Scouting through the season: Petal fall |
Petal fall is the point when the majority of petals have dropped from the developing fruitlets and commercial beehives have been removed from the orchard. This may be the most critical stage of the season for insect pest management decisions. Pests present now pose a direct threat to the fruit intended for eventual harvest. Orchard sprays include a wide array of selective or broad-spectrum materials, therefore, it is imperative to pay close attention to worker re-entry intervals required for some pesticides. The plum curculio may have been in the orchard for some time, but now that females are mated, they will be begin to lay eggs in fruit. The damage from this egg laying is a crescent shaped scar on the fruit. Typically, most plum curculio damage will be found first on trees bordering fencerows or woodlots. The orchard owner may be able to direct you to hot spots based on past experience. Obliquebanded leafroller larvae are over a half-inch in length and may move to feed on fruit as well as foliage. Fruit damage appears as surface chewing that may be deep into the flesh. Green fruitworm may also be active at this time, and because the damage is similar, identification of the larva is important. Tarnished plant bug is difficult to monitor because it spends much of its time in the ground cover. Adults move into trees and feed on developing fruit, leaving a distinctive funnel-shaped dimple. Rosy apple aphid colonies are declining by this time, but damage of fruitlets will now be evident as stunted, deformed fruit. Oriental fruit moth eggs will be hatching in this time and bore into the actively growing terminal, causing terminal flagging. Green apple aphids will be moving to actively growing terminals. Predators such as syrphid fly and lacewing larvae may also be found feeding in aphid colonies. European red mite adults will begin laying eggs, which will appear on the underside of fully expanded leaves. The predator mites may be present and their abundance will be important for making management decisions. It is therefore important to make accurate identification. Continue to monitor traps for Oriental fruit moth and document weekly counts. Traps and lures may have to be replaced at this time. Continue to monitor traps for codling moth and note the first sustained catch for biofix purposes. Apple scab and powdery mildew continue to be active and the symptoms are more readily apparent. Fireblight damage will begin to show up as darkened, wilted and oozy strikes on fruit clusters, or brown wilted terminal shoots resembling a shepard's crook in appearance. To assess pest populations, you will inspect fruit clusters, terminals and leaf samples. Select a total of 100 fruit clusters, 100 terminal and 100 fully expanded leaves from inside and outside of 10 to 20 trees throughout the block. Inspect each sample and record the total number of each kind of pest and pest damage present. |
Management of first generation codling moth |
Apple bloom time marks the beginning of first generation codling moth (CM) flight. Trap catches of CM were reported in some southern Michigan locations as early as May 10, but flight is just beginning in most areas north and east of Grand Rapids. It is important to check traps frequently at this time to establish CM biofix, the start of adult moth activity in the orchard. Biofix is the date at which the first moths are trapped, provided moths are captured on two successive trapping dates. At biofix, the degree day model is set at zero, and we begin accumulating degree days base 50° F. The codling moth growing degree-day (GDD) model is a far more accurate method of predicting the timing of egg-laying activity, larval emergence and other important events than are predictions based solely on calendar dates. Use of the GDD model, in conjunction with traps to estimate population levels and visual scouting of fruit in the tree canopy, will help optimize codling moth management. Traditionally, newly hatched codling moth larvae have been the primary targets of insecticide sprays. When targeting larvae, apply the first spray at 250 GDD50 following biofix. This timing coincides with the start of egg hatch. Older chemistries, such as Guthion or Imidan, and some newer insecticides, such as Assail, would be applied at this same timing when used for codling moth control. Some of the newer insecticides now available for codling moth control are active not only on larvae, but the egg or adult life stages as well. For Intrepid the best fruit protection is achieved when the first application is initiated before egg hatch. Suggested timing for Intrepid is biofix plus 150-200 GDD. Pyriproxyfen (Esteem®) acts by suppressing development within the egg, as well as larvae that consume it. Hatching of eggs laid by treated adults will also be inhibited. Eggs are particularly susceptible to Esteem, thus, the first application is Biofix plus 100 GDD (usually close to petal-fall). Inclusion of these materials into a CM control program in addition to the larvacides (i.e. Guthion & Assail) offers growers who experienced heavy CM pressure in 2002 the option to target multiple CM life stages as a strategy to reduce those population pressures. An example would be an Intrepid application at 150 GDD50 targeting the adult and egg stages, followed two weeks later with a Guthion, Imidan or Assail application targeting newly hatched larvae. If you didn't get control last year with Guthion or Imidan, it is possible that OP resistance has become an issue on your farm. Pheromone trap bioassays conducted in Michigan over the past few years have indicated over 10-fold resistance in some farms in the Fruit Ridge area. These orchards are prime candidates for using CM mating disruption combined with some of the new insecticide chemistries or older non-OP materials such as the synthetic pyrethroids. Careful monitoring of mite populations is recommended when adopting this program, as multiple applications of Assail and the pyrethroids have been linked to mite flare-ups. Codling moth
|
Managing blueberry fruitworms during bloom |
The larvae of two moth species can infest young blueberry fruit starting at the early fruit set stage, in some years before 100 percent petal fall. Their presence is often not noticed until several weeks after 100 percent petal fall with premature ripening of infested berries or the webbing of berries together by cranberry fruitworm. However, an Integrated Pest Management approach using monitoring, scouting and appropriate application of effective controls can prevent fruit contamination by these pests. The cranberry fruitworm and the cherry fruitworm
have similar biology, so they are usually controlled together. Adults
of both species can be monitored using pheromone traps hung in the
top third of bushes, preferably on edge bushes near wooded borders.
