West Michigan tree fruit update – Sept. 5, 2017

Harvest is fast approaching – what you need to consider.

Crop stage and horticulture information

Our 2017 predicted apple harvest dates seem to be right on target when looking at the early varieties harvested so far and the apple maturity indices from fruit collected in the past few weeks. The 2017 predicted harvest dates for upcoming varieties in the Grand Rapids are: Gala and McIntosh – Sept. 5 and Honeycrisp Sept. 15.

Pest report

Codling moth adult counts have declined to zeros for the past few weeks and overall the second generation was low in number for most blocks. There are exceptions and hot spots, but injury from codling moth is very low this season. A third generation is not expected.

The Michigan State University Extension trap line is catching all stages of brown marmorated stink bug in various traps. So far, numbers are higher than 2016, but still overall quite low compared to other regions of the U.S. with very high pressure and damage. In 2016, damage to apples that was noticed at harvest time most likely occurred in right around this time or the end of August to the first weeks of September. Damage was reported in many varieties of apples, but was most pronounced in Golden Delicious and Honeycrisp. Hopefully, if you had damage last year, you applied a brown marmorated stink bug targeted spray in mid-August. Now, follow-up applications to borders near wooded areas or alternate hosts (i.e., soybeans) should be considered. I am noticing that beans are starting to decline and brown marmorated stink bug is likely to move from that host to other nearby hosts (apples). We gave a great publication from the MSU Extension fruit team for “all things brown marmorated stink bug.” Check it out: Managing Brown Marmorated Stinkbug in Michigan Orchards.

Apple maggot adults have been caught on red spheres for the past several weeks, but overall, numbers seem to be very low for 2017. Perhaps the lack of rainfall has lessened their flight. Monitoring should continue in blocks with a history of apple maggot damage, especially in blocks with late harvested varieties.

All stages of European red mite can now be found. Predators are also more readily found. Where mites were mostly not present all summer, there seemed to be a flush of activity in the past six weeks. At this late date, there would be no reason to apply management applications to mite populations in apples. Let the predators build.

Peak egg hatch for third generation oriental fruit moth is upon the Ridge area at this date. A regional biofix was set for April 28, 2017 (307 DD45) with 2522 degree days base 45 accumulated since that date. If you have had high numbers (50 plus per trap per week) of oriental fruit moth in apples in the past month, a cover spray to prevent fruit stings is warranted. Having an oriental fruit moth trap in codling moth disrupted blocks will tell you what’s going on with oriental fruit moth and if it needs to be managed.

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