East Michigan fruit update – Aug. 8, 2017

Scattered brown marmorated stink bug feeding damage is starting to be found in apples, with apple maggot flight remaining strong across the region.

Weather

The season-long story of the precipitation haves and have not’s remains across east Michigan. Rainfall totals for the last week have again been variable, ranging from 0.2 inch to 2.4 inches. Further, the rainfall totals for the season have been extremely variable over relatively short distances. As I shared in last week’s report, traveling across the region I find farms less than five miles apart with saturated soils and soil that are bone dry. Most farms have been dry for the last three weeks. For growers with dry soils, keep a close eye on newly planted tree and small fruit crops.

Several farms report light damage from pea-sized hail that came with thunderstorms last Thursday and Friday afternoons and evenings, Aug. 3 and 4.

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

East Michigan GGD totals for March 1 to Aug. 7, 2017

Location

GDD42

GDD45

GDD50

Commerce (Oakland County)

2,617

2,247

1,681

Deerfield (Monroe County)

2,951

2,558

1,956

Emmett (St Clair County)

2,574

2,210

1,658

Flint (Genesee County)

2,803

2,425

1,843

Freeland (Saginaw County)

2,597

2,235

1,683

Lapeer (Lapeer County)

2,593

2,225

1,668

Pigeon (Huron County)

2,364

2,012

1,483

Romeo (Macomb County)

2,740

2,367

1,797

Tree fruits

Apples have continued to size well, with most being around 3 inches in size. However, there is a wide range of apple sizes on trees this season. Apples continue to color well for this time of season. More varieties have now set most of their terminal buds, thus summer pruning is taking place on these varieties. Summer apple varieties continue to be harvested. Some apple drop is starting to take place as fruits continue to enlarge, mostly pushing off the limb; this is mostly larger sized fruit.

Brown marmorated stink bugs continue being caught in traps at several orchards, and just yesterday, Aug. 7, I started seeing a few apples that were fed on by brown marmorated stink bugs. This feeding damage is hard to find, and I did not find any brown marmorated stink bug nymphs or adults in the same trees where I found the damage. Sometimes this damage is hard to distinguish from bitter pit, hail damage and feeding by native stink bugs.

If you had brown marmorated stink bug fruit damage in 2016 or are finding them feeding on apples, now is the time to start controlling them with a full cover required. They seem to prefer feeding on green varieties at this time of the season, but not always.

Apple maggot trap catch numbers continued to climb this week. Trap catch is occurring even on farms where soils are dry, which is unusual. Codling moth trap catch numbers remained high in non-mating disrupted blocks for the second week in a row.

A few fall webworm, a new pest to report this week, webs were found in apple blocks, mostly in blocks where an insecticide has not been used in the last few weeks.

Woolly apple aphid populations continue to build in untreated blocks. Japanese beetle numbers seem to be declining in most fruit crops. I am generally finding fewer beneficial insects over the past few weeks in most apple blocks.

Black rot infected fruit continue to be seen in a few blocks, mostly in the same blocks where it was a problem last season. Sooty blotch and flyspeck symptoms continue in more blocks. A few new fire blight strikes showed up, mostly in bearing apple blocks.

Pears are just over 2 inches in size, with much of the fruit having frost marks. Harvest is expected to begin in a few weeks for those few growers with a good crop. Sooty mold from pear psylla feeding was found in many blocks.

Peach harvest for Red Haven continues at most farms. I am starting to see terminal flagging from oriental fruit moth, and I have had a few reports of oriental fruit moth larvae found in fruit, mostly in split pit fruit. I also had a report of spotted wing Drosophila (SWD) larvae found in fruit that was heavily damaged by hail. This is unusual, as SWD normally does not infest peaches.

Leaves and fruit in several blocks have a touch of bacterial spot, this week causing some yellowing of leaves on the interior of the tree. These leaves will drop in the next week or so, but are not of major concern.

Sweet cherry harvest has wrapped up. Cherry leaf spot was found in a few sweet cherry blocks, causing leaf yellowing and premature leaf drop. This is found mostly in the top middles of large trees, indicating a spray coverage problem.

Tart cherry harvest has wrapped up. Cherry leaf spot was found in most tart cherry blocks, causing leaf yellowing and premature leaf drop. Leaf drop is extensive in some blocks.

Plums continue to color and size well for European types, and some Japanese varieties are being harvested. This season’s plum crop is extremely variably, with some varieties having little to no fruit this season. Twospotted spider mites continue being found in isolated hotspots in plums.

Small fruits

Strawberries are regrowing from renovation where soil moisture has been adequate. This week I can really see that some strawberry varieties are responding well to renovation, with some varieties growing rapidly and others slow to regrow. New plantings continue to runner well.

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

Raspberry harvest is quickly winding down for summer red raspberry varieties; fall raspberry harvest is expected to begin in a week or so. The bud berries on shorter canes of fall red raspberries are ready to harvest. Fall bearing black raspberry harvest is just beginning. Blackberry harvest is underway for summer bearing varieties, with fall bearing varieties at full bloom.

SWD are continuing to be caught in traps in summer raspberries in very high numbers. I have had several reports of SWD infested fruit and farms closing to harvest.

Blueberry harvest continues for many varieties this week, berry size is on the small side at this time. Overall, we had a very nice blueberry crop this season at most farms.

SWD trap catch numbers continue to be very high. I have had several reports of SWD infested fruit in the past few weeks, causing a halt in harvest operations. Some of these farms that were closed with SWD issues have now reopened. Blueberry maggot trap catch started in the last week, especially on farms that have had good rains in the last few weeks.

Phomopsis canker is apparent in several farms. It causes sudden wilting and death (flagging) of canes.

Grape fruit clusters continue to fill out for Concord and Vinifera types.

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