RESISTANCE TO MELOIDOGYNE-INCOGNITA RACE-3 AND ROTYLENCHULUS-RENIFORMIS IN WILD ACCESSIONS OF GOSSYPIUM-HIRSUTUM AND GOSSYPIUM-BARBADENSE FROM MEXICO

Forty-six accessions of G. hirsutum and two of G. barbadense were exam ined for resistance to Meloidogyne incognita race 3 and Rotylenchulus reniformis in environmental growth chamber experiments, with the objec tive of finding new sources of resistance. Only the G. barbadense acce ssions, TX-1347 and TX-1348, supported significantly less reproduction by R. reniformis than the susceptible control, Deltapine 16 (USDA acc ession SA-1186). However, they were highly susceptible to M. incognita race 3. The G. hirsutum accessions TX-1174, TX-1440, TX-2076, TX-2079 , and TK2107 had levels of resistance to M. those of Clevewilt 6 and W ild Mexican Jack Jones, which are the primary sources of resistance to M. incognita race 3 in the most resistant breeding lines. No accessio n was as resistant as the highly resistant line Auburn 623 RNR (SA-149 2). Resistant accessions were from the Mexican coastal states of Campe che, Quintana Roo, Tabasco, Veracruz, and Yucatan. Populations of R. r eniformis from Alabama, Mississippi, Louisiana, and Texas, and of M. i ncognita race 3 from Mississippi, Texas, and California, had similar r eproductive rates on resistant genotypes. Thus, new sources of resista nce to M. incognita race 3 but not to R. reniformis were identified in wild accessions of G. hirsutum from southern Mexico.