Traps are checked weekly to provide information on the start of
moth flight and duration of adult emergence. Although the traps
have caught very few moths so far this year, the expected warming
trend this week is expected to bring the first consistent emergence
of these pests. No degree day model has been developed for this
insect, so once adults have been trapped scouting for eggs should
commence. Egg scouting should initially be focused on bushes near
to woods or un-managed blueberry fields where abundance is usually
the highest. Eggs are laid in or around the calyx cup of young developing
fruit and usually clustered three to five feet high on the bush.
A hand lens is generally needed to see these eggs, and a fact sheet
on identifying fruitworms in blueberry is available at the MSUE
blueberry information page at: Once eggs hatch, the young larvae burrow directly into the fruit, so there is only a small window of time when insecticide residues can be picked up by the insect. Cherry fruitworm will spend all of their larval stage within one or two berries, whereas cranberry fruitworm larvae will move from berry to berry until the whole cluster is webbed and full of brown frass. Correct timing and coverage are critically important, and so regular scouting of fields, use of sufficient spray volume and selecting appropriate spreader-stickers can increase activity of most insecticides applied for fruitworm control. During bloom period when there is some early fruit set, options for control are limited due to the need to protect foraging bees. However, three products registered for use during bloom have provided consistent control of fruitworms in trials at the Trevor Nichols Research Complex over the past several years. These are the B.t. products such as Dipel® and the insect growth regulators Esteem® and Confirm®. B.t. products must be ingested by the larva to be effective and are best applied when daily temperatures are likely to reach 70°F. B.t. has relatively short activity, providing five to seven days active residue depending on the weather conditions. Confirm is also active primarily through larval ingestion, but has a longer residual activity of 14 days. Esteem is active primarily on the egg stage of fruitworms, therefore should be applied soon after egg-laying commences. After 100 percent petal fall, the range of options for fruitworm control increases with Guthion®, Imidan®, Asana®, and SpinTor® all providing effective control. With all these products, maintaining good coverage is still important to get residue to the parts of the berry where fruitworms are found. Large-scale research trials with Michigan blueberry growers have also demonstrated that use of Confirm® can also provide control of fruitworms in the post-petal fall period. Because of the selectivity of this product, it has minimal impact on natural enemies that lay their eggs inside fruitworm larvae. |
Gray mold control in strawberries |
Gray mold, caused by Botrytis cinerea, one of the most important fruit diseases of strawberries. It is also a major cause of post-harvest losses during storage and transit, since the fungus grows at refrigeration temperatures. Botrytis cinerea infects a wide range of plants including many fruit, vegetable, and weed species. On strawberry, infection begins at the flower stage but symptoms are observed on green or ripening fruit. Fruit lesions are typically found on the stem end of the berry and are frequently associated with infected stamens, or with dead petals that stick to the fruit or become trapped under the calyx. Lesions begin as small, firm, light-brown spots that quickly enlarge and become covered with white fungal growth and gray to brown spores. Botrytis eventually consumes and mummifies fruit that are not harvested. When moldy fruit are disturbed, large numbers of spores can be released. Gray mold epidemics are typically started by spores produced on dead strawberry leaves within the field. Young expanding strawberry leaves are colonized by the fungus without producing any symptoms. As the leaf senesces, the pathogen spreads quickly through the dying tissue and sporulates. Spores are dispersed by air, water or harvesting and ultimately infect different floral parts including stamens and petals. After infecting the flower, the fungus eventually invades maturing fruit and causes rot. The fungus can also spread to adjacent fruit by direct contact. As the epidemic progresses, the pathogen sporulates on diseased flowers and fruit, and these become important sources of inoculum. Control of gray mold requires a combination of chemical, cultural, and genetic control methods. Although no strawberry cultivars are highly resistant to gray mold, cultivars with large clasping calyxes are often more susceptible, because moisture collects between the calyx and the receptacle and encourages the spread of the pathogen from stamens and petals to the developing fruit. The removal of all diseased and unmarketable fruit from within the plant canopy is critical for effective management of gray mold, as this fruit is an important source of inoculum that directly infects nearby flowers and fruit. The removal of senescent foliage also reduces inoculum but provides only limited control of gray mold. Effective fungicidal control