Vol. 20, No. 8, May 31, 2005

Tree fruit news
     Codling moth control using granulosis virus

     

     

     

     

     

     

Larry Gut
Entomology

Among the new options available for control of codling moth (CM) is a naturally occurring virus that goes by the scientific name of Cydia pomonella granulovirus (CpGV). It is commonly referred to as the codling moth granulosis virus. CpGV is highly specific to the codling moth. It may infect the larvae of a few very closely related species, but it is noninfectious toward beneficial insects, fish, wildlife, livestock, or humans.

Each CpGV particle is contained within a protein occlusion body (OB). Preparing a concentrated suspension of OB's using mass-reared CM larvae infected with CpGV produces commercial formulations of the virus. Viral OB's are very small. Indeed, over a trillion OB's are present in an ounce of formulated product. These tiny particles must be ingested by the CM larva to be effective, but it only takes a few to cause death. Upon ingestion, OB's are dissolved by the insect's alkaline gut lining, releasing the viral particles. The virus replicates itself within the gut cells and rapidly spreads to other organs. Within a few days the larva stops feeding, becomes discolored and swollen, and melts into a mass of billions of viral OB's.

Rate and timing of application
There are many options for incorporating virus into your CM management program. Deciding how much, when, and how often to apply product can be quite confusing. Keep in mind the following factors when trying to sort things out: 1) CpGV must be ingested by the CM larva and may not kill it immediately, 2) the virus breaks down in the environment, thus a spray may only be effective for a week or so, and 3) the virus is highly lethal, a few OB's are all that are required to cause death.

Optimal use of the virus is against young larvae before they penetrate the fruit. The best way to target young larvae is to have the virus present on the surface of the eggs when they begin to hatch. Hatching CM larvae will ingest the virus as they consume their eggshells. If the virus is intended as a primary CM control, the first application should be made at about 250 GDD50 after biofix. At least four applications will be required to cover the egg hatch period. Weekly applications at a low rate are a better approach than high dose sprays applied at wider intervals. In orchards with high CM pressure, this sequence of sprays will need to be repeated beginning at about 1250 GDD post-biofix or 250 GDD after the start of the second-generation flight.

Growers can opt to use the virus as part of a multi-tactic CM control program. Rotating it with chemical insecticides is a good means of combating resistance. We suggest the following approaches to incorporating CM virus into a management program. If you want to restrict your use to a single generation, target the first generation. Some virus-infected larvae will not die immediately, allowing them to cause fruit damage and even complete larval development. Fortunately, stings or deeper entries in small fruits attacked by first generation larvae often fall off the tree or are removed by thinning. Additionally, research conducted in 2003 revealed that less than 4 percent of the individuals that managed to complete larval development survived to pupate and emerge as summer generation adults. Thus, applications against the first generation can greatly reduce the size of the summer generation that will need to be controlled.

Regardless of the generation targeted, it is best to make at least two applications. If you want to rotate a CpGV product with other controls, I favor applying a chemical insecticide as the first spray at the start of egg hatch (250 GDD) and the virus as the second spray. This is because more eggs will be present and covered by the virus spray at the later timing. The insecticide and virus could then be rotated again, or the virus could be applied weekly at a low rate for the remainder of the egg hatch period.

Use of spray adjuvants
A number of adjuvants have been recommended and tried as a means of increasing the longevity or improving the effectiveness of CpGV products. The virus is sensitive to the UV rays in sunlight, thus powdered milk and other adjuvants have been added to limit this effect. Since the virus must be ingested to be effective, feeding stimulants such as molasses are often used in an attempt to increase larval feeding on the spray droplets. Although these options may prove useful, my experience is that applying more virus, rather than adding a spray adjuvant, is the best means of increasing efficacy.

MSU and the Organic Apple Team invite you to visit the Clarksville Horticulture Experiment Station Organic Apple Orchard on Thursday, June 16, 2005 from 1:00 to 4:00. The five acre site with over 2500 trees is in the fifth growing season. We will review the ground floor management, soil biology/fertility, and pest management strategies and answer questions about organic certification and marketing.

