SW Michigan Fruit Update

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May 24, 2005

Mark Longstroth
Bill Shane
Al Gaus;

Weather

Last week was cool with highs in the 60s and lows in the 40s and 50s. The weekend highs were in the low 70s with lows in the 40s. Rain fell on May 19 and 22. The rain event on May 19^th was an infection event for most diseases. Precipitation totals for last week were a half-inch to almost an inch. Topsoils are moist. Soil temperatures are about 65. This week is forecast cool through the weekend with chances of rain.

Southwest Michigan Growing Degree Day Totals March 1 through May 22, 2005				Grapes April 1
Location	GDD 42	GDD 45	GDD 50	GDD 50
SWMREC:	689	539	364	342
Bainbridge:	713	561	382	369
Lawton:	677	569	364	344
Hartford:	640	500	330	310
Grand Junction:	733	578	395	370
Fennville:	610	464	307	287

Tree fruit

Cool weather has kept insect activity low. Fresh plum curculio egg laying scars were found on Monday in plums. We expect to see more egg laying when we get warmer weather. See the notes on plum curculio monitoring in May 3, 2005 Fruit CAT Alert.

Apricot fruits are almost an inch in diameter.

Peach fruit are 12 to 14 mm in diameter. Oriental fruit moths in Southern and Central Berrien County are laying eggs. Biofix for the first flight was April 15 at 175 GDD base 45, we are now at 539 GDD, 354 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 220 GDD past Biofix. Tarnished plant bug feeding scars have been found on young fruit. Plum curculio should be a pest later. Check the insecticide efficacy table on page 56 of the Fruit Management Guide, E-154.

Cherries: Sweet Cherries are past pit hardening and about 12 mm in diameter. Fruit set in sweet cherries is very heavy and a significant June drop is underway. Tart Cherries are also 12 mm in diameter. Fruit set looks better now that all the fruit is out of the shuck. It looks like most of the tart cherry fruit we see now will stay. Rain on the 19^th was a cherry leaf spot infection. Growers should be monitoring for plum curculio when the weather warms into the 70s for several days. Now is a good time to apply Gibberellic acid (Pro-Gibb) to young cherry trees to suppress bloom and fruit next year. 

Plums are 12 mm in diameter. There are many smaller fruit that will fall off. Plum curculio feeding and egg laying scars were found in plums near Paw Paw. 

Apple fruit are generally 10 to 12 mm in diameter. Earlier varieties are about 15 mm in diameter. Fruit set is spotty and varies quite a bit from site to site and by variety. Many growers applied thinners late last week. Because of the cool temperatures predicted this week, thinning applications this week will probably be less effective. It would be better to wait until warm weather returns and then apply higher rates of thinning materials. There is still some rat-tail bloom and a danger of fire blight is not past. Warm weather and rain resulted in blossom blight infection periods on May 20 and 22. Symptoms of systemic fire blight from overwintering canker are being found. Oozing cankers and collapsing shoots and spurs were found in several orchards. It is still too early for blossom blight infections symptoms to be visible. The May 19 rain was an apple scab infection period. No new apple leaf scab symptoms were found. We are at or near the end of primary scab. Growers should apply one last spray containing a protectant fungicide. If no new scab symptoms are found by the first week of June then no more scab sprays should be needed. If scab lesions are found in the orchard, growers should continue to apply protectant materials to suppress fruit scab. European red mites are scarce. Redbanded Leafroller trap catches are low. Spotted Tentiform Leafminer eggs should be hatching and growers should scout for sap feeders and mines. We have caught only a few Codling moth adults to date. Cooler temperatures have shut down flight and many sites have not caught codling moth. We have caught only a few Codling moth adults to date. Cooler temperatures have shut down flight and many sites have not caught codling moth.  We are initially biofixed for codling moth on May 20 at 334 GDD base 50. 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 next week. Check the article on using new insecticide materials in last year’s Fruit CAT Alert, which includes information on timing.

Pear bloom is over. Fruit are 10 mm in diameter.  Set is generally light.

Small fruit

Blueberry bloom is ending. Many varieties and sites are at petal fall. Cherry Fruitworm and Cranberry fruitworm adults are being caught. Egg hatch has not begun so insecticide sprays can wait until after bloom. Protect bees during bloom by only using insecticides with low toxicity to bees and apply when bees are not foraging. Fungicide applications should be focused on mummyberry and anthracnose control.

In Grapes, Concord and Niagara flower clusters are elongated and beginning to separate.  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.  Growers should be protecting the shoots and flower clusters from phomopsis and other diseases.

Strawberry bloom continues. Growers should apply fungicides during bloom to control fruit rots.

Some Summer Raspberries are such as 'Prelude' are blooming.

Cranberry buds are elongating. The most advanced buds show individual flowers. Cranberry beds have begun to green up.

Miscellaneous

There will be no Monday Update next Monday Memorial Day. The next Monday Update meeting will be, Monday June 6, at the Fruit Acres Farm in Berrien County at 5 PM. There will be one MDA restricted use pesticide recertification credit available at this meeting.