Wednesday, October 27, 2010

Weird Worm Year Continues In Virginia - Armyworms Hitting Small Grains Early

I started getting calls and visits yesterday from homeowners and growers with complaints about worm infestations. Fall armyworm is the culprit, and apparently the problem is severe and widespread.

Fall armyworms are spreading into newly planted fields of oats, rye and other fall grass forages, and into newly seeded home lawns. Calls are coming in mainly from Surry and Isle of Wight Counties, but that could be the result of the attention growers and crop advisers are paying to fields in those areas.

One common denominator seems to be that most infested fields are adjacent to pasture or hay fields. Apparently, the worms have been developing in those fields and are now on-the-move into fields with tender newly emerge leaf shoots.

Based on the number of reports, I suspect this problem is even more widespread. Emerging wheat and barley fields are certainly also at risk. Fall armyworm has two strains and I suspect this is the grass strain. I also suspect that this widespread infestation is the result of a huge migratory flight from the south, another in a long line of caterpillar invasions that started with early corn earworm problems back in July.

This late-season fall armyworm invasion is certainly an unusual problem.

I have never seen anything like this in the 22 years I have been working in this area. Rod Youngman on the main campus (he works with insect pests of turf and forages) advised that any of the pyrethroids labeled for forages or small grains should provide good control if applied at the high rate, but should be applied NOW.

He believes that seedlings are the most at risk and should be treated ASAP. Fall armyworms are surface plant feeders, so they are pretty vulnerable to pesticides. We also believe that fields grazed off by these worms should spring back once they have cycled out. Their life cycle should put them into to the pupal stage in another week or less. And of course, a good hard frost would take-em-out.

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