Vol. 18, No. 7, May 27, 2003

In this Issue
Tree fruit news
2003 TNRC trapline data: American plum borer
Winter injury in Northern Michigan
Small fruit news
Winter injury in raspberry
Angular leaf spot showing up in strawberries
Other news
2003 MSU Weed Tour
"Grow a Row" and help a Lansing food bank
Regional reports
Weather news

Winter injury in Northern Michigan

Jim Nugent
District Horticulturist, MSUE

The winter of 2002-03 will be remembered as one of the more severe for causing winter damage to several fruit crops. Why was the damage so bad and what can we learn from this event?

There are two particularly important factors that affect winter injury. First is the degree of acclimation of the plant to cold and second is the temperature.

In Southeast Michigan this year, Bob Tritten is seeing extensive winter injury in some crops that resulted from very cold temperatures in early winter following a fall when plants were slow to lose leaves and acclimate to cold. This same condition was seen in northern Michigan in 1987 following a November 1986 freeze event, and again in the early 90's.

As plants are exposed to extended periods of cold temperature, they acquire the ability to tolerate colder temperatures. During winter, temperatures above freezing result in some loss of hardiness, which is then regained with extended below freezing temperatures. However, hardiness is lost more rapidly then it is regained.

In northern Michigan this past winter, the event that caused the major problem occurred on March 3 when temperatures reached -10° to -20°F. The result was damage to buds and tissue that varies greatly by crop and site.

In February 1979, the temperature in Traverse City reached a record low of -37°F at the airport. Many fruit sites experienced temperatures of -22° to -32°F, 10° to 14°F colder than in 2003. This caused severe winter injury but quite interestingly, some fruit crops have been damaged more in 2003 than they were in 1979. Why?

The difference is explained by what happened prior to the cold events. In 1979, there was a period of about ten weeks prior to the record cold with temperatures never exceeding 32°F. By contrast, at the NWMHRS in 2003, highs were in the upper 30's February 28 and March 1. On the electronic weather instrument, the temperature dropped from 39°F at 4:00 PM on March 1 to -13°F at 5:00 AM on March 3. The loss of some degree of hardiness combined with the cold to cause significant damage to some crops.

The following are observations about winter injury from the 2003 event:

Grape

Vinifera grapes are generally dead to the snow depth on March 3. The best scenarios are generally where a cane or shoots were left below snow. Hybrids generally fared better, but of course injury varies by variety.

Cherry

Sweet cherries are generally damaged worse than tarts, and of course damage varies by variety and site. Trees that lost leaves early last year due to cherry leaf spot are more apt to have experienced winter damage. First year trees were more severely affected if damaged by deer last summer or were small, weaker trees at planting.

Of particular interest in 2003, we are seeing severe tree injury in some Montmorency tart cherries that are going into their third and fourth leaf. It occurs in relatively cold sites. When looking for winter injury, one generally cuts into the inner bark (phloem) area to check for browning. In the case of this age Montmorency, the injury is in the wood (xylem) tissue. Cutting limbs or the trunk with loppers reveals browning in the wood tissue. In cases where trees look weak but are partially leafing out, one may find good tissue only in the outer portion of last year's growth, i.e., most of the xylem is injured but a little good tissue remains. I expect these injured trees that do survive will not put on strong growth for a couple of years.

Also of interest in 2003 is that flower bud damage in sweet cherries is more severe than occurred in the 1979 winter freeze.

Peach

Peaches are showing significant fruit bud and wood injury, but probably not as severe as the injury in 1979.

Apricot

Apricots have severe damage to flowers, but most older trees appear to have survived.

Apple

So far winter injury appears quite minimal in apples; not as bad as an event in the early 90's when the cold came earlier in the winter.

In summary, it appears that the deaclimation prior to the March 3 cold affected crops differently. In general, cherries and grapes seem to have been more negatively affected by the deaclimation than were apples.

