A team of scientists from the Agricultural Research Service Nematology Laboratory in Beltsville, Md., and New Mexico State University has found that root-knot nematode, Meloidogyne partityla, was the cause of a recent decline in yields from mature pecan trees in New Mexico.

The decline occurred despite normal fertilization and irrigation practices.

This finding of M. partityla is significant because it is the first report of its presence in New Mexico and only the second report of it in the Western Hemisphere, according to ARS nematologist Zafar A. Handoo. He examined a collection of fresh pecan roots sent by NMSU scientists in October 2000 and made the identification.

The first discovery of M. partityla in the United States was in Texas in 1996. Host range tests conducted there revealed that the pest prefers to feed on hickory, pecan and walnut trees. Georgia and Arizona have reported cases of the nematode since the New Mexico outbreak.

M. partityla was first discovered in South Africa in 1986.

Nematodes are microscopic worms that attack plant roots. Root- knot nematodes are particularly dangerous because they are root parasites that can seriously damage many economic plants and crops worldwide. Although not likely to kill pecan trees, M. partityla will debilitate them and lower their productivity.

New Mexico is the second largest pecan-growing state in the United States, producing 32 million pounds in 2000, and is home to more than 30,000 acres of pecan trees. To help avoid future threats to the state's $50 million pecan industry, scientists are now evaluating control measures and educating growers to recognize M. partityla and prevent its spread.

More information can be found in the March issue of Agricultural Research, on the World Wide Web at: http://www.ars.usda.gov/is/AR/archive/mar02/pecan0302.htm