The project, funded primarily by Project GREEEN and a USDA Sustainable Agriculture Grant through the Michigan Agriculture Experiment Station includes over 40 faculty, staff, extension agents, farmers, advisors, and students. Project results will benefit both organic and conventional growers.

There are five primary project areas:
§      Soil Quality and Fertility
§      Tree and Ground Floor Management
§      Pest and Disease Management
§      Orchard Management Education
§      Marketing, Costs and Certification

Primary presentation and discussion topics will include:

Building soil quality, fertility and biological diversity. Alfalfa hay mulch, compost, and clover are the primary sources of nutrients for most of the orchard. Routine soil sampling has been used to document changes in nutrient availability and the quantity of bacteria and fungi in the soil as the length of time in organic production increases.

Orchard ground floor and tree management. A comparison of three root stocks of varying vigor levels and three different methods (mulching, flaming, Swiss Sandwich System) of managing the vegetation competing with the tree roots has generated differences in tree growth and soil fertility. The results are applicable to all orchards.

Disease and insect monitoring and management. Primary concerns are apple scab, fire blight, codling moth and plum curculio. The orchard is large enough for testing a variety of management strategies including trapping, attractants, organic approved sprays and introduction of plant biodiversity. The planting includes three cultivars of different disease susceptibility and two different management strategies.

The field day will begin at 1:00 PM sharp with wagon transport from Clarksville headquarters into the orchard plots and continue to 4:00 PM. There will be three stations in the field and first time participants will visit each station in small groups. Return participants will take part in a separate tour that builds on the introductory foundations. A printed summary will be provided.

Registration: To help us prepare adequate transportation and handouts, please RSVP to Sandy Allen by Monday, June 13, 2005. Let us know if you are a first time or return participant.

Voice: 517-355-5191 x 1339. Email: allens@msu.edu or register online at: http://www.hrt.msu.edu/Registrations/OrganicApple.htm

For additional program information call CHES at 616-693-2193 or email the station at: stewar28@msu.edu

Directions: Take I-96 to Clarksville Exit #59. Go South 1/2 mile to Portland Road then west 3/4 mile. The Experiment Station is on the north side of the road.

Annemiek Schilder
Plant Pathology

In five years of trials in New York, good black rot control was achieved with one immediate pre-bloom and 1 to 2 post-bloom fungicide sprays. The second post-bloom application is strongly advised if black rot has been a problem in the vineyard the previous year, and should be considered prudent if wet weather is anticipated. Only in one vineyard with a history of severe black rot did a spray two weeks before the immediate pre-bloom application improve disease control. During three years of fungicide trials in a ‘Concord’ vineyard in Fennville, Michigan, just two post-bloom applications of SI fungicides have provided very good control under high black rot pressure. However, an immediate pre-bloom application is advised so as not to miss potential infection periods.

Sterol-inhibitor fungicides (e.g., Nova and Elite) provide outstanding control of black rot, and provide about 3-4 days of post-infection activity. When using SI fungicides on a post-infection schedule, use the highest label rates, because post-infection activity is strongly rate-dependent, particularly when extended “kickback” activity is required. The strobilurin fungicides (Abound, Flint, Sovran, Pristine) are excellent protectants but provide only limited post-infection activity (about 24 hours). Flint should not be used on Concord grapes because of potential phytotoxicity. Pristine should not be used on Labrusca-type grapes.

EBDC fungicides can still be used as long as the grapes are not in bloom. If at this time there are a lot of lesions on the leaves and canes, infection pressure will be high for the fruit also. Best fungicide options for control of Phomopsis during and after bloom will be Abound or Sovran. Pristine is also a good option for wine (non-Labrusca-type) grapes, but should not be used in Concord or Niagara grapes. ProPhyt also appears to be a good alternative. In trials done in Michigan, ProPhyt provided very good control of Phomopsis when sprayed on a 14-day schedule. Tighten the schedule and increase the rate if disease pressure is high. EBDC fungicides are good protectants but cannot be applied after bloom has started in grapes grown for the National Grape Cooperative. EBDC’s have a 66-day pre-harvest interval.

