Causal Agent: (unknown, suspected to be a bacterium)
This disease is found mainly in the Cross Timbers vegetation zone in central Texas and Oklahoma, but it has been found outside of this area, specifically, in Anderson county in east Texas. The symptoms appear two weeks before harvest. There is a general yellowing of leaves and terminal leaves of the vine are turned up (Image 1). Not all plants within a field initially show symptoms (Image 2). Plants eventually die. These symptoms are not diagnostic for this disease. The distinctive symptom of yellow vine is a honey-brown discoloration of the phloem in lower crown and primary root of plants (Image 3). The cause has not been conclusively determined, but a phloem-limited bacterium has been consistently associated with diseased plants and a deltacephaline leafhopper is thought to transmit this bacterium. Other susceptible cucurbits include squash, pumpkin, and cantaloupe. There are no control measures available for this disease, but resistance in triploid seedless watermelon (e.g. ‘Tri-X 313’) has been identified.