Submitted to: Journal of Nematology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: September 2, 1999
Publication Date: N/A
Interpretive Summary: Thousands of species of small worms known as plant-parasitic nematodes infect nearly every agronomic and horticultural plant important to agriculture. In the United States, these pests cause economic losses from decreased food, fiber, and ornamental production estimated at $8 billion. One problem with controlling nematode-induced crop damage is that only a few chemicals are available to control these pests; these chemicals are frequently inadequate, unsuitable or too costly for certain crops or soils. Therefore, a safe, effective, and economic means to control these worms is badly needed. In this investigation, ARS researchers used a harmless material known as dry ice, which is solid carbon dioxide, to lower soil temperature and thereby either kill or reduce nematode infection and reproduction on tomato plants. Results indicated that this treatment reduced by several hundred fold the number of nematode eggs that could be subsequently found on mature plant roots. These results are significant because they are the first report of nematode control by rapidly lowering the soil temperature. Although further studies by researchers are needed to optimize and economize this procedure, the preliminary results indicate that a modified dry ice treatment will be used by some farmers in order to obtain environmentally safe and effective control of certain types of plant-parasitic nematodes.
Technical Abstract: Solid CO2 (dry ice) was added to pots containing soil that was infested either with eggs of the root-knot nematode, Meloidogyne incognita, or with tomato (Lycopersicon esculentum) root fragments that were infected with various stages of the nematode. Two hr after the dry ice was added, thermocouples in the soil recorded temperatures ranging from -15C to - 59C. One day after treatment with the dry ice, the temperature of the soil was allowed to equilibrate with that of the greenhouse and susceptible tomato (cv. 'Rutgers') seedlings were planted in pots containing the two infested soils that had been treated with the dry ice and in pots with identical soils that had not received the cryogen treatment (controls). After five weeks, the plant roots were removed from the pots and freed from the soil to recover and count nematode eggs. Data indicated that plants grown in soil infested with eggs and receiving dry ice treatment had less than 1% of the eggs found in the controls; plants from soil infested with root fragments and receiving dry ice treatment had less than 4% of the eggs found in controls. These results indicate that dry ice used to lower soil temperature may have potential as a cryonematicide.