West Central Michigan vegetable regional report – June 11, 2014

Leafhopper activity is increasing in carrots and celery, and insects are becoming active in other crops as well.

As young asparagus fields are shut down, it is time to start thinking about your disease control program for asparagus purple spot and asparagus rust. Once fern is fully expanded, a first application of a protectant such as Bravo (active ingredient chlorothalonil) can be made. Thereafter, data on leaf wetness and temperature can be used to time additional applications of protectants using the TomCast disease model to protect against purple spot. Be on the lookout for the early stages of rust in these younger fields. Early in the season, rust aeciospores can develop. If you detect these or later stages of rust, Michigan State University Extension recommends growers to consider including Folicur (active ingredient Tebuconazole) with Bravo, as this product is a more effective rust material than Bravo alone. Only three applications of Folicur are allowable per season.

In carrots, infectivity of aster leafhoppers was 4 percent at one Oceana County location sampled June 5. At this infectivity, the threshold is 12 leafhoppers for 100 sweeps for carrots.

In general, aster leafhopper numbers have increased in recent weeks in the celery growing region of Michigan. Infectivity of aster leafhoppers was 5 percent for a sample collected in a Southwest Michigan location earlier this week. At this infectivity, the threshold is seven leafhoppers for 100 sweeps for celery.

In cucurbits, striped cucumber beetle has become active in Michigan in recent weeks. This insect is a problem because especially early on, adults can defoliate seedlings, and throughout the season, it can transmit bacterial wilt. At-plant seed or soil treatments with a neonicotinoid insecticide can protect plants for two to three weeks during this critical period. After this treatment wears off, pyrethroid insecticides can provide control.

Onion thrip numbers have still been low and below threshold in locations where MSU researchers have scouted. Unless weather is unusually hot and dry, the first application of the thrips insecticide Movento (active ingredient spirotetramat) is often made at the end of June. Always apply Movento using a penetrating surfactant.

The herbicide Command (active ingredient clomazone) now has a Special Local Needs label for banana peppers in Michigan.

According to www.lateblight.org, there is currently a low risk for potato late blight for four to five out of the next five days in most West Michigan locations.

According to forecast models, there is currently a very low risk of western bean cutworm or corn earworm moth activity in corn for the Midwest.

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