1. Develop sensitive and reliable serological and molecular based pathogen detection methods for the emerging and endemic viral diseases of vegetable crops. ? Sub-Objective 1.1. Develop a traceable clone of Cucumber green mottle mosaic virus to study the mechanism of seed transmission and to improve seed health assay on watermelon seeds. ? Sub-Objective 1.2. Develop traceable clones of pospiviroids (Tomato planta macho viroid and Potato spindle tuber viroid) that can be used to study the mechanism of seed transmission and to develop a reliable seed health assay on tomato. 2. Apply RNAi technology to reduce whitefly vector transmission of plant viruses, including Tomato yellow leaf curl virus in tomato and other viruses in cassava. ? Sub-Objective 2.1. Develop dsRNA constructs to evaluate their RNAi effect on whitefly (Bemisia tabaci) as a sprayable insecticide. ? Sub-Objective 2.2. Develop transgenic tomato plants with RNAi effect against whitefly as a proof of concept to control whitefly-transmitted viruses. 3. Develop molecular markers associated with host resistance to viral diseases in vegetables and Fusarium wilt on watermelon. ? Sub-Objective 3.1. Genotyping-by-sequencing to identify SNPs in association with disease resistance breaking of tomato by the emerging Tomato mottle mosaic virus. ? Sub-Objective 3.2 Develop molecular markers associated with fusarium wilt resistance in watermelon. 4. Develop environmentally sustainable disease management strategies against diseases of vegetable crops. ? Sub-Objective 4.1. Develop bacterial blight resistant germplasm in Brassica rapa. ? Sub-Objective 4.2. Develop an anaerobic soil disinfestation system effective in reduction or elimination of Ralstonia solanacearum in solanaceous crops.