West central Michigan vegetable regional report – June 1, 2016

A quick update on late-spring pest activity in west central asparagus, carrots, celery and cucurbits.

For asparagus, common asparagus beetle egglaying was spotty through late last week. Some growers have applied insecticide. Products such as Sevin XLR Plus (active ingredient carbaryl) and Perm-Up (active ingredient permethrin) are effective and have one-day pre-harvest intervals. Consider applying your first fungicide cover to new or young asparagus fields once cladophylls (leaves) expand after shutdown.

Asparagus miner adults were active at one field I visited late last week. Note, last year some growers reported significant rust problems in some fields, but not others. These fields likely have overwintered inoculum that could produce problems in this year’s fern if environmental conditions are suitable. Once shutdown nears, Michigan State University Extension suggests scouting these problem fields for aeciospore lesions on harvest stubble and considering including fungicides such as Onset or Tebustar that contain Tebuconazole in July for your first cover spray.

For carrots and celery, it is possible that recent weather patterns have transported aster leafhoppers into our area, increasing numbers. Leafhoppers were active this week in west Michigan and testing for aster yellows infectivity is ongoing.

For cucurbits, the MSU Enviro-weather seedcorn maggot degree-day model predicts peak egglaying by the first generation of flies will occur within the next week at Hudsonville and Standale/Walker, Michigan. At Hart and Fremont, Michigan, peak is not expected within the next week, but flies should still be active and laying eggs. This pest becomes less of a concern as soil temperatures warm. This pest is of most concern for organic growers who do not have effective seed treatments.

Predicted degree-days (DD) until the next expected peak of seedcorn maggot egglaying and forecast accumulation based on Enviro-weather data from select stations and a DD model for this pest.

Weather station

DD base 39 F to next peak

DD base 39 F forecast for 6/1-6/7

Hart

309

154

Hudsonville

168

187

Fremont

269

178

Standale/Walker

186

186

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