Saginaw Bay area vegetable regional report – June 18, 2014

Pest pressures across the region vary, and rain would be nice.

An “inching” cabbage looper larva.

An “inching” cabbage looper larva.

Rainfall and growing degree day (GDD) base 50 degrees Fahrenheit accumulations as of June 18, 2014, from Michigan State University Enviro-weather stations at the following Bay and Thumb area vegetable growing regions are as follows:

We are caught up on GDDs in most regions.

In my Michigan State University Extension visits to the major Macomb, Lapeer and Bay county vegetable areas, my best estimates of crop planting progress are below.

Sweet corn is at 90 percent and in various stages in all regions, tassels emerging in some. I have not captured any European corn borers, but I have found low level true armyworm damage in Macomb County. Spotted cucumber beetles or southern corn rootworms were also spotted on sweet corn in low numbers this week in Macomb County, but it is an irregular early appearance of this migratory species. Weekly scouting will determine if these insect populations are growing to economic levels.

Cabbage loopers have been seen on cabbage in low numbers in Macomb County. These caterpillars are distinguished from other cabbage caterpillars by their “inchworm” way of moving. Treat when more than 30 percent of plants show signs of caterpillars and feeding damage prior to the cupping stage. Once the plants start cupping, the threshold gets tighter to 20 percent infestation. Between heading and harvest, the threshold becomes 10 percent infestation. Bt works well on all three species of cabbage caterpillars, such as cabbage whites, diamondback moths and cabbage loopers, and the thresholds are the same.

Lettuce drop (Sclerotinia spp.) has been spotted already in fields where it was present at harvest last year. This pathogen survives for years in dormancy as hard, black lumps indistinguishable from soil with the naked eye. Host plants “awaken” them, and it can only be treated at this point. Endura, Fontelis, Meteor and Rovral 4F are fungicides rated for this disease, and if the label allows, they are most effective on transplants before transplanting into the field. Rotation with a no-host is extremely important to set back growing populations of this disease.

In carrots, aster leafhoppers are being found more frequently around the state on wheat, and their infectivity for aster yellows disease is increasing. Once wheat is harvested, these leafhoppers will move into carrots, lettuce and brassicas, which are susceptible to the aster yellows disease.

Onion thrips have not reached threshold, and some rain will set them back.

Colorado potato beetles can be found now in potatoes as adults and larvae. Rimon is a product that can be used effectively as the first control application, but that does not work well on older larvae and adults. Abamectin works well with a non-ionic surfactant. The threshold is one larva or adult per plant threshold.

In string, bush, and wax beans, potato leafhoppers have been spotted in Indiana and Southern Michigan within the last week. These are important pests because they feed on many crops and transfer many viral diseases as they “taste test” plants. They are important to scout for after alfalfa cuttings, and can be identified underneath leaves by their sideways movement.

In melon and summer squash varieties without a seed treatment, striped cucumber beetle pressure has been high. 

Tomato and pepper field plantings have been set back from a lack of rain, while greenhouse tomatoes are nearing harvest.

Slicing cucumbers are the same as tomatoes and peppers.

Pickling cucumbers are at 35 percent in the Bay area. About 5 percent of the pickles going in this year are seedless varieties. Greenhouse hand-picks are harvesting.

Radishes are pretty much done, and red beets are going to be ready soon. Celery root is all in.

In winter squash and pumpkins, black cutworms have been reported in sugarbeets across the southern tier counties. They would not normally be a problem for sugarbeets, but planting was so late this year due to the wet spring. In a couple weeks, sugarbeets will outgrow any damage. However, direct seeded pickling cucumbers and pumpkins are susceptible to clipping over the next two weeks. Scout for clipped seedlings and dig around pencil-sized holes in the ground to find larvae in the daytime. Treat in the evening if more than 3 percent stand loss occurs.

Birds and mammals have been feeding on seeds before they can germinate. Overplanting and thinning is the best method to ensure a good stand with this sort of thing at a larger scale, while protecting with screens or bottomless coffee containers works well for smaller scale operations.

June-bearer strawberries are being harvested. Seagulls have been picking through fields after harvesters leave the field in many areas. They may only be eating damaged berries, or culled berries, but they should be harassed to leave to mitigate feces contamination on fresh market berries.

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