Abstract
Effects of hot water treatments on populations of the root-knot nematode (Meloidogyne incognita) were examined in four experiments to determine a temperature and time combination capable of lowering nematode populations on caladium (Caiadium x hortulanum) tubers without damaging plant performance. In a preliminary experiment, tubers were grouped by weight and immersed in a water bath at 5(FC for 30min, 52C for 20 min, 54C for 10 min, or a control (24 C for 1min). After treatment, tubers were planted in the greenhouse for evaluation of plant growth. Emergence and leaf growth were fastest (0.10 > P > 0.05) in the treatment using 50 C for 30minutes and the control group. In experiments II and III, the effectiveness of four similar hot water treatments in lowering nematode numbers on tubers infested with Meloidogyne in cognita was determined. All treatments successfully reduced extracted nematode numbers on tubers to zero, significantly (P < 0.01) lower than the mean number of nematodes per untreated tuber. A fourth experiment demonstrated that rootknot nematodes surviving on untreated tubers were transmit ted to steam-pasteurized soils. All tubers receiving a hot water treatment did not carry root-knot nematodes to sterile soil and produced more plant mass than the control group. Immersion of tubers in a hot water bath maintained at 50°C for 30 min lowered extractable nematode numbers to zero and improved plant performance.
