Department of Plant and Environmental Sciences, Clemson University, Coastal Research and Education Center, Charleston, SC 29414.
U.S. Department of Agriculture, Agricultural Research Service, U.S. Vegetable Laboratory, Charleston, SC 29414.
Plant Dis. 2020 Sep;104(9):2481-2488. doi: 10.1094/PDIS-11-19-2385-RE. Epub 2020 Jul 6.
Fusarium wilt of watermelon (), caused by the soilborne fungus f. sp. , is the most serious disease of watermelon in South Carolina and other southeastern U.S. states. Isolates of collected from field-grown plants, greenhouse-grown seedlings, and field soil between 1999 and 2018 were inoculated onto three differential watermelon cultivars to identify races. Of 197 isolates obtained from plants, 12% were nonpathogenic, 2% were race 0, 23% were race 1, and 63% were race 2. One collection of isolates from greenhouse seedlings was exclusively race 1 and the other was exclusively race 2. Seventeen of 81 soil isolates were pathogenic: five were race 1 and 12 were race 2. Reactions of PI 296341-FR, Carolina Strongback, and SP-6, cultigens with resistance to race 2, did not differ significantly among five highly virulent race 2 isolates and a standard race 2 isolate, indicating a lack of a race 3 phenotype. Forma specialis-specific primers matched phenotypic race identification for 74% of the isolates. Race-specific primers based on a secreted-in-xylem elicitor present in race 0 and 1 isolates matched phenotypic race identification for 66% of the isolates. Because a majority of the f. sp. isolates from South Carolina were race 2, integrated management practices should be used until commercial cultivars with resistance to race 2 are available.
西瓜枯萎病（），由土传真菌 f. sp. 引起，是南卡罗来纳州和美国东南部其他州西瓜最严重的病害。1999 年至 2018 年间，从田间生长的植物、温室生长的幼苗和田间土壤中采集的 分离物被接种到三个不同的西瓜品种上，以鉴定品种。从植物中获得的 197 个分离物中，12%是非致病性的，2%是品种 0，23%是品种 1，63%是品种 2。从温室幼苗中采集的一个分离物种群仅为品种 1，另一个仅为品种 2。81 个土壤分离物中有 17 个是致病性的：5 个是品种 1，12 个是品种 2。对 PI 296341-FR、卡罗莱纳强背和 SP-6 的 17 个分离物进行接种，这三种栽培品种对品种 2 具有抗性，它们与一个标准的品种 2 分离物之间的反应没有显著差异，表明缺乏品种 3 表型。针对特殊形式的特异性引物与 74%的分离物的表型品种鉴定相匹配。基于存在于品种 0 和 1 分离物中的木质部分泌诱导子的品种特异性引物与 66%的分离物的表型品种鉴定相匹配。由于南卡罗来纳州的 f. sp. 分离物大多数是品种 2，因此应采用综合管理措施，直到有抗品种 2 的商业品种可用。
