West central Michigan vegetable regional report – May 27, 2015

Disease, weed and insect activity is ramping up with recent weather patterns.


Asparagus harvest was ongoing this week. Spotty frost last week had minimal impact on established stands. It will be helpful to start thinking about what weeds you need to target in your lay-by application; choose products and discuss these with your consultant. Learn more about products and the weeds they target from the “2015 Weed Control Guide for Vegetable Crops” from Michigan State University Extension.

Carrot stands are reported to be good for dicing varieties in the Oceana and Mason County areas. Slicing varieties are being planted. Note, aster leafhopper numbers did increase at one location to our south. If you are a commercial carrot grower and would like alerts on aster leafhopper infectivity, sign up for MSU aster leafhopper text alerts.

Celery transplanting is ongoing. MSU Extension sampled aster leafhoppers at one southwest Michigan location last week and this week based on a cooperators’ scouting reports. Numbers had increased this week, likely due to recent southerly air currents bringing this migratory pest northward. If you are a commercial grower and would like text alerts on aster leafhopper infectivity, sign up for MSU aster leafhopper text alerts.

Cole crop pest activity has been reported from other areas, including flea beetles and cabbage loopers. Growing degree day (GDD) models suggest peak egglaying by the overwintering flight of cabbage maggots has been ongoing in Hudsonville, Fremont, Sparta and Standale/Walker, Michigan, over the last week, and will start soon in Hart, Michigan. Row covers immediately placed over transplants can reduce egglaying if cole crops were not grown in that location last year.

Onions are in various stages across the region, with the largest onions observed having four true leaves and a fifth developing, and others with the second true leaf just emerging. Thick stands of volunteer onions were visible in some locations this week. These can serve as sources of early season development of onion downy mildew, which could spread to nearby onions via air currents. They can also support higher overwintering onion maggot populations, though current seed treatments provide good control of this pest. I did observe a small number of onion thrips this week on volunteer onions as well. Smartweed continues to be challenging to control in some muck growing areas.

Pepper transplanting has been ongoing at some Ottawa County locations.

Potato planting has been ongoing. Colorado potato beetles should be emerging soon.

Tomato bacterial diseases – possibly bacterial speck or spot – have been observed on transplants.

Sweet corn early season pests could be active. Recent storm fronts could have brought black cutworm or true armyworm moths into the area. Watch for clipped plants, a symptom of cutworm activity, over the next few weeks and dig up soil around the base of plants to determine if larvae are present. True armyworms are a defoliator, often worse in areas with weedy grasses as females lay eggs on these plants. Based on degree days, the first flight of European corn borers should be starting or have already started.

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