Winter injury in raspberry

Bob Tritten, Eric Hanson, Annemiek Schilder, Gary Thornton

Over the last three to four weeks, we have noted a collapse of summer raspberry canes at many farms across the state. These canes appeared to be healthy earlier this spring, and in most cases began to develop normal bud swell and leaf development. Later it became more apparent that these canes were injured by some cold weather events that occurred this past winter.

Our best guess is that most of the injury to raspberries in the southern part of the state occurred during a cold event last December 3 and 4, 2002. For southern Michigan, recall back to last fall when we had an untypical mild season. According to weather records at several reporting stations around the region we did not experience the typical gradual cooling of temperatures in October and November. Many stations reported temperatures of in the range of -12 to -15°F on the nights of December 3 and 4, 2002. Up until that time we only hit 15°F once, and only saw temperatures in the low 20's a couple times. Many raspberry plants still retained leaves in early December, additional evidence that they had not harden off as they typically do in the fall. In northern parts of the state, injury appears to have resulted from a cold event in early March. On March 1, temperatures approached 40°F, and by 5:00 AM on March 3, it was -12°F. In some fields, this abrupt change killed the canes back to the snow line. In other plantings only the tops of the canes were killed back.

Not all fields were heavily damaged. One variable that affects the hardiness of canes appears to be disease control. For the past few years we've also noticed in fungicide trials in southeast Michigan that winter injury is much less where disease control programs have been implemented the previous season (see Table 1). This is most likely due to the reduction in foliar and cane diseases, such as leaf spot, anthracnose, spur blight and cane blight. Anthracnose and cane blight in particular can weaken canes and predispose them to winter injury. Spur blight may kill buds at lesion sites and leaf spot may result in premature leaf senescence, which may also reduce winter-hardiness in severe cases. These diseases may not be apparent until later in the season (e.g. after harvest). We believe cane diseases play a bigger role in winter injury than previously assumed. Some varieties are particularly prone to cane diseases and may experience repeated problems when disease control is poor. Fungicides that are effective against foliar and cane diseases are Captan+Benlate, Cabrio, Abound and Nova. Ideally, these materials should be alternated to prevent development of fungicide resistance in target fungi. Remember that Cabrio and Abound belong to the same chemical class and therefore have the same mode of action. Lime sulfur will reduce overwintering inoculum when applied as a delayed dormant spray.

Of course varieties differ in winter hardiness. The 2002-03 winters were a good test of hardiness for 15 varieties in a trial at the Southwest Michigan Research and Extension Center in Benton Harbor. The previous two winters were relatively mild and only injured the tenderest varieties. The varietal differences have held across years (Table 2). The hardiest types in this trial are Boyne, Killarney, Lathan, Nova and Prelude. Those that appear hardy enough for southern Michigan but may suffer injury in northern parts of the state include Canby, Encore, Reveille, Titan and K81-6. Those that do not appear adequately hardy, even for southern Michigan, are Lauren, Malahat, Qualicum, and Tulameen.

Winter-injured canes should be removed from fields as soon as possible. In severely affected fields where there are few healthy canes, it may be best to mow entire rows or sections off and simply start over for next year. While this is a severe treatment, it will reduce pruning and spray costs and may reduce disease by eliminating injured wood.

Angular leaf spot showing up in strawberries

Annemiek Schilder
Plant Pathology

Angular leaf spot, caused by the bacterial pathogen Xanthomonas fragariae, is showing up on strawberry leaves. Typical symptoms are small angular, watersoaked spots on the undersides of leaves. The spots may appear shiny or wet due to bacterial ooze. On the upper leaf surface, the spots are less distinct and may appear reddish brown. If you are not sure whether the spots you see are bacterial or fungal in origin, hold the leaf up to the light: angular leaf spot is translucent, whereas fungal leaf spots are opaque. While the foliar phase of angular leaf spot may cause leaves to senesce prematurely, it is not of much economic concern. Of more concern are calyx (fruit cap) infections, which are caused by bacteria originating from leaf lesions. Infected calyces become black and shrivel up, make the berries look less desirable, thereby reducing their marketability. If angular leaf spot on the foliage is severe, the likelihood of calyx infections is greater.

