Evaluation of cultural practices to reduce the incidence of tomato spotted wilt virus (TSWV) in North Carolina peanut (Arachis hypogaea)

by 1979- Hurt, Christie Anne

HURT, CHRISTIE ANNE. Evaluation of Cultural Practices to Reduce the Incidence of Tomato Spotted Wilt Virus in North Carolina Peanut (Arachis hypogaea). (Under the direction of Rick L. Brandenburg.) Tomato spotted wilt virus (TSWV), a thrips-vectored tospovirus, has recently become one of the most devastating pathogens of peanut (Arachis hypogaea L.) in North Carolina. North Carolina peanut growers saw a dramatic increase in infestations of TSWV in 2000 compared with previous years. Certain cultural practices in Georgia have shown to reduce the incidence of virus, and these were evaluated to determine their effect on TSWV incidence in North Carolina. The production systems are discrete between the runner-type peanuts grown in Georgia and the virginia-type peanuts in North Carolina, thereby requiring that these practices be evaluated in the North Carolina. Treatments included plant populations, cultivars, tillage systems, planting dates, and infurrow insecticides. During the growing seasons of 2001 and 2002, treatments compared were plant populations of 7, 13, and 17 plants/m-row; cultivars Gregory, NC V-11, and Perry; conventional tillage and strip tillage; early and late planting dates; and aldicarb [Omethylcarbamoyl)oxime], acephate (O, S-Dimethyl acetylphophoramidothioate), and phorate {O, O-Diethyl S-[(ethylthio)methyl]phosphodithioate}. Research plots were scouted for thrips feeding damage, percentage of plants infected with TSWV, and estimates of severity of TSWV. Yields and market grades were recorded for research plots at harvest. High plant populations had less incidence of virus than lower plant populations, Gregory was infected with fewer infected plants than either NC V-11 or Perry, preliminarily strip tillage has had less infected plants than conventional tillage, and peanut treated with in-furrow phorate had less incidence of virus than those treated in- furrow with aldicarb. Pod yield increased as plant populations increased regardless of other treatments. The cultivar Gregory had the higher percentage of extra large kernels (%ELK) and of fancy pods (%FP) across treatments and locations.