Ridomil Gold MZ and Ridomil Copper have excellent curative and protectant activity against downy mildew. Under moderate infection pressure, they will provide 3 to 4 weeks of protection. Of the strobilurins, Pristine, Abound, and Sovran are good choices. Again, don’t apply Pristine on Labrusca-type grapes. Other effective fungicides are mancozeb, ziram, and fixed coppers. ProPhyt is also a good alternative: it provides curative action and about 14 days protective activity. Phostrol and Agri-Fos are similar products but have not been tested sufficiently in Michigan to make a recommendation at this point.

Demonstration and Update of Blueberry Insect IPM Research Project
Wednesday, June 15 at two locations. 10:00 AM – Noon at Bodtke Farm, 57th St near CR 388 (Phoenix Road) west of Grand Junction. 2:00 PM – 4:00 PM at A&L Farms, 144 th Ave about 1 mile north of M 45 in Grand Haven. The meetings are open to anyone interested in blueberry insect management. Topics for both meetings include: updates on new pesticide registrations, fruitworm management with new insecticides, potential natural enemies for control of blueberry pests, and updates on blueberry maggot and Japanese beetle management. More details in next week's CAT Alert.

Field tour and meeting on blueberry cover crops
A meeting and farm tour is scheduled for Wednesday, June 22, 1:00 PM – 3:00 PM to observe and discuss test plots of various cover crops at a blueberry farm. Double R Blueberry Farm, Buchanan Street, West Olive (about 2 miles east of US31 (1 mile north of M45)). More details in a future CAT Alert. 

§      Strawberry insect control update, ipm, and new insecticides
§      Strawberry diseases, IPM, and new fungicides
§      Weed control update
§      Strawberry variety update
§      Strawberry season in perspective
§      Strawberry fungicides – costs and combinations

Our speakers will include: Dr. Rufus Isaacs, MSU small fruit entomologist; Dr. Annemiek Schilder, MSU small fruit plant pathologist; Frank Corrin, Corrin’s Strawberry Patch; and Bob Tritten, MSU Extension district horticultural educator.

We have applied for MDA recertification credits. For more information about the meeting, contact the Genesee County Extension office, 810-244-8500 or email Bob Tritten at tritten@msu.edu

Regional reports

1 – Southwest

Mark Longstroth
Bill Shane
Al Gaus

Tree fruit
Insect activity increased despite the cool evening temperatures. Plum curculio egg laying scars have been found. Growers should apply protectant materials. We expect to see a lot of plum curculio egg laying this week in all fruits. See the notes on plum curculio monitoring in May 3, 2005 Fruit CAT Alert.

In peaches, June drop is underway. The crop is looking very thin in some areas. Oriental fruit moths are laying eggs. Biofix for the first flight was April 15 in southern and central Berrien County at 175 GDD base 45, we are now at 617 GDD, 442 GDD past biofix. Oriental fruit moth egg hatch has begun in Berrien County. For the rest of the region, Oriental fruit moth biofix was May 6 at 320 GDD base 45 and we are about 400 GDD past biofix. The expected end of Oriental fruit moth egg hatch is at 650 GDD after biofix. Tarnished plant bug feeding scars have been found on young fruit. Plum curculio should be attacking peaches with the warm weather.

Fruit symptoms of bacterial canker were found on sweet cherry fruit. Cherry leaf spot symptoms were also found in sweet cherry. Growers should treat for plum curculio if they have not already done so.

More fresh plum curculio egg laying scars were found in plums near Paw Paw.

In apples, fruit are generally 14 to 18 mm in diameter. Frost rings can be found on some of the larger fruit. There has been little response to thinners applied two weeks ago, because of the cool temperatures. Growers should reapply thinners in this warm weather at higher rates of thinning materials. This will be the last good thinning window. Many fruit are already too large for easy thinning. The warm temperatures forecast should make thinners effective this week. The warm temperatures will also increase the natural drop we are seeing.