of gray mold involves protecting the flowers from infection. Applying specific fungicides during bloom is therefore especially important, e.g., at 10 percent bloom and again seven days later. Fungicide applications close to harvest can aid in control of post-harvest gray mold. Fungicides labeled for control of gray mold are: Elevate, Switch, Rovral, Topsin M, Thiram and Captan. The strobilurin fungicides Cabrio and Quadris are not very strong against Botrytis, however, they control various fungal leaf spots and anthracnose. Elevate and Switch have unique modes of action and are very effective against gray mold. Only one application of Rovral at first fruiting flower is allowed, so it has limited utility. Be sure to alternate fungicides of different modes of action for resistance management purposes. |
Elevate receives 2(ee) recommendation for suppression of mummy berry in blueberry |
The fungicide Elevate 50 WDG (fenhexamid) has received a FIFRA 2(ee) recommendation for suppression of mummy berry in blueberry in the states of Michigan, Georgia, New Jersey, North Carolina, Oregon and Washington. This means that it can aid in control of the disease when used in a program containing fungicides labeled for control of mummy berry. Field data (at a use rate of 1.5 lbs/acre) from Michigan supports this claim, especially with respect to fruit infection. Elevate is currently labeled for control of Botrytis diseases in blueberries, brambles, gooseberries, currants, grapes, pistachios and strawberries; control of Monilinia diseases of almonds and stone fruit; and suppression of powdery mildew in grapes. The 2(ee) recommendation is valid until December 31, 2003. Elevate is a locally systemic fungicide that provides protectant as well as post-infection activity when applied early in the disease life cycle. Elevate is absorbed into the waxy layer of the cuticle, which makes it rainfast within 2 hours after application (once the spray deposit has dried). Elevate is not harmful to bees and most beneficial insects, mammals, birds, fish and soil organisms. Given its low level of toxicity and low environmental impact, Elevate has been classified as a "reduced risk" fungicide by the EPA and is compatible with most commonly used fungicides, insecticides, micronutrients, growth regulators and spray adjuvants. Elevate has a 0-day PHI. |
Gibberellic acid to increase blueberry fruit set (and overcome frost damage?) |
Gibberellic acid (GA) can increase fruit set when pollination conditions are poor. Studies in the late 1960's showed that GA can substitute partially for pollination and fertilization. GA can cause seedless (parthenocarpic) fruit to grow and mature, and increase the size of fruit without a full complement of seeds. GA may be most useful on the Jersey variety since this is relatively unattractive to honeybees, and berry numbers and size are often limited by inadequate pollination. However, GA is expensive, so it is important to understand when treatments are likely to provide a benefit. GA is only helpful if natural pollination is inhibited by windy, rainy or cold weather during bloom. Keep in mind that blueberries can bloom over an extended period, and often only a day or two of optimum conditions at the right time is enough to provide adequate pollination and fruit set. For this reason, it is difficult to predict with certainty whether GA sprays will pay. Pollination success may be judged by observing petal fall. The corollas (petals) of pollinated flowers drop readily while still white, whereas those on poorly pollinated flowers tend to hang on the bush and turn light purple. Several GA products labeled for use on Michigan blueberries are listed below, along with the label instructions for their use. If pollination conditions have been poor, apply GA at the rates and times indicated in the accompanying table. For best results, provide thorough coverage in 40 to 100 gallons water. Slow drying conditions are best (night). Make sure your spray water pH is not strongly alkaline (greater than 7.5), and leave non-treated areas so you can tell whether the treatment was helpful. Some GA products labeled for use on Michigan blueberries (no preference intended)
Researchers have found that GA can also help overcome partial freeze damage to southern Rabbiteye blueberries. Unfortunately, we do not know if northern highbush blueberries will respond in the same way. The southern recommendation for Rabbiteye is to apply 24 to 32 oz ProGibb just after freeze damage occurs and repeat the application in 10 to 18 days. If you are interesting in testing this on Michigan highbush, please take the time to leave some untreated areas as checks, so the effect can be seen with more certainty. |
Working with beekeepers when applying pesticides |
Fruit growers want to maximize fruit production and beekeepers want to maintain their colonies healthy and productive. Sometimes there can be a conflict between the two when bees are placed in orchards for pollination and spraying is needed for disease or pest control. Because bees are insects, most insecticides will have some toxicity to bees, so close cooperation is needed to protect bees against poisoning among growers, pesticide applicators and beekeepers. Bee
poisoning can be subtle
