Onion growers are adopting integrated pest management practices and benefitting from IPM strategies, according to a recently published national Pest Management Strategic Plan for dry bulb storage onions, created with Western Integrated Pest Management Center funding.
“We’re seeing good adoption of IPM by growers, either as individuals, or coming from crop consultants,” said Howard Schwartz, a professor of plant pathology at Colorado State University and the lead author of the plan. “We’ve been pleased with that.”
The recently published PMSP updates a 2004 document that was less national in scope, and highlights some of the advances made over those nine years.
“A new PMSP provides a good snapshot of current pest management issues and practices,” said Western IPM Center Director Jim Farrar. “An update like this is beneficial because it also shows the gains we’re making.”
One area that’s improved in onion is managing thrips and the Iris yellow spot virus that they carry.
“Cultivar selection is making a difference when it comes to thrips,” explained Mark Uchanski, an assistant professor of horticulture at New Mexico State University who contributed to the new onion Pest Management Strategic Plan and is involved in related research. “More glossy and green foliage is less attractive to thrips. More waxy and blue foliage is more attractive.”
Plant breeders are also developing more vigorous onion cultivars as well.
“They’re better able to stand up to the feeding of thrips,” Schwartz explained. “That’s one thing we’re able to share through field trials.”
Both Schwartz and Uchanski see widespread adoption of other IPM practices by onion growers trying to manage thrips, including crop rotation, better management of debris and weeds where thrips populations can grow, and pest scouting to time pesticide applications appropriately.
“They’re heavy on the scouting to make sure they stay ahead of the curve,” Uchanski said. “I’m seeing growers who will time or at least be aware of alfalfa cutting in nearby fields because that will cause thrips to move.”
Despite the gains, thrips remain the leading onion pest in the U.S., especially when combined with the damage done by Iris yellow spot virus.
Other Pests and Pathogens
Other major disease challenges for onion producers are soil-borne and bulb-infecting fungal and bacterial pathogens.
“White rot is still an issue,” Schwartz said, “and so are Fusarium, pink root and Botrytis neck rot.”
Fungicides and proper storage practices can help combat losses to those diseases, and Schwartz sees a need for a quick bacterial and fungal diagnostic tool for the onion industry.
“There are 10 or 15 different bacterial pathogens that can attack onions,” he said. “A DNA-based test is being developed by Brenda Schroeder at Washington State University so you can blot a sample on a card and within a few hours be able to say what’s attacking your onions and be able to treat it correctly.”
One of the biggest benefits of a new Pest Management Strategic Plan is that it identifies needs and helps direct research going forward.
“Because of the PMSP, we’re on the same page and organized,” Uchanski said. “This was written by representatives of the onion industry, USDA, academics and growers and packers, so now when we apply for a research grant, there’s weight behind that request.”
The Western Integrated Pest Management Center promotes IPM practices to solve pest problems in agriculture, urban areas and natural lands throughout the West. It encourages a science-based approach to pest management using pest biology, environmental information and all available technology to reduce pest damage to acceptable levels by the most economical means, while reducing the risk to people, property, resources and the environment. The Western Integrated Pest Management Center is one of four regional centers funded by the USDA to promote IPM practices, and serves 14 Western states and Pacific island territories.
The dry bulb storage onion PMSP can be downloaded at http://www.ipmcenters.org/ pmsp/pdf/USonionPMSP.pdf.
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