Development of the disease is favored by mild, humid days (65-70C) and cold nights with near-freezing temperatures. Spread is facilitated by rainfall, overhead irrigation, and harvest operations. Irrigation for frost protection can inadvertently increase angular leaf spot severity. Control of angular leaf spot takes an integrated approach, including the use of healthy transplants to exclude the bacterium from newly planted fields. Most epidemics are thought to originate from infected plant material because X. fragariae is restricted to strawberry and does not persist well in fields after the crop has been removed. Other control methods could be the use of resistant or less susceptible cultivars (e.g., Delmarvel); avoiding harvesting or moving equipment through fields when the plants are wet; working in highly infected fields last to avoid spreading the disease to less affected fields; and overhead-irrigating only when absolutely necessary. The only chemical currently available for control of this disease is copper (e.g., Kocide, Cuprofix). Thorough coverage is important as copper is strictly a protectant. Be careful when using copper compounds under cool, slow-drying conditions, as phytotoxicity may result. Copper injury will be visible as a purple discoloration of the foliage.

2003 MSU Weed Tour

Jim Kells and Karen Renner,
Crop & Soil Sciences

There's great news for Lansing area needy and the Greater Lansing Food Bank. This year Van Atta's Greenhouse and L&L Food Centers are teaming up to produce The 2003 Greater Lansing Great Harvest.

Last year, Van Atta's asked area gardeners to "Grow a Row" for the food bank. Area gardeners responded with 2,500 pounds of fresh fruit and vegetables all delivered to the Van Atta's drop-off location. This year, L&L Food Centers agreed to join forces with Van Atta's to offer 11 drop-off locations in and around the Lansing area.

"Grow a Row" is the spring campaign of The Greater Lansing Great Harvest. This year there will be two Great Harvest collection Sundays in September: September 7 and 21, 12:00-3:00 PM. Food contributions can be dropped off at Van Atta's Greenhouse in Haslett, and all ten L&L Food Centers around the Lansing area.

It's easy! Grow a Row for the Food Bank!

For more information, contact Ronda Liskey, Van Atta's Greenhouse Community Projects Coordinator at 517-651-6198 or Sharon Krinock, Greater Lansing Food Bank.

1 - Southwest

Mark Longstroth
Bill Shane
Al Gaus

Weather

Last week started warm then cooled down. We picked up about 30 GDD50. Some rain fell on the evening of May 19. Total precipitation was about a quarter inch. Most soils have dried out enough to allow the soil to be worked and planting is well underway. Lows were in the 40's and highs near 60. This week's forecast is for warmer weather.

Insects

Cool conditions have kept insect activity low. Many growers applied insecticides this weekend. Tarnished plant bug and plum curculio feeding can be found. Few plum curculio egg-laying scars were found. Warmer days and nights bring plum curculio out. We are catching Oriental fruit moths and codling moth in fair numbers.

Tree fruit

Apricots are at pit hardening. Fruit are almost an inch in diameter. Fruit should be thinned down to three inches between the fruit. Bacterial spot symptoms can be seen on leaves and fruit.

Peach fruit are out of the shuck, about 6 to 10 mm in diameter. The peach crop looks good. Tree color looks poor due to the cool weather and poor movement of nitrogen in the trees. Some growers are applying urea. The trees should green up when the weather warms up later this week. Oriental fruit moth trap catches are still high. We are now at 570 GDD45, 320 GDD since Biofix for Oriental fruit moth on April 24. Growers who delay insecticide applications because conditions are not right for plum curculio egg laying are leaving peach shoot tips and fruit unprotected. Green peach aphids are out and forming colonies.

