MSU researchers find rice seed treatments effective
“We’re targeting primarily rice water weevils, and they only move into the field when producers establish the permanent flood about three to six weeks after planting,” Gore said. “So seed treatments for rice have to last longer than in other crops, because they are sitting in the field a lot longer.”
Gore said all of the seed treatments are water soluble, and water can have both positive and negative effects on seed treatments.
“Because rice is grown in aquatic or semi-aquatic environments, we needed to find out how different water management practices might impact the seed treatments’ performance,” he said.
Andrew Adams, an MSU graduate student from Greenville, set up tests in grower fields across the Delta and at the Delta Research and Extension Center.
“To determine the impact of a delayed flood, we looked at flood timings of six and eight weeks after planting, which is about two months that the seed treatment was sitting in the soil without having insect pressure,” Adams said. “Where we delayed the permanent flood until eight weeks after planting, the seed treatment was not compromised and no yield losses were observed.”
Flushing fields …
Adams also looked at the impact of flushing fields. Flushing a field is a form of irrigation where the field is brought to a shallow flood and then drained.
“Flushing is used for herbicide incorporation, seed germination or for irrigation during hot and dry conditions,” he said.
Adams tested zero, one and two flushes with water across a rice field to check the efficacy of three different seed treatments.
“We found that zero and one flush had no negative impact,” he said. “The seed treatments Cruiser and NipsIt were negatively impacted with the application of the second flush and yield losses were observed. However, Dermacor wasn’t negatively impacted by the application of the second flush.”
Seed treatment rates …
Gore and Adams also tested the efficacy of seed treatment rates in hybrid rice.
“Hybrid rice varieties are grown at 20 to 25 pounds of seed per acre, versus 75 to 85 pounds with conventional varieties,” Gore said. “Because seed treatment rates are based on a per-seed basis, we wanted to know if the lower seeding rate, and hence the lower seed treatment rate on a per acre basis, impacted insect control. It did not.”
No additional benefit was observed from increasing the seed treatment rate. Currently labeled rates for hybrid rice production are correct, Gore said.
“The management practice that showed significant improvement in rice water weevil control beyond the seed treatment was a foliar overspray with a pyrethroid on hybrid rice,” Gore said.
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