Insect Vectored Cucurbit Diseases

A number of cucurbit crops can be grown in the Cross Timbers area of Texas. The watermelon industry is important and will likely become even more so as the peanut production quota moves west. Growers normally plant in the early spring, hoping for a crop that matures for the 4th of July market. However, watermelon, cantaloupe and squash crops grown from central Oklahoma to north-central Texas have fallen victim to a new disease named Yellow-Vine of Cucurbits. The disease causes the plant to die just before the melons ripen. Losses can be severe, and since the disease strikes late, there is no time to replant. The USDA station at Lane, Oklahoma has been working on the disease since its appearance in the late 80's. The Stephenville program initiated last year in collaboration with the USDA. Research being conducted is focused on identification of the insect that is vectoring yellow-vine. While this insect is suspected to be a leafhopper, much work needs to be done to verify this. Once the vector is identified, then management opportunities will be identified.

Growers planting cucurbits in north-central Texas through central Oklahoma have a further problem. A market exists for later planted crops, such as pumpkin, but it is difficult to grow such a crop. Aphids, or plant-lice, are common throughout the growing season. However, as the season lengthens, more aphids become contaminated with plant viruses called potyviruses. These are borne on the aphid mouthparts and then transferred to susceptible plants. While it takes many aphids to damage a plant through feeding action, it only takes one of them contaminated with a potyvirus to infect the plant and thus ruin the yield of that plant. These viruses are so common in the fall months in our region that is almost impossible to grow a cucurbit crop. Scientists at the Stephenville Center recently received a grant from the Southern Regional Integrated Pest Management grants competition in collaboration with scientists at Oklahoma State University to work on the problem. The grant proposal is discussed in the PDF file below.