SW Michigan Fruit Update

Check the Index for earlier postings

August 10, 2004

Mark Longstroth
Bill Shane
Al Gaus

Weather

The beginning of August was fairly normal. High temperatures were above 80 and lows above 60. About an inch of rain fell last Wednesday and the temperatures have been cool in the 70s with lows about 50 since then. Soils are dry. Soils temperatures are in the mid 70s. This week’s weather forecast is cool weather with a chance of showers or thundershowers.

Southwest Michigan Growing Degree Day Totals March 1, 2004 through August 8, 2004
Location	GDD 42	GDD 45	GDD 50
SWMREC:	2713	2337	1760
Bainbridge	2770	2390	1809
Lawton:	2782	2394	1837
Hartford	2608	2230	1658
Grand Junction:	2796	2415	1828
Trevor Nichols:	2441	2080	1530

Tree fruit

Fruit continue to size well. Fruit flies are out in cherries, apples and blueberries. Japanese beetles numbers are low. Leafhopper and mite numbers are building. Codling moth trap catch is steady. Oriental fruit moth trap catch numbers are up in the South. The second-generation flight of redbanded leafroller and obliquebanded leafroller is finished. All of these pests should pick up back soon.

Peach harvest is underway. Size is excellent. Varieties being harvested range from the end of Red Haven to PF 17. Split pits, which were common in early varieties are rare. The flight of the third generation of Oriental Fruit Moth is beginning. Oriental Fruit Moth Biofix was April 29 at 300 GDD 45. We are at 2035 GDD-45 since Biofix and egg hatch begins at about 2250 GDD after Biofix. With the cool weather forecast we should pick up about less than 20 GDD a day, so egg hatch should not begin until the middle of next week at the earliest.

In Cherries, there was only one cherry leaf spot infection period on Wednesday August 4. There were two more this week on Monday August 9 and again on the 10th.

Plums are colored. Harvest of early European varieties has begun. Brown rot is showing up as the plums ripen. Growers should protect against apple maggot and leaf pest such as leafhoppers and European red mites.

Apple growers are harvesting summer apple varieties. Necrotic leaf blotch is showing up in area golden delicious orchards. If it becomes wetter, growers include fungicides in their cover sprays to reduce sooty blotch and flyspeck. Fire blight is common in the region and severe in some orchards. The disease does not appear to be moving much at this time since there is little growth in the trees. We should be seeing the early coloration and collapse of rootstock blight soon.

Codling moth trap catches are 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 1760 GDD, and we are at 1525 GDD after Biofix. Egg hatch for second-generation codling moth is underway. The end of egg hatch is expected at 2100 GDD after biofix. Since this is 580 GDD away and we are picking up 10 to 15 GDDbase 50 per day, the end of egg hatch is several weeks away.
The third generation flight of Oriental Fruit Moth has begun in the southern orchards and egg hatch should start late next week or later north of I 94. We did catch apple maggot after a Wednesday’s rain. There are few leafroller larvae feeding on the shoot tips and I expect that trap catches of adults will increase when we get warmer weather. Both obliquebanded leafroller and redbanded leafroller should be flying now. Spotted tentiform leafminer mines are appearing and another wave of adults should emerge in mid August. 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.

In Pears, second generation codling moth can attack pears. Pear psylla numbers are building in some orchards.

Small fruit

In Blueberries, Jersey and Rubel harvest are well underway. Some growers are picking Elliot and the end of the season is approaching fast.  Both blueberry maggots and Japanese beetles are out. Tussock moth adults are being caught as well as a few leaf roller adults. Tussock moth larvae are also being found. Low numbers of blueberry aphids can be found in the bottoms of the bushes. Alternaria is the main fruit rot showing up on the fruit. Growers should protect the fruit. Birds eating the fruit are a major problem.

Grapes are beginning veraison. Color has been developing slowly over the last two weeks and the cool weather forecast means that the will not color up quickly. Niagara harvest is scheduled to begin September 7 with Concord harvest following 10 days later. The second generation of grape berry moth is flying and stings in fruit can be found. Growers should be scouting hot spots and the edges of their vineyards for stings and other signs of recent berry moth activity. Grape leafhopper numbers are building. Phomopsis symptoms are easy to find in most grape vineyards. Downy mildew is showing up in susceptible varieties and growers should be applying protectants such as Ziram. If Prophyt is used as an eradicant it should be mixed with a protectant.

Southwest Michigan Grape Growing Degree Days from April 1, through Sunday August 8, 2004.
Location	Grape GDD
SWMREC:	1713
Bainbridge	1760
Lawton:	1747
Hartford	1611
Grand Junction:	1773
Trevor Nichols:	1493

In Strawberries, now is a good time to fertilize new growth in strawberry new growth looks good except where potato leafhoppers have been feeding.

 

Summer Raspberry harvest is over. The old floricanes are yellowing and should be pruned out. Japanese beetle and potato leafhoppers are common in brambles and should be controlled. Fruit is being harvested in fall bearing raspberries.