ROLE OF WARM SEASON WEEDS AS HOSTS OF TOMATO SPOTTED WILT VIRUS AND THRIPS VECTORS IN VIRUS EPIDEMIOLOGY IN THE SOUTHEASTERN COASTAL PLAIN.

Authors: Johnson, Wiley - Carