East Michigan fruit regional report – August 9, 2016

Drought conditions continue at most farms. Harvest continues for peaches, summer apples, plums, blueberries, blackberries and fall raspberries.

Weather

Another dry week was the story for fruit farms across east Michigan. Signs of plant stress from the drought continue to become more evident, especially in younger plantings. Even well-established tree and small fruits are showing signs of wilting, leaf drop and smaller fruit size.

Degree-day totals are building due to hot daytime and nighttime temperatures; we are at least a full week ahead of normal. In terms of the fruit crop growth stages and beginning of harvest, we are running about five days ahead of normal.

East Michigan growing degree day totals for March 1 to August 8, 2016

Location

GDD42

GDD45

GDD50

Commerce (Oakland County)

2,762

2,395

1,839

Deerfield (Monroe County)

3,057

2,663

2,061

Emmett (St Clair County)

2,690

2,334

1,794

Flint (Genesee County)

2,967

2,595

2,028

Freeland (Saginaw County)

2,695

2,345

1,809

Lapeer (Lapeer County)

2,716

2,359

1,819

Pigeon (Huron County)

2,520

2,184

1,674

Romeo (Macomb County)

2,856

2,488

1,931

Tree fruits

Apples are mostly 2.5 inches for most growers, with some approaching 2.75 inches in diameter. For the few growers that received good rains a few weeks ago, I am seeing much improved fruit size. Harvest of summer apple varieties continues. Ginger Gold harvest is about a week to 10 days away. Paula Reds are coloring and may be two weeks to beginning of harvest. Water core in Paul Red was seen at a few farms this week. Growers continue Retain applications on Gala and McIntosh, and are planning applications to other varieties soon. Sunburn is being seen in a few early varieties. More growers are reporting bird feeding injury in apples, most likely due to drought.

Codling moth trap catch from the second generation adult flight has really taken off this week, with single digit numbers in most matting disrupted blocks and very high numbers (90 to 110) in traditional blocks. This flight is later than in most seasons. Growers who have biofixed in the last few days will need an insecticide application late next week to control young larvae. No brown marmorated stink bug trap catches have been seen this week. Apple maggot catch on yellow sticky board traps has been strong on farms that had good amounts of rain a few weeks ago, but for most growers with dry soils, trap catch has been low. Apple rust mite numbers have climbed to threshold levels in a few blocks. European red mite numbers have generally dropped this week, however twospotted spider mite numbers have increased this week, a few blocks are above threshold levels. Beneficial numbers continue to build; this week I am seeing good numbers of Zetzellia mali and velvet mites.

I have about a dozen apple growers that have had serious issues with fire blight this season. Half of these are in new plantings and the other half in existing orchards where fire blight has never been seen. In all cases, I believe we are looking at trauma blight and not blossom blight. In the existing orchards, it is generally limited to a few varieties, and even here only a few strains of a variety were infected. I am seeing signs for fire blight on wild or abandoned apples as well. Black rot symptoms are being seen on fruit and leaves. Sooty blotch and flyspeck disease symptoms should be appearing soon.

Pears are mostly 2.25 inches in diameter. Fruit size is being reduced due to the drought. I have a few pear blocks this week with San Jose scale marks on fruit. Pear psylla numbers are high on suckers.

Peaches are mostly 2.5 to 3 inches in diameter at most farms; smaller fruit size is common in peaches this season, due mainly to drought. Red Haven and PF Lucky 13 harvest continues, and Bellaire harvest is just starting in the south. I have not seen any brown rot symptoms, but for growers who received a good amount of rain this past week, you may consider a brown rot fungicide application fairly quickly.

Sweet cherry leaves are yellowing and dropping to the orchard floor, some is from cherry leaf spot symptoms but most of this leaf drop is from drought. This week, I have seen a number of sweet cherry blocks where twospotted spider mites are starting to bronze leaves.

Tart cherry leaves are also yellowing and dropping, mostly due to drought and to a lesser amount from cherry leaf spot symptoms.

Plums are coloring for European types, with fruit size mostly 1.375 inches in diameter. Japanese variety harvest continues. The crop load is variable for both types, especially in some Japanese varieties, as they have little to no crop.

Small fruits

Grape growth continues to be slow. Concord fruit are starting veraison and clusters of European varieties are at berry touch. Japanese beetle adults are being seen, but in very low numbers.

Strawberry leaves are re-growing in renovated fields and have filled in well where rain was received or irrigation has been applied. Michigan State University Extension encourages growers to keep new and established berries well-watered. New berries are runnering well and have filled the row at most farms. Potato leafhopper populations are building in new plantings. Growers should watch for curled leaves, although this symptom can be somewhat confusing as the same symptoms can be seen with drought stress.

Raspberry harvest continues for fall red raspberry varieties. Blackberry harvest is continuing at most farms.

Trap catch of spotted wing Drosophila (SWD) is very high, with another big jump across the region. A few farms have seen small SWD larvae in fruit and have stopped harvest for a few weeks while they bring populations under control. Growers should protect all bramble crops now for SWD infestation. For more details on the SWD life cycle, control strategies and specific insecticide recommendations, consult the MSU Spotted Wing Drosophila website.

Blueberry harvest continues, although small berry size is a problem at most farms, mainly due to drought. As in raspberries, this week trap catch of SWD in blueberries has taken another big jump across the region. Growers should protect blueberries for SWD infestation. For more details on SWD life cycle, control strategies and specific insecticide recommendations, consult the MSU Spotted Wing Drosophila website.

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