectious spores for fruit infection. Good pollinating weather increases the risk of fruit infection, as bees serve as carriers of infectious spores when they move from infected shoots to susceptible flowers. The spores germinate on the stigma of the flower and then the fungus grows alongside the pollen tubes through the pistil into the ovaries. Individual flowers are most susceptible right after they open and susceptibility decreases over the next several days (Figure 1). Once the fungus reaches the ovaries, it colonizes in the developing berry. This infection is not noticeable while the fruit is still green, but can be seen as white fungal growth if the berries are cut open. Since all of the scouted fields were at least at 25 percent bloom, fungicide sprays to prevent fruit infection are recommended. A systemic fungicide such as Indar will be most effective, since we are trying to specifically protect the flower stigmas from infection. Indar is also effective against Phomopsis twig blight and canker. However, protection against anthracnose fruit rot is also important at this time, so add a protectant fungicide like Ziram or Captan to the Indar spray. Pristine is also good against the fruit infection stage of mummy berry (though maybe not quite as strong as Indar) and has excellent efficacy against anthracnose and Phomopsis as well. |
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| back to top |
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Regional reports Last week was pleasant with lows in the mid 40s and highs in the upper 60s and 70s. We had thunderstorms and rain, Wednesday morning May 9, causing infection by most fruit diseases. We had a long warm wetting event with fog and the next morning we had fog and heavy dew. The resulting wet period spanned over 30 hours, with about 24 hours of leaf wetness and an average temperature of 60ºF. Precipitation totals were about a third to a half inch of water. But windy conditions have dried the soils. Monday, May 14, was warm, over 80. Thunderstorms are possible Tuesday. This week’s forecast is for cool weather with lows in the 40s and highs near 60 with cooler temperatures forecast for rest of the week.
Tree fruit The May 9 rain was an infection period for apple scab, cherry leaf spot and brown rot in stone fruit. Plum curculio egg laying scars have been found in stone fruit. Plum curculio activity should fall off with the cooler temperatures this week and return with warmer temperatures. Insecticide applications should be targeted for later in the week when temperatures warm back up. We are catching American plum borer and lesser peach tree borer. Peaches are out of the shuck and fruit are up to 14 mm in diameter. The peach crop looks better and better. Large numbers of Oriental fruit moth adults are still being caught in pheromone traps. Egg hatch began May 5. No peach leaf curl has been reported. Growers should protect susceptible varieties from peach mildew or rusty spot. Tarnished plant bug damage can be found on fruit. Pheromone disruption of LPTB also suppresses GPTB. This tactic works best in large homogeneous blocks. Tart cherries are out of the shuck. Fruit are about 10 mm in diameter. Now that the fruit is clearly visible the crop looks much better. Growers need to protect against plum curculio. Growers need to assess their crop and determine if the amount of cherries available warrants a full pesticide program or a reduced spray program to maintain the leaf canopy and suppress cherry leaf spot. Conditions for plum curculio will be marginal after Tuesday until it warms up, but with a light crop growers cannot afford to lose any fruit. Copper is an effective protectant material to reduce cherry leaf spot but it needs to be applied before a rain and growers should avoid multiple applications without rain, which would lead to a build up of copper on the leaves and result in toxicity even in tart cherries. Sweet cherries are out of the shuck. Fruit are about 12 mm in diameter. Growers need to protect against plum curculio. Sweet cherries should be protected from brown rot from bloom until harvest and the possibility of warm wet rains exist this week. Copper should not be used on sweet cherries. Plum fruit are about 12 mm in diameter. Growers should be protecting against black knot and brown rot. Apple bloom is ending. Fruit are 8 to 12 mm in diameter. Warm temperatures on Monday raised the bacteria population to high levels and rain Tuesday could cause fire blight blossom infections of open flowers. We are updating our Code-A-Phones daily with fire blight conditions. Blossom blight symptoms should begin to appear next Monday. Streptomycin symptoms are appearing in susceptible apple varieties for last week’s fire blight spray. Conditions this week will be too cool for apple thinning. Growers should assess their crop and be ready to thin when highs begin to rise this weekend or next week. Apple scab symptoms can be found from the April 26 infection. The Enviroweather website is forecasting that all the apple scab spores are mature, but not all have discharged. Growers should maintain fungicide protection through the next good rain. Oriental fruit moth is being caught in good numbers in pheromone traps. Egg hatch began May 5. Codling moths began flying May 5, and were biofixed on Wednesday, May 9 in some locations, but the flight has been very spotty, light and variable. Unless you are sure you have biofixed with