Southeast Michigan fruit regional report – August 11, 2015

Blister spot and silver leaf diseases are being found on a few apple varieties. Harvest of many fruits continues, including Red Haven peaches, blueberries, Japanese plums and summer apple varieties.

Weather

With cooler than normal daytime temperatures and especially cool nighttime temperatures, our seasonal growing degree day (GDD) totals have slipped back to a few days to almost a week behind normal for the region. In terms of the beginning of harvest of our fruit crops, this season has been a few days ahead of normal. The next apple varieties to be harvested are Gingergold and Paula Red, so we will see if our harvest windows are still ahead of normal.

Most of the region received around 0.5 inches of rain in the past week, coming in two to three wetting events. Our soils are mostly slightly below normal to normal in terms of moisture levels.

East Michigan GDD totals for March 1 to Aug. 10, 2015

Location

GDD42

GDD45

GDD50

Commerce (Oakland)

2,587

2,225

1,664

Emmett (St Clair)

2,558

2,200

1,651

Flint (Genesee)

2,837

2,464

1,884

Lapeer (Lapeer)

2,609

2,251

1,695

Petersburg (Monroe)

2,755

2,382

1,804

Pigeon (Huron)

2,385

2,043

1,520

Romeo (Macomb)

2,722

2,358

1,789

Tree fruits

Apple harvest continues for summer apple varieties. Gingergolds are very close to being ready to harvest and Paula Reds continue to color well; harvest is expected to begin in a week to 10 days. Apple size at most farms continues being very good this season, for most growers they are 2.5 inches to the largest fruit at 3 inches in diameter. Summer pruning continues at most farms. Many growers have applied Retain to Gala blocks to delay harvest and are scheduling applications to later varieties.

Insect pressure generally remains low in apples with three exceptions. The first is the start of the second generation codling moth flight, the second is the continuing very strong San Jose scale second generation adult male flight and the third is woolly apple aphids moving out to fruit in a few apple blocks. Most growers biofixed early to mid-last week for the second generation codling moth adult flight, so control will need to begin next week or so. For the third week in a row, San Jose scale male trap catch has been very high in many blocks. Growers need to be on the lookout for crawler activity any day now, especially where San Jose scale infestations were found earlier this year or the past few years. This is a pest that has been on the rise the past few seasons. Many growers were surprised to find fruit marked up from the first generation crawler activity of San Jose scale. Woolly apple aphids have moved from internal pruning scars and terminal branches to the fruit in a few apple blocks in the past week.

European red mites seem to have been controlled nicely in most blocks by either miticide applications in hotspots or by predators. Apple maggot trap catch has been lower the past two weeks and are mostly being caught on yellow sticky traps. 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, this week many stigmaeid or yellow mites are being found.

In the past week, I have seen several Mutsu (Crispin) and Fiji with blister spot infections, mostly on the fruit. It is too late in the season to control it. I have seen a few individual apple trees at a few orchards in the past week 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 2.25 to 2.5 inches in diameter. Clapp’s Favorite will be ready for harvest later this week. Some light amounts of pear sheet scab are continuing being seen, as well as all stages of pear psylla.

Peaches are mostly 2.5 to 3 inches in diameter; Red Haven harvest is underway. The brown rot that was mostly on early peach varieties seems to have run its course for the season. Bacterial leaf spot-infected leaves and fruit continue to be seen in many peach blocks.

Tart cherry leaf yellowing and drop from cherry leaf spot disease continues at most farms.

Plum harvest is finishing for Shiro and Ozark Premier are getting started. European plums are mostly 1.25 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 European varieties for the few varieties with a crop on them this season. Downy mildew and powdery mildew continues being found.

Strawberry fields continue to look much different this week with even more new leaves putting on new growth, mostly as the result of good rains the past two weeks. Growers need to keep an eye on both newly planted and renovated fields for potato leafhopper infestations.

Raspberry harvest of fall fruiting types is expected to begin in the next week for early maturing varieties. Fall red raspberry canes have put on good new growth this season and continue to set flower buds. I am finding numerous flower buds or “bud berries” this season that were formed on the shorter lateral canes of fall raspberries and are being harvested at this time. These early berries are not a part of the main crop. New canes or primocanes of summer fruiting types have also put on an exceptional amount of new growth this season, mainly due to abundant moisture supplies in June. Spotted wing Drosophila (SWD) adults continue being caught in traps in raspberries. Michigan State University Extension recommends growers continue control programs.

Blueberry harvest continues with berry size holding up well at most farms. Blueberries continue to ripen quickly. I have not caught blueberry maggots in traps. SWD trap catch is continuing to climb in blueberries and growers need to continue 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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