Field evaluation of two rootstocks to manage Fusarium wilt in watermelon

摘要

The experiment was conducted in a field of Yonges loamy fine soil at Clemson University's Coastal Research and Education Center, Charleston, South Carolina. Fusarium oxysporum f.sp. niveum (FON) had been previously documented in the field. A watermelon cultivar susceptible to Fusarium wilt was planted in the field in the summer of 2012, and the field was seeded to rye (60 lb/A) on 18 Oct 2012. The experiment was conducted as a Latin square with six replications and six treatments. The treatments consisted of the seedless watermelon variety 'Tri-X 313' grafted onto three rootstocks; watermelon cultivar 'Fascination', resistant to FON race 1; non-grafted 'Tri-X 313' with Paladin, a dimethyl disulfide fumigant; and a non-grafted, non-fumigated controltreatment. The rye cover crop was mowed and disked on 14 Jan 2013. Fertilizer (15-0-15) was added at a rate of 500 lb/A and disked-in on 20 Mar. Sandea (1 oz/A) was sprayed on all treatments on 20 Mar. Paladin, dimethyl disulfide + chloropicrin (79:21),was injected at a rate of 50 gal/A on one treatment before all treatments were bedded, pressed, and covered with virtually impermeable film (VIF) on 21 Mar. Watermelons were seeded in the greenhouse on 28 Feb. Two rootstocks, 'Emphasis' (Bottle gourd, Lagenaria siceraria) and 'Strong Tosa''(Cucurbita maxima x C. moschata),were seeded on 4 and 6 Mar, respectively. On 25 Mar 'Tri-X 313' scions were grafted onto 'Emphasis', 'Strong Tosa', and 'Tri-X 313' rootstocks using the single-cotyledon grafting method. Plants were transplanted on 16 Apr and were spaced 48 in. apart within rows with pollenizers ('SP-6') transplanted between every fourth plant. Each plot was 47 ft long with 3-ft-wide beds on 6-ft centers. One application each of Actara (3 oz/A), Venom(4 oz/A), and Agrimek (3.5 fl oz/A), and three applications of Brigade (6.4 fl oz/A) were used to manage insects. Foliar diseases were managed with one application each of Monsoon (8 fl oz/A), Inspire Super (16 fl oz/A), Previcur Flex (1.2 pt/A), Dithane Rainshield (2.4 qt/A), Presidio (4 fl oz/A), Pristine (18.5 fl oz/A), and two applications of Bravo (2 pt/A). Additionally, 32 oz/A of Ridomil was applied through the drip tape shortly after transplanting to manage oomycetes in the soil. Plants with Fusarium wilt symptoms were assessed weekly between 1 May and 28 Jun. Marketable fruit was harvested and weighed on 28 Jun and 3, 10, and 17 Jul. Data were analyzed using PROC GLM in SAS statistical software package version 9.3.