2 new pests costly for farms
Sugarcane aphid, kudzu bug menaces for milo, soybeans
Two new pests have entered Arkansas, and experts say they pose serious threats to the state’s milo and soybean crops.
“We’ve had invasive insects before, but they’re not usually this impactful,” said Gus Lorenz, distinguished professor and associate head of entomology for the University of Arkansas System Division of Agriculture.
Both pests — the sugarcane aphid and the kudzu bug — were first detected in the state in 2014, Lorenz said, and both have expanded their territory since then. The cost of controlling the insects cuts into growers’ already thin profit margins, he said.
The sugarcane aphid, which attacks milo, also known as grain sorghum, has been the biggest challenge to date.
Lorenz estimated that Arkansas milo growers spent $12 million this year applying insecticide to combat the pest.
Jason Kelley, extension wheat and food grains agronomist, said sugarcane aphids have wiped out some of the state’s milo fields.
“We have seen fields that were shut down,” Kelley said. “The aphids just destroyed the plants.”
On the other hand, Bob Griffin, owner of Griffin Ag Consulting in Marianna, said the milo farmers he works with in Lee and Phillips counties saw only a “moderate” impact this year.
“It wasn’t really heavy, but what do you compare it to when you’ve never had it before?” Griffin said.
Sugarcane aphids were first spotted in Louisiana and Texas and moved up through south Arkansas. Kelley said some of the worst effects have been seen in the state’s southern tier of counties.
Lorenz said the aphids are difficult to kill partly because of their short reproductive cycle. They don’t have to to mate and they give birth to live offspring when they’re just 3 to 5 days old, he said, enabling them to rapidly infest untreated milo fields.
The fact that the aphids travel from field to field further complicates decisions about when to apply insecticide, Lorenz and Kelley said. Farmers who act early run the risk of missing the next wave of aphids, while those who wait too long could see their crops heavily damaged or even destroyed.
Each application targeting the sugarcane aphid adds $15 to growers’ per-acre production costs, which total about $350, Lorenz said. About 80 percent of the state’s 500,000 acres of milo required two applications this year, he said.
That’s bad news for growers, especially since the expected average yield of 100 bushels an acre would enable them to break even at current market prices for milo only if they didn’t have to spray for aphids, Kelley said.
“This is an expensive pest to control,” Lorenz said. “What we’ve got to do is find a better way of controlling this pest that lets us reduce our dependence on insecticides.”
Planting milo early — in April — is one tactic that reduces the odds of a sugarcane aphid infestation, Lorenz said.
The kudzu bug is still establishing itself in Arkansas but is expected to become a widespread threat to the state’s soybean crop in 2016, Lorenz said.
The danger is complicated by the fact that the only insecticide effective against kudzu bugs also kills beneficial insects such as lady beetles and damsel bugs that prey on other soybean pests, Lorenz said. And those pests — bollworms and loopers, in particular — aren’t especially vulnerable to the insecticide that kills kudzu bugs.
The insecticide that kills kudzu bugs costs $8 to $10 per acre, Lorenz said, while those that kill bollworms and loopers run $15 to $25 per acre.
“With current bean prices at about $8.50 per bushel, it’s hard to break even,” Lorenz said. “That’s another nail in the coffin.”