East Michigan vegetable regional report – July 29, 2015

Drying trend and warm temperatures have allowed vegetable growers to breathe easier and get back on a regular schedule of fertigation.

Weather

We put on some heat units over the last week, and many growers had to turn on their irrigation or deploy some emergency delivery system.

Here are the rainfall and growing degree day (GDD) base 50 degrees Fahrenheit accumulations to date from Michigan State University Enviro-weather stations.

Rainfall and GDD summary

Location

GDD (50 F, March 1)

Rainfall (inches, April 1)

Linwood

1,540.2-1,381 (159.2 behind average)

8.95 (0.23 since last week)

Frankenmuth

1,660.7-1,475 (185.7 behind average)

8.66 (0.02 since last week)

Lapeer

1,642.3-1,459 (183.3 behind average)

12.55 (0.00 since last week)

Romeo

1,639.3-1,522 (117.3 behind average)

12.37 (0.00 since last week)

Crops

Sweet corn harvest is well underway eastern Michigan. Many farms are having trouble keeping up. Efforts that went into staggering plantings or emergence with plastic were set back by a series of prolonged rain events that put everything back on a level playing field. No traps in my region have caught more than one corn earworm within a week. We haven’t had too many migration events brought on by southwesterly weather since silking began.

Many cucumber and pickle plantings are on their last pickings and looking ragged. Second plantings are just beginning to produce. Leaving the first planting to sit unmanaged will not do you any favors. Disc, pull plastic – do whatever you need to do. I have not found downy mildew in cucumbers or melons in my region, and I have been looking. However, it is afoot, and protective fungicide applications are important. Michigan State University vegetable pathologist Mary Hausbeck is recommending an application interval seven days or less.

  • Spray 1: Ranman (high rate: 2.75 fluid ounces) plus Bravo WeatherStik (high rate: 3 pints)
  • Spray 2: Previcur Flex plus Zing!
  • Spray 3: Zampro plus Bravo WeatherStik (high rate: 3 pints)

Melons and watermelons liked the 90-degree days. Bees will sometimes stay home if mornings are too hot.

Zucchini and summer squash are being continually harvested. Powdery mildew is getting a grip on early plantings, and those should be turned under when convenient. Unlike many other diseases, powdery mildew likes the heat.

First plantings of cauliflower, broccoli and cabbage are nearly finished, and fall plantings were transplanted over the last two or three weeks.

Field tomatoes and peppers are being harvested. Greenhouse tomatoes are on their last legs. White mold has showed up in peppers at one farm that experienced prolonged wet periods and after using multiple applications of milk as a fungicide. There is no solid evidence that milk or whey has fungicidal action against this pathogen. Gray mold showed up in one tomato field patch. Usually gray mold occurs first in greenhouse tomatoes before being found in the field. Managing the microenvironment around the plants through pruning and moisture management is a good preventative tactic for this issue. Some blossom drop may be occurring if temperatures stay above 90 in the day, or above 75 at night, which would impact fruit set.

Late blight in potatoes was confirmed in Michigan this week, and tomato and potato growers should be judiciously applying protectant fungicides for this pathogen. Please see “Tomato Late Blight Fungicide Recommendations 2014” or Michigan State University Extension Bulletin 312, “2014 Insect, Disease and Nematode Control for Commercial Vegetables,” for a listing of fungicides that are registered. Like downy mildew in cucumbers, this is fast, deadly to plants and early this year. For information on organic control options, see Amanda Gevens’ short research publication out of University of Wisconsin, “Managing Late Blight in Organic Tomato and Potato Crops.”

Large candy onions are being harvested from plastic and bare ground fields. Long-day onion fields may experience a spike in onion thrips with this hot and dry weather, and growers should maintain their onions thrips scouting schedule to guide their sprays. MSU vegetable entomologist Zsofia Szendrei has done some great research on onion spray programs for onion thrips.

Japanese beetles have been infesting basil in southeast Michigan.

Please contact me at .(JavaScript must be enabled to view this email address) or 989-758-2502 to pick up any suspected disease samples, or send the diseased plant parts to MSU Diagnostic Services.

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