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Research for insect pests of rice continued in 2020 with the addition of a project to study an emerging pest for row rice.
Blake Wilson, LSU AgCenter entomologist, said billbugs have become more of a problem.
“They’ve emerged as a serious threat to row rice,” Wilson said.
He said a trial at the St. Joseph Research Station shows billbugs can cause a 10%-20% yield loss if left unprotected.
Wilson said seed treatments don’t seem to be effective, but an insecticide, Belay, offers a remedy.
“That was effective at controlling infestations and reducing them,” he said.
Wilson said the row rice technique has created new research needs, and “we’re having to learn as we go with row rice.”
Billbug damage results in whiteheads similar to the sign of stem borer feeding.
“You won’t see the larvae until you see the damage,” Wilson said.
Wilson said Belay applied at green ring seems to work when it is used preemptively.
“We don’t know much about the timing,” he said.
More work with the project will be done in 2021 at the St. Joseph facility.
Wilson said his work in 2020 included studying the increasing range of apple snails. For the first time, he said, a rice crop was affected by the invasive species. The snails fed on emerging rice plants, but the farmer had water-seeded his crop into a field with a heavy snail infestation. Wilson said.
Hurricane Laura appeared to move the snails into new areas along the Vermilion River, he said. He said snails usually are spread with irrigation water.
Wilson said it is hoped that a new foliar pesticide will be available for stem borers.
Wilson will continue his work on stored rice pests, and one study is looking at the susceptibility of varieties to the insects. For example, he said, the hybrid XP753 has 10 times the damage of varieties Caffey and Mermentau from stored grain pests. The primary insects are rice weevils and the lesser grain borer.
Wilson said the second year of a study has shown that weevil damage can be detected by drone.
In addition, he said another study is underway to determine if different varieties are resistant or tolerant to weevils. He said the study so far shows that hybrids have less yield loss with weevil pressure.
He said another study is aimed at finding out when rice is more vulnerable to stem borer infestations. Wilson said he hopes to determine scouting strategies and an economic threshold for spraying the insects.
He also is working on a project to find out if stem borers or weevils cause the most yield losses