Tart cherry growers need to protect against cherry leaf spot. Plum curculio will be a problem when temperatures warm above 65°F. Many growers have a marketable crop. Sweet cherries need to be protected from brown rot all season long.

Plum growers need to protect against plum curculio and black knot. Bacterial spot symptoms can be seen on Japanese plums.

Apple bloom is ending. Most varieties are still showing bloom. Fruit size varies from 10 to 14 mm. Post bloom drop is heavy in Jonathan. Fruit set is heavy in Red Delicious, Gala and Rome orchards. Set is spotty in Golden Delicious with heavy and light in the same orchard. We have a good thinning window with temperature into the 70's for the next several days. These are not the best conditions for thinning but they are good. Grower should apply thinners aggressively. Read the apple thinning article by Phil Schwallier in the April 29 Fruit CAT Alert or the May Fruit Grower News.

A scab infection occurred on May 19. Scab lesions from the April 29 infection period are large and easy to find. Scab lesions from the May 14 infection period should just be appearing. Cool temperatures have kept fire blight bacterial populations low. A few oozing cankers were found in orchards with cankers from last year. Canker blight symptoms, collapsing spurs and oozing shoots. Most cankers had not begun to ooze - too cool. There is little risk of fire blight this week.

We biofixed 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 numbers are down indicating they have begun to pupate. Many growers have applied petal fall sprays to control insects including leafrollers, plum curculio and Oriental fruit moth.

Pear psylla are easy to find.

Small fruit

In blueberries, Jersey is at full bloom. Bluecrop is at petal fall, about 10 percent open flowers. Good timing for fruit rot sprays to control anthracnose and alternaria. Many growers are pruning out dead canes in Jersey fields. 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 warmer weather is good for Bt use.

In grapes, shoots are 10 to 14 inches long and flower clusters are elongating. It is easy to tell the difference between Concord and Niagara Concord vineyards have a reddish cast from all the pink hairs on the leaves. Some growers are thinning the potential crop by pruning. Wine grape shoots are about 6 to 8 inches. Growers have applied protectant materials to reduce phomopsis. Some phomopsis lesions have 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. Most of the primary bloom has set. Spittlebugs are out. Growers need to apply fungicides during bloom to reduce fruit rots. Leafrollers and leaf spots are problems we see in grower fields.

Raspberries are in early bloom.

Meetings

The next Monday Fruit Management meeting will be June 2 at Bjorge's Fruit Acres Farm, at the corner of Friday and Carmody roads, approximately 2 miles south of the Coloma exit I-94 at 5:00 PM.

The next Grape IPM Meetings will be June 4, 2003. 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 SWMREC 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.

2 - Southeast

Bob Tritten

Weather

Our weather continues to be rather cool compared to our normal spring. With cool night time temperatures our insect activity has been relatively slow to develop this year. Fortunately, we have also not had any fireblight weather and a low risk of potential infection. We are currently looking at a narrow apple thinning window over the next few days with cooler temperatures predicted later in the week. Strawberry growers have needed to frost protect a couple of times over the last week. Soil temperatures remain cool most days in the lower 60's. Very little rainfall occurred late last week and over the weekend at most farms.

