Poster: Biology & Disease Mgmt: Nematology
Gossypium arboreum accessions resistant to Rotylenchulus reniformis identified
S. STETINA (1), J. Erpelding (1) (1) USDA, Agricultural Research Service, U.S.A.
Reniform nematode (Rotylenchulus reniformis) is a serious pest of upland cotton (Gossypium hirsutum) in the southeastern United States. Resistance does not exist naturally in G. hirsutum and no resistant cultivars are available. To identify sources of reniform nematode resistance, 225 G. arboreum accessions were evaluated in repeated growth chamber experiments. Root infection was measured on 3 plants 4 weeks after inoculation with 1,000 nematodes. The 16 accessions supporting the fewest infections were evaluated again in confirmation tests lasting 8 weeks. The numbers of nematodes extracted from soil and eggs extracted from roots of 5 plants were combined and totals were analyzed (ANOVA and differences of least squares means, P ≤ 0.05). Susceptible controls G. hirsutum cv Deltapine 16 and G. arboreum A2-101 had 85,999 and 46,902 reniform nematodes, respectively; the resistant control G. arboreum A2-190 had 1,665 reniform nematodes, and only 136 reniform nematodes remained in fallow pots. All 16 accessions tested supported smaller reniform nematode populations than the susceptible controls, ranging from 10,883 to 707 individuals. Nine accessions (A2-254, A2-272B, A2-294, A2-362, A2-456, A2-497, A2-514, A2-558, and A2-665) supported reniform nematode populations comparable to the resistant control, and accession A2-354 had fewer reniform nematodes than the resistant control.