Some types of poison cause direct kill of foragers. This happens when bees are on flowers when the pesticide application is conducted or when the pesticide used is highly toxic to bees. The highly toxic pesticides actually leave no evidence because nearly all bees die in the field, before bees make their way home. Other types of pesticides allow bees to return home, and then die inside the hive. This type of poisoning is the easiest to diagnose with a large pile of dead bees in front of a bee hive, usually with their tongues sticking out. Some chemicals do not directly harm adult bees, so they are brought back to the colony and cause damage to young, immature stages of bees (brood). Captan is of this type and does not kill adult bees but larvae exposed to it die or develop into malformed adults. The French beekeepers have experienced the "mad bee disease" recently, in which millions of bees simply become disoriented and do not find their way home. The culprit was suspected to be a chemical called Gaucho, applied to sunflowers to protect against parasites. The French government in 2001 ordered a two-year extension of a ban on spraying this chemical on sunflowers to allow more study of its impact on the nervous systems of bees. The take-home message is that diagnosis of bee poisoning can be difficult. Formulations
and time of application
As a rule of thumb, if you have the same pesticide in both dust and liquid form, use the liquid form. Because bee morphology has been designed to maximize pollen collection (a dust), pesticides applied as dusts are more hazardous than sprays to honey bees. Micro-encapsulated pesticides are worse because bees sometimes mistake these granules as pollen (bees are like us, they make mistakes!) and bring them home, causing long-term, chronic damage to the entire colony. Spray of pesticide directly (e.g. ULV) is more toxic to bees because of its higher concentration. Aerial application of pesticides is bad news because many bees in flight will be hit. Time of application can be important because many foragers will die when sprayed pesticides land on bees directly or is mixed with nectar and bees are foraging on it. Consider working with beekeepers on the spray schedule. Give him/her some options considering the chemical sprayed and the schedules of both the grower and beekeeper. For example, tell the beekeeper a spray is really necessary but you are concerned about his bees. "Should I spray tonight 7:00-9:00 PM, when bee activity is minimal; or do you think it is better to close the colonies tonight and I spray tomorrow morning 7:00-9:00 AM, and then release the bees around noon?" This type of discussion will often lead to satisfactory comprise for both sides. It does not cause any harm to bees for the colonies to be closed for a few hours. During a very hot day, overheating can be an issue, but can be worked out also, if water is provided abundantly (use soaked burlap to clog the entrance and apply water every two hours in July to September). Use
a less toxic chemical for bees
Use a specific pesticide targeting the pest you want to control is often better for you (less harm to other beneficial insects) and for the beekeeper. Most pesticides are labeled as not toxic, moderately toxic, or highly toxic to honey bees. A list of pesticides of low, moderate and high
toxicity, as well as considerations for both growers and beekeepers,
can be found online at: |
The other bees: alternative pollinators for tree and small fruits |
Many other bees are better pollinators than honeybees, on a bee-to-bee comparison, on a variety of crops. However, when push comes to shove, honeybees are still preferred because of relatively lower price, easier management and finally, the sheer larger number of its foraging populations. For example, suppose a certain bee is 30 times better than a honeybee on an individual basis, in pollinating one particular crop, and a nest has 300 foragers (probably the largest bumble bee box you can buy would have 600 workers and half can be foragers); this would have 40x300=12,000 honey bee equivalents. In a regular honeybee colony, you have 40,000 workers and assume a 30 percent foraging population, that is 12,000 foraging bees. In other words, it is difficult, although possible, for other bees to beat our old friend the honeybees. Nevertheless, in some cases, such as cherry that is blooming very early, perhaps other bees may do a much better job than honey bees, simply because our bees are just too warm-blooded (most of them evolved in the temperate European climates) to go out at 40 to 50 degree weather. Bumble
bees
