West central Michigan vegetable update – May 24, 2017

Though temperatures have cooled slightly, crops are finally developing at a faster pace.

Asparagus harvest is ongoing.

Aster leafhopper numbers were higher than normal in one west central Michigan celery field this week. Infectivity results should be coming soon. This information is also relevant for carrot growers, and Michigan State University Extension suggests sweeping wheat or barley windbreaks for leafhoppers. Neighboring wheat and oats (pre-heading) can also be good places to sample before carrots are large enough to sweep.

The FarMore FI400 seed treatment provides protection against striped cucumber beetle and seedcorn maggot in a Cornell University trial with cucurbits. If the variety you are using is not treated with FarMore FI400, you can soil-apply insecticides with the active ingredient imidacloprid or apply them through trickle to protect against striped cucumber beetle. Capture LFR is labelled for many cucurbits and has been used to target seedcorn maggot.

The risk of seedcorn maggot damage declines greatly once maximum daily soil temperatures at 4 inches deep consistently reach 70 degrees Fahrenheit. Direct sowing of winter squash was commencing at additional west central locations this week.

Continue to keep an eye out for caterpillar pests, including imported cabbage worm and diamondback moth in leafy cole crops. There is flea beetle activity that is likely ongoing.

In onions, nurse crops of barley were dying in some Ottawa County fields this week. MSU Department of Horticulture professor Bernard Zandstra has observed abundant, small weeds in Michigan onion fields. Research has shown that prompt application of GoalTender at the one-leaf stage can help kill small weeds and provide benefits for the overall weed control program.

Pepper transplanting was ongoing on some Ottawa County farms this week.

For root crops, cabbage maggot damage was readily detected last week in Ottawa County turnips and has been noted in radishes as well.

If you feel you had early tomato blight problems in 2016, keep an eye out in 2017 and obtain a diagnosis from MSU Diagnostic Services. Applications of chlorothalonil alternated with a strobilurin (e.g., azoxystrobin) are very good at preventing issues with early blight.

There are bacterial diseases that can be difficult to diagnose that could be confused with early blight. Disease issues including gray mold (botrytis) and bacterial disease are present on some tomato transplants in the greenhouse. Problems may increase if plants need to be held longer than normal in the greenhouse due to field delays. MSU Department of Plant, Soil and Microbial Sciences professor Mary Hausbeck’s lab has been collecting isolates of bacterial diseases and there are still copper-susceptible populations, so copper can still be used as part of a disease prevention program.

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