Tree fruits

Apples are mostly at 8 to 10 mm in the south and 5 to 6 mm in the northern part of the region, including Flint and Romeo areas. There was an extended bloom period for many apple varieties this year. There continues to be lingering bloom in Gala and a few other varieties as well. For growers in the southern part of the region today looks like an excellent day to be applying thinners as we have two to three days that are predicted in the lower 70's. The proper timing for thinning in the northern part of the region will most likely be early next week. We'll hope for several warm days that we can accomplish this in. Codling moth trap catches are generally in the range of 3 to 9 moths per trap. With low nighttime temperatures codling moth have not been flying consistently every day. However, the Romeo area biofixed for codling moth on Monday, May 19 and in the Flint area biofixed last Tuesday on May 20. Plum curculio have been found in apple, plum and cherry. However, few if any egg laying scars have been seen. With warmer temperatures predicted today and tomorrow and a possibility of some warmer night time temperatures, I would expect to see plum curculio egg laying scars on fruit in the next few days. Oriental fruit moth trap catches remain high with numbers in the range of 5 to 21 per trap. Larvae of several different insects continue to be seen at low levels, these include obliquebanded leafroller, green fruitworm, fruit tree leafroller, climbing cutworm and redbanded leafroller. Spotted tentiform leafminer eggs continue to be seen. No mines have been detected. Adult trap catch continues to wind down from the first generation. Rosy apple aphids continue to be seen in fairly low levels, as do tarnished plant bugs. European red mites continue to be seen "here and there." Numbers are consistently low for this time of year in almost all apple blocks. Very few white apple leafhoppers and potato leafhoppers continue to be seen. Apple scab lesions are now being seen in a few apple blocks around the district. There is a general lack of lesions at most farms this year. Spore discharge continues with each wetting event. We've had some fairly good numbers of spore discharge in the last rain event. We are not at the end of primary apple scab season. The daily risk assessment (EIP) remains fairly low for fireblight activity this year. Many growers have not applied a bactericide yet this season for fireblight control.

Pears are mostly at 10 to 12 mm in size. Pear psylla are fairly easy to find this year.

Peaches are at early shuck split at many farms across the region. Peach leaf curl symptoms are now more evident and have been reported at fairly low levels at a number of farms this year. Our peach crop looks good at this time. Again, Oriental fruit moth trap catches are fairly high. Green peach aphids are starting to be seen and are beginning to form colonies at a few early sites.

Sweet cherries are at 5 mm. There is a variable crop of sweet cherries at this time across the region. See the note under apples on plum curculio, which should be seen in the next few days or so.

Small fruits

Strawberries are at bloom at most farms across the region. It appears that we have a good crop of strawberries coming along at this time. Twospotted spider mites continue to be seen at a few farms, however numbers are low and control recommendations are generally not needed at this time. Some low amounts of strawberry clipper continue to be seen. Spittle bugs are just now starting to be seen on a few weeds surrounding strawberries, however none have been seen on strawberries. Growers are applying fungicides to control fruit rots at this time.

Raspberries are at early bloom and fall red raspberry canes are about 6 to 8 inches tall. Raspberry cane collapse continues from winter injury from last December 3 and 4. If possible, I would recommend cutting back these canes to good healthy green tissue. It may be possible to pick a fairly decent crop of raspberries from these canes this year.

Blueberries are at early bloom at several farms across the region. Mummy berry shoot strikes have been seen at a few farms. Dead twigs continue to be seen on many varieties of blueberries as a result of winter injury last December. Cranberry fruit worm have been reported in traps at several blueberry farms.

3 - Grand Rapids Area

Phil Schwallier
Amy Irish Brown
Tom Kalchik
Carlos Garcia-Salazar

Tree fruit

Most apple varieties are in the petalfall stage right now with some lingering bloom still out there. Spotted tentiform leafminer flight has declined and the first sap feeders are being seen. Whiteapple leafhopper nymphs started to be found last week. No plum curculio damage has been seen at this time, but it should show up any time in many fruit species.

Petalfall sprays, in general, will target plum curculio, spotted tentiform leafminer, obliquebanded leafroller, aphids and early hatch of white apple leafhopper. We have more insecticide choices than in the recent past for petalfall timing, but many of them are rather specific to certain pests - be sure to read carefully about which insects they each target and to scout your blocks closely to know what insects you need to control.

Codling moth trap numbers are very high for this early in the season and timings for early egg hatch and first cover sprays will be very important this year, but we are probably at least 14 days away from the 250 GDD50 threshold.

