2012 Annual Report
1a.Objectives (from AD-416):
1. To develop novel sustainable programs to manage thrips and thrips vectored tomato spotted wilt virus, one of the key pest complexes of vegetable crops in the southern USA.
2. Design, implementation and demonstration of four different cover crop systems:.
1)conventional black plastic mulch;.
2)conservation tillage cover crop, with spring cash crops transplanted into overwinter leguminous cover crops;.
3)transitional cover crop, with the cash crops planted on black plastic overlaid in a cover system;.
4)beneficial insect cover crop system, designed for spatial/temporal enhancement of beneficial insects and the biotic resistance against pest thrips and the spread of tomato spotted wilt virus (TSWV) in vegetable crop systems.
1b.Approach (from AD-416):
To assess the traditional benefits of cover crops, we will compare the four cropping systems for their effects on soil characteristics and cash crop characteristics. In early March of each year, before cash crops are to be planted, soil fertility and organic matter content will be determined. Cash crop samples will be collected over the course of the growing season to determine plant nitrogen content. These data will provide information on overall soil quality and plant health and vigor in the different cropping systems. Weed pressure will be assessed by making visual estimates of weed coverage. Visual estimates of weed control will be a composite of weeds emerging through the plastic mulch or cover crop bed and weeds emerging in the row middle. Pest and beneficial insect communities will be evaluated by systematic sampling of cash crops, cover crops, and incidental weeds over time. Insect samples will be collected during the spring season from the cash crops and cover crops twice per week. Tomato spotted wilt virus (TSWV) incidence will be assessed in weekly systematic inspection of all cash crops over time. To assess whether cover crops possibly contribute to TSWV incidence, we will also monitor disease spread within the cover crops.
Research will determine the effectiveness of these four systems in terms of plant vigor, yield, vegetable quality, the traditional advantages of cover crops (including soil fertility and weed suppression), and pest pressures (thrips abundance, disease incidence, and secondary pest populations) on tomatoes, peppers and cucumbers.
Research conducted in this subordinate project relates directly to Objective 1 of the parent project in developing habitat manipulation strategies as a part of improving management of thrips and tomato spotted wilt virus.
Tomato spotted wilt virus (TSWV), a viral disease transmitted by thrips, is the most important pest problem for vegetable producers in the southeastern USA and cannot be controlled with insecticides. Therefore, scientists with USDA-ARS CMAVE and cooperators at the University of Florida have initiated studies to determine if the use of certain companion plants can help reduce thrips and tomato spotted wilt in tomatoes, peppers and cucumbers, and to increase the sustainability of producing these crops. ARS scientists and cooperators from the University of Florida established the first year of a three year trial to evaluate four different cover crop systems for enhancement of beneficial insects and biotic resistance against pest thrips and the spread of TSWV in vegetable crop systems. The cropping systems are: i) conventional black plastic mulch; ii) traditional cover crop, with spring cash crops transplanted into overwinter leguminous cover crops; iii) transitional cover crop, with the cash crops planted on black plastic overlaid in a cover system; iv) beneficial insect cover crop system. The effects of cover crop systems on soil fertility and vegetable crop vigor and yield are being determined through systematic, periodic sampling.