DETERMINATION OF REACTIONS OF SOME UPLAND COTTON VARIETIES (GOSSYPIUM HIRSUTUM L.) AGAINST VERTICILLIUM DAHLIAE KLEB

Verticillium wilt (Verticillium dahliae Kleb.) is a major wilt pathogen impacting cotton farming in Turkey. The most efficient and cost-effective method of controlling the disease is the use of resistant cotton varieties. The aim of the study was to determine the reactions of new upland cotton varieties (G. hirsutum L.) in Turkey against the defoliating and non-defoliating pathotypes of V. dahliae Kleb. randomized plot design with five replications was set up in the growth chamber conditions. A total of twenty upland cotton varieties were used resistant-control Giza 75, tolerant-control Carmen and susceptible-control Acala SJ2 varieties. Varieties were significant at (P≤0.05) probability level for disease severity values in pot trial. Disease severity values of the varieties were determined higher in PHCVd47 isolate (defoliating pathotype) than PHCVd3 isolate (non-defoliating pathotype). None of the upland cotton varieties were found resistant in the experiment. Using PHCVd3 and PHCVd47 isolates of V. dahliae, resistant-control Giza 75 variety (0.34-0.96) had the lowest disease severity and followed by tolerant-control Carmen variety (1.52), Harem 1 (1.54), Efe (1.56), Harem 2 (1.56), May 455 (1.58) and Lima (1.58) varieties in PHCVd3 isolate; tolerant-control Carmen variety (1.96), Harem 1 (2.00), Lima (2.04), Harem 2 (2.04) and Efe (2.04) varieties in PHCVd47 isolate. The highest disease severity values against both pathotypes were determined in the susceptiblecontrol Acala SJ2 variety (3.20-4.00).