SW Michigan Fruit Update

Check the Index for earlier postings

August 1, 2005

Mark Longstroth
Bill Shane
Al Gaus

Weather

Last week was cooler with highs near 80 and lows in the 50s and 60s. The passage of a cold front with general rain relieved some stress. Precipitation totals were less than an inch.  Drought stress symptoms are still common close to the lake. Soil temperatures are in the 80s. This week’s forecast is for hot humid weather and a cooler weekend. 

Southwest Michigan Growing Degree Day Totals March 1 through July 30, 2005				Grapes April 1
Location	GDD 42	GDD 45	GDD 50	GDD 50
SWMREC:	No data from July 27 on
Bainbridge:	2747	2404	1875	1852
Hartford:	2527	2195	1681	1661
Grand Junction:	2733	2394	1871	1846
Fennville:	2529	2201	1694	1674

Tree fruit

We are catching more apple maggot and blueberry maggot. Japanese Beetles are still common in some areas. Japanese Beetles usually emerges in three waves in SW Michigan. Expect another wave after the next wide spread rain. Aphid and mite numbers are high in many crops. The second generation of Codling moth and the third generation of Oriental fruit moth are flying. Obliquebanded leafroller trap catches are up. Redbanded Leafroller trap catches are down.

Peach harvest continues. Red Haven peaches are being harvested in Southern Berrien County. Oriental fruit moth trap catches are up indicating the start of the third generation. We set Biofix as July 27 at 2300 GDD base 45 in Bainbridge. Treatment is timed for 8 to 10% egg hatch at 150 to 170 GDD base 45 after Biofix about 2450 to 2470 GDD and egg hatch will continue to about 3200 GDD base 45. Brown rot is showing up here and there. Two spotted spider mites are a problem in some peach blocks.

Cherry growers should protect against cherry leaf spot. Some growers are pruning cherries. Japanese Beetles are common in cherries and causing damage in young planting. 

Plum growers should protect against apple maggot and brown rot.

In Apples, we are catching more apple maggots. August is usually the month for this pest. See the Fruit CAT article on apple maggot monitoring and control. At this time most growers are applying pesticide sprays every two weeks. We biofixed the second generation of Codling moth on July 20, Bainbridge had 1620 GDD base 50. We are now at 1875 GDDs, 255 GDD after biofix and treatment is timed for 250 GDD after biofix. Growers are still finding leaf roller larvae. Trap catch for Obliquebanded leafroller was up last week. This could be the start of the next generation, but it seems a little early. We expected the next generation to emerge at about 2935 GDD base 42 in a couple weeks. Redbanded Leafroller flight is low.  See the article on summer leafroller control in the June 21, 2005 Fruit CAT Alert. Oriental fruit moth trap catches are up indicating the start of the third generation, see the notes under peaches. European red mite numbers are exploding. If you have seven mites per leaf you should control European red mite. The mines of the second generation of Spotted Tentiform Leafminer are showing up. Growers should be scouting for white apple leafhopper nymphs. Examine 50 leaves from 10 different trees and treat if the average is more than one nymph per leaf.

In Pears, European red mites and pear psylla numbers are building.

Small fruit

Blueberry: Growers are harvesting second and third pick of Bluecrop and second picking of Jersey. In non-irrigated fields harvest is ending early due to poor fruit size and quality. Blueberry maggot and Japanese Beetles are out. Rufus Isaacs had an article on blueberry insecticides in the June 28 Fruit CAT Alert. Blueberry aphid numbers are low. Harvest fungicides should target Alternaria fruit rots. See the article in June 14 Fruit CAT Alert.

Grape veraison has begun in early varieties and early sites. Grape berry moth feeding continues. See the article in the July 26 Fruit CAT alert on “Controlling mid-season grape berry moth.” Disease pressure this dry summer has been light. We have found powdery mildew symptoms on Concord fruit but not much downy mildew. These are the only two diseases we are worried about at this time. See Annemiek Schilder’s article on late season grape disease control in the July 26 Fruit CAT Alert.  The timing for controls of phomopsis and black rot has passed. Fruit rot symptoms of black rot have been found but the fruit is becoming more and more resistant as we approach veraison.

Strawberry growers should protect against leaf diseases and potato leafhopper.

Summer Raspberry harvest is ending. Blackberry harvest is underway.

Miscellaneous

Now is the time for tissue sampling to determine fertilizer needs in fruit plantings.