Bumble bees (Bombus spp) are better pollinators than honey bees in many aspects. One, they fly at cooler temperatures and work at earlier and later hours than honey bees. Two, they have a special mode of pollination behavior called "buzz pollination" in that they vibrate their body in high frequency to shake the pollen loose from flowers. This behavior is more efficient and almost required for pollination in some crops such as eggplants, tomatoes (both solanaceous plants) and blueberries. Thirdly, they seem much better than honeybees in getting home when inside enclosures. The buzz pollination and homing ability makes them the ideal pollinator for greenhouse plants (mainly cucumbers and tomatoes). They also work on flowers much faster than honeybees. In a three-year study (1992-94), Javorek, MacKenzie and Vander Kloet reported that a bumble bee pollinated twice as many lowbush blueberry flowers as a honeybee in the same amount of time. Bumble bees also pollinated in 80 percent of their floral visits while honeybees only about 25 percent. Bumble bee workers also deposited 34 tetrads (four pollen grains are fused together in blueberries) per visit while honeybees only 13. This makes a bumble bee about 24 times more efficient than a honey bee, for blueberry pollination (still less than 40 in the above assumption). Unfortunately, bumble bees have an annual cycle, most foraging bumble bees you see now are queen bees, while the queens are even more efficient than workers, their abundance is much lower. However, you can purchase commercially produced bumble bee boxes with 300 to 600 workers per box. They can be ordered from Koppert International* (http://www.koppert.nl/english/), which has a laboratory near Ann Arbor, Michigan. The prices range from $150 to $250 per box depending on season and bee condition. Leaf
cutter bees
The female of leaf cutter bees (Megachile rotundata) are right between honey bees and bumble bees in their efficiency for pollinating blueberries. In Canada and western US there is a well established industry to rear these bees, mainly for alfalfa seed production (honey bees do not like to work with alfalfa flowers because of their "tripping mechanism" - floral parts forcefully hitting bee heads causing pollen release). An example of commercial leaf cutter bee farm is Greve Farm* (http://www.grevefarms.com/main.html). The
blue orchard bees (BOB)
The hottest item for blueberry pollination nowadays
seems to be BOB, also called the orchard mason bee, or osmia bee
(Osmia lignaria). In a USDA study, when honeybees were used for
sweet cherries in an Orchard in North Ogden, Utah, yield ranged
from 6,700 to 12,225 lbs when there was harvest (In 1992 and 1997,
there was no harvest due to freezing temperatures.). When BOB was
used (1998 to 2000), yield increased 2.1 to 5.4 fold (2000 yielded
37,335 lbs). In 1999, when freezing weather caused most local growers
to have no harvest, this orchard still harvested over 9000 lbs of
cherries. Management can be as intensive as honeybees. According
to the newly published USDA book, right now might be the latest
time you can put straws or sticks with holes to attract these bees
(Apri-May), the female then, much like the leaf cutter bees, gather
pollen pellets and make sections inside the straw or stick, each
section with a pollen ball and an egg. Eggs hatch and larvae develop
very slowly (a few months compared to 21 days in honey bees). The
nesting materials are then moved into summer storage area around
end of May. Around August-September, materials are moved into winter
storage area. Temperature must be regulated precisely to allow adults
to emerge around the time when apple or cherry blooms. As few as
250 nesting females per acre is enough for apple (and presumably
also cherry) pollination (this puts the bee 300 - 400x more effective
than honey bees!) and bees will flying around 54°F. The soft-cover handbook by Kemp and Bosch, entitled
How to Manage the Blue Orchard Bee, is an 88-page booklet
packed with information for the biology and management of this highly
efficient bee. You can order this book ($9.90 plus $3.95 s/h) by
calling 802-656-0484 or email sanpubs@uvm.edu. A list of companies providing
nesting materials for BOB is available at the Logan Bee Biology
and Systematic laboratory website (http://www.loganbeelab.usu.edu/). Back to honey bees againSteve Sheppard at Washington State University (Phone: 509-335-5180, e-mail: shepp@wsu.edu) has recently discovered a new subspecies of honeybees in the Tien Shan Mountains (Northwest China). He named the bees Apis mellifera pomonella. The subspecies status is based on morphology and molecular data. This finding extends the distribution of A. mellifera more than 1,200 miles eastward than previous estimates. What is most interesting to the fruit growers is the fact that this bee can forage at much lower temperatures (40 to 50's) and has been doing pollination for apples in their native area. Theoretically, importing this bee is a possibility, because it is simply a subspecies of our bees here, not a different species, which is nearly impossible to import. If the demand is high among fruit growers for this bee, I am sure USDA will look into the possibility. After all, about five years ago we imported a Russian strain of bees to combat the varroa mites here, which has been largely successful. *Disclaimer: Mentioning of a product or a particular company or farm does not indicate endorsement by MSU or Zachary Huang, neither of the two has any commercial interest or ties to them. These products or weblinks are provided for information only. |
| Regional reports |
1 - Southwest |
WeatherLast week was warmer than cool but seldom warm. Rain fell on May 14 and 15. This was an infection period for most foliar diseases. Total precipitation was about an inch. Heavy and low soils are still very wet. Lows were in the 40's and highs in the 60's. Saturday and Sunday saw highs near 70. This week's forecast is for cool weather.
