Southeast Michigan fruit regional report – August 5, 2014

Bob Tritten, Michigan State University Extension - August 05, 2014

First trap catches of spotted wing Drosophila have been reported in raspberry and blueberry plantings at many farms across the region.

Weather

Several rounds of thundershowers have moved over the region this past week. Most areas have received around 0.5 inches of rain from these storms, but rainfall totals have varied widely over short distances. Unfortunately, there have been many reports of hail in these storms as well. Our season remains close to normal for growing degree day (GDD) totals and ahead of normal in terms of beginning of harvest of our fruit crops.

Soil moisture supplies have continued to dry at most farms, with only a few farms having adequate soil moisture. Soil moisture supplies at the 8- to 12-inch depth are very dry at many farms. Growers have been irrigating in the past week.

East Michigan GDD totals for March 1to Aug. 4, 2014

Location	GDD42	GDD45	GDD50
Commerce (Oakland)	2,294	1,960	1,451
Emmett (St Clair)	2,323	1,991	1,485
Flint (Genesee)	2,531	2,185	1,657
Lapeer (Lapeer)	2,340	2,007	1,503
Petersburg (Monroe)	2,482	2,139	1,619
Pigeon (Huron)	2,166	1,850	1,366
Romeo (Macomb)	2,437	2,097	1,576

Tree fruits

Apples continue to have good fruit size this season and have put on a great amount of color over the last 10 days or so. Apples in the Flint, Michigan area are mostly 2.5 to nearly 3 inches in size. Harvest of Jersey Mac is expected soon. Summer pruning of apples continues. Leaf tissue samples for nutrient analysis can be taken now through mid-August or so.

Trap catch numbers of codling moth and oriental fruit moth continue to be on the rise for the second generation flight for both. Many apple growers are finding a few fruit infested with codling moth. Obliquebanded leafroller-damaged fruit is more common this season compared to most seasons. Apple maggot trap catch has been low at most farms this season, only being trapped on yellow sticky traps. A few mite hotspots continue to be found in apple blocks, but generally predators are now controlling them well and trees are starting to green up again.

I continue to find a few woolly apple aphids on terminals and fruit in the past week, but generally their numbers are low this season. Japanese beetles continue to be seen in generally low numbers in all fruit crops; it appears that we will not see high numbers of this pest this season. Other than these pests, there has not been much insect pressure in apples in the last three weeks. Predators are abundant this season, feeding heavily on mites and the late appearing green apple aphids the last few weeks.

Blister spot in Crispin (Mutsu) was first reported last week and continues to show up at more farms. The fire blight strikes that were reported several weeks ago are now very visible. I have not seen any symptoms of sooty blotch and fly speck diseases.

Pears have put on a spirt of growth in the past week, with most being 2 to 2 .25 inches.

Peach growers are continuing to remove dead trees and pruning less severely winter-damaged trees.

Sweet cherry pruning is continuing; this post-harvest window is less invigorating than late winter or spring pruning. Trees that have filled their space can be modestly trimmed in the post-harvest to early August window with less risk of bacterial canker than the traditional delayed dormant pruning time. Cherry fruit fly trap catch continues in low numbers.

Tart cherry leaf drop from cherry leaf spot is continuing to be seen, with a new set of yellowing leaves being found in most blocks in the last week. Growers need to apply a post-harvest fungicide to control this disease.

Plums have colored well in the past week, with European plums mostly at 1.25 inches and Japanese varieties starting to be harvested. Most growers have very few plums this season.

Small fruits

Grapes are continuing to fill the clusters for Concord and Niagara varieties. Wine grape shoots continue to emerge from latent buds on the winter-damaged trunk. Michigan State University Extension recommends the shorter and weaker shots be pruned off at this time. A few grape berry moths are continuing to be caught in traps. A few Japanese beetles and grape berry moths are being found in grapes.

Strawberry leaves continue to emerge from the crown following renovation.

Raspberry harvest is beginning for fall-bearing varieties, with summer raspberry harvest wrapping up last week at most farms.

There have been first trap catch reports of spotted wing Drosophila (SWD) at many farms in the last five days or so. This means that control measures need to be taken now and continue through harvest. Consult recommendations in the “Spotted Wing Drosophila Management Recommendations for Michigan Raspberry and Blackberry Growers” guide at the MSU Spotted Wing Drosophila website for details. Japanese beetles continue to be found in low numbers in both summer and fall raspberries.

Blueberry harvest continues across the region. There have been first trap catch reports of SWD at many blueberry farms in the last few days. This means that control measures need to be taken now and continue through harvest. No blueberry maggots have been caught in traps, but are expected soon. A few Japanese beetles continue to be found in blueberries. Consult recommendations in the “SWD Management Recommendations for Michigan Blueberry Growers” guide at the MSU Spotted Wing Drosophila website for details.

This article was published by Michigan State University Extension. For more information, visit https://extension.msu.edu. To have a digest of information delivered straight to your email inbox, visit https://extension.msu.edu/newsletters. To contact an expert in your area, visit https://extension.msu.edu/experts, or call 888-MSUE4MI (888-678-3464).