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Looking Ahead

Forages & Grains

Corn

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Looking Ahead
Volume 62 Number 16 Date 08/17/2017


CORN ROOTWORM - The annual survey completed earlier this week documented the lowest beetle populations in the history of Wisconsin rootworm surveys dating back to 1972. Sampling for beetles in 229 cornfields yielded a state average of 0.2 beetles per plant, with uniformly low averages of 0.1-0.3 per plant across all nine agricultural districts. Economic populations of 0.75 or more beetles per plant were recorded in only 11% of the fields examined, while no beetles were observed at 153 (67%) of the sites. The very low 2017 survey average indicates a pronounced decrease in beetle abundance and a reduced risk of larval root damage next summer.

LATE BLIGHT - Development has been confirmed by the UW in commercial potatoes in Portage County and on tomato in Dane, Pierce and Waukesha counties. Protective fungicidal treatments of green vines on a five- to seven-day schedule should be maintained. This advisory is particularly important for growers and gardeners in southern, central and northwestern Wisconsin since late blight is present in the area.

CORN EARWORM - Migrants have not yet arrived in significant numbers. Captures during the week ending August 16 were extremely low 1-2 per trap, with only six of DATCP's 15 monitoring locations reporting moths. The early July to mid-August cumulative count of 128 moths in 15 traps suggests that the CEW migration flights registered this season have been too minor to produce widespread or severe larval infestations, although this could change if a large influx were to occur by early September.

EUROPEAN CORN BORER - Egg deposition has been underway since late July and is expected to continue through August. The treatment window for second-generation larvae has closed in advanced portions of southern Wisconsin, and remains open only a few more days in the central areas. Final inspection of sweet corn for egg masses and small larvae is advised before 2,100 degree days (modified base 50°F) have been reached.

WESTERN BEAN CUTWORM - Counts have declined to low levels as the annual flight subsides. Only eighteen of DATCP's 70 monitoring network traps captured moths this week, for a total of 36 moths compared to 110 the week before. The cumulative count as of August 17 is 1,850 moths in 70 pheromone traps (26 per trap average). Network participants may remove their traps at this time.

BROWN MARMORATED STINK BUG - Seven specimens were captured in the pheromone trap near Janesville from August 10-16. Late-summer populations are likely increasing in areas of the state where BMSB is established, including Brown, Dane and Rock counties, and it will be particularly important for fruit and vegetable growers, gardeners, and property owners to remain alert for stink bug activity in August and September. This new invasive pest is naturally attracted to lights, so growers who suspect its presence in their orchards or on their farms should watch for BMSB adults near lights throughout fall.

-- Krista Hamilton, DATCP Entomologist