East Michigan fruit update – August 7, 2018

Most fruit growers in the region have received much needed rain in the last week. Drought conditions still exist, but soil moisture needs are not as critical for many.

August 7, 2018 - Author: Robert Tritten

Weather

Widespread precipitation finally arrived at most fruit farms over the last week coming from several rain events. Many farms received 1.5 to 2.5 inches of rain in the last week spaced over 3 to 4 days.

The range of precipitation over the last week at our MSU Enviroweather stations listed in the following table was on the low end at 0.18 inches and on the high end 2.42 inches. However, total rainfall was extremely variable over short distances. For example, on one smaller farm I visited late last week the eastern edge of the farm received 1.5 inches of rain from one rain event, and the western edge of this narrow farm received no rain at all in the same event.

For a few unfortunate fruit growers, less than a half of an inch of rain has been received since the first week of June. For these growers, the drought conditions continue.

While we appreciate recent precipitation, I want to remind growers that drought conditions still exist on most fruit farms, as most are still 2 to 3 inches short on rain since early June. We are at a point now where we need to receive many long soaking rain events over several weeks for soils to come back to normal moisture levels.

Our season is still running 10 to 14 days ahead of normal in degree day totals and about five days ahead of normal in terms of the start of harvest for some of our summer fruit crops. Degree day totals have continued to build rapidly with hot day time temperatures and just as importantly warmer morning lows.

East Michigan Growing Degree Day Totals for Mar. 1 to Aug. 6, 2018

Location

GDD42

GDD45

GDD50

Commerce (Oakland County)

2690

2367

1849

Deerfield (Monroe County)

2894

2557

2025

Emmett (St Clair County)

2547

2230

1727

Flint (Genesee County)

2858

2530

2006

Freeland (Saginaw County)

2626

2303

1790

Lapeer (Lapeer County)

2636

2317

1808

Pigeon (Huron County)

2440

2129

1636

Romeo (Macomb County)

2817

2491

1972

Tree fruits

Apples have continued to size well on farms where irrigation has been applied, but for others without irrigation, size has stalled over the last few weeks. Apples are mostly in the range of 2.25 to 2.75 inches for Honeycrisp, with most other varieties at 2.0 to 2.5 inches in diameter. Some Paula Reds are seeing fruit drop, but most of the drop is from fruit pushing other fruit off the limb. Now is the time for apple growers to be laying out plans for harvest management aids such as AVG (Retain, 1-MCP [Harvista]) and Blush.

Most farms have had normal codling moth trap catch over the last few weeks. However, there are a few farms with very high trap catch numbers, in the range of 25 to 70 per trap. In these problem blocks, codling moth is at about 20 percent egg hatch, so now is a good timing for an insecticide application. These same blocks will need another application in 10 to 14 days to control the rest of the hatch. With the heat of the season, we might have a partial third generation of codling moth. The second-generation San Jose scale adult trap started two weeks ago, so based on the model, crawlers should be emerging this week. So, controls can go on in the next 7 to 14 days in problem blocks. This is the last window of the season to control them. Apple maggot trap catch has continued to level off at most farms. European red mite populations also seem to have leveled off at most farms, with no new bronzing being found. The threshold for mites also increases on August 1. Potato leafhopper leaf cupping continues to be found in many apple blocks.

Brown marmorated stinkbug (BMSB) trap catch continues to very slowly and steadily raise. I have had more reports of feeding damage being found in a few more apple blocks. For some strange reason, most of the BMSB damage thus far this season has been seen in Gala blocks, last season most of the damage was found in Honeycrisp and the season before most damage was found in Golden Delicious and Northern Spy blocks. This is a hard pest to scout for, as many times at this time of the summer we will find damage in fruit where there are traps close by and yet no adults can be found. Entomologists think that the pheromone used to attract this pest does not work well in the summer as it is an aggregation type of pheromone, and this pest does not start to aggregate until sometime in the fall, maybe mid- to late- August.

Necrotic leaf blotch in Golden Delicious and a few related strains is the only new pest to report this week. Leave spotting and yellowing symptoms appeared very rapidly starting late last week. Black rot symptoms on fruit are being seen at more farms in the last week. Sooty blotch and fly speck symptoms are yet to be seen this season, but fungicide applications need to be made into later this month to control it.

Pears are mostly at 2.0 to 2.5 inches in diameter. All stages of pear psylla continue to be present in poorly managed blocks, especially in blocks where suckers have not been removed.

Peach harvest of Red Haven is expected to begin later this week. Harvest of early season varieties continues. They continue to color well, and in blocks where soil moisture has been adequate, they have taken on another good swell. Most peaches on these sites are 2.5 to 3.5 inches in diameter. On dry soil sites, fruit size will be a problem this season.

Brown marmorated stinkbug (BMSB) trap catch continues to slowly and steadily rise in peaches. I have not had any recent reports of BMSB feeding damage peaches, I have received feeding damage reports in apple blocks. If you find feeding damage or adults in peaches, I would like to hear from you.

Sweet and tart cherry growers have continued to see leaf yellowing and drop, caused at most farms from a combination of cherry leaf spot disease and drought.

Plum harvest continues for Japanese varieties, with most having a short crop. European varieties have colored well in the past week. Most Stanley types are 1.25 inches in diameter. Some blocks continue to have light amounts of bacterial spot infection on the fruit causing spotting.

Small fruits

Strawberries continue to rebound well from renovation, especially where irrigation has been applied. Regrowth has not been so good on dry soils. Many new plantings have now filled in the row with good runner development. Some new plantings continue to have high populations of potato leafhopper.

Raspberry harvest has wrapped up for summer varieties and light pickings continue on fall-bearing red raspberries. Most plantings of fall raspberries have a big crop coming on. Now is a critical time for moisture to size these growing fall raspberry fruitlets.

Spotted wing Drosophila (SWD) populations continue to build in summer red raspberries as they wrap up harvest as well as for fall raspberries as they begin harvest. In the past two weeks I have seen the number of larvae in fruit take a dramatic climb. Growers need to be watchful that covers for control for SWD are being made on a 5 to 7-day basis, and more often after rain events.

Blueberry harvest is just over half completed at most farms. The further we get into blueberry harvest the more issues growers are having maintaining berry size. Spotted wing Drosophila (SWD) populations continue to build as we move through the season. In the past two weeks, I have seen the number of larvae in fruit take a dramatic climb. Growers need to be watchful that covers for control for SWD are being made on a 5 to 7-day basis, and more often after rain events. Trap catch of blueberry maggot seems to have leveled off this week. However recent rains may bring another good emergence of this pest.

Grape growth continues. Many growers have pruned off root suckers and branches in the lower part of the canopy in order to increase sunlight and spray penetration into the fruit.

Tags: east michigan, fruit update, msu extension


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