a sustained flight of moths you should wait to apply codling moth controls. It is entirely possible that many orchards will not biofix until next week because of the cool evening temperatures. Codling moths controls are applied at 100, (Rimon and Esteem, with residue under the egg) 150 (Proclaim Intrepid, Assail, Calypso, and Clutch, with residue over the egg) or 250 (Guthion, Imidan, Warrior etc., which are targeted for contact kill of the emerging larvae) growing degree-days after biofix. See the Enviroweather codling moth page. Obliquebanded leafroller larvae are feeding in shoot tips. European red mites and rosy apple aphids are out and growers and scouts should be looking for sap feeding spotted tentiform leafminers and the first mines. Pear fruit are 10 mm in diameter. Very little bloom remains, but growers should protect against fire blight. Pear psylla nymphs are feeding in the axils of leaves. Pear blister mite symptoms have appeared. Pear scab is similar to apple scab and pear scab symptoms should appear this week as with apple scab. Small fruit Blueberries are at full bloom and bees are very active. Mummyberry shoot strikes are appearing. The May 9 rain was an infection period for mummyberry. Growers should check the new Blueberry IPM Newsletter at the MSU Blueberry Site. Both cranberry and cherry fruit worms were reported caught in pheromone traps. Obliquebanded leafroller larvae are feeding on fruit buds. Grapes: Concord shoots are about 6 to 10 inches long and flower clusters are elongating. Vinifera have 4 to 6 and French hybrids have about 4 to 8. The rain we had May 9 was an infection period for powdery mildew, black rot and phomopsis in grapes. Growers have been applying early season disease control materials. This first fungicide spray is especially important for phomopsis control. Growers should apply protectants before the next rain. Large numbers of grape berry moth are still being trapped, but no treatment is necessary at this time. Check the MSU Grape website (www.grapes.msu.edu) for scouting updates. Strawberries are at full bloom. Given the dry conditions growers should be irrigating and applying bloom fungicides. Raspberries: Summer raspberry flower buds are visible. Fall raspberry shoots are about 6 to 12 inches high. Blackberries and summer raspberries are showing more decline due to winter cold and the Easter freeze. Cranberry buds have burst and are elongating. Now is the time for the first fungicide treatment. Miscellaneous Soils are dry and growers should irrigate if they can. Some fruit plantings from last year look stressed. This may be a result of the winter cold snaps. Herbicides applied to dry soils or drought stressed weeds are less effective. The Van Buren County MSU Extension Office is moving and there is a new number for the Paw Paw Code-A-Phone. The new Code-A-Phone number is 657-8217. You can use the old office phone number 657-7745 to contact Mark Longstroth until it is changed.The next Monday Fruit Update meeting will be Monday May 21, 5:00 PM, at the Fruit Acres Farm in Berrien County. We will discuss apple thinning. The next Grape IPM meetings are Thursday May 24. 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 2:00 PM in the Berrien County MSU Extension Office at the Southwest Michigan Research & Extension Center. These meeting are co-sponsored by National Grape Cooperative and MSU Extension and are open to all grape growers. There are RUP credits available for both the Monday Fruit Updates and the Grape IPM meetings. |
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| back to top |
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
2 -- Southeast The season is still running about three to five days ahead normal in terms of phenology and degree days. We have had rapid and lush growth over the last week. We had a significant rain event on Wednesday, May 9 that brought about 2 inches of rain across the region. With wet soil conditions last week, planting of tree and small fruit slowed. Most growers have nearly completed that job. Even though we had a couple of inches last Wednesday, there was a fair amount of field work going on yesterday. I think the high winds and warm temperatures have helped to now dry soils dramatically. We had another frost event on Saturday night into Sunday morning, with most growers having low temperatures in the range of 28 to 31ºF. This is not a concern on tree fruits. Most strawberry growers frost protected that morning. With high winds on May 14 coupled with some remaining bloom and young succulent terminal growth, trauma blight was a major concern. Southeast Michigan Growing Degree Day Totals for March 1 to March 21
