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- Author or Editor: Shimat V. Joseph x
The fall armyworm, Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae), is an important pest of warm-season turfgrass species, including bermudagrass (Cynodon spp.). Bermudagrass is a popular turfgrass that is widely planted on golf courses, athletic grounds, and ornamental landscapes across the country and throughout the world. Spodoptera frugiperda infestation is often sporadic; however, when it does occur, damage can be severe. Host plant resistance against S. frugiperda can be a valuable tool for reducing or preventing the use of insecticides. Therefore, the objective of this study was to determine resistance against S. frugiperda in a few promising bermudagrasses. Fourteen experimental bermudagrass genotypes plus two control cultivars, ‘Zeon’ zoysiagrass (resistant control) and ‘TifTuf’ bermudagrass (susceptible control), were evaluated against S. frugiperda to determine host plant resistance in the laboratory. The results showed that the resistant control, ‘Zeon’ zoysiagrass, was more resistant than the other genotypes to S. frugiperda larvae. To determine the response of the experimental lines to S. frugiperda as compared with that of the controls, three indices were developed based on survival, development, and overall susceptibility. According to the susceptibility index, ‘13-T-1032’, ‘T-822’, ‘11-T-510’, ‘12-T-192’, ‘11-T-56’, ‘09-T-31’, ‘11-T-483’, and ‘13-T-1067’ were the top-ranked bermudagrasses. Among these, the responses of ‘13-T-1032’, ‘T-822’, ‘11-T-510’, ‘11-T-56’, ‘09-T-31’, and ‘11-T-483’ were comparable to that of ‘TifTuf’, and antibiosis was the underlying mechanism of resistance. Additionally, larval length, head capsule width, and weight were negatively associated with the days of pupation and adult emergence and positively associated with pupal length, thorax width, and weight. These results will help refine future breeding and with investigations of resistance against the fall armyworm.
Commercially available cultivars of tomato Solanum lycopersicum L. were field-tested for resistance to Tomato spotted wilt virus (TSWV) over a 5-year period (from 2006 to 2010) at the Coastal Plain Experiment Station at Tifton, GA. Selected cultivars were transplanted each year into staked, black plastic mulch beds on drip irrigation in the spring of each year when the incidence of Tomato spotted wilt (TSW) tended to be highest. The presence of TSWV was confirmed by double antibody sandwich (DAS) enzyme-linked immunosorbent assay (ELISA). Also, the presence of thrips vectors was monitored using beat-cup sampling of foliage and flower samples. Tomato cultivars with the Sw-5 resistance gene provided high levels of control of TSW expression over all 5 years. However, these genotypes had no apparent effect on the thrips vectors, western flower thrips, Frankliniella occidentalis (Pergande), and tobacco thrips, Frankliniella fusca (Hinds), that transmit TSWV. Overall, the top 15 commercial tomato cultivars based on consistent TSW resistance and ranked from highest marketable fruit yield were: ‘Tycoon’, ‘Tous 91’, ‘Talladega’, ‘Red Defender’, ‘BHN 444’, ‘Nico’, ‘Carson’, ‘BHN 685 (Roma type)’, ‘Picus’, ‘Redline’, ‘Tribute’, ‘Quincy’, ‘BHN 640’, ‘BHN 602’, and ‘Top Gun’.