Released February 19, 2009
COLUMBIA, Mo. - A statewide survey of urban gardens found that almost one-third had infestations of root-knot nematode, a microscopic worm that attacks plant roots.
The worms produce knots or galls on roots, impeding water and nutrient flow. Infested plants yellow, wilt easily in summer heat and show reduced yields, said Bob Heinz, University of Missouri plant research specialist. The pest has a host range of more than 2,000 plants and can reproduce on most lawn and garden pants.
The pest has been established for many years in the state's southern regions but now appears in mid- and northern Missouri, primarily due to mild winters, Heinz said.
"Drawing a line across the state at about 30 miles south of I-70, the area north of that line has historically not had problems with root-knot nematode," he said. However, of the 67 samples taken in this area for the 2008 root-knot nematode survey, 30 percent showed infestation.
The best control is prevention through garden hygiene, he said. Nematodes can enter a garden only by soil or plant roots. Nematode-infected transplants, unwashed garden tools, muddy boots, vehicle tires or improperly composted material are potential carriers.
The survey indicated that community gardens were more susceptible than family or private gardens. Just 13 percent of the 38 samples from private gardens surveyed tested positive while 44 percent of the 43 community garden samples were positive.
In Springfield, two out of the three community gardens tested showed root-knot nematode.
Results in other areas:
- Jefferson City community gardens: 2 of 11, or 18 percent, were positive.
- St. Louis area community gardens: 3 of 5, or 60 percent.
- Columbia community gardens: 6 of 8, or 75 percent.
- Kansas City area community gardens: 4 of 8, or 50 percent.
- St. Joseph community gardens 2 of 7, or 29 percent.
"With more traffic in sharing of plants and equipment by many gardeners, as is common in community gardens, the more likely the gardens will become infested," he said.
Heinz offers these tips on avoiding root-knot nematode
- Clean shared garden implements in a bleach solution. A tablespoon of infested soil on a borrowed garden tiller can contain thousands of root-knot nematodes.
- Use only garden transplants from a reputable dealer.
- Don't add compost or soil to your garden unless you are sure that it is not infested.
- Destroy infested roots, but do not compost them. Rotating sections of the garden or leaving a garden fallow also may help.
"Sometimes, if there is land available, it is easier to start a fresh garden and plant the infested one in grass," he said.
Pulling up old plants at the end of a growing season is an easy way to check for root-knot nematodes. The roots of plants such as tomato or peppers should be smooth. If they have bumps or knots, there's a good chance that root knot is present.
University of Missouri Extension's Plant Nematology Lab will analyze soil samples for plant-parasitic nematodes for a $20 fee. For more information, see http://soilplantlab.missouri.edu/nematode or call 573-884-9118.
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http://agebb.missouri.edu/news/ext/showall.asp?story_num=4722&iln=907
Contacts: Bob Heinz, 573-884-9118
Robert E. Thomas, 573-882-2480, ThomasR@missouri.edu