Tree fruits Apples are mostly at late petal fall to fruit set around the region. There is still a fair amount of lingering bloom in many apple varieties. As of yesterday, I saw four to eight inches of new growth on many varieties of apples, this amount of new terminal growth is very unusual. I’ve not seen any codling moth trap catch in apples, however I expect to see it later today and more as we move throughout the week. Tarnished plant bug is a new pest in apples, however, their numbers are very low at this time. I’ve not seen any mullen bug, but I would expect to find activity here later this week. Plum curculio adults were seen in apples this morning, but no fruit stinging has been observed. White apple leafhoppers were seen for the first time this morning. Oriental fruit moth trap catches are generally higher across the region, with the most farms catching in the range of 20 to 30 per trap. Redbanded leafroller adult trap catch has dropped off a bit more, however I’m finding larvae around. I continue to see light amounts of several larvae, including obliquebanded leafroller, climbing cutworm, redbanded leafroller, Eastern tent caterpillar and others. This week, I saw fresh dogwood borer frass as larvae are actively feeding again in bur knots. As reported last week, I continue to see apple green aphid and rosy apple aphid. Apple scab spore discharge was heavy with last Wednesday’s rain event. We are not close to calling an end to primary apple scab season at this time. I have seen apple scab lesions on leaves at a few farms, however, I would expect to see more lesions mid week from last Wednesday’s major rain event. Most growers had a high apple scab infection period from that event. With the bloom last week in apples, there was a fair amount of streptomycin applied at several farms across the region. Fireblight control continues to be a high concern at this time. Pears are at fruit set, with about six inches of terminal growth thus far this year. Pear psylla continue to fly in fairly good numbers, with abundant egg hatch. Peaches are just beginning shuck split on a few of the varieties. There are some areas of east Michigan that have a good crop of peaches, however most areas have a poor peach crop this year. Tarnished plant bugs are now being found in peaches. Growers need to protect from early season pests as we are approaching shuck split. Sweet cherry growth has exploded this year, with most sweet cherries being around 10 mm in size. We also have an extensive amount of new terminal growth for this time of the season, with most terminals having four to five inches of new growth. The extent of our sweet cherry crop is now becoming more apparent. I estimate that we have about 30 to 40 percent of a crop. Plum curculio adults were found in sweet cherries this morning, but were not causing damage. Tart cherries are mostly at 6 mm in size, however there is a wide spread of fruit sizes, with even some bloom remaining. Some minor amounts of leaf spot are starting to show up on tart cherries. Our tart cherry crop is lower than I estimated a few weeks ago, most people are looking at about a 40 percent of a crop. Plums are at shuck split, with good crops of plums coming along at this time. Small fruits Strawberries are at 30 to 50 percent bloom in the southern part of the region and about 10 percent bloom in Flint and to the north. Most growers had a frost event on Saturday night/ into Sunday morning with temperatures in the 28 to 31ºF range. This was generally the first frost protecting event for the season. I saw my first strawberry clipper damage along the edge of woodlots and fence rows yesterday. I also saw tarnished plant bug for the first time in strawberries yesterday. Raspberries continue to put on new growth. Many varieties of summer red raspberries are now starting to show extensive tip death from winter injury. Fall red raspberries continue to grow quite nicely with most being about six to eight inches in length. Flower buds are now visible on red raspberries. Blueberries are at full bloom. I saw my first mummy berry shoot strikes at a few farms yesterday. Grapes are at about five inches in length with flower buds starting to be visible. |
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| back to top |
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
3 -- Grand Rapids Area Growth over the last week has continued to be at a normal pace for all tree fruit crops. Apples are mostly at or just past full bloom with some early varieties at petalfall. Weather conditions during bloom have been outstanding this year with much bee activity happening. We are expecting nearly a full apple crop potential and thinning will be required. Apogee applications should be made right away if not already – both for fire blight suppression and growth control. Tree fruit Apple scab should be near 95 percent of spore maturity now, which is a bit earlier than usual, but we are running about nine days ahead in degree day accumulations. Some light rains moved through last week, resulting in some very high ascospore discharges for the season and only marginal conditions for apple scab infections depending on location. No lesions from the April 1 rains have been found, and I don’t expect to find them. Lesions from the infections in late April have just begun to show up over the past weekend as expected. With bloom open and higher than normal temperatures last week, the risk for fire blight blossom infections were great with at least two days and in some locations, three days of infection according to the MaryBlyt model, depending on which weather station data you use and which location saw rain or heavy dew. Blossom blight symptoms could be seen anytime this week in non-sprayed trees. High winds on Monday (May 14) afternoon and through the night, into Tuesday morning have triggered a trauma blight situation in the Grand Rapids area. As the warm weather continues, growers will still need to think about adding a mildewcide in the tank for powdery mildew in the next week or so for those varieties that are susceptible to it. A regional biofix for oriental fruit moth was set for the Grand Rapids area on May 10. Adult numbers in traps last week were lower overall