InsectsCool nights last week and windy conditions for the last several warm days reduced insect activity. Very few plum curculio egg laying scars were found. Generally warm humid nights and daily highs in the 70s are needed before plum curculio egg laying begins. See the plum curculio article in last week's Fruit CAT Alert. We are still catching good numbers of Oriental fruit moths. We have started to catch codling moth. Leaf roller larvae and green fruitworm larvae can be found in all fruit. Tree fruitBacterial spot lesions were visible on apricots, peaches, Japanese plums and sweet cherries. Stone fruit should be protected from brown rot. Apricots are growing rapidly. Growers should be thinning. Fruit should be thinned down to three inches between the fruit. Bacterial spot symptoms can be seen on leaves. Tarnished plant bug and plum curculio feeding can be found. Peaches are at shuck split. The peach crop looks good. Some peach leaf curl symptoms have appeared but very little. Oriental fruit moth trap catches are still high. We are now at 510 GDD45, 260 GDD since Biofix for Oriental fruit moth on April 24. Now is the time for a second follow up application to protect the fruit. Growers who delay insecticide applications because conditions are not right for plum curculio egg laying are leaving the shoot tips and fruit unprotected. Green peach aphids are out and forming colonies. Tart cherries are out of the shuck. Now that the fruit is visible it looks like we have an average crop. The crop looks a lot better than last week. Growers need to maintain protection against cherry leaf spot. Plum curculio will be a problem when temperatures warm above 65°F. Sweet cherries are 12 mm. Many growers have a marketable crop. Sweet cherries need to be protected from brown rot all season long. Apple bloom is ending. Scattered bloom is visible in most varieties. Post bloom drop is heavy in many orchards. We had a short thinning window temperature into the 70's on Saturday and Sunday. Growers should evaluate their fruit set later this week. By the weekend, the largest fruitlets should be 12 mm and entering the main thinning window. Growers should apply thinners unless conditions are unfavorable for fruit thinning. A good thinning window with a warming trend into 70's is unlikely. Steady temperatures would be acceptable. Cooling temperatures would be unacceptable and then growers should delay thinning and wait for a warming trend. Keep track of the weather and read the apple thinning article by Phil Schwallier in the April 29 Fruit CAT Alert or the May Fruit Grower News. The wet cloudy conditions should make uptake of thinners more effective. A scab infection occurred on May 14-15. We are finding more scab lesions from the April 29 infection period. Cool temperatures have kept fire blight bacterial populations low. Maryblyt predicts that cankers should start to ooze soon. Very few oozing cankers were found in orchards with cankers from last year. Most cankers had not begun to ooze - too cool. There is little risk of fire blight this week. Cool temperatures will keep bacterial populations low. Codling moth adults were trapped in Berrien County and several other areas, but trap catch in the Southwest was spotty with low numbers compared to other parts of the state. This may be due to the windy conditions we had during our warm weekend, which would have kept moths from flying. We are biofixing codling moth on May 18 at 300 GDD50. Controls are usually timed for 250 to 350 GDD after biofix. See the discussion on codling moth control in the 2003 Fruit Management Guide. Adult European red mites are scarce. No spotted tentiform leafminer mines have been found yet. Leafroller larvae such as obliquebanded leafroller and fruittree leafroller are attacking terminals. Growers should apply petal fall sprays to control insects including leafrollers, plum curculio and Oriental fruit moth. Fruit drop has started in pears. Small fruitBlueberries are in full bloom. Petal fall has begun in some Bluecrop fields. There are still open flowers on early varieties. Dead wood in Jersey and other varieties is probably due to several factors. Drought stress from last year's dry summer would have weakened the plants going into winter so that cold winter temperatures would cause injury to stressed plants and canes damaged during last year's harvest and phomopsis seems very common in fields that show a lot of dieback. I do not think it is any single factor but the combination of several factors that has caused the loss. Some growers are pruning out deadwood. Growers need to protect against the blossom or fruit phase of mummy berry. Leafroller larvae are attacking fruit buds and terminals. Both