Southeast Michigan fruit regional report – June 16, 2015

Strawberry harvest is underway across the region; growers are challenged by rain with as many fields are saturated. Primary apple scab season has come an end.

Weather

Over the last three weeks, our spring and early summer has gone from droughty to now far too much rain. While rainfall totals have varied widely over short distances, generally most growers have received between 4 and 5.5 inches of rain. Of the seven Michigan State University Enviro-weather stations I checked this morning, June 16, there is an average of only eight rain-free days over the last 21 days. Strawberry growers are especially having a tough time dealing with this much rain during harvest. Our subsoil moisture levels are back to normal.

With the heat of the last week, our season is running a few days ahead of normal for growing degree day (GDD) totals for most of east Michigan, with almost all of our Enviro-weather stations having GDD base 42 totals in the thousands. Our season also has jumped forward a bit as well.

More widely scattered reports of pea-sized hail have been reported across the region in the past week. While damage to fruit can be found, it was not extensive.

East Michigan GDD totals for March 1 to June 15, 2015

Location

GDD42

GDD45

GDD50

Commerce (Oakland)

1141

 946

665

Emmett (St Clair)

1059

 906

637

Flint (Genesee)

1261

1056

756

Lapeer (Lapeer)

1176

 985

705

Petersburg (Monroe)

1262

1057

759

Pigeon (Huron)

 977

 803

555

Romeo (Macomb)

1178

 981

692

Tree fruits

Apples have sized very well in the last week, averaging 1.25 inches to the largest being 1.625 inches in the Flint, Michigan, area. June drop is in full swing for most growers. While crop load remains mixed and extremely variable across the region, and it is early in the season to accurately assess crop load, I think in the end there will be more apples than growers currently think they have. Hand-thinning of some varieties has begun for many apple growers.

As of Sunday’s rains, June 14, I did not catch any apple scab spores on rods at my apple scab spore trapping location. Thus, we are at the end of primary apple scab season. I did not catch any spores again in rains last evening. I did catch a few spores in rains that came last Thursday, June 11, so apple growers needed to be covered for that event. I am finding more and more apple scab in the region, just a touch on fruit, mostly on leaves. Growers need to do a thorough job of scouting to be sure they are free of apple scab symptoms before ending protection strategies to control apple scab. My Michigan State University Extension colleague, Amy Irish-Brown, still caught a few spores at one of the two trapping locations in the Grand Rapids, Michigan, area. Lastly, concerning apple scab, with all the rain we have received in the last three weeks and a touch of apple scab being present in many apple blocks, I am nervous about apple scab showing up in previously clean blocks in a few weeks.

Widely scattered fire blight strikes continue to be seen in apple blocks. A few newly planted and young apple blocks had a good amount of fire blight, with as high as 15 to 20 percent tree mortality. Growers need to inspect fire blight-sensitive varieties closely for infections and remove infected limbs or trees as soon as possible. Powdery mildew-infected twigs continue to be seen in a few apple blocks. The leaf stage of black rot, known as frogeye leaf spot, continues in a few apple blocks. I continue to see orange leaf spots from cedar apple rust in a few apple blocks.

San Jose scale crawlers are just starting to be found. We are approaching a critical control period. Obliquebanded leafroller adults are just starting to be caught in traps. Codling moth trap catches continue to decline in conventional apple blocks for the first generation flight. Most mating disrupted blocks have had no trap catch this season. Many growers biofixed for codling moth May 19 or 20 and in the last week have applied cover sprays for early codling moth egg hatch. Spotted tentiform leafminer mines from first generation adult flight 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 are being seen. Predators or beneficials seem to be doing a good job of controlling all three aphid pests at this time. A few potato leafhopper adults and curled leaves as a result of their feeding injury continue to be seen. European red mite egg hatch continues, as are a few rust mites. Good numbers of beneficial insects continue to actively feed in most apple blocks.

Pears are mostly 23 to 27 millimeters in size. All stages of pear psylla continue to be seen.

Peaches are 1.25 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.

Sweet cherries took on a good amount in size in the last week, most are 18 to 20 millimeters, and continue to color well. A few early varieties will be ready for harvest in the next week. Birds appear to be starting to gather around sweet cherry blocks waiting for fruit to ripen. Cherry leaf spot-infected leaves have been seen for the last two weeks in several blocks. As new leaves continue to emerge, they need to be protected.

Tart cherries are also sizing and coloring well in the last week, with most being 14 to 16 millimeters in size. Cherry leaf spot needs to be controlled at this time.

European plums are 17 to 19 millimeters and Japanese plums 10 to 22 millimeters. Some Japanese plum varieties have little to no crop this season. Black knot is starting to be seen on wild and unsprayed plum trees.

Small fruits

Grape bloom is starting for Concords and is close for European varieties. Shoots for Concord types have extended quickly again this past week with many 60 inches in length. Downy mildew is starting 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 is underway across the region. Growers are struggling to cope with heavy rainfall at most farms in the last week. 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. Demand for wholesale, ready-picked and pick-your-own strawberries has been very strong so far 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.

Leather rot has been found at a few farms, mainly at the ends of rows where fungicide sprays may not have been completed. Angular leaf spot has been reported at a few farms, some in newly planted fields. Slugs are being found at several strawberry farms and need to be scouted for at this time. No gray mold has been seen, but growers need to be on the lookout for it. Leaf spot disease was reported earlier this season, but no new infestations have been seen. It was mostly on older or first leaves of the season.

Raspberries have large, green fruit for early flowering summer varieties. Fall red raspberry canes continue to put on good new growth, with the longest canes 36 to 40 inches in length.

Blueberries have small, green fruit, the largest being 15 millimeters in size. Fungicide applications are key at this time for growers that have had heavy rains in the last week or so.

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