Southeast Michigan fruit regional report – June 23, 2015

Strawberry growers struggle with wet fields as harvest continues. Early season summer red raspberry and sweet cherry harvest is close.

Weather

Strong winds and thunderstorms swept across the region last night, bringing another good amount of rain for many fruit growers. This storm event will raise the risk of another round of trauma fire blight infections for apple growers and more wind-whipped fruit for cherry growers.

While most of the region had between 0.3 to 1.3 inches of rain in the last week, many farms are still dealing with saturated soils from heavy rainfall events of the last four weeks. Over that period, our spring and early summer have gone from droughty to far too much rain for most fruit growers. While rainfall totals have varied widely over short distances, generally most growers have received between 5 and 6.5 inches of rain in the last four weeks. This being said, there are a few farms that have consistently been “missing” these major rain events, and soils remain dry.

Our season is running three to four days ahead of normal for growing degree day (GDD) totals for most of east Michigan. In terms of the beginning of harvest, it now appears we are ahead of normal for sweet and tart cherries.

East Michigan GDD totals for March 1 to June 22, 2015

Location

GDD42

GDD45

GDD50

Commerce (Oakland)

1,324

1,108

793

Emmett (St Clair)

1,275

1,065

760

Flint (Genesee)

1,460

1,234

899

Lapeer (Lapeer)

1,362

1,150

836

Petersburg (Monroe)

1,463

1,237

904

Pigeon (Huron)

1,138

 943

662

Romeo (Macomb)

1,369

1,152

827

Tree fruits

Apples continue to size very well and put on a good amount of new terminal growth. Most apples are 1.5 inches with the largest fruit measuring 2.125 inches. June drop has pretty much ended for most growers and hand-thinning has begun for many growers.

Overall, insect pressure has been very light over the past few weeks. A few masses of woolly apple aphids are just starting to be found, mostly on large pruning cuts in the inside middles of apples. San Jose scale crawlers are very active at this time; now is a critical control period. Obliquebanded leafroller adult trap catch continues. Codling moth and oriental fruit moth trap catches continue to decline for first generation flight. Most codling moth mating disrupted blocks have had no trap catch this season. Spotted tentiform leafminer mines continue to be found in low numbers. A few colonies of rosy apple aphids continue to be found on interior twigs. A few green apple aphids and apple grain aphids continue to be found, but predators or beneficials seem to be doing a good job of controlling all three aphid pests.

A few potato leafhopper adults and curled leaves as a result of their feeding injury continue to be seen. European red mites continue to be seen in very low numbers. Heavy rains have been doing a good job of keeping the numbers much below the June threshold of five mites per leaf. Good numbers of beneficial insects continue to actively feed in most apple blocks. This week, good numbers of tachinid flies are being found.

Apple scab lesions continue to show up on leaves and fruit. Widely scattered fire blight strikes continue in apple blocks, with a few growers continuing to see new strikes on a regular basis. A few newly planted or young apple blocks had a good amount of fire blight this season. With strong winds last night, June 22, growers need to be very watchful of new fire blight strikes.

Powdery mildew-infected twigs continue to be seen in a few apple blocks. The leaf stage of black rot, known as frogeye leaf spot, is being found in more apple blocks this week. I continue to see orange leaf spots from cedar apple rust in a few apple blocks.

Pears are mostly 1.25 inches in size. All stages of pear psylla continue to be seen.

Peaches are 1.75 inches for those few growers with a crop this season. Growers continue to prune winter-damaged trees and remove dead and dying trees. Green peach aphids are found in a few blocks. Bacterial leaf spot-infected leaves are found in many peach blocks, especially in blocks with no crop this season where pest control has been reduced.

Sweet cherries are continuing to color well, most are 19 to 23 millimeters in size. Most growers are hoping to see another swell in fruit size, but I think they “have what we have” and will not size any more this season. A few early varieties will be ready for harvest in the next few days. Birds appear to be gathering in sweet cherry blocks as fruit begins to ripen. Cherry leaf spot-infected leaves have been seen for the last few weeks in several blocks. As new leaves continue to emerge, they need to be protected.

Tart cherries are also coloring well in the last week, with most at the same size as last week – 14 to 16 millimeters in size. Cherry leaf spot needs to be controlled at this time. Birds are also starting to be seen in tart cherries.

European plums are 19 to 23 millimeters and Japanese plums are approaching 1 inch. Black knot is starting to be seen on wild and unsprayed plum trees.

Small fruits

Grape bloom has ended for Concords, with bud burst-sized fruit. European varieties are in full bloom for the few varieties with a crop this season. Downy mildew continues to be found in wild grape vines. Many European varieties have extensive winter kill and growers have either pruned them back to just above the bud or pulled them out entirely.

Strawberry harvest continues across the region. Growers are continuing to struggle with heavy rainfall at most farms over the last few weeks. This is the worst time of the season for heavy rains as it greatly increases the potential for gray mold, leather rot, angular leaf spot and slugs. Berry quality from heavy rainfall is an issue for some growers as well. Berries have a pinkish cast or a water-soaked part, mostly on the shoulder of large berries. Some growers also report berries having a fermented smell to them.

Demand for wholesale, ready-picked and pick-your-own strawberries continues to be very strong this season. Wholesale and ready-picked berry growers are having a hard time finding labor this season with a few reports of ripe berries going unharvested.

Gray mold has been seen at a few farms in the last few days, mainly due to extensive moisture. Leather rot and angular leaf spot continues to be found at a few farms. Slugs are found at most strawberry farms.

Raspberries have large green fruit for summer varieties, with a few early varieties just a few days away from beginning harvest. Black raspberry fruit are quickly developing color and will be ready for harvest in a week or so. Fall red raspberry canes continue to put on good new growth, with the longest canes being 40 to 48 inches in length. Flower buds are just beginning to develop on some of the shorter canes. No spotted wing Drosophila have been caught in traps.

Blueberries have small green fruit, the largest being 17 millimeters in size. A few early varieties are just starting to develop color. No spotted wing Drosophila have been caught in traps.

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