Northwest Michigan fruit regional report – July 22, 2014

Sweet cherry harvest is in full swing and growers are applying ethephon in tart cherries. Tart cherry harvest will likely begin over the weekend and into next week. Overall fruit quality is good.

Weather report

As we head into the week of July 21, we have started off very warm in the mid-80s, but by Wednesday, July 23, we will drop down into the high 60s. The cooler conditions will be welcomed as we are in the height of cherry harvest. We have accumulated 1,753 growing degree days (GDD) base 42 and 1,090 GDD base 50. We are still slightly behind our 24-year average of 1,929 GDD base 42 and 1,212 GDD base 50.

Conditions are particularly dry at this time. We have received very little rainfall throughout the month of July, and grass and orchard row middles are now brown. Soil moisture is low, but growers are hoping the rain holds off until sweet cherries are off the tree.

Crop report

Recent travels across the wine grape growing region have revealed nothing new; there is a great deal of devastation to vinifera vines from winter injury. More growing shoots have collapsed now that the stresses of berry growth and a bit of drought have created demands on the woody tissues that simply cannot be met in their injured condition. Our “guesstimates” for crop loss continue to run from 50-70 percent for Riesling and Chardonnay, and up to nearly 100 percent for some Pinot Noir and Cabernet Franc blocks.

For more information on how to battle back from winter injury with proper vine canopy management decisions, see “Wine grape growers need to think ahead to the 2015 growing season.”

Sweet cherry harvest is underway, and overall quality of the fruit is decent. Disease incidence is low, but some Sams have been infected by American brown rot. The crop load is heavy and fruit are smaller than in a typical year. Growers are also waiting for dark sweets to color up.

Tart cherries are coloring, particularly on trees with a lighter crop. As cherries turn red, the tart crop appears even more variable from tree to tree within an orchard, and the crop also varies between orchards. Ethephon applications are going on in tart cherries and growers have been consulting the forecast – hot versus cool – to determine the optimal rate. The estimates for northwest Michigan range from 115-125 million pounds.

Apricots are ripe and ready to harvest.

Pest report

Most sweet cherry orchards continue to look clean other than a few isolated reports of American brown rot infection in dark sweet cherries. The weather has been warm and dry during the last week, and most of the northwest region has not had conditions conducive for cherry leaf spot infection. The last significant rainfall and cherry leaf spot infection periods that were recorded in the region were on July 15 in East Leland, Eastport, Elk Rapids, Kewadin and Northport, Michigan, and July 17 in Old Mission. Michigan State University Extension reminds growers to continue to keep tissue protected from American brown rot and cherry leaf spot infection through harvest and, if possible, after harvest.

We found a total of four female spotted wing Drosophila (SWD) at the Northwest Michigan Horticulture Research Center (NWMHRC) this week in Montmorency tart cherries. We did not detect SWD in traps on Old Mission and in Antrim County this week. However, SWD was found in Grand Traverse, Leelanau and Antrim counties earlier this season. We detected SWD a month earlier than last year, and SWD numbers have been significantly lower this season than in past years. We hypothesize that SWD numbers will greatly increase in the coming weeks as this increase in population size has been observed in southwest Michigan in the last two weeks. Maintaining coverage and tight intervals to protect cherries from SWD and cherry fruit fly egglaying during full swing of sweet cherry harvest has been challenging.

Cherry fruit fly catches have also been low this season; we did not find cherry fruit flies at the research station this week, but have detected cherry fruit flies in the region (Leelanau, Old Mission, Antrim). Growers need to be diligent about controlling both SWD and cherry fruit flies through harvest to prevent infested fruit at harvest.

Obliquebanded leafroller activity is on the decline at the station with an average of 4.3 moths per trap in tart cherries. We have been looking for the summer generation of obliquebanded leafroller larvae, but have not seen any substantial populations. Obliquebanded leafroller activity is ongoing and trap numbers remain low at seven moths per trap. Growers should consider a pre-harvest application targeting larvae in orchards with high (20-plus moths per trap) adult catch to prevent shaking larvae into tanks at harvest. Again, obliquebanded leafroller larval populations have been low in scouted orchards.

Mites are a concern in the recent warm and dry conditions, and we would like to remind growers that some insecticides, like pyrethroids, have high mite-flaring potential. We have observed a few hot spots of two-spotted spider mites and European red mites in tart cherries in orchards across the northwest region

In apples, spotted tentiform leafminer numbers are up with an average of 212.5 moths per trap at the station. We are still catching codling moth at very low numbers, one moth per trap, and obliquebanded leafroller catches are also down this week at two moths per trap. The first apple maggot fly was detected at the station this week. In orchards where primary apple scab infection occurred, growers may need to start protecting for apple scab prior to infection periods. The last possible scab infection periods recorded by the MSU Enviro-weather apple scab model were July 15 for East Leland, Eastport, Elk Rapids, Kewadin and Northport, Michigan, and July 17 for Old Mission.

Upcoming meetings

The next Parallel 45 vineyard meeting will be on Friday, August 1, 3-5 p.m. at the NWMHRC, 6686 S. Center Hwy, Traverse City, MI 49684. We’ll meet in the research vineyard. Topics will be a continuing look at vine recovery issues and examinations of trunk problems.

The Parallel 45 summer pig roast will be held July 26 on Old Mission Peninsula. More details can be found at the Parallel 45 website.

Dr. Rothwell’s work is funded in part by MSU‘s AgBioResearch.

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