Identifying Germplasm with Resistance to Fusarium Oxysporum f. Sp. Vasinfectum

Fusarium oxysporum f. sp. vasinfectum (Fov) is one of the most important fungal pathogens of cotton. The Fusarium races found in the Southeastern cotton belt are typically associated with plant parasitic nematodes. Significant yield loss can occur in some fields every year resulting in prominent monetary losses for the grower. Symptoms of FOV can range from chlorosis or necrosis of leaves, wilting, stunting, plant death, and poor fruit retention. Vascular discoloration is often used as the key symptom to indicate the pathogen has made significant infection. No acceptable chemical management options are available for control of this pathogen. Controlling nematode populations can sometimes inhibit infection, as nematode presence can influence disease progression made by FOV. Nevertheless, indicating genetic resistance in germplasm is ultimately important in managing fusarium wilt of cotton. In 2018, 430 lines were evaluated for resistance to FOV by planting into a previously known location where FOV was present. Evaluation of disease severity and vascular discoloration determined 29 lines to exhibit a high level of resistance to FOV, while 4 lines were observed to have essentially no vascular staining as well as exhibiting high resistance. On June 24th, 2019, in the same location, the second screening evaluation was planted to validate and conclude results from the previous year. Six replications of 33 different lines were placed in the study. These germplasm lines consisted of some of the most resistant that where identified in 2018 as well as other lines with varying levels of resistance. From this study we can conclude that these lines will be very useful in breeding germplasm with a high level of resistance to FOV.