Southeast Michigan fruit regional report – August 4, 2015

European red mite bronzing is apparent in some apple blocks. Harvest continues for summer apple varieties, early peaches, blueberries and Japanese plums.

Weather

Strong thunderstorms moved over much of the region north of Ann Arbor, Michigan, and Detroit on Sunday evening, Aug. 2, bringing close to 1.5 inches of precipitation, 60 mile per hour winds and even dime- to penny-sized, sharp hail at a few locations. Combined with additional rain on Wednesday, July 29, and yesterday, Aug. 3, most of the region received a “good drink” of much needed precipitation, with rainfall totals for the last week ranging from 1 inch to most of the region receiving 2.1 inches. Our soils are back toward having more normal moisture levels.

Hot temperatures during the last week brought on bronzing from European red mites in many apple blocks and rapidly generated a good number of growing degree days (GDD). With this heat during the last week, our season is generally running a few days ahead of normal for GDD totals for most of east Michigan. In terms of the beginning of harvest for fruit crops, they continue to generally run a few days ahead of normal for most fruit farms.

East Michigan Growing Degree Day Totals for March 1 to Aug. 3, 2015

Location

GDD42

GDD45

GDD50

Commerce (Oakland)

2,408

2,067

1,542

Emmett (St Clair)

2,384

2,048

1,534

Flint (Genesee)

2,647

2,295

1,750

Lapeer (Lapeer)

2,433

2,096

1,575

Petersburg (Monroe)

2,565

2,214

1,670

Pigeon (Huron)

2,232

1,911

1,422

Romeo (Macomb)

2,537

2,193

1,659

Tree fruits

Apple harvest continues for summer apple varieties, including Jersey Mac, Vista Bella, Melba, Williams Pride, Sunrise and Pristine. Paula Reds are coloring well; harvest is expected to begin in two to two and a half weeks. There was a fair amount of fruit drop in Paula Reds in the past few days, mostly due to fruit sizing and some fruit being pushed off the limb. Apple size at most farms continues to be very good this season, most are 2.25 inches with the largest fruit 2.875 inches in diameter. Summer pruning continues at most farms.

Pest pressure generally remains low in apples, with the exception of European red mites and San Jose scale second generation adult male flight. Where European red mite adult and egg numbers were high last week, leaves have now bronzed in these generally isolated hotspots because of the heat during the last week. Miticide applications will most likely be needed in these hotspots. For the second 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 in the next week or so. Many growers were surprised to find fruit marked up from first generation crawler activity of San Jose scale.

Apple maggot trap catch has been lower this past week and mostly occurred on yellow sticky traps. Codling moth and oriental fruit moth trap catch was generally lower last week. Potato leafhopper adults are generally gone this week, however their telltale signs of curled leaves remains. Japanese beetle adult numbers are on the decline this week, wrapping up for the season. Their population levels have been down the past few years. 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, this week many assassin bug egg clusters are being seen.

Apple scab lesions continue to show up on leaves and fruit. Leaf drop from apple scab continues in unsprayed and wild apple trees.

Pears are mostly 2.125 to 2.5 inches in diameter. Clapp’s Favorite will be ready for harvest in about 10 days; they are coloring nicely this week. Some light amounts of pear sheet scab is starting to be seen. All stages of pear psylla are being seen.

Peaches are mostly 2.5 to 3 inches in diameter; Red Haven harvest is expected to start later in the week. Brown rot started to show a few weeks ago, mostly on early varieties. It is even in blocks where control measures were tightened up during the heavy rains in June. Bacterial leaf spot-infected leaves and fruit continue to be seen in many peach blocks, especially in blocks with no crop this season where pest controls have been reduced.

Sweet cherry scaffold limbs continue to collapse and die from injury these past two winters. Spotted wing Drosophila (SWD) trap catches have exploded in many sweet cherry blocks, even though harvest ended several weeks ago. I am not sure why this is the case.

Tart cherry leaf yellowing and drop from cherry leaf spot continues at most farms, with entire limb defoliation being seen in some trees.

Plum harvest is underway for Shiro Japanese plums. European plums are mostly 1.25 inches in diameter, and are starting to color nicely this week. Some blocks have a lot of bacterial spot, mostly on leaves. Black knot continues being seen on wild and unsprayed plum trees.

Small fruits

Grape clusters continue to fill out for Concord types and European varieties for the few varieties with a crop on them this season. Japanese beetle adult numbers are on the decline this week; their numbers have generally been lower for the past few seasons. Downy mildew and powdery mildew continue being found.

Strawberry fields look much different this week, with new leaves putting on a tremendous amount of new growth, mostly as the result of good rains and warm to hot temperatures. Growers with dry soils need to irrigate now.

Raspberry harvest of summer fruiting types is wrapping up 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 that were formed on the shorter lateral canes of fall raspberries and are harvested. These early berries are not part of the main crop.

SWD adults continue being caught in traps in raspberries; growers need to continue control programs. Japanese beetle adult numbers are on the decline this week; their numbers have generally been lower for the past few seasons.

Blueberry harvest continues with good to excellent berry size at most farms. Blueberries continue to ripen quickly. Blueberry maggots have not been caught in traps, which is odd. SWD trap catch is continuing in blueberries, and growers need to continue control programs. Japanese beetle adult numbers are on the decline this week; their numbers have generally been lower for the past few seasons. Phomopsis canker and twig blight-infected canes continue being found as wilted leaves and twigs, with leaves turning light brown.

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