Oozing fire blight cankers and collapsing shoots and spurs have been found in several orchards on trees infected last year. It is still too early for blossom blight infection symptoms to be visible. Few new apple leaf scab symptoms were found. Symptoms from the May 13-14 infection should be showing up now. We are at the end of primary scab. Scab symptoms from the May 22 infection should appear by June 5. If scab lesions are found in the orchard, growers should continue to apply protectant materials to suppress fruit scab. Growers need to protect the fruit from plum curculio. European red mites are scarce. Redbanded leafroller trap catches are low. Spotted tentiform leafminer eggs are hatching and growers should scout for sap feeders and mines. Obliquebanded leafroller larvae have been reported in several orchards. These larvae will pupate soon, so there is no need to apply materials targeted specifically for this pest. Codling moth trap catches increased dramatically this week. We biofixed for codling moth on May 20 at 334 GDD base 50. We are now at 405 GDDs, 70 GDD past biofix. Traditional materials are applied at about 250 GDD after biofix, but some new materials need to be applied as early as 100 GDD past Biofix. This means these early treatments should go on early this week. Check the article in last week’s Fruit CAT Alert, which includes information on timing. The warm temperatures forecast for this week mean that we will be picking up 20 GDD base 50 for much of the week and timings for more conventional materials will come quickly.

In pears, frost ring are apparent on many fruit. Pear psylla are out at all different stages.

Small fruit
Blueberries are in petal fall. Cherry fruitworm and cranberry fruitworm adults are being caught. Egg hatch has not begun so insecticide sprays can wait until after bloom. Remove beehives before applying insecticides in blueberries. Tussock moth larvae are being reported in fields where they are a problem. Fungicide applications should be focused on mummyberry and anthracnose control.

In grapes, grape berry moth adults are being trapped, but egg laying has not begun, so insecticide sprays are not needed now. Thursday’s rain was a black rot infection. Phomopsis and downy mildew were found late last week. Growers should be protecting the shoots and flower clusters from phomopsis and other diseases before the forecast rain this weekend.

Strawberry bloom continues and many fruits are thimble sized.

Early summer raspberries, such as Prelude, are blooming.

Cranberry flower buds are visible. Cranberry beds are greening up. Pre-bloom sprays to reduce fruit rots should be applied before the flowers open.

Bob Tritten

Weather
While we have had some warmer day time temperatures over the last week with cooler night time temperatures, there has been little insect development. The exceptions have been increased activity for codling moth and plum curculio in apples. We’ve not had any frost or freeze events over the last week. Our season is still running about 4 to 6 days behind normal in terms of growth stages and about 7 to 9 days behind normal in terms of degree days. The Romeo area is particularly behind this year compared to other areas of the southeast region. Additionally, I’m continuing to see a broad spectrum of sizes of fruit across the region. Much of this is related to lake effect colder temperatures which we saw for much of April and early May at many orchards. The closer orchards are to either Lake Eric or Lake Huron, and even Lake St. Clair, the further behind they are the rest of the area.

Many growers have experienced dry soils over the last three to four weeks. The region had very scattered rain events on Saturday and Sunday (May 28-29), but most farms had only a trace of rain. A few lucky areas had around a quarter of an inch of rain. This is particularly true for growers in Lenawee and Monroe counties. As you travel north, soil moisture levels are better, however still fairly dry. Many growers have been irrigating newly planted trees and small fruits on a regular basis. A few growers reported pea to marble sized “soft” hail in thunderstorms early last week. Our soil temperatures have generally warmed to the lower 60’s for most days.

Tree fruit
Apples are mostly at 11 to 13 mm in size, with Red Delicious being between 9 and 11 mm. While there is not as much bloom to report in apples as last week, there is still some rag tag bloom out there, which continues to be susceptible to fire blight infection. Several growers were able to make an early application of thinner during a warming trend last week, and it appears with warmer temperatures expected this week that the next thinning window will be open fairly quickly. So combined with controlling some early season insects, the next major activity for most apple growers will be thinning.

