Survival of rice root-knot nematode juveniles in moist soil
1989
Soomro, M.H. (Reading Univ., Reading (United Kingdom). Agriculture Dept.)
Severe infestations of the soil by Meloidogyne graminicola can cause up to 50% yield losses. To develop an efficient control method for this nematode, its survival capacity should be known in the absence of a host plant. To measure rice root-knot nematode survival, eight plastic pots were filled with sterilized soil and inoculated with 4,000 freshly hatched M. graminicola juveniles/pot. The soil was kept moist. Pots were incubated at two temperatures: four pots at 26 +- 4 deg C, and four pots at 20 +- 1 deg C. Survival and viability of the nematodes were measured by a bioassay method at 2, 3, 4, and 5 mo after inoculation. After assay, a 2-wk-old seedling of Echinochloa colona was planted in one pot from each incubation temperature and kept at 26 +- 4 deg C. Seedlings were uprooted 2 mo after transplanting. Roots washed free from soil were weighed and fixed in FA 4:1. Fixed roots were stained in acid funchsin in lactoglyceral and cleared for 24 h. Number of nematodes in the roots was estimated by counting nematodes in three 0.5 g subsamples. Second stage juvenile of rice root-knot nematodes can survive in soil without any host plant for up to 5 mo at temperatures up to 26 deg C and remain viable to invade host roots and reproduce.
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