West Central Michigan vegetable regional report – June 18, 2014
Wet and warm weather could promote asparagus rust and purple spot in asparagus, as well as late blight in potatoes and tomatoes.
In asparagus, wet and relatively warm weather over the past week could promote development of asparagus rust and purple spot in fields where harvest has ceased. One of the mainstays of our rust control program, Folicur (a.i. Tebuconazole), has often been used by growers after rust develops due to price and that it has some curative activity. Like most fungicides, it is most effective when used preventively.
In celery, infectivity of aster leafhoppers was 4 percent for a first sample collected in Allegan County on June 16. At this infectivity, the threshold is eight leafhoppers per 100 sweeps for celery. Infectivity was 0 percent for a second sample from Allegan County. A local scout reports capturing variegated cutworm moths in Ottawa County again this week.
In cucurbits, squash vine borer adults were trapped in Southeast Michigan this week. Michigan State University Extension recommends that traps should be placed out now to monitor for this pest if it has caused problems in the past. To date, a North Carolina location where cucurbit downy mildew was confirmed on June 10 is the farthest north this disease has been detected.
Onions were in the 4-5 leaf stage in the Hudsonville, Michigan, area this week. A local crop scout reports onion thrip numbers have been low to date. Numbers were also low and below the threshold of one thrip per leaf at one Kent County location, scouted by Zsofia Szendrei. Download the 24(c) label for use of Goaltender on 1-leaf stage onions for next year.
In potatoes and tomatoes, weather will be very conducive to late blight development through this Sunday, June 22, according to www.lateblight.org.
According to forecast models, there will be a low risk of corn earworm moth activity for the Midwest through this upcoming weekend in sweet corn. Continue to be on the lookout for black cutworm damage in sweet corn at stage V5 and earlier.