SW Michigan Fruit Update

Check the Index for earlier postings

July 6, 2005

Mark Longstroth
Bill Shane
Al Gaus

Weather

Last week was cooler with highs in the 80s and lows about 60. Strong thunderstorms moved across the area Monday afternoon and a general rain fell overnight. Areas close to the lake received one or two tenths of an inch while inland areas received a half or more. Hail was associated with several thunderstorms. Soils are still dry close to the lake. Soil temperatures are about 75. This week’s forecast is for continued warm weather with highs in the upper 80s.

Southwest Michigan Growing Degree Day Totals March 1 through July 3, 2005				Grapes April 1
Location	GDD 42	GDD 45	GDD 50	GDD 50
SWMREC:	1802	1547	1166	1144
Bainbridge:	1854	1595	1206	1183
Hartford:	1695	1446	1073	1054
Grand Junction:	1871	1617	1224	1199
Fennville:	1666	1422	1055	1035

Tree fruit

We are catching picture wing fruit flies such as apple maggot, blueberry maggot and cherry fruit flies.  San Jose scale crawlers should be out. Japanese Beetle adults are out. Potato leafhoppers have been found. The second generation of Redbanded Leafroller is flying. Redbanded Leafroller trap catches increased sharply. Codling moth and Obliquebanded leafroller trap catches are declining. Aphid and mite numbers are building in many crops.

Apricot harvest has begun.

Peach fruit are 1.5 inches in diameter. June drop continues and pit hardening has begun. We are at peak egg laying for the second generation of Oriental fruit moth at 1500 GDD base 45. Trunk sprays for Peach Tree Borer are applied in July. Green peach aphids numbers are increasing.

Cherries: Sweet cherry harvest is underway. Tart cherry harvest should end this 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.

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

Apple fruit are about 2 inches in diameter. We are catching apple maggot adults. See the article on apple maggot monitoring and control in the June 28 Fruit CAT Alert. Fire blight has appeared in some new locations. Green apple aphids are becoming common and can spread the infection to healthy trees. Codling moth trap catches are still high. We biofixed for codling moth on May 20 at 334 GDD base 50. We are now at 1166 GDDs, about 832 GDD past biofix. The first generation of Codling moth should end at about 1000 GDD after biofix, and the number of adults trapped is declining. Obliquebanded leafroller Biofix was June 6 at 935 GDD base 42. The end of egg hatch is 1000 GDD after biofix, so egg hatch should end this 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. The second generation of Spotted Tentiform Leafminer is flying.

Pear fruit are 1.5 inches in diameter. Pear psylla numbers are building and many growers have recently treated for this pest.

Small fruit

In Blueberries, the general harvest of early varieties in underway. Blueberry maggot adults are being caught. Japanese beetles are becoming easier to find. Rufus Isaacs has an article on blueberry insecticides in the June 28 Fruit CAT Alert. Harvest fungicides should target Alternaria fruit rots. See the article in June 14 Fruit CAT Alert. More and more reports of cane collapse due to Phomopsis are coming in but the dimensions of the disease are still less severe than reported in the northern growing regions. Growers who can irrigate should maintain their irrigation so that they can size the smaller berries for later pickings. Under the hot conditions that we have blueberry fields can use as much as a quarter inch of water per day.

Grape berries are buckshot sized. Vinifera is berry touch. We are at the 1200 GDD base 50, and grape berries are about half of their final weight. Now is the time to estimate the crop and decide whether the crop should be adjusted by thinning. 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.

Strawberry renovation is underway.

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

Cranberries are at pinhead fruit.

Miscellaneous

The final 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.