SW Michigan Fruit Update

Check the Index for earlier postings

July 19, 2005

Mark Longstroth
Bill Shane
Al Gaus

Weather

Last week was warm and humid with highs in the 80s and 90s and lows near 70. Numerous thunderstorms moved across the area July 11. This general rain has relieved drought stress except close to the lake. Precipitation totals range from less than an inch to 3 inches.  Drought stress symptoms are still common close to the lake. Soil temperatures are about 75. This week’s forecast is for cooler weather. 

Southwest Michigan Growing Degree Day Totals March 1 through July 17, 2005				Grapes April 1
Location	GDD 42	GDD 45	GDD 50	GDD 50
SWMREC:	2250	1953	1501	1480
Bainbridge:	2340	2000	1540	1517
Hartford:	2113	1822	1379	1350
Grand Junction:	2236	2025	1566	1541
Fennville:	2100	1815	1378	1358

Tree fruit

We are catching picture wing fruit flies such as apple maggot, blueberry maggot and cherry fruit flies. Japanese Beetles are out. These pests emerge from the soil and we expect their numbers to increase following last week’s rains. The second generation of Codling moth is flying. Aphid and mite numbers are building in many crops. The second generation of Oriental fruit moth has ended, as has the summer flight of Obliquebanded leafroller. Redbanded Leafroller trap catches are down.

Apricot harvest continues. Late varieties are still ripening

Peach harvest continues. Garnet Beauty, Rising Star and Bright Star are being harvested in Berrien County. We are nearing the end on egg hatch for the second generation of Oriental fruit moth at 2100 to 2200 GDD base 45. We are picking up about 35 GGD base 45 per day.  Two spotted spider mites and European red mites can be found in peaches.

Cherry harvest is over and cherry growers should protecting against cherry leaf spot.

In Plums, White apple leafhopper injury can be found. Second generation eggs will begin to hatch soon so growers should be scouting for nymphs. Brown rot has shown up on fruit damaged by insects.

In Apples, Lodi, the first early apple is being harvested. We are catching more apple maggots after the rain. See the article on apple maggot monitoring and control in the June 28 Fruit CAT Alert. Codling moth trap catches are low. The second generation of Codling moth begins to emerge 1200-1250 GDD after Biofix. We biofixed for codling moth on May 20 at 334 GDD base 50. We are now at 1500 GDDs, about 1165 GDD after biofix and the trap catch is up in southern Berrien County indicating the beginning of the second generation. Obliquebanded leafroller Biofix was June 6 at 935 GDD base 42.  We are at 2250 GDD base 42, past the end of egg hatch at 1000 GDD after biofix. Some growers report small leaf roller larvae. So growers should be scouting terminals for this pest. See the article on summer leafroller control in the June 21, 2005 Fruit CAT Alert. The second generation of Oriental fruit moth has finished laying eggs. Many growers are treating European red mite and some report bronzing of the leaves. The treatment threshold for European red mite from mid July to mid August is 7.5 mites per leaf. The mines of the second generation of Spotted Tentiform Leafminer are showing up. White apple leafhopper eggs will begin to hatch soon so growers should be scouting for nymphs. Examine 50 leaves from 10 different trees and treat if the average is more than one nymph per leaf.

Sooty blotch and fly speck, leaf wetness sensors in for the MAWN network indicate that we are reaching 200 to 250 hours of leaf wetness since petal fall. Now is the time to resume fungicide sprays in cover sprays to control sooty blotch and fly speck.

Accumulated hours of leaf wetness My 16 through July 17, 2005
Location	Hours of leaf wetness
SWMREC:	140
Bainbridge:	190
Hartford:	245
Grand Junction:	237
Fennville:	190
Constantine	270

In Pears, European red mites are turning pear leaves black. Pear psylla numbers are building even though growers have recently treated for this pest.

Small fruit

Blueberry: Growers are harvesting Bluecrop, and some have begun harvesting Jersey. Growers should irrigate to maintain fruit size in later pickings. Blueberry maggot and Japanese Beetles are out. Rufus Isaacs has an article on blueberry insecticides in the June 28 Fruit CAT Alert. Blueberry aphid numbers are low and colonies are small. Harvest fungicides should target Alternaria fruit rots. See article on pre- and post- harvest fruit rots in blueberries, July 12 Fruit CAT Alert.

Grapes berry size has increased a lot in the last week due to rain. Grape berry moth feeding continues. Growers should be protecting the fruit and leaves from downy and powdery mildew. Rain and heavy dews this last week have been good conditions for downy mildew infection. These hot humid conditions are also prefect for powdery mildew and we have found powdery mildew symptoms on Concord fruit. 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 renovation is completed and new growth looks good. Growers should protect against leaf diseases and potato leafhopper.

Summer Raspberry harvest is underway. Fruit size is small and crumbly berries are common due to drought.