Southeast Michigan fruit regional report – July 21, 2015

Apple maggot trap catch has started and obliquebanded leafroller larvae continue being found. Summer apple variety harvest has begun and early peach varieties are expected soon.

Weather

Another inch of rain came in three wetting events in the past week for most fruit growers in east Michigan. Most of our soils remain on the above average side of normal for soil moisture levels, but there are a few isolated farms where soils remain dry.

With just a few warm days and many cool mornings in the past week, our season is generally running about normal for growing degree day (GDD) totals for most of east Michigan. With the heat over the weekend, several of our Michigan State University Enviro-weather stations have now accumulated more than 2,000 GDD base 50. In terms of the beginning of harvest of our fruit crops, they are generally ready three to five days ahead of normal for most fruit farms.

East Michigan GDD Totals for March 1 to July 20, 2015

Location

GDD42

GDD45

GDD50

Commerce (Oakland)

2,003

1,703

1,248

Emmett (St Clair)

1,973

1,679

1,235

Flint (Genesee)

2,202

1,892

1,417

Lapeer (Lapeer)

2,042

1,746

1,295

Petersburg (Monroe)

2,164

1,854

1,381

Pigeon (Huron)

1,819

1,540

1,121

Romeo (Macomb)

2,097

1,796

1,331

Tree fruits

Apples at most farms continue to size very well this season, but for the few farms where soils remain on the dry side, fruit size seems to have stalled in the past few weeks. Harvest of a few of the earliest summer apple varieties is just getting started at a few farms. For most growers, apples are 2 to 2.5 inches in diameter. Hand-thinning has wrapped up and some growers are looking to start summer pruning in varieties where most of the terminal buds have set for the season. Leaf molding in Honeycrisp continues to get more intense in the last few weeks.

The first trap catch of apple maggots on red sphere traps started late last week at several farms. The first trap catch on yellow sticky traps was seen July 3, and trap catch numbers on both traps continued to build this week. Now that apple maggots are laying eggs in apples, fruit will need to be protected for about the next four weeks. This week, I am continuing to find good numbers of small larvae of mostly obliquebanded leafroller feeding in the small terminal leaves at more farms, and in the last few days I am finding them feeding on fruit where two apples are touching or where a leaf is laying on a fruit. It seems to be the case that growers either have a good number of these larvae or none at all. Growers need to do a good job of scouting for the larvae at this time.

Codling moth trap catch is on the rise for the second straight week, most likely the start of the second generation adult flight. More potato leafhopper adults and nymphs are being seen feeding on and curling leaves. Japanese beetle adults continue being seen clustered together. European red mite adult and egg numbers continue to build on leaves and a few eggs being laid in the calyx end of fruit in a few apple blocks, mostly on the inside middles of larger trees. Apple rust mites are being found on leaves in increasing numbers in many apple blocks. There are good prey for predator mites to feed on. No brown marmorated stink bugs have been caught in traps this season in east Michigan at fruit or vegetable farms. However, reports of homeowners finding them inside homes and outbuildings continue. Excellent numbers of beneficial insects continue to actively feed in most apple blocks.

Widely scattered fire blight strikes continue being seen, but the numbers of new strikes is declining quickly. Apple scab lesions continue to show up on leaves and fruit in some blocks. Leaf drop from apple scab is starting to be seen in unsprayed and wild apple trees. Powdery mildew-infected twigs continue being seen in a few apple blocks. The leaf stage of black rot, known as frogeye leaf spot, is being found in more apple blocks, even in young apple blocks.

Pears took on a nice swell in fruit size this past week, most are 1.875 to 2 inches in diameter. All stages of pear psylla continue being seen.

Peaches are mostly 2.25 to 2.625 inches in diameter; harvest of early varieties will begin later in the week for growers with a crop this season. Bacterial leaf spot-infected leaves and fruit continue being seen in many peach blocks, especially in blocks with no crop this season where pest control has been reduced.

Sweet cherry harvest has wrapped up in the last week. Cherry fruit flies have been caught in traps in the past week. If trap catch numbers are high, growers may consider a post-harvest insecticide application to reduce populations for next season. Spotted wing Drosophila (SWD) continues being caught in traps in more sweet cherry blocks, but now that harvest has ended, no control is needed.

Tart cherry harvest has wrapped up in the last week. Cherry fruit flies have been caught in traps in the past week. If trap catch numbers are high, growers may consider a post-harvest insecticide application to reduce populations for next season. Cherry leaf spot-infected leaves are yellowing at most farms, with a fair amount of leaf drop on trees that had a big crop on them. Cherry leaf spot should be controlled at this time and for the rest of the summer. SWD continue being caught in traps in more and more tart cherry blocks, but measures are not needed.

Plums are seeing a fair amount of fruit drop in some Stanley and related varieties this past week. European plums are mostly 1.875 inches in diameter and Japanese plums 1.25 to 1.5 inches in diameter. Methley plum harvest is starting this week at some farms. Japanese plums continue to color. Some blocks have a lot of bacterial spot, mostly on leaves. Black knot continues being seen on wild and unsprayed plum trees.

Small fruits

Grapes are at berry touch for Concord types and European varieties are at marble-sized fruit for the few varieties with a crop on them this season. Japanese beetle adults continue being seen and are clustering together in groups of four to six adults. Downy mildew and powdery mildew have been seen at a few more farms this week.

Strawberry renovation is underway at most farms where the soils have dried from heavy rains in June.

Raspberry harvest of summer fruiting types continues, but is on the downhill side and will be wrapping up in the next week. Black raspberry harvest is finishing at most farms. New canes or primocanes have put on an exceptional amount of new growth this season, mainly due to abundant moisture supplies in June. Fall red raspberry canes have also put on good new growth this season and continue to set flower buds. I am finding numerous flower buds or “bud berries” this season being formed on the shorter lateral canes of fall raspberries and are being harvested at this time. These early berries are not part of the main crop.

SWD adults continue being caught in traps in raspberries in the past week. Growers are starting control programs. Japanese beetle adults continue being seen and are clustering together.

Blueberry harvest continues with excellent berry size at most farms. Blueberries have ripened quickly over the past few weeks. No blueberry maggots have been caught in traps. SWD are just starting to be caught in traps over the past week, so growers are starting control programs. Japanese beetle adults continue being seen and are starting to cluster together. Phomopsis canker and twig blight-infected canes continue being found as wilted leaves and twigs with leaves turning light brown.

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