Effects of DL-methionine on hatching and activity of Meloidogyne incognita eggs and juveniles

Several concentrations of DL-methionine were tested in the laboratory for their effects on Meloidogyne incognita (Kofoid & White) Chitwood egg hatching and juvenile activity in aqueous suspensions and infested soil. After 7 days in methionine solutions, the proportions of hatched eggs were reduced by 23.3% at 0.25 mg litre(-1) methionine and by 76.4% at 25 g litre(-1) when compared with controls in tap water. An effect of methionine solutions on juvenile activity was also apparent after 24 h in the 25 g litre(-1) treatment, where the percentage of active M incognita juveniles was reduced by 16.3%. Further reductions in nematode mobility were observed as the time of exposure increased, and at lower methionine concentrations over longer exposure times. When methionine solutions were applied to soil infested with M incognita, reductions in egg hatching and juvenile activity were observed at 0.1 and 1 mg methionine g(-1) soil in both sand and clay-loam soils. The percentage of hatched eggs one week after methionine application at rates of 1 mg g(-1) was lower in sand (5.6%) and clay-loam soil (20.8%) than in controls where egg hatch was 52.0% and 48.0% in sand and soil, respectively. Non-active juveniles were found at 1 mg methionine g(-1) soil one week after its application to soil.