Like a prizefighter catching a second wind after an early round beating, the Arkansas rice crop appears to be making a comeback. At least that's the way it looked early in the week of May 20. The combination of maladies affecting the crop — including cold weather, pests and salt — may yet deliver a knockout haymaker, but Rick Cartwright says he's hopeful that won't happen.
“I think this crop has turned the corner. The problems we're seeing — even with the continuing cold weather — don't appear to be getting worse. The fields that weren't totally destroyed by the cold and insects are looking better.
“It's amazing how resilient this plant is. It's been struggling for three weeks, and if we can get a few warm days, it should be okay. Stands will be thinner, but at least entire fields won't be lost,” says Cartwright, Arkansas Extension plant pathologist.
At this point, the thing many farmers were most worried about — pythium (seedling blight) — has yet to appear in a major way. Cartwright says many things are contributing to seedlings dying, but pythium doesn't seem to be as important as he originally thought it was in mid-May.
Cartwright and colleagues are finding an abundance of the grape colaspis insect (also called the lespedeza worm) that's eating roots off rice plants. This is turning out to be a bad year for the pest and a lot of dead seedlings seen in Arkansas rice fields from Jonesboro south are due to the worm.
“In places, it's eaten us up. We're having to replant parts of fields in some places. We have this pest every year, but this year, for whatever reason, it's really working the rice crop over.”
According to John Bernhardt, rice insect expert with the University of Arkansas, the adult grape colaspis feeds on soybean leaves and lays eggs just beneath the soil surface. The eggs hatch into larvae that feed on roots and grow until they pupate. Adults emerge from the pupae in three days to a week. Depending on the year, there may be two to four generations during a soybean growing season. The last generation of larvae overwinter and attack rice roots the following spring.
A preventative chemical seed treatment called Icon that works very well against the pest, says Bernhardt.
Cartwright says an example of Icon efficacy is a field near Hazen, Ark. The field of Icon-treated seed is adjacent to an untreated field. The Icon crop looks “dramatically better… and is really impressive.” Meanwhile, across the fence, part of the untreated field is being replanted.
It's too early for stinkbugs to move into rice, but the tremendous population of stinkbugs in the wheat crop has many farmers worried, says Cartwright. “The stinkbug numbers don't bode well for our summer crops. The stinkbugs will lay a bunch of eggs and will be waiting on soybeans, milo and rice when it starts heading out. We've got to keep our heads up for stinkbugs.”
How has wet weather affected the rice crop and needed treatments?
“It's hurt us, and the cool, wet weather is the most important factor in the seedling rice problem. If we had a warm spring like last year's, the rice plant can fight off many problems.”
Bernhardt notes that with warm weather, the lespedeza worm will still eat a rice plant's roots, but the plant is able to overcome injury by constantly sending out new roots. The plant may be not reach it's full potential due to insect damage, but it will survive and produce.
This year, it's been so cold and wet that rice growth has been terribly hindered. That means the insect has an advantage and ends up killing the plant by chewing off the bottom portion.
If a plant can't grow it can't fight anything off, says Cartwright. A plant that can't grow properly “is like a fat man trying to cross a freeway: an easy target. We think the cold, wet conditions aren't just a factor in the seedling blight but also in the fields with salt injury we've been seeing.”
On the plus side with the state's rice, Cartwright says, Command herbicide is working well this spring — “almost too well in a few fields where the rice is literally ‘white’ rice.” Before panicking with these fields, farmers might want to wait for warmer temperatures. Once those arrive, “the ‘white’ fields should turn green in short order as we've seen in the past.”
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