Wireworms, aphids active in wheat

In early November, a field hand in Arkansas' Prairie County called Extension agent Brent Griffin over to look at some odd wheat. The wheat, says Hank Cheney, Griffin's Extension colleague, “looked like it had been chewed on. It turns out there have been quite a few fields with the same type of damage. The wheat had started to die, and no one knew what was going on. The cause wasn't what we were expecting.”

The culprit in the wheat field: wireworms. Wireworms, normally seen in corn and grain sorghum, are showing up where wheat was planted on fallow ground allowed to grow up during the summer. The pests were feeding on the summer vegetation — grasses and broadleaf weeds.

“When the farmers went in and disked all that vegetation into the ground to kill it, the wireworms were waiting,” says William Johnson, Pioneer agronomist. “Farmers then planted wheat, with hungry wireworms just waiting to jump all over the young plants. The worms have eaten all the roots off below the soil leaving a little shoot sticking in the ground.

“This has been pretty prevalent around England and Des Arc on fallow ground. Some producers with non-irrigated land are going with just a wheat rotation. That's where it's hitting.”

Once a field gets wireworms, there's nothing that can be done. Producers can prevent the pest, though, through use of a Cruiser or Gaucho seed treatment. Those treatments might run a producer $12 per acre. But since this is the first year wireworms have been a problem in wheat, few think many farmers planted treated seed.

“I've heard that feed grain producers see this in Oklahoma where combines go through and leave straw,” says Johnson. “Apparently, the residue is a refuge for wireworms. When wheat is planted where the straw is worked behind the combine, wireworms show up.”

Aphids are another pest taking advantage of balmy weather. Reports are that aphids are especially prevalent in wheat planted in late September and early October.

“This warm weather isn't producing any kills of aphids,” says Rick Cartwright, Arkansas Extension plant pathologist. “And since aphids transmit barley yellow dwarf disease, it is worth watching for. I was just walking wheat today and had no problem finding aphids. In Arkansas, we never felt it was worth trying to control aphids in wheat since there are several flights. But normally by this time, it's gotten cold enough to shut down aphid reproduction. This year, though, they're still working the wheat crop over. They seem to be flying around and establishing themselves easily in wheat fields.”

It's a long winter and lot could happen, but if these aphids are carrying the barley yellow dwarf virus, it could mean problems next year.

“How bad it is, will remain or be, we don't know,” says Cartwright. “If this weather continues, all kinds of things will survive the winter. We need a considerable period of freezing weather.”

All interviewed for this story also mentioned another consequence of warm weather: larger-than-normal wheat plants.

“If this weather continues much longer, that will be a concern for freeze injury next spring,” says Johnson. “If wheat overdevelops on the front end and doesn't go into a kind of dormancy, it's vulnerable to freeze.”

Cartwright also points to diseases. “I can tell you if we have stripe rust in the state, it's liable to survive if we don't get some cold in here. Even leaf rust could survive in the southern part of the state if we don't get a normal winter. There's still a long way to go, but warm weather this late certainly gives us pause. The aphids concern me as much as anything.”

e-mail: [email protected]

Hide comments


  • Allowed HTML tags: <em> <strong> <blockquote> <br> <p>

Plain text

  • No HTML tags allowed.
  • Web page addresses and e-mail addresses turn into links automatically.
  • Lines and paragraphs break automatically.