Insect activity has picked up a bit since last week. Codling moth trap catches have risen dramatically at a few farms. I had my first orchard biofix for codling moth around the 13^th to the 15^th of May, and another biofix last Wednesday (5/25). I expect that codling moth either biofixed over the weekend or early this week at most other orchards. This is the year that I’ve seen a great spread in biofixing over the region. Thus, growers who are doing their own scouting or hiring a scout and have regular monitoring of codling moth traps will be able to pinpoint their control measures, possibly saving insecticide costs and improving control. Plum curculio are now being seen in higher numbers. Stinging of fruit was reported at two orchards late last week. Oriental fruit moth trap catches remain low at 1 to 4 per trap. Redbanded leafroller trap catches also remain low. Tarnished plant bugs continue to be seen in apples, however numbers are fairly low. Spotted tentiform leafminer larvae are starting to be seen, however they are very small at this point in time. Campylomma or mullein bug continue in low moderate numbers at a few orchards. Rosy apple aphid populations have been rising over the last two weeks or so, however predators are starting to reduce those numbers dramatically. White apple leafhopper populations are beginning to rise at a few farms. Careful monitoring this week will help identify potential problems with this pest. Larvae of several insects have been seen over the last week. These include large larvae of redbanded leafroller and obliqueband leafroller. Lower numbers of green fruitworm, climbing cut worm and Eastern tent caterpillar continue to be seen. European red mite egg hatch continues at most farms. Leafminer numbers are very low at this time with most being around 1 per leaf. Egg laying has begun as well.

Predators continue to be seen in good numbers in many apple blocks across the region. Ladybird beetles and eggs are being seen in increasing numbers, as are syrphid fly eggs and adults. I also continue to see many minute pirate bugs and brown lacewings adults and eggs. Good numbers of Amblyseius fallacies, Stethorus punctum, and velvet mites continue to be seen as well.

Apple scab spore lesions are being seen in several apple blocks across the region, however the number of lesions are quite low. These lesions are from the major wetting event which occurred during the snowstorm of April 22-24. We are still catching a good number of apple scab spore with each wetting event, so we are still in primary apple scab. No oozing fire blight cankers have been seen yet this year. Many growers had a moderate to high risk infection last week and over the weekend, particularly as rain showers moved through with warmer temperatures. Some frog eye leaf spot is starting to be seen at a few orchards, as well as the possibility of powdery mildew.

Pears are at 11 mm to 13 mm. There appears to be a thinning crop of pears across the region. Pear psylla are developing longer wing pads.

Peaches continue to size quite well and are all at shuck split. Most peaches are around 8 mm to 10 mm in size. Some bacterial spot on foliage is fairly evident on peaches.

Sweet cherries are mostly at 13 mm to 15 mm in size, however there continues to be a great number of smaller sweet cherries in the range of 6 mm to 10 mm. Some of this smaller fruit appears to be turning brown and may drop. Most sweet cherries are at early pit hardening. With the exception of the Romeo area, which has a fantastic crop of sweet cherries coming along, most growers have singles and a disappointing crop. Twospotted spider mites were reported last week for the first time on sweet cherries.

Tart cherries are mostly at 9 mm to 11 mm in size with a light crop. Some tattering of leaves from bacterial spot also continues to be seen on tart cherries.

Plums are mostly at 8 mm to 10 mm in size, with bacterial spot symptoms showing up on these as well.

Small fruit
Strawberry bloom continues at most farms across the region. It is apparent that we are going to have a late harvest this year, as there is not much green fruit present at this time. Tarnished plant bug and strawberry clipper feeding continues to be seen in light amounts at many strawberry farms. I encourage growers to scout for slugs as they have been detected at four or five farms.

Raspberry buds are visible on summer red raspberries with no flowers open at this time. Fall red raspberries are growing more normally than they did earlier this spring with most being around 10” to 12” in length.

