NOVEL CORONAVIRUS UPDATES AND RESOURCES

East Michigan fruit update – Aug. 21, 2018

Harvest of early fall apple varieties continues. The entire region has had extremely variable rainfall, with drought continuing for a good number of growers.

Weather

Most fruit growers received precipitation over the last week, however the trend of great variability over short distances continues this season. Some fortunate growers received good rains over the last few weeks, most have had just moderate rainfall and fewer growers have not had good rainfall events since early to mid-June.

The trend for most growers has been that soils remain on the dry side. There is an area of moderate to extreme drought that starts over Hillsdale County and extends to the northeast into the Thumb. Most areas are still running 2 to 4 inches below normal rainfall for the season. Most growers are still irrigating on a regular basis, and signs of drought stress are common in tree and small fruits.

Our season continues to run 10 to 14 days ahead of normal in growing degree-day (GDD) totals and about five days ahead of normal in terms of the start of harvest for some of our summer fruit crops. However, some early fall apple and most peach varieties are starting harvest just a day ahead of their normal harvest dates. Degree-day totals have continued to build rapidly with hot daytime temperatures and warm morning lows.

East Michigan GDD totals for March 1 – Aug. 20, 2018

Location

GDD42

GDD45

GDD50

Commerce (Oakland County)

3,113

2,747

2,160

Deerfield (Monroe County)

3,321

2,941

2,339

Emmett (St Clair County)

2,935

2,576

2,003

Flint (Genesee County)

3,295

2,925

2,332

Freeland (Saginaw County)

3,033

2,668

2,085

Lapeer (Lapeer County)

3,042

2,681

2,102

Pigeon (Huron County)

2,781

2,429

1,865

Romeo (Macomb County)

3,260

2,893

2,304

Tree fruits

Apples have continued to size well on farms where irrigation has been applied throughout the season. Also, for farms that have received good rainfall in the past few weeks, apples have responded well and taken on another good swell in fruit size. For others who are still experiencing drought and without irrigation, fruit size has stalled over the last month.

Where soil moisture has been adequate, Honeycrisp are mostly 3.25 inches in diameter. For most other varieties, fruit are between 2.5 and 3.125 inches in diameter. Leaf mottling or yellowing symptoms have gotten much more pronounced in most Honeycrisp blocks in the past week, especially on young trees and droughty sites.

Paula Red, Gingergold and Zestar harvest has started, some farms have finished harvest on all three varieties. Wildfire Gala harvest has begun as well. Fruit color has been a problem so far this season.

Applying harvest management aids have continued on several varieties, but mostly on Gala and Honeycrisp. Growers are lining up applications on other varieties as well.

Most apple insect pest populations have been winding down or declining this past week. This includes apple maggot, European red mite, codling moth at most farms, woolly apple aphid and San Jose scale crawlers. The exceptions to this are brown marmorated stink bug trap catch and problem or high pressure codling moth blocks where trap catch has remained strong.

Brown marmorated stink bug trap catch continues to rise slowly but steadily at most trapping locations. This week, I am seeing mostly young nymphs in traps. I continue to see and get reports of more limited and very scattered feeding damage in some apple blocks and varieties. Most of this feeding damage is three to four weeks old.

There is a reduced numbers of predators, as their food supplies are declining. I am still finding lacewing adults, lady bug adults and minute pirate bugs.

Sooty blotch and fly speck are new pests to report this week in apples. Symptoms started to show up late last week and this week, even on some farms that have been very dry. Black rot symptoms on fruit are apparent at more farms. Necrotic leaf blotch in Golden Delicious and related strains are more commonly visible this week as well. Lastly, many unsprayed apple and crabapple trees are experiencing extensive leaf yellowing and drop caused by apple scab. Watching these trees can give you an idea of pest pressure for next season, and even the possibility of pin head scab developing in stored fruit this ]all.

Pears are mostly 2.5 to 2.625 inches in diameter. Bartlett harvest will start next week on a few of the largest fruit. Some fruit drop is visible. All stages of pear psylla continue to be present in poorly managed blocks, especially in blocks where suckers have not been removed.

Peach harvest continues for Redhaven and other main season varieties across the region. Where soil moisture has been in good supply, they took on a final swell and fruit size and overall quality is good. Most peaches on these sites are between 3.0 and 3.5 inches in diameter.

On dry soil sites, fruit size is a problem. Also on these sites, leaves are curled and trees look tough. I hope they recover before the season ends, otherwise I am concerned about tree health and winter survival.

Brown marmorated stink bug trap catch continues to slowly raise in peaches. Over the last few weeks, I have been in a number of peach blocks where brown marmorated stink bug feeding damage was found at harvest or during grading. The fruit damage is light and scattered. If you find suspected feeding damage or adults in peaches, I would like to hear from you (contact me at tritten@msu.edu or 810-244-8555).

Sweet and tart cherry growers have continued to see leaf yellowing, cupping and drop, which has been found mostly where soils have been dry. Most of this leaf damage was caused by a combination of drought stress and cherry leaf spot disease.

Plum harvest is wrapping up for Japanese varieties, most varieties had a short crop. European varieties have continued to color well as they move toward harvest. Here again, the crop load is generally light. Most Stanley types are 1.5 to 1.625 inches in diameter. Some blocks continue to have light amounts of bacterial spot infection on the fruit, causing spotting.

Small fruits

Strawberries are looking much better on farms that have received good rainfall. New plantings continue to runner well on farms where soil moisture has been adequate, with the rows filling in nicely. Runners need to be pulled in one last time. Some new plantings continue to have high populations of potato leafhopper. Some hard-to-control weeds are growing well in renovated berries, especially white cockle, butter and eggs and this week wild carrot. An herbicide application window will be opening in early September.

Raspberry harvest continues on fall bearing red raspberries, although they have been slow to ripen this year, most due to heat. A few late season summer red raspberry varieties continue with harvest. Most plantings of fall raspberries have a big crop coming on; now is a critical time for moisture to size these growing fruitlets.

Spotted wing Drosophila (SWD) populations continue to build in fall raspberries and will continue to rise throughout fall. Be watchful that covers for SWD control are being made on a five-to-seven-day basis, and more often after rain events.

Blueberry harvest has wrapped up at many farms and for others is quickly moving along. The further we got into blueberry harvest, the more issues growers had maintaining berry size. Spotted wing Drosophila (SWD) populations continue to build and need to continue to be controlled to the end of harvest. Tighten up control measures after rain events. Trap catch of blueberry maggot has dropped off again this past week.

Saskatoon leaves on unsprayed plants have begun to drop due to post-harvest feeding damage from apple skeletonizers.

Grape berry size and vine growth continues, veraison has begun on a few varieties. Pruning of root suckers and branches in the lower part of the canopy continues.

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