Fruit Update - SW Michigan

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Mark Longstroth
Bill Shane
Al Gaus

The last three weeks have been cooler with highs in the 80s and lows in the 60s. For the last week highs were in the 90s. Humidities were high and morning dews are common. The next week is forecast for cooler temperatures. Last significant rain was Aug. 22 with 2.5 inches.

Several direct pests are still out. Codling moth trap catch is still low. We are still waiting for the beginning of the third flight of codling moth. The third flight of oriental fruit moth is ending. Grape berry moths are still flying and damage is easy to find in grapes.

Peach harvest is winding down. Growers are picking later varieties, such as Redskin, Fayette, Harcrest and PF-27A. Late peaches interfere with apple harvest so most peach growers are finishing up the last pickings of the season. Oriental fruit moth trap numbers are down in most orchards.

Plum harvest is winding down.

Apple harvest is well underway. Growers are harvesting Gala and Macintosh this week. In many apple blocks, fruit size is poor because of the dry conditions earlier in the season. Apple maggot numbers are low. The third generation of Oriental fruit moth is still flying. Trap catch for codling moth last week was low in some orchards, but was rising in some orchards. We expect a partial third generation of codling moth in Southwest Michigan. Growers need to maintain their protection. First emergence of the third generation of codling moth is around 2200 GDD. Treatment is timed for 350 GDD after biofix for the first generation or 2550 GDD base 50. Check the Code-A-Phones in Van Buren and Berrien to see when this flight shows up. Damage from worms in the fruit by both codling moth and oriental fruit moth is common in the region. The second flight of obliquebanded leafroller is flying and larvae can be found on the leaves and fruit. White apple leafhopper nymphs are common. European red mites are not yet laying their winter eggs. Growers should be monitoring their orchards.

Barlett Pear harvest is over. Bosc and Harrow Sweet will be harvested this week.

Blueberry harvest is finished. The flower buds for next spring are forming now. Now is the time to consider treatment for Blueberry bud mite. Thiodan is labeled for this use after harvest the treatment window is when the mites are moving to the newly formed buds. See the article in this week's Fruit CAT Alert Remember that Topsin M has a shorter PHI than Benlate, but cannot be used post harvest.

In Grapes, harvest has begun. Table grapes and early wine grapes are being harvested. Niagara harvest will begin Thursday, Sept. 12 and Concord harvest is tentatively scheduled to begin on the September 25. Grape GDDs at Lawton from April 1 to September 8, 2002 are 2686 Base 50. Grape berry moth pressure has been heavy. Adult trap catches are low, but mated females are laying eggs in the vineyards. Growers need to sample their vineyards to determine the timing of sprays to control grape berry moth. See the article in the July 22 CAT Alert. Examine clusters along the wooded edges of vineyards and near other hot spots such as buildings and vineyard edges. Treatments should be applied when 11% of the clusters show some damage from berry moth larvae. If in doubt, spray now, not later.

Fall bearing Raspberries are showing sunburn symptoms due to the bright sunny weather.

Trevor Nichols Research Complex (TNRC) will have a research field day Thursday, September 19 from 1 PM to 5 PM. The field day will focus on insect and disease research and efficacy trials that were carried out this season at the TNRC by Larry Gut, Rufus Isaacs, Mark Whalon, Annemiek Schilder and John Wise. A social time will precede the tour with food and refreshments starting at noon. The TNRC is located at 6237 124th Ave. in Fennville, MI.

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Posted: September 10, 2002