by Fae Holin
Managing Editor, Hay & Forage Grower

It wasn't a pleasure trip from his Idaho base to California last week, says Don Miller, forage breeder with Producer's Choice Seed. Miller spent several days inspecting alfalfa stem nematode damage in alfalfa fields. Some fields have lost half their crop, he believes.

But the damage, found in the Sacramento and San Joaquin Valleys, usually affects first-cutting alfalfa only, says Dan Putnam, University of California Extension forage specialist. “We've seen fields that looked absolutely devastated and dead, but they actually do come back in the second cutting. However, some fields this year are so badly affected, they may not come back very well.”

“It's a question of number of plants. If there were enough plants that were killed, then you would consider some other options, like overseeding with grass or plowing the crop under. But if you still have a halfway decent stand that produces maybe not 100% of yield but 80% or 90%, most of you will want to keep it in,” he says.

Yet the stem nematode problem appears to be increasing in the state. “Is this something that is just two bad years out of 10 or 20 or is it something that we're going to see more of as time goes on? My thought is, it may be the latter,” Putnam says.

“That nematode is as bad as I've ever seen,” agrees Miller. “Part of the problem down here is that they reuse irrigation water, and nematodes live in the water or on the equipment.” Growers who run tailwater from one field to another, or move a windrower or swather from field to field, help spread the pest.

Few chemical control options are available, and planting stem nematode-resistant alfalfa varieties gives the best control, Miller says. Yet resistant lines now available may not be resistant enough. For more of Miller's and Putnam's comments on the stem nematode outbreak, and what Putnam thinks alfalfa breeding companies should do about it, read “Stem Nematodes Strike California Alfalfa – Again.”