than usual, but trap catch is consistent in most areas. OFM trap numbers seem to be quite a bit higher this week. A regional biofix for codling moth has not been set yet, but flight has begun in some locations – not every block is catching them at this time and trap numbers are all over the board this year. It’s always best to set a biofix for your individual blocks and not run with the regional biofix. This season might be a good example of why that is true. Apple grain aphid can still be found in low to normal numbers. Rosy apple aphids are being found, still as individuals, in low to normal numbers in commercial apple blocks. Green fruitworm larvae are present. European red mites are becoming much easier to find, but not adult stages yet. Spotted tentiform leafminer adults are flying and sap feeders will most likely be present by the end of this week or early next week. Plum curculio should start their activity at any time in plums, cherry and peaches. Plum curculio activity in apple will probably be seen sometime next week, as many small apple fruits will be at a favorable size by then for egg laying. Small fruit Blueberries in West Central Michigan are in bloom. Early varieties are at 25 percent petal fall and late season varieties are in 50 percent to full bloom. As of May 15, Growing Degree Days (GDD, base 50 °F) accumulation in west central Michigan is around 300 ± 20 with an average daily accumulation of 10 GDD. Cumulated rainfall for the last seven days ranges from 0.25 to 0.30 of an inch. At this time, fruitworm activity is mainly related to the cherry fruitworm. We are finding the first damage from cherry fruitworm in Allegan County in early season varieties; Bluejay and Blueray. In addition, the first cranberry fruitworm has been reported in the same area. These findings are consistent with previous observations that indicate that the first moths appear around 300 GDD. Although, most blueberries are still in bloom, early season varieties at this time are in petal fall. Therefore, pest control measures are recommended against fruitworm damage. One recommendation is applying Confirm followed one week later by a Bt application. This will take care of the cherry fruitworm damage and well prevent the initial damage of Cranberry fruitworm larvae. |
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| back to top |
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
4 -- West Central The weather last week was warm with maximum temperatures mainly into the 70’s, with the exception of yesterday, when it climbed up into the 80’s. We did have a minor frost event on May 13 in Mason County, where the weather station recorded 30.5°F. The other two stations in the district did not register temperatures below freezing. The rain event resulted in 0.34 to 0.5 inches of accumulation. Apples are starting petal fall except for the late bloomers that are in full bloom. Pears are in petal fall to small fruit. Peaches are in shuck to beginning of shuck split. Plums are in shuck to beginning of shuck split. Tart cherries are in shuck. Sweet cherries are from shuck split to cherries about 8mm in diameter. West Central Michigan growing degree day totals since March 1-May 13
Tree Fruit The rain of May 9, followed by the heavy dew the next day resulted in moderate apple scab infections in Ludington and Manistee/Bear Lake areas and no infection in Hart. There was significant spore discharge. Scouts are reporting finding first lesions from some of the previous infections, most likely from the heavy infections that occurred between April 26 to 29. The most recent weather update is showing a strong hot air mass from the south on a collision course with the cold front that originated in Canada. This is likely to result in some turbulent and stormy weather with high winds and possible hail in a forefront of a wave of colder temperatures for the rest of the week. There is a reason for concern regarding fireblight. After yesterday’ s 80 degree weather, our EIP levels have gone up significantly in Oceana and Manistee Counties. Even the temperatures into the low to mid 60’s will be sufficient for high infection potential. With the high winds or hail that will result in physical damage to the trees, there is a real danger of having a trauma blight event. Last week’s events resulted in two fireblight infection periods (May 9-10) in pears. No infections were recorded in apples. There was low cherry leaf spot infection on May 9 in the northern parts of the district (Manistee and Mason Counties). Weather forecast is predicting rain for Tuesday and Wednesday now. It appears that we will have yet another long wetting period that will facilitate disease development. All blocks need to be covered. This is one case where the spray intervals would need to be very tight. There is a lot of new growth, at least 5-7 inches. These tender shoots and leaves are the most susceptible to the infections. Since last week, insect activity has been intensified. Since the first catch, oriental fruit moth numbers have been on the rise. Scouts are reporting first catches of codling moth. For now, they are still sporadic and found in a few blocks, one to four moths per trap. There are a few blocks with “hot spots” for European red mites, but by far, the European red mite numbers are not presenting a problem. The number of rosy apple aphids is on a rise, as well as green apple and green peach aphids. Obliquebanded leafroller larvae are readily found in apple blocks. Spackled green fruit worm larvae about half an inch long, are easily found in many blocks. |
