Arkansas scientists organize International Spinach Conference

Dec. 19, 2011
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Jim Correll, Professor of Plant Pathology, University of Arkansas

Howell Medders, Agricultural Communication Services

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FAYETTEVILLE, Ark. -- Agricultural scientists and production experts from five countries attended the International Spinach Conference in Amsterdam, Netherlands, in October. Jim Correll, professor of plant pathology, and Shelby Goucher, entomology department fiscal support analyst in the University of Arkansas System Division of Agriculture, organized the conference.

The group meets periodically and was last held in Fayetteville and at the Division of Agriculture's Vegetable Research Station at Alma in 2009.

The conference included a day of presentations on research projects and a tour of variety trials and commercial fields in West Friesland, Enkhuisen, Netherlands.

Spinach is grown commercially in the Arkansas River Valley in Arkansas and Oklahoma for canning and freezing, although the Arkansas acreage has declined substantially, said Craig Andersen, a Division of Agriculture horticulture specialist. Allen Canning Company based in Siloam Springs markets the popular Popeye brand of canned and frozen spinach.

The dense foliage of spinach that grows close to the soil creates challenges for managing plant diseases and insect pests, which are focuses of current research in Arkansas. A long-term Division of Agriculture plant breeding program developed spinach varieties with high levels of genetic disease resistance, which has been incorporated into most new varieties, Andersen said.

At the conference, Correll reported on research by an international group on downy mildew disease, or blue mold, which has led to development of spinach varieties with increased resistance to this globally important pathogen. Researchers have identified six loci (specific locations of a gene on a chromosome) in spinach DNA that appear to be keys to increased resistance to the downy mildew pathogen, Correll said.

Seed companies can use DNA technology to screen breeding lines and identify those with the loci for increased disease resistance. These lines may then be used in conventional breeding programs to develop improved disease-resistant varieties, which greatly reduces reliance on plant protection chemicals.

Paul McLeod, professor of entomology, reviewed spinach pest management since the 1970s in Arkansas. Damage by the green peach aphid, a major pest in spinach, was managed for many years by an insecticide that was banned in spinach by the U.S. Environmental Protection Agency in 1994. Later in the 1990s, a different insecticide, Provado (imidacloprid), was approved for spinach and has been proven effective, McLeod said.

More recently, caterpillars (Lepidopterous larvae) such as armyworms and webworms have become major pests of spinach. This may be due to widespread use of row crop varieties that are genetically resistant to these pests, causing them to find other hosts, McLeod said. Management of these larvae is now based on judicious use of several newer and safer insecticides, he said.