We've had eight infection periods for apple scab this season and lesions from the early and mid-May infections are being found in unsprayed and sprayed blocks. Now is a very key time to scout your blocks very carefully to be sure you do not have any scab lesions that got through. This is important as we get to the end of primary scab, so that you know you won't have to deal with secondary.

Regarding fire blight in apple, no blossom blight symptoms found yet. No oozing cankers seen, but they should be seen soon.

The next couple of days will provide a nice thinning window for early apple varieties. There are reports of heavy fruitlet drop in Red Delicious - it will be important to check orchards and varieties carefully before thinning applications go on.

Small fruit

Blueberries in west central Michigan are blooming. Bluecrop and Blueray are in 50 to 75 percent bloom while Jersey is in 25 to 50 percent bloom stage.

Regarding insect pests, the redbanded leafroller (RBLR) moths are still flying but in low numbers. We have not had any captures of OBLR moths in pheromone traps, yet. However, there is some leafroller feeding ranging from 2 to 20 percent. One important event is the trapping of the gray-banded leafroller, Argyrotaena mariana Fernald, in great numbers in all OBLR pheromone traps installed in Ottawa County, 25 to 40 moths per trap. This moth seems to be attracted to the OBLR pheromone but so far, only larvae of the RBLR and OBLR have been found in all blueberry fields scouted in both Allegan and Ottawa counties.

We are observing the emergence of adults of the cherry fruitworm in both Allegan and Ottawa counties with moth captures in the pheromone traps ranging from 2 to 12 moth per trap per week. We also caught the first moths of the cranberry fruitworm in farms located in south Allegan, 1 to 4 per trap per week. No obliquebanded leafroller has been caught yet.

Degree days accumulated

4 - West Central

Mira Danilovich

Weather and crop development

The weather has been cool with the high temperatures in the low to mid-60's. We did have two freeze events on May 21 and 22 when the temperatures dipped down as low as 26.3°F in Ludington and 28.6°F in Bear Lake. The weather station in Hart did not show temperatures below 33.9°F associated with this cold front.

 Growing degree day totals as of Sunday, May 25

 Tree fruit

Apples and pears are, for the most part, in petal fall. With the weather being so cold, fireblight has not been an issue so far. Our EIP numbers are very low. Looking at the forecast for the next few days, temperatures are supposed to get into 70+ range, which will improve chances for potential fireblight infection in varieties that are notorious for having prolonged or secondary blooms. There have been no symptoms of canker blight yet. Apple scab has been easy on us this season, so far, only three infection periods. The last was on May 10 for Hart and Ludington, and May 19 for Bear Lake area. The rains we had on May 20 throughout the district did not cause any infections. There are a few leafrollers, mainly redbanded and obliques. Scouts are reporting finding cutworms, green fruitworms, lacewings and ladybugs. Codling moth numbers in traps have gone up since last week. We will be biofixing this week.

Peaches (Red Havens) are in shuck. Bacterial spot lesions are present in Babygolds. Oriental fruit moth trap catches are on the rise. Based on our biofix dates, sprays for first generation control need to be applied in the next two to three days. Due to the cooler weather insect activity has been suppressed.

European plums are in shuck. Scale injury (in some cases quite severe) has been reported in many blocks.

Sweet cherries are in shuck split, tarts are in shuck. There were no infection events in the past week. Plum curculio has been out for a while now. We are finding them in traps, but no fruit damage has been found. We are finding quite a bit of winter injury in younger Montmorency blocks that are in their third or fourth leaf. The injury resulted from the early March frost that followed after a few days of warmer temperatures. The injury is not typical of what we would expect to see when checking for winter damage cutting into the bark.the injury is confined to xylem (the inner, water-conducting tissue). Provoked by the warmer temperatures, water filled the xylem spaces when the sudden temperature drop occurred causing water to crystallize thus inflicting a physical damage to the cell walls.

