East Michigan fruit update – Aug. 22, 2017

Brown marmorated stink bugs and limited feeding damage continues in apples. Late summer apple varieties are being harvested, and early fall red raspberries are starting to be harvested this week, with blueberry and peach harvest ending soon.

Weather

Our soils remain dry at most fruit farms across the region. We did receive an average of 0.56 inch of precipitation over the last week, but the range of rainfall for the eight Michigan State University Enviroweather stations listed below varied widely, from only a few tenths of an inch to 1.04 inches from widely scattered thunderstorms. No hail was reported with these latest rounds of thunderstorms. The southern tier of counties finally had some decent rains in the last week.

The season-long precipitation story of the “haves and have nots” continues, with rainfall totals for the season being extremely variable over relatively short distances. I am seeing more signs of drought stress on many farms, especially on tree and small fruit crops under five years old and in the last few weeks on apple size.

Our season remains three to six days ahead of normal in terms of growing degree-day (GDD) totals and even further ahead for the beginning of harvest of our late summer fruit crops.

East Michigan GGD totals for March 1 to Aug. 21, 2017

Location

GDD42

GDD45

GDD50

Commerce (Oakland County)

3,013

2,601

1,966

Deerfield (Monroe County)

3,367

2,933

2,262

Emmett (St Clair County)

2,969

2,562

1,940

Flint (Genesee County)

3,227

2,807

2,154

Freeland (Saginaw County)

2,988

2,584

1,961

Lapeer (Lapeer County)

2,951

2,541

1,912

Pigeon (Huron County)

2,742

2,347

1,748

Romeo (Macomb County)

3,151

2,763

2,097

Tree fruits

Apple harvest continues for Paula Red, Zestar and Gingergold. Many growers needed to spot-pick Paula Reds for the third time, as there is such variability of apple maturity this season. There will most likely be one more picking of Paula Red because we had such a long bloom period this spring. I expect this trend to continue for other apple varieties as we move through apple harvest.

Apple varieties appear to be maturing even earlier than we predicted in MSU Extension’s predicted apple harvest dates article published in late July. Recall that we had an early bloom this spring that is calling for an early harvest. Additionally, drought at many farms may be moving maturity forward. The light crop load may also be pushing maturity forward. This seemed to be the case for Gala, McIntosh and Honeycrisp that I sampled and collected for analysis yesterday, Aug. 21, for the first week of testing for the Apple Maturity Project. Look for the first east Michigan apple harvest report to be published Wednesday, Aug. 30, with more details. Reports can be found on MSU Extension’s Apple Maturity page.

Apples have continued to size and color well, surprisingly despite the dry soils at most fruit farms this summer. There is a wide range of apple sizes on the tree this season, caused from the long bloom period. However, during the last few weeks, fruit size has been slowing down on farms where drought was more extensive this summer. This is particularly true in the southern tier of Michigan counties.

Apple drop continues to slowly take place as early varieties continue to size, mostly pushing off the limb; this dropped fruit is mostly the larger-sized apples.

Brown marmorated stink bug adults and nymphs continue to be caught in traps in many apple blocks. For the last two weeks I have found a few apples fed on by brown marmorated stink bugs, causing a depression, dimpling, corky or water-soaked area on the skin. This feeding damage is difficult to scout for and is sometimes hard to distinguish from bitter pit, hail damage and feeding by native stink bugs.

Protect fruit if you had brown marmorated stink bug fruit damage in 2016 or are finding them feeding on apples this season. Many growers thought border sprays applied for apple maggot control will control brown marmorated stink bug as well—this is not the case. A full cover will be required to control them. They seem to prefer feeding mostly in the tops of trees and on green varieties at this time of the season, but not always.

Apple maggot trap catch numbers have continued this week, but at reduced levels. Trap catch is occurring even on farms where soils are dry, which is unusual. Codling moth trap catch numbers have dropped back this week.

Bitter pit is being seen in more varieties this week, usually on the larger sized fruit. Black rot-infected fruit are apparent in several blocks, mostly in the same blocks where it was a problem last season. Sooty blotch and flyspeck symptoms continue in more blocks.

Pear harvest is starting for Bartlett this week. Much of the fruit in many blocks has extensive frost marks.

Peach harvest is quickly winding down for late-season varieties. Most growers report they will finish harvest this week. Older leaves continue to turn yellow, mostly caused by bacterial spot with some leaf yellowing being attributed to the effects of drought stress. I am finding a few terminals flagging from oriental fruit moth.

Sweet cherry leaf yellowing and drop continues, mainly from cherry leaf spot. This is being found mostly in the top middles of large trees, indicating a spray coverage problem. Last week, I saw a few limbs dying from bacterial canker; I am not finding any new strikes this week.

Tart cherry leaf yellowing and drop continues, mostly from cherry leaf spot. Some trees are nearly defoliated.

Plum harvest continues for Japanese varieties, with Stanley harvest expected to start in a week to 10 days. Stanley’s have colored very well in the last week.

Small fruits

Strawberry regrowth in renovated fields looks good this week, especially where potato leafhopper populations were controlled. New plantings continue to runner well, especially where soil moisture was adequate.

Potato leafhopper populations are building in new plantings where they have not been controlled. Keep an eye on the newest foliage in newly planted fields for signs of continued leaf curling from this insect feeding.

Raspberry harvest is complete for summer red raspberry varieties and is starting for early maturing fall raspberry varieties. Fall bearing black raspberry harvest continues, as does blackberry harvest.

Spotted wing Drosophila (SWD) is being caught in traps in fall raspberries in very high numbers. Begin SWD protection programs in fall raspberries as harvest approaches.

Blueberry harvest is winding down quickly for many varieties this week, such as small berry size and loss of flavor. SWD trap catch numbers continue to be very high in blueberries, so continue SWD control programs if you are still harvesting. Blueberry maggot trap catches continue this week, especially on farms that have had good rains in the last few weeks. Phomopsis canker is visible at several farms, causing sudden wilting and death (flagging) of canes.

Grapes fruit clusters are filling out for Concord types, and Vinifera types are continuing veraison.

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