cranberry fruitworm and cherry fruitworm are flying. During bloom, growers can use Bt formulations to control leafrollers, cranberry fruitworm and cherry fruitworm. Bts should only be used after egg hatch has begun because Bt breaks down rapidly and has a very short residual time. Bts are best used under warm conditions so this week's cool weather is poor for Bt use. Juice grapes have three leaves out and most shoots have three flower clusters. Some growers are thinning by pruning and reducing the potential crop. Wine grape shoots have less growth. Due to heavy soils, cold sites or winter injury, growth in some vineyards is very uneven. Growers have applied protectant materials to reduce phomopsis. After the rain we had last week these sprays need to be reapplied. Some phomopsis lesions have already been reported. Grape berry moths are flying. Growers need to time their pesticide applications for egg hatch, near bloom time (several weeks away) and not the flight of adult males caught in traps. Early season trap catch is more an indication of population levels in a vineyard than the need to treat now.
Strawberries are in full bloom. Spittlebugs are out. Growers need to apply fungicides during bloom to reduce fruit rots. Raspberry flower buds are visible and bloom has begun on early varieties such as Prelude. Fall raspberry primocanes are 6 inches tall. MiscellaneousOne year-old peach and cherry trees planted last year have been killed by winter cold. The trunks were killed from just above the ground to a foot or two above the ground. Cutting away the bark reveals that the cambium between the wood and bark is brown and dead. In some cases, the bark and the wood are dead also. Some of these trees did not leaf out but most produced leaves which are small and the trees wilt even though the soil is moist, which indicates extensive damage to the tree. Severely damaged trees are not salvageable. The next Monday Fruit Management meeting will be Memorial Day at Bjorge's Fruit Acres Farm, at the corner of Friday and Carmody roads, approximately 2 miles south of the Coloma exit I-94, on May 26 at 5:00 PM. The next Grape IPM Meetings will be June 4. These meeting will be held in both Berrien and Van Buren counties on the same day. The first meeting will be in Lawton at 10:00 AM and the second at SWMEC at 2:00 PM. The focus of this meeting will be early bloom insect and disease control in grapes. For more information check the Fruit Hotlines at Van Buren (269) 657-6380 and Berrien (269) 944-4126 ext. 1 counties. |
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2 - Southeast |
WeatherTypical
spring conditions continue to exist across the Southeast region. With the continued cool night time temperatures
insect activity has been kept at a relatively low level. However when we do get warmer night time temperatures
I expect to see a rapid increase in insect activity. Soil moisture conditions remain good across
the region. Many people
received around ½" to ¾" of rain over the last week.
Newly planted tree fruits and small fruits are responding
very well to this growing season.
Soil temperatures are in the low 60's most days.
Tree FruitsApples are at petal fall in the southern part of the region and mostly at late
king bloom for Red Delicious in Flint and Romeo areas. Many varieties in this area are at early petal
fall. Codling moth adult
trap catch is just beginning yesterday or this morning at many sites
across the region. The Romeo
area biofixed for codling moth yesterday (May 19th) and
today (May 20th) in the Flint area.
Trap catches are in the 5 to 10 moths per trap range at many
farms. Oriental fruit moth
trap catch remains high to very high at several farms across the
region. There seems to be
a tremendous population of adult oriental fruit moth this year. One curious note this year has been a fairly
high number of oriental fruit moth being found in codling moth traps. While this has occurred in previous years,
it is a bit unusual to see up to 30 oriental fruit moth adults in
codling moth traps. Plum
curculio fruit stinging have not been observed on any farm as of
yet. Several larvae continue
to be seen in fairly low numbers, these include oblique banded leafroller,
eastern tent caterpillar, climbing cut worm and tufted apple bud
moth. Spotted tentiform
leafminer eggs are abundant to very high in several blocks across
the region. Scouting for
spotted tentiform leafminer needs to take place fairly quickly to
assess where growers are at for the 1st generation flight.
Adult trap catch is pretty much shut down for spotted tentiform
leafminer as we are between the 1st and 2nd
generation adult flights. Rosy
apple aphids continue to be seen in greater numbers.
