Field evaluation of triploid cultivars for resistance to Fusarium wilt of watermelon in Maryland

摘要

The experiment was conducted at the University of Maryland's Lower Eastern Shore Research and Education Center, Salisbury, MD. The field of Fort Mott loamy sand had been planted to watermelon for many years, had a high level of Fusarium oxysporum f.sp. niveum (FON). Race1 and 2 of FON had been detected in the field in previous years. The experiment was conducted as a randomized complete block design with three replications. Plots consisted of single row beds, 22 ft. long, on 7-ft centers, and coveredwith 1.25-mil black plastic mulch under which a single drip irrigation tube was placed in the center. Plastic was laid on 16 May. Each plot had 11 triploid plants. Plots were irrigated via drip tape as needed. Fertility was supplied by an application of150 lbs 20-03-18 N-P-K on 16 May. Twenty-seven triploid watermelon cultivars were evaluated. 'SP-5', which has resistance to FON race 1, was used as the pollenizer. Triploid cultivars were transplanted into the field on 20 Jun, 24 in. apart in the row.Weeds were managed with herbicide applications of Curbit, 1 qt/A plus Sinbar 3 oz/A on 22 May and Poast 1.5 pt/A plus 820 Surf, 8 fl oz/A on 9 Jul as well as hand weeding as necessary. Foliar diseases were controlled with applications of Bravo 1 qt/A 9,26 Jul and 22 Aug; Folicur 4 fl oz/A on 17 Jul; and Pristine 15 oz/A on 8 Aug. Insects were managed with Admire Pro 2 fl oz/A on 9 and 17 Jul and 26 Aug, and Warrior 3.0 fl oz/A on 26 Jul and 8 Aug and Agri-Mek 10 fl oz on 8 Aug. Fusarium wilt was evaluated as the number of plants in a plot that were wilted or dead due to FON. Wilt was assessed on 8, 16, and 24 Jul, and on 5 and 27 Aug. All fruit were weighed and counted on 13 and 27 Aug. Yield was variable because of pollinator loss following planting(data not shown). The area under the Fusarium wilt incidence progress curve (AUWPC) was calculated from wilt incidence data. Fusarium wilt incidence and was analyzed with the procedure PROC mixed in SAS. Means were separated using Fisher's protected LSDtest.