East Michigan fruit regional report – July 26, 2016

Drought conditions continue across the region. Harvest continues for blueberries and early Japanese plum varieties. Spotted wing Drosophila trap catch numbers are building.

Weather

Most growers saw some showers last Thursday afternoon, July 21, and again Sunday morning, July 24, but the total rainfall from both events was less than a tenth of an inch. Our drought conditions continue across the eastern part of Michigan, and soils are very dry.

If I average the precipitation since April 1 at eight of the Michigan State University Enviro-weather stations that I track degree-day totals in most of these reports, our season is an average of 4.88 inches behind normal. However, the range of shorter than normal precipitation runs between 2 and 7 inches, so these drought conditions vary dramatically across the region.

Newly planted and younger tree and small fruits continue showing signs of wilting and some plants have died as a result of lack of rainfall. Growers continue to devote a great deal of time to irrigation activities. Fruit size is being reduced for all of our fruit crops due to the drought.

With the heat of the last week, our degree-day totals have continued to build quickly, thus we are now at least a full week ahead of normal, except for farms along the shore of Lakes Erie and Huron, where the season is a few days behind normal. In terms of the fruit crop growth stages and beginning of harvest, we are also running about a week ahead of normal.

East Michigan growing degree-day totals for March 1 to July 25, 2016

Location

GDD42

GDD45

GDD50

Commerce (Oakland County)

2,331

2,005

1,519

Deerfield (Monroe County)

2,609

2,257

1,725

Emmett (St Clair County)

2,265

1,951

1,481

Flint (Genesee County)

2,519

2,190

1,693

Freeland (Saginaw County)

2,291

1,982

1,517

Lapeer (Lapeer County)

2,307

1,992

1,522

Pigeon (Huron County)

2,115

1,820

1,380

Romeo (Macomb County)

2,410

2,084

1,597

Tree fruits

Apples are mostly 2.25-2.625 inches in diameter for growers across the entire region. Lodi harvest is continuing, and Paula Red and McIntosh continue to color well. Growers are hand-thinning high value apple varieties. Growers should begin planning Retain applications for fall as Gala harvest is anticipated to begin the first week of September. The first Retain applications can be made four weeks prior to harvest.

Apple maggot catch on yellow sticky board traps continues to slowly build at most farms, although a few farms have seen very high numbers. I suspect the slow emergence of apple maggots may be related to dry soils. Where growers are getting high trap catch, a border insecticide application is needed.

Woolly apple aphid populations are slowly declining in blocks where an insecticide application was made, however woolly numbers are building in untreated blocks, with many woolly apple aphids moving out to terminals and on to fruit. These may be a major problem as we move toward fall. Insecticide treatments are more effective the earlier they are applied in the season, generally first cover timing, since they are able to decrease the population before it becomes more widespread throughout the tree. Also, the insects’ waxy covering is less extensive earlier in the season.

Eastern tent caterpillar larvae are being seen on terminal branches. Potato leafhopper and white apple leafhopper numbers are slowly building in many apple blocks. Twospotted spider mites are being found in a few apple blocks. Some San Jose scale red halo marks are being seen on fruit. European red mite adult, Japanese beetle adult, obliquebanded leafroller, codling moth, green apple aphid and oriental fruit moth numbers have dropped off in the past week where predator numbers have grown. I expect to see codling moth trap catch numbers rise any day now. Beneficial numbers are building, especially lacewings and assassin bugs this week.

I’m seeing more black rot symptoms on fruit. A few more growers reported fire blight strikes in very high numbers in new plantings; this started to be seen about three weeks ago. This is trauma blight that infected the new leaves and shoots. The infection most likely came nine to 12 days earlier from strong wind events. Sooty blotch and flyspeck disease symptoms should be appearing soon.

Pears are mostly 1.875 to 2.125 inches in diameter. Pear fruit size is being affected by the drought. Pear psylla numbers are high on suckers.

Peaches are 2.25 to 2.5 inches in diameter for most growers. Garnet Beauty and Risingstar harvest are starting, and Red Haven harvest is expected to begin mid- to late next week. I have not seen any brown rot symptoms.

Sweet cherry harvest has wrapped up. Spotted wing Drosophila (SWD) larvae-infested fruit was a problem for a few growers at the tail end of their harvest. Bird feeding was heavy in many blocks, mostly related to our lack of rain. I am just starting to see some lighter colored leaves in sweet cherry; this may be drought related or early leaf spot symptoms.

Tart cherry harvest has wrapped up. SWD larvae-infested fruit was a problem for a few growers at the tail end of their harvest. As with sweet cherries, bird feeding was an issue in tarts this season.

Plums have sized in the past week, despite the drought. European types are coloring and are 1.25 inches in diameter. Early varieties of Japanese types are being harvested. The crop load is variable for both types, especially in some Japanese varieties, as they have little to no crop.

Small fruits

Grape growth is slow. Concord fruit clusters are filling out and European varieties are at berry touch. Japanese beetle and rose chafer are being seen, but in low numbers. I am seeing a few grape berry moth larvae, mostly in Concord grape.

Strawberry renovation is complete and where irrigation has been applied, plants are continuing to put on new leaves. MSU Extension strongly encourages growers to water well as soon as the renovation process is complete; with the drought this season, this is more important than in most seasons. New berries are runnering well and are filling 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 some of the same symptoms can be seen with drought stress.

Raspberry harvest is winding down for summer red raspberry and black raspberry varieties. Blackberry harvest is starting for most farms. For fall red raspberry growers, limited lite harvest is just beginning. Fall red raspberry canes are much shorter this season than most years, and are much shorter than last season’s unusually long canes. Small berries are a problem at many farms due to drought.

SWD trap catch has taken a big jump across the region, from an average of less than one per trap to an average to just over 14 SWD per trap this week. In my opinion, due to this jump in trap catch, growers should begin protecting red raspberries now for SWD infestation. For more details on the SWD life cycle, control strategies and specific insecticide recommendations, consult the MSU SWD website.

Blueberry harvest continues. Berry size is dropping off at most farms, mostly due to drought. As in raspberries, SWD trap catch has taken a big jump across the region this week, from an average of less than one per trap to an average of just over 14 per trap. Due to this jump in trap catch, blueberry growers should begin protecting now for SWD infestation. For more details on SWD life cycle, control strategies and specific insecticide recommendations, consult the MSU SWD website.

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