Blueberry bloom continues at most farms with an excellent crop of blueberries.

Grapes are currently at 6 to 8 inches of new growth with young flower buds present.

Phil Schwallier
Amy Irish Brown
Carlos Garcia-Salazar

Tree fruit
Most apple varieties are around the 10 to 12 mm size with some early setting varieties at 15 mm and larger. Chemical thinning is going on and fruit set in apple appears to be heavy and very strong for most varieties. We’re moving into some very nice weather for chemical thinners to work nicely over the next several days.

If growers are using Apogee for shoot growth control, it’s time for second applications to be made – be sure to leave a few days in between Apogee applications and thinning sprays – we are unsure if there would be any incompatibilities with these two applications yet.

Fire blight risk for blossom blight infections has dropped to low because most of bloom is complete, but there are still some blossoms out there on one-year old wood that could be a source for blossom blight infection if we get rain. No blossom blight symptoms have been reported, but they should start to show up soon, especially with the warmer weather forecasted for this week,

All of the primary apple scab spores should be mature at this time, so a couple of good rain events and primary scab will probably be over for 2005. Spore numbers have been declining with the last rain events, but they are still present, so growers need to continue to protect leaves and fruits for the next rain event at least. There are some scab lesions showing up from the infection period back in late April.

Most apple blocks have had a petal-fall application made for various insects.

Plum curculio egg-laying scars have just started to be found in plums and should be showing up in apple at any time if not already. Codling moth trap numbers have been much higher over the last week and a half. Early-timed codling moth egg materials should be on as we are just about to the 100 degree day base 50 mark from a regional biofrix of May 19, 2005 – we have accumulated 93 degree days base 50 from this regional biofix.

Regarding insect problems, we have observed emergence of cherry fruit worm for weeks but cranberry fruit worm emerged just 2 week ago. We captured the first moths in Allegan County around Fennville on May 18 and May 20 at approximately 300 GDD (Base 50 ºF) accumulated since March 1, 2005. When preparing the first application against fruitworms, remember that if reduced-risk insecticides are used (i.e. Confirm), the applications should be timed to coincide with the appearance of the first fruitworm eggs. In contrast to organophosphate insecticides, Confirm does not kill adult moths. Thus, we should not expect to have a decrease in moth captures in pheromone traps following the Confirm application.

Mira Danilovich

Growing degree day totals since March 1, 2005 as of Sunday, May 29

Tree fruit
We are several days past petal fall for apples and the young fruit is showing. The fruit is a bit more advanced in the southern parts of the district. We are seeing more of the geographical fruit size separation. Overall, we are within the optimum thinning window with the reported fruit sizes around 10-11 mm not exceeding 15mm. According to the weather forecast, it appears that we will have excellent thinning conditions. Gradual warm up started yesterday and is expected to continue throughout the week with the temperatures getting into mid to high 70’s and, possibly, getting above the 80-degree mark. Several growers started thinning over the weekend. Most of the thinning will be going on this week.

The reported rain event produced moderate apple scab infection period only in the Ludington area. In the rest of the district there was no infection. We are starting to see very few scab leaf lesions from the infections in early May. Blocks with the late, secondary bloom present on the trees will be subject to potential fire blight infections under the predicted weather conditions. Powdery mildew is becoming more prevalent in many apple blocks.

We’ve seen a significant increase in codling moth activity. Most of the commercial blocks have had enough increase in codling moth activity to warrant a biofix. Regional biofix is May 27 with 265 DD50. Timing for the first generation control application will depend on the material intended for use. Some materials would need to be applied than what was generally recommended for the use of organophosphates and pyrethroids (250 DD50 post biofix). Newer materials like Esteem and Diamond should be timed for 100 DD50 post biofix. Timing for Intrepid would be 150 DD50post biofix. Calypso and Assail application should be targeting 200-250 DD50 after the biofix. Scouts are reporting finding larvae of green fruitworms, various leafrollers and small number of rosy apple aphids and green apple aphids.

