Southwest Michigan grape regional report – September 18, 2012

Progress of the 2012 harvest season for grapes in southwest Michigan.

The scent of ripened grapes fills the air and the steady hum of grape harvesters can be heard in the vineyards. Both are sure signs of harvest season and autumn in southwest Michigan. Harvest of Niagara grapes has ended. Yields were better than expected with about 9,866 tons harvested. Sugar levels in the Niagara grapes averaged 15.7 brix and quality was good.

Concord harvest started last Friday (September 14) and is expected to last another 10 days or so. Brix levels for Concords have been running in the mid-17s and yields have been higher than originally expected, considering the multiple frosts in April that kept pushing down yield potential. Wine grape harvest continues with generally good yields and high sugars.

Bird netting has been applied in some vineyards and bird distress calls are being played in an attempt to limit bird damage to wine grapes.

Bird netting
Bird netting application to wine grapes.

The fourth generation of grape berry moth is still flying and laying eggs. Adult numbers in traps and larval damage in fruit has been light.  At Trevor Nichols Research Center, trap counts from Monday, September 17, averaged one adult moth per trap. We have ended our grape berry moth trapping and regular scouting of vineyards for this year.

There appears to be somewhat higher incidence of fruit fly larvae this season than in past years. Fruit fly larvae are present in some fruit, particularly where there has been hail damage, but they are not necessarily spotted wing Drosophila.

Bunch rots are quite noticeable in some winegrape varieties. Botrytis bunch rot and sour rots have increased with the more frequent rainfall that has been occurring lately.

MSU’s Annemiek Schilder is testing grapevines suspected of being infected with viruses again this year. Among the viruses that can be tested for are tomato and tobacco ringspot viruses, peach rosette virus, leafroll virus and others. There is still time to have vines tested for viruses this fall, but don’t delay. If you wish to participate in this free service, contact Jerri Gilette for further information at 517-355-7539.

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