I have seen a few leaves curling from rosies and scouts report
seeing a few stem mothers. Colonies
are yet to form, but would expect to see them fairly quickly. White apple leafhopper have been observed in a few apple blocks.
The first potato leafhopper has been seen on one farm.
Apple scab lesions are just now starting to be seen at a
few farms. I have been surprised at the lack of lesions
in many abandoned blocks that I monitor regularly throughout the
season. Spore discharge continues with each wetting
event, however the spore numbers are dropping off fairly quickly. It is not time however to call an end to primary
apple scab season as of yet. Fireblight
EIP (daily risk assessment) numbers have been fairly low thus far
this season. This has been
the result of fairly cool temperatures.
Many growers have not applied a bactericides yet this season. Pears are mostly at 5 mm to 7 mm in size and have good growth. Pear psylla eggs continue to be at a few farms. Peaches are mostly at petal fall or in the shuck, with a good crop of peaches
coming along this year. A
few early peach leaf curl symptoms are starting to develop. Sweet cherries are at petal fall and tarts are nearing petal
fall at this time. Small FruitsStrawberries are at early bloom to 25% bloom at many farms.
Some strawberry clipper continues to be seen in fairly low
numbers. I also had a report
of two-spotted spider mite at a few farms. However the numbers have been fairly low.
I would not tend to make a recommendation for control of
two-spotted spider mites at most farms as it is unnecessary at this
time. Raspberries continue to grow fairly well. However I am continuing to get calls from raspberry growers and visit farms seeing collapsing canes on summer red, purple and black raspberries. These canes appeared healthy at pruning time and began to collapse about 3 weeks ago. I recommend that canes be trimmed back to good, healthy green viable tissue. It is still possible to pick a decent crop of raspberries from these canes this year, however they will be lower to the ground than most years. Blueberries are nearing bloom at several farms across the region. Dead twigs continue to be seen on most varieties
of blueberries. These twigs
tend to be smaller twigs that I feel were winter killed last December
when we had the sudden cold temperatures. |
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3 - Grand Rapids Area |
Degree days accumulated
Tree fruitMost apple varieties are in the full bloom stage right. More rosey apple aphids colonies are being seen. Spotted tentiform leafminer flight is declining, and the first tissue feeders should be found at any time. First trap catches of codling moth occurred over the weekend. Numbers have been rather high in some areas. A regional biofix was set for May 19. Petalfall control timing for insects in apples will be very important this year because of all the rain we've had since Pink. Be sure bees are out of blocks - both in your blocks and your neighbors - before using any insecticides. Oriental fruit moth trap numbers have continued to increase over the past week. A regional biofix for OFM was set for May 4, and we have accumulated 150 GDD45 post-biofix. Cover sprays to prevent OFM flagging in peaches should go on at any time. We've had six infection periods for apple scab this season and lesions from the late April and early May infections are just starting to be found in unsprayed blocks. Lesions can be found on leaves and fruit stems. Concerning fire blight in apples, there was a threat for blossom blight infections with the rains on May 20. No oozing cankers seen, but they should be seen soon. Apogee applications should be applied at the petalfall stage of the king bloom, so some of the earlier apple varieties will need the first Apogee applied soon. It is a good idea to leave a two- or three- day window between Apogee applications and thinning sprays. Small fruitBlueberries in west central Michigan are blooming. Bluecrop and Blueray are in 25 percent bloom while Jersey is in late pink bud stage. Low temperatures that occurred in the region during the weekend brought rain to west central Michigan. Rain accumulation during the past 48 hours was in the range of 0.20 to 1.2 inches. On May 13 and 14, the lower temperatures registered in the Grand Haven-Holland area were 33.8 and 33.4 but they did not affect the blueberry bloom stages. Regarding
insect pests, the redbanded leafroller moths are still flying but
in low numbers, 3 to 40 per trap per week. However, there is an
increment in the observed feeding damage, 2 to 23 percent leaf cluster
damage. The higher percentage occurred in Allegan and the lower
percentage at Ottawa counties. We are observing the emergence of
adults of the cherry fruitworm in both Allegan and Ottawa counties.
However, moth captures are still low, one to two per trap per week.
We also caught the first moths of the cranberry fruitworm in farms
located in south Allegan, one to four per trap per week. No obliquebanded
leafroller has been caught yet. |
4 - West Central |
WeatherWarmer and drier weather over the past several days coincided with the full bloom in most of our crops. Bees should have been happy w |