Sweet cherries are gaining in size. Looks like a good-size crop. Tart cherries are from just getting out of shuck to being out of shuck. Some early crop estimates are indicating that some 55-60 million pounds may come out of this area. Only Ludington area had a light cherry leaf spot infection out of the wetting event on May 27. A few lesions from some earlier infections could be found scattered throughout the area.

European plums are out of shuck with heavy fruit set. Crop outlook is good.

Peaches are out of shuck and gaining in size. Looks like a good crop (at this point).

Bacterial leaf spot is present in sweet cherry blocks, peaches and plums.

Oriental fruit moth trap catch numbers are going down. Biofix for the first flight in Ludington was May 10 at 293 DD45_. According to the degree-day model, 8-10 percent first generation egg hatch is expected 150-170 DD45 post biofix or at 443-463 DD45. As of yesterday, we are at 467 DD45_.

First plum curculio scars on the fruit have been reported in the Hart area. With the temperature warm up plum curculio is expected to be very active laying eggs this coming week. Blocks need to be protected.

Jim Nugent
Jim Bardenhagen
Duke Elsner
Nikki Rothwell

Weather
We finally had a week of "normal" temperatures. The month of May continued a two month trend of below normal precipitation. For growing degree day accumulations, GDD 42 totals are at 618 and GDD 50 are at 290.

Later this week may be a good window for apple thinning where fruit is advanced enough.  Thinners are most effective when daily highs will be warm (above 70º F) for two to three days following application. Many factors influence the desired aggressiveness of thinning, including vigor of bloom, tree vigor, frost damage, and weather during pollination. Fruit thins easiest between 8-12 mm king bloom fruit size with warm temperatures. If fruit size is slightly smaller than this but the weather looks to be good, consider thinning early. Thinners applied at 5-7 mm during warm weather work better than applied at 8-12 mm with cool weather.

In cherries, only one wetting event was reported last week in Northport, and it did not result in a cherry leaf spot infection.  We have captured plum curculio in baited traps, and we have egg-laying in the entomology block here at the station.  We expect plum curculio egg laying to increase sharply this week. We are still capturing American plum borers, and green fruitworm was present in blocks of tarts in the Suttons Bay area.  We have had our first report of cherry leaf spot symptoms, and occasional bacterial canker is showing up in tarts.

Jeff Andresen
Agricultural Meteorology
Geography

An extended period of seasonably warm and dry weather is in store for the Great Lakes region this week as high pressure dominates the northeastern third of the U.S. At the same time, an upper air troughing feature is expected to develop across western sections of the country, leaving Michigan under southwesterly flow aloft. As a result, look for a gradual warming of temperatures into the weekend with some 80EF or greater highs likely in some sections of the state through Saturday (June 4). Daytime highs Tuesday (May 31) will range from the upper 60's in lakeshore areas to the upper 70's inland, warming to a range from the low 70's north to the low 80's south by Thursday. Daily lows will warm from the 40's Wednesday morning to the 50's by Thursday to the 60's in some southern areas by Saturday. These temperatures will translate to daily base 50EF growing degree day accumulations of 16-24 units, the greatest daily values observed yet this season.

At this point, dry weather is expected through at least Friday (June 3). Winds will gradually shift to the south by late in the week, which (besides the warmer temperatures) will allow some Gulf of Mexico origin moisture to finally return to the region. With a cool front expected to slowly move into the state by late in the weekend, showers and thunderstorms will be a possibility once again by Sunday, likely continuing on into Monday as well.

Latest medium range forecast guidance calls for a basic continuation of upper air troughing across the western U.S., with broad ridging pattern across central and eastern sections of the country. The NOAA Climate Prediction Center 6-10 day outlook (June 5-9) calls for above normal temperatures and precipitation totals. During the 8-14 day time frame (June 7-13), both variables are expected to fall to near normal levels. Due to some differences in the tools used to create these the outlooks, it is worth noting that forecaster confidence in these outlooks is considered lower than normal.