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| back to top |
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
5 -- Northwest GDD42 460 GDD50 215 Growth stages at NWMHRS (May 14—8:00am) Last night, Monday, we had some extremely high winds in the area. There have also been reports of hail in some locales. Last week, the weather was sunny and pleasant, but on Mother’s Day evening, we finally had significant rain. At the research station, we received 0.92 inches on Sunday evening and Monday morning. More rain is predicted for this week. Most cherries in the southern part of the Northwest are in some stage of petal fall, but further north, they are still in full bloom. Apples at the research station are in various stages of bloom, with MacIntosh at 85 percent bloom, Gala and Golden Delicious at king bloom, and Red Delicious at 60 percent bloom. Tree fruit The major disease of concern today is fire blight in apples. Most apples in the region are in bloom, and we have had a recent rain event, and the forecast is calling for more rain today. According to the MaryBlyte model on Enviroweather, five stations in the Northwest have EIP’s over 100: Elk Rapids, NWMHRS, Bear Lake, Benzonia and East Leland. The Kewadin station is at an EIP of 95, which is extremely close to the necessary heat accumulation for an infection. Northport and Eastport both have EIP’s in the mid-70’s. Growers should also be concerned about trauma blight with the high winds of last evening, particularly in susceptible varieties or in orchards that had fire blight problems last year. Based on the current forecast, the potential for fire blight remains high for much of the week; however, the forecasts change quickly, so growers should refer back to the Enviroweather model often. Although we had rain on Sunday night, the wetting period ended in most areas, and a scab infection period was not reported. However, the East Leland and Northport areas have recorded continuing wetting events (spans of 34 and 33 hours respectively), and both stations are reporting a high apple scab infection. We have not yet observed lesions from previous scab infection periods. Powdery mildew is still a concern at this time. Powdery mildew overwinters in buds infected the previous summer, and about the time of tight cluster, spores start to be released. Therefore, infections can occur at tight cluster and through pink and bloom. Hence, controlling mildew early is advantageous so growers do not have to fight it all season long. We can also hope that the last rain event washed off some powdery mildew spores. For insects this week, we have seen lots of rosy apple aphids, obliquebanded leafroller larvae, and European red mite nymphs. Our spotted tentiform leafminer count rose dramatically this week; we captured over 300 per trap at the station. We captured a few oriental fruit moths, and we caught our first codling moths this week at the station. We have also seen predator mites for the first time this week. Leaves are starting to really move along in cherry, and we need to be sure to be making Bravo applications at this time for cherry leaf spot (CLS) control. For some growers that may have missed a needed spray on Mother’s Day, the strategy should still be to apply Bravo through shuck split. For those growers that were not able to make a pre-rain application, we can assume we have a bit of cherry leaf spot started in those small leaves, so making sure to cover up the rest of the foliage from here, on out is extremely important. Growers should be using a full rate of Bravo at this time. Remember that we have documented sterol inhibitor (SI) resistance in cherry leaf spot, so growers should not be applying an SI for its back action against cherry leaf spot. If growers missed a spray for cherry leaf spot, we recommend full sprays to ensure proper coverage. American plum borers are still flying here at the station, and we picked up an average of 14 borers per trap trap. Obliquebanded leafroller larvae are also moving around, and we have seen a few green fruitworm larvae. Plum curculios are migrating into the orchard at this time. Small fruit For grapes at this time, powdery mildew is our only concern and will continue to be for the next few weeks. |
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| back to top |
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Weather news A Canadian-origin area of high pressure will move into the Great Lakes region by Wednesday, May 16, bringing cooler than normal temperatures to Michigan for the next several days. A cool front at the leading edge of the air mass will set off showers and thunderstorms over much of central and southern Lower Michigan Tuesday afternoon and evening, with widespread 0.50-1.00 inch rainfall totals (with some isolated 1.00-2.00 inch amounts), especially across southeastern sections of the state, where some of the storms may also contain hail. Given relatively cool air aloft Wednesday, a few scattered showers or a thundershower are possible during the afternoon and early evening hours, otherwise, mostly dry conditions are expected. Fair and dry weather are a good bet Thursday and Friday. |
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| back to top |
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Email the web developer.