Manda Anderson holds a hand lens close to her face and peers intently at a cotton leaf.
“There it is,” she says. “It” is a kurtomathrips, a small insect pest that had not been seen in West Texas cotton fields for years until 2011, when, accompanying the worst drought in memory, the tiny pests added another threat to an already stressed crop.
“We’re beginning to see them again this year,” says Anderson, Gaines County, Texas, AgriLife Extension integrated pest management specialist. “They are not at levels yet that we need to treat, but when farmers begin to shut off irrigation systems, we may see populations explode.”
Defying what would seem commonsense, kurtomathrips “thrive on stressed cotton plants. In fields with nematode infestations, they do a lot of damage.”
Anderson says farmers should employ a “systems approach,” to manage the thrips. That includes controlling the thrips when they reach threshold levels, but also should mean planting nematode-tolerant cotton varieties and controlling weeds. “Tumbleweeds are hosts,” she says. Acephate and imidacloprid are both effective and fairly inexpensive insecticides.
On this overcast, pleasantly mild September afternoon, Anderson had agreed to show Farm Presssome peanut and cotton fields, following a morning field day near Seminole.
A few timely rainfall events over the summer, she says, helped farmers make the best of what started out as a very dry summer. Peanuts “seem to be one of the best crops in years,” she says. “Cotton is all over the board.”
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Cooler temperatures and a few timely rains set up peanuts for a promising harvest. “We got humidity into the canopy and better pollination, pegging and pod set,” she says. “The rain came at an ideal time for bloom and pod set.”
Farmers have seen a few problems, however, with an as yet unexplained plant decline. “We’re seeing salinity issues,” Anderson says. “We’re involved in a soil sample project and are also looking at water samples in fields where we see plants crashing.”
Salinity in water is the most likely culprit. Chloride levels and electrical conductivity “are showing up above critical levels for peanuts. We need more investigation. We’re pulling leaf samples to see if leaf tissue shows above critical values.”
Boron also could be a contributor. “We run a fine line with boron,” Anderson says. “Too much can cause toxicity.
“We’re not sure yet what causes the decline, but it seems to be a water issue, chloride or boron. “I’m working with Scott Russell (IPM specialist in neighboring Yoakum and Terry Counties). By the end of the year we hope to know more about this issue.”
She says the effects are more noticeable in peanuts than they are in cotton fields. “Peanuts seem to be more susceptible.”
No mitigation material is available. “Soil scientists say we need a good flushing rain, more than 5 inches in one rainfall, to flush the salts out of the soil profile. We have one field where we are sampling that had a 5-inch rain. That one came in mid-to-late July.”
The entire county has benefitted from rainfall this summer, at least to some degree. “Every part of the county got some rain,” Anderson says. “The peanut crop started responding and I think flushing the salts out of the soil helped. We needed the water.”
She says the biggest change in peanut production this year has been a switch in market types. “Until this year, acreage has been dominated by runner-type peanuts, but growers couldn’t get contracts before planting time. They made the change from runners to Spanish, Virginia and Valencia peanuts.” Those options offered better contracts.
Acreage for 2013 is around 25,000 to 26,000, she says. “That’s down from 10 years ago but holding steady for the last few years, even though we do have a slight decrease from 2012 acreage.”
She says cotton also has some issues other than kurtomathrips. Root-knot nematode is one. “I’ve seen them in a lot of cotton fields, but we have technology to manage them. The question is whether farmers will adopt it. I don’t know.”
Several cottonseed companies offer nematode-tolerant varieties and at the morning field day Deltapine officials announced two more that should be available for 2014.
“Varieties are a key,” Anderson says, “especially in the sandy soils we have here.” She’s not certain of the overall loss cotton farmers suffer from nematode infestation, but she’s seen a difference of as much as 400 pounds per acre with a tolerant variety compared to a susceptible one.
Rotation is another part of the puzzle and the decline in peanut acreage has affected rotation options. “People seem to forget why they need to rotate,” she says.
Controlling nematodes also helps farmers manage thrips, which seem to be attracted by stressed cotton.
Other pests, including “a flush of bollworms in non-Bt cotton,” caused some concern. “Other than that, insect pressure has been light. We are seeing some aphids and the kurtomathrips but not at treatable levels.”
Cotton potential is directly proportional to the amount of rainfall received, the availability of irrigation water and a cover crop, Anderson says.
“Cotton that survived the harsh conditions early and then caught good rains in June and July may make a good crop. With a little more water and a cover crop, the better it looks,” she adds.
Cover crops made a big difference. “The wind never stopped,” setting up young plants for significant damage without cover crop residue to protect them. “A lot of fields without a cover crop were knocked back. It’s a fine line for farmers to determine whether to water wheat in the fall to get residue or to save all their water for cotton season. But it is hard to make a crop without that cover.”
The issue is complicated by a water table that continues to decline.
Anderson says weeds have also been an issue this year, partly due to Mother Nature and a drought that prevented pre-emergence herbicides from activating properly, but some farmers did not apply those herbicides and continue to rely on Roundup-only to control weed pressure.
“We have to use products other than Roundup,” she says.