West central Michigan vegetable update – June 20, 2018

We have had high dew points with warm temperatures earlier than normal this year, so be vigilant for foliar diseases.

Foliar disease may accelerate soon for all crops, as we have had high dew points with warm temperatures, more so than is normal for the time of year. Keep an eye out for foliar disease symptoms; staying on top of protectant fungicide applications now could prevent early infections that lead to later outbreaks.

Asparagus shutdown is now in full swing in Oceana County. As far as possible given sprayers are busy, consider protecting ferned out plantings with chlorothalonil, as recent weather has been conducive for asparagus purple spot.

Pigweed has continued to be an issue in some carrot fields. Aster leafhoppers were present in one Mason County field I swept yesterday, June 19. The largest processing carrots I have seen had about eight to 10 leaves yesterday.

For celery, 0 percent of leafhoppers tested positive for aster yellows in a sample taken this past Monday, June 18, in Allegan County.

For cucurbits, planting of processing zucchini was ongoing in Oceana County, depending on the timing of grower contracts. There was an outbreak of cucurbit downy mildew in Maryland recently, which is earlier than normal.

For potatoes and tomatoes, it was noted that volunteer potato survival was lower than expected despite some fields having been abandoned to our east in Montcalm County. This is good news, as volunteer potatoes are a main source of inoculum. An outbreak of late blight has been reported in central New York. Stay tuned as genotyping will help determine fungicide sensitivity of this strain.

Place out your earworm trap in sweet corn as your first plantings silk. InsectForecast does not forecast any risk of migration for the next five days.

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