5 - Northwest

Gary Thornton
Jim Nugent
Jim Bardenhagen
Duke Elsner

Growing degree day accumulations

GDD42      504

GDD50            226

Weather

This was the second week of generally dry, mostly sunny, generally cool conditions. Rain at the NWMHRS the past two weeks has totaled 0.21. Degree day accumulations at the NWMHRS entered the week at the 13 year average, but are now slightly behind. Frost occurred on the mornings of May 21 and 22. Temperatures were slightly colder on May 22, resulting in some frost damage to fruit crops in colder sites.

Tree fruit

Dry weather gave apple growers a break from apple scab. Fireblight does not appear to be a threat the rest of the week. If the actual temperatures end up being higher than predicted, then protectant sprays of Streptomycin will be warranted. First catch of codling moth emerged early last week. Apple growers should put out their traps for codling moth if they plan on scouting for this pest. Spotted tentiform leafminer averaged 106 per trap. European red mites are commonly found. If they are above threshold at this time, it is only a temporary situation, as the vegetation will dilute the current populations. Be careful to not rely entirely on Apollo or Savey as resistance can occur. Rotate with Agrimek, adulticides and oil. Rosy apple aphid populations continue to expand.

Pear psylla nymphs are easy to find on the young leaves. Populations vary from very low to very high. Blocks that struggled to control this pest last year generally have high populations of nymphs this year.

There were no infection periods for cherry leaf spot since early last week. Brown rot pressure remains low. Sweet cherries in early sites are starting to come out of the shuck. Once cherries are out of the shuck, they are susceptible to plum curculio egg laying activity. Plum curculio have already been found in area orchards, although no stings have been reported. American plum borer averaged 7 per trap. Sprays for this pest should be applied in about two weeks.

Deer injury is already showing up in tart cherry.

Weather news

Tracy Aichele
Agricultural Meteorology
Geography

The trough that has kept temperatures cool is expected to persist over Michigan through the next week. Temperatures could reach the 70's (some potential for temperatures in the 80's south) on Wednesday and Friday (May 28-30). Clouds and a chance of rain are in the forecast for Wednesday night through Monday, although showers and thunderstorms appear to be spotty. Forecasts are for below normal temperatures in the 6-10 day and 8-14 day ranges. In the 6-10 day outlook, precipitation is forecast to be below normal, but the 8-14 day forecast calls for above normal precipitation.

The following website is helpful in visualizing National Weather Service forecasts; select the variable (Maximum Temperature, Probability of Precipitation, Relative Humidity, etc.) from a pull-down menu and loop through the available forecast times. Temperature and precipitation forecasts are available for the coming week.

Grand Rapids:
http://www.crh.noaa.gov/ifps/ifps.php?site=grr
Detroit:
http://www.crh.noaa.gov/ifps/ifps.php?site=dtx
Gaylord:
http://www.crh.noaa.gov/ifps/ifps.php?site=apx
Marquette:
http://www.crh.noaa.gov/ifps/ifps.php?site=mqt
Northern Indiana:
http://www.crh.noaa.gov/ifps/ifps.php?site=iwx

Growing degree days are very close to normal in much of the state, and above last year's totals by this time. The Saginaw Bay region and some areas of the Upper Peninsula, however, seem to be lagging in GDD accumulation. The growing degree day table is linked at the top of the web CAT Alert, and printed in the back of the paper CAT Alert. This table is updated every day at:
http://www.agweather.geo.msu.edu/agwx/current/report.asp?fileid=degreeday

Although the drought warnings have been lifted (thanks to the April and May showers), rain totals since October 15 are below normal in some areas of the state (Figure 1). Modeled soil moisture is lower than normal in some areas of the state (Figure 2), but local conditions may vary from the model based on soil type and land cover. Both Figure 1 and Figure 2 are updated daily at the following web site:
http://mrcc.sws.uiuc.edu/Watch/Drought/moisture.htm