SW Michigan Fruit Update

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June 28, 2005

Mark Longstroth
Bill Shane
Al Gaus

Weather

Last week was hot with highs around 90. No rain fell in most of the region. A strong thunderstorm moved across parts of Van Buren County Monday. Areas close to the lake are very dry. We are seeing drought stress symptoms of wilting and leaf loss in many areas. Soil temperatures are about 75. This week’s forecast is for continued weather with highs near 90.

Southwest Michigan Growing Degree Day Totals March 1 through June 26, 2005				Grapes April 1
Location	GDD 42	GDD 45	GDD 50	GDD 50
SWMREC:	1578	1341	995	975
Bainbridge:	1627	1389	1034	1011
Hartford:	1486	1258	919	900
Grand Junction:	1644	1406	1052	1027
Fennville:	1457	1233	900	880

Tree fruit

We are catching cherry fruit flies, and expect to catch blueberry maggot and apple maggot after any rainstorms with over a quarter inch of rain. Codling moth and Obliquebanded leafroller trap catches continue. San Jose scale crawlers should be out. Japanese Beetle adults are out. Potato leafhoppers have been found. We are now catching greater and Lesser Peach Tree borers and growers should be thinking about trunk sprays for Borer control. The second generation of Redbanded Leafroller is beginning to fly. Aphid and mite numbers are building in many crops. We are catching cherry fruit flies, and expect to catch blueberry maggot and apple maggot after any rainstorms with over a quarter inch of rain.

Apricot fruits are about 1.75 inches in diameter and earlier varieties are beginning to ripen. I expect harvest to begin soon.

Peach fruit are 1.25 inches in diameter. June drop continues and pit hardening has begun. The second flight of Oriental fruit moth has started. We are at peak emergence for the second generation and peak egg laying should occur at about 1500 GDD base 45. Oriental fruit moth trap catches were down in many areas, probably because of the heat. We are catching Peach Tree Borer adults and growers should be thinking about trunk sprays. Green peach aphids numbers are increasing.

Cherries: Sweet cherry harvest is underway. Tart cherry harvest should begin in the middle of the week. Cherry growers should be protecting against brown rot. Cherry fruit flies are being trapped in abandoned cherry plantings. No symptoms of cherry leaf spot have been found. There is very little leaf yellowing of any kind from Ethrel, sour cherry yellows or cherry leaf spot. All the yellow leaves are on weak trees that are shedding their leaves.

Plums are over an inch in diameter. Brown rot has shown up on fruit damaged by insects.

Apple fruit are 1.5 inches in diameter.  Fire blight is still spreading and is becoming severe in some orchards. Jonathon is the most severely affected variety. Green apple aphids are becoming common and can spread the infection to healthy trees. Growers are treating for aphids in their cover sprays for codling moth. Codling moth trap catches are still high. We biofixed for codling moth on May 20 at 334 GDD base 50. We are now at 995 GDDs, about 660 GDD past biofix. Activity for the first generation of Codling moth should end at about 1000 GDD after biofix, so we are only about half-way though the first generation. Obliquebanded leafroller Biofix was June 6 at 935 GDD. We are at 1578 GDD and egg hatch began last week. See the article on summer leafroller control in the June 21, 2005 Fruit CAT Alert. We are finding leaf roller larvae in abandoned orchards. The second generation of Oriental fruit moth is laying eggs. European red mite numbers are increasing and this hot weather may make them explode. The treatment threshold for European red mite from mid June to mid July is five mites per leaf.  Spotted Tentiform Leafminer mines are easier to find.

Pear fruit are 1.25 inches in diameter. Pear psylla numbers are building and many growers have recently treated for this pest.

Small fruit

Blueberry fruit are coloring. Harvest of early varieties (Bluetta, Weymouth, Bluejay and Duke) began Monday in Van Buren and Berrien counties. Cherry fruitworm and Cranberry fruitworm eggs are scarce. The danger from these pests has past. Tussock moth larvae are out and causing severe damage in some fields. Blueberry aphids are becoming more numerous. Cane collapse due to phomopsis still is not major problem in Van Buren County. Preharvest fungicides should target both Anthracnose and Alternaria fruit rots. See the article in June 14 Fruit CAT Alert. Powdery mildew, a minor leaf disease, has been reported.

Grape berries are buckshot sized. Vinifera bloom is ending. Grape berry moth feeding continues. Phomopsis, black rot and downy mildew symptoms can be found. These hot humid conditions are prefect for powdery mildew, but we have been getting temperatures high enough to inhibit fungal growth and spore germination. Growers should be protecting the fruit clusters from diseases with bloom sprays or post bloom sprays before our next rain.

Strawberry harvest is winding down. Heat will end the harvest soon. Renovation of strawberry fields should begin soon.

Summer Raspberry harvest is underway. Many varieties look poor due to winter injury.

Cranberries bloom is ending. A second fungicide application to control fruit rots is targeted for the end of bloom on rapidly growing pinhead fruit.

Miscellaneous

There is no Monday Update on July 4. The next Monday Update meeting will be, Monday July 11 at the Overhiser Fruit Stand in Allegan County at 5 PM. There will be one MDA restricted use pesticide recertification credit available at this meeting.