Southeast Michigan fruit regional report – August 18, 2015

Fall red raspberry harvest begins, peach harvest continues and blueberry harvest winds down at most farms.

Weather

With the heat of last week, our seasonal growing degree day (GDD) totals have continued to bounce around from being ahead of normal to normal to a few days behind normal. In terms of the beginning of harvest of our fruit crops, we have been running a few days ahead of normal for most of our fruits, and it appears the next two apple varieties to be harvested, Ginger Gold and Paula Red, will also be a few days ahead of normal.

A few parts of the region received around 0.5 inches of rain in widely scattered thunderstorms last Friday, Aug. 14, but most of the region missed any significant rain events. As a result, most of our soils are running on the dry side in terms of moisture levels.

East Michigan GDD totals for March 1 to Aug. 17, 2015

Location

GDD42

GDD45

GDD50

Commerce (Oakland)

2,795

2,412

1,817

Emmett (St Clair)

2,771

2,393

1,809

Flint (Genesee)

3,064

2,670

2,054

Lapeer (Lapeer)

2,817

2,437

1,846

Petersburg (Monroe)

2,959

2,565

1,952

Pigeon (Huron)

2,572

2,209

1,651

Romeo (Macomb)

2,948

2,562

1,958

Tree fruits

Apple harvest for Ginger Gold is a few days off and Paula Red harvest is close to a week away. A few growers have spot-picked a few of each variety for immediate sales, but a bit more time is needed for them to develop better flavor. Apple size at most farms continues to be very good this season, for most growers they are approaching 3 inches in diameter. Summer pruning continues at most farms. Many growers have applied Retain to Gala and McIntosh blocks to delay harvest for better fruit color and size, and are scheduling applications to later varieties.

Woolly apple aphids continue to move out from interior wood to terminals and to fruit in a few apple blocks where they have not been controlled. San Jose scale second generation crawlers are being found in problem blocks. Other than these two pests, insect pressure is generally light in apples at this time. Very few apple maggots are being caught in traps. Second generation codling moth trap catches are trending downward, as are oriental fruit moth trap catches. European red mites seem to have been controlled nicely in most blocks by either miticide applications in hotspots or by predators. No brown marmorated stink bugs have been caught in traps this season in east Michigan at fruit or vegetable farms. Good numbers of beneficial insects continue to actively feed in most apple blocks, although with the lack of food predator numbers are starting to decline.

In the past week, I have had several calls of apple growers finding a few more new fire bight strikes, mainly in young apple blocks. This week, I am seeing a few more apple trees with the fungal disease called silver leaf. I have never seen this much of this disease show up in any one season. It is usually found on older, poor vigor trees and may not show the silvered leaves ever again.

Pears are mostly 2.5 inches in diameter. Clapp’s Favorite are being harvested. Bartlett harvest is expected to begin in 10 to 14 days.

Peach harvest continues. Red Haven harvest is complete and growers are working on harvesting Bellaire. Brown rot is being found again in later peach varieties. Bacterial leaf spot-infected leaves and fruit continue being seen in many peach blocks.

Tart cherry leaf yellowing and drop from cherry leaf spot disease continues at most farms. Some trees are completely defoliated.

Plum harvest has mostly wrapped up for Japanese plums and European plum harvest is expected to begin in a few weeks. European plums are mostly 1.375 inches in diameter and are continuing to color well. Some blocks have a lot of bacterial spot, mostly on leaves.

Small fruits

Grape clusters continue to fill out well for Concord types, and for the few European varieties with a crop this season, fruit size seemed to have slowed this past week. I am not seeing any color change in fruit. Downy mildew and powdery mildew continues being found.

Strawberry fields continue to rebound from renovation, with even more new leaves putting on new growth. I am concerned leaf size is small at most farms this last week. I suggest some additional nitrogen be applied to encourage more normal leaf growth. Michigan State University Extension recommends keeping an eye on newly planted and renovated fields for potato leafhopper infestations.

Raspberry harvest of fall raspberries is just getting underway. Unfortunately, I have visited a few fall raspberry farms this week and found spotted wing Drosophila (SWD) infected fruit. Trap catch continues to climb in raspberries.

Blueberry harvest continues, but is winding down at most farms. Berry size is starting to diminish at most farms. I have still not caught blueberry maggots in traps this season. SWD trap catch is continuing to climb in blueberries; growers need to continue control programs. As is the case at a few fall raspberry farms, I am finding SWD infested fruit at several farms where control measures were either started too late in the season or growers had longer gaps in control programs. Phomopsis canker and twig blight-infected canes continue being found as wilted leaves and twigs, with leaves turning light brown.

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