Prevalence of fusarium wilt (Fusarium oxysporum f.sp. pisi) in pea fields, race detection and reactions of some pea genotypes

In this thesis study, the presence of F. oxysporum was determined in plants showing root rot symptoms in arbitrarily selected pea fields of Bursa, İzmir, Aydın and Afyonkarahisar provinces during the 2020-2021 vegetation period, the pathogen was identified using classical and molecular methods, the pathogenicities of the isolates were tested and the races represented by the isolates were assessed. In addition, the reactions of several pea genotypes to the most common race were studied. In the study, 548 Fusarium sp. isolates were isolated from the roots and stems infected plant samples from the pea fields. Both classical and molecular methods verified that 33,39% of these isolates were F. oxysporum. Pathogenicity experiments with 183 F. oxysporum isolates in pots under controlled conditions revealed that the isolates caused varying levels of disease severity and stem lesions of different sizes. When 50 Fusarium oxysporum f.sp. pisi isolates chosen using both criteria were inoculated to the genotypes in the race differentiatial set, 40% of the isolates represented race 6, followed by race 2 with 34%. The percentages of isolates representing race 1 and race 5 were 6% and 20%, respectively. The reactions of some pea genotypes were tested using two isolates that caused the highest disease severity and lesion size, representing race 6, which was determined to be the most prevalent race. As a result of the clustering analysis using both isolates and evaluation criteria, 9 genotypes (078PS098, 110PS097, 121PS097, 22-B-0013, 22-B-0049, 22-B-0085, Boogie, Esprit, Senador) were included in the same cluster with WSU 31, which showed high resistance against race 6. It is highly beneficial to take these genotypes into consideration in studies on developing resistant cultivars in pea breeding. The existence of races of the pathogen and the reactions of pea genotypes against the prevalent race in Turkey have been determined for the first time.