SW Michigan Fruit Update

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August 24, 2004

Mark Longstroth
Bill Shane
Al Gaus;

Weather

Temperatures have been cool. Highs in the 60s and 70s with lows about 50. This week’s weather forecast is warmer weather with highs in the 80s and lows near 70 with a chance of showers or thundershowers each day. Soils are becoming quite dry. Heavy thunderstorms formed in the area last night and some areas received 2 or more inches of rain. But other areas have received less than a half-inch of rain over the last two weeks, so soil moisture varies widely.

Southwest Michigan Growing Degree Day Totals March 1, 2004 through August 22, 2004
Location	GDD 42	GDD 45	GDD 50
SWMREC:	3035	2615	1964
Bainbridge	3058	2636	1986
Lawton:	3092	2660	2030
Hartford	2874	2455	1817
Grand Junction:	3084	2661	2008
Trevor Nichols:	2687	2287	1676

Tree fruit

Cool weather has kept insect activity low. Warm rainy weather will cause a dramatic increase in insect activity. Fruit fly numbers have declining for most sites. Recent rains may bring out more. Cherry fruit flies are common around most sites. Japanese beetles numbers are low. Codling moth trap catch and Oriental fruit moth trap catch numbers should increase over the coming week with the warm night temperatures. See the article in this week’s Fruit CAT Alert. Trap catch of redbanded leafroller is up but obliquebanded leafroller trap catch is low.

Peach harvest is starting to slow down. Size is excellent. Varieties being harvested include PF25 and PF 27a. The flight of the third generation of Oriental Fruit Moth is well underway and egg hatch has begun. Oriental Fruit Moth Biofix was April 29 at 300 GDD 45. We are at 2315 GDD-45 since Biofix and egg hatch began at about 2250 GDD after Biofix. We expect trap catch numbers to increase with the return of warm weather.

In Cherries, cherry leaf spot has defoliated many orchards. Some growers have applied another cherry leaf spot spray to keep their leaves on a little longer.

Plum harvest has begun. Stanley harvest is underway. Brown rot is a problem.

Apple growers are finishing Paula Red and Ginger Gold. Some growers have started to color pick Gala and Macintosh.

Codling moth trap catches have been low and steady. We are in the middle of the second-generation flight and egg hatch. Biofix on May 7 at 235 GDD base 50, our current total is 1844 GDD, and we are at 1729 GDD after Biofix. Egg hatch for second-generation codling moth is underway. The end of egg hatch is expected at 2100 GDD after biofix. The warm weather forecast for the coming week means that there will be a strong flight of codling moth. This means there will be a large egg hatch in the middle of next week so growers should be sure to protect their fruit. It is doubtful we will see a third generation of codling moth this year, but a strong flight at the end of the second generation will have the same effect.
The third generation flight of Oriental fruit moth and egg hatch is underway. We can expect their numbers to increase also. Late season Oriental fruit moth may migrate out of the orchards were they are established to nearby plantings. Spotted tentiform leafminer adults are emerging. White apple leafhopper larvae are out. Some apple orchards are bronzing from European red mite. For European red mite the treatment threshold for this pest is 7.5 mites/leaf.

Pear harvest has begun.

Small fruit

In Blueberries, growers away from the lake are picking Elliott the last variety of the season. Growers close to the lake are still picking earlier varieties. Many growers are finished for the season.  Both blueberry maggots and Japanese beetles are out in low numbers. Tussock moth larvae are heavy in some areas and growers report that larger larvae are hard to kill. Alternaria is the main fruit rot showing up on the fruit. Growers should protect the fruit. Birds eating the fruit are still a major problem.

Grapes veraison is ending. Color is well developed in most vineyards. Grape berry moth is flying and stings in fruit can be found. Damage is heavy in some vineyards. Growers should be scouting hot spots and the edges of their vineyards for stings and other signs of recent berry moth activity. Most of the activity seems to be on the edges of vineyards. Grape berry moth numbers will also increase with the warm weather and a strong flight is expected this week with lots of eggs being laid before harvest. Grape leafhopper nymphs are spotty, some sites have very few and others will require treatment. Phomopsis symptoms are easy to find in most grape vineyards. Downy mildew is common. The wet conditions with heavy dews forecast for the coming weeks will require protection to control the spread of downy mildew. To see a regional grape scouting report go to http://www.grapes.msu.edu/.    

Southwest Michigan Grape Growing Degree Days form April 1, through Sunday August 22, 2004.
Location	Grape GDD
SWMREC:	1917
Bainbridge	1937
Lawton:	1938
Hartford	1770
Grand Junction:	1954
Trevor Nichols:	1639

In Strawberries, new growth looks good except where potato leafhoppers have been feeding. Strawberries are setting buds for next years crop and weed killers should not be used at this time.

Fall Raspberry harvest is in full swing. With the wet weather growers should be protecting their fruit from botrytis fruit rot.