Developing sustainable strategies for managing watermelon diseases in southeastern United States

Authors: Kousik, Chandrasekar - Shaker

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 1/1/2019
Publication Date: 2/26/2019
Citation: Kousik, C.S. 2019. Developing sustainable strategies for managing watermelon diseases in southeastern United States. Abstracts of the National Symposium on Recent challenges and opportunities in sustainable plant health management at the 71st Annual Meeting of the Indian Phytopathological Society. February 26-28, 2019. BHU, Varanasi, India. Pp. 267

Interpretive Summary:

Technical Abstract: Watermelon is an important vegetable crop grown across the United States (U.S.) on 115,300 acres and valued at 595 million dollars. Over 50 % of the U.S. watermelons are produced in the southeastern states (FL, GA, SC, NC, and VA) where weather conditions that favor fungal and viral disease development routinely prevail. Various diseases impact watermelon production in these states including, gummy stem blight, Fusarium wilt, powdery mildew and Phytophthora fruit rot. We specifically work on developing integrated pest management (IPM) strategies against three major diseases of watermelon including: Phytophthora fruit rot (PFR, Phytophthora capsici), Powdery mildew (PM, Podosphaera xanthii), and Watermelon vine decline (WVD, whitefly transmitted Squash Vein Yellowing Virus). Several (>10) disease resistant (PFR, PM, or WVD) germplasm lines have been developed and released for use by the seed industry in their breeding programs. Similarly, Environmental Protection Agency reduced risk fungicides have been identified for managing PFR. In addition, mustard cover crop was shown to reduce the incidence of PFR. Bottle gourd and Cucurbita disease resistant (PM, crown rot) rootstocks are also being developed for watermelon grafting as a part of the IPM strategy. Some of the PM resistant bottle gourd rootstocks were shown to provide significant level of resistance to grafted susceptible watermelon scions. The neuro-hormone melatonin was found to be a key player in inducing resistance in the grafted watermelon scion and it also appeared to play an important role in plant defense signaling. A PM susceptible watermelon plant transformed with the melatonin biosynthetic gene SNAT (Seotonin N-acetyltransferease), displayed tolerance to PM compared to non-transformed plants. Melatonin sprays also helped suppress PFR development. A combination of silver plastic mulch bed covers and insecticide sprays helped reduce WVD. During the past decade we have developed and provided various IPM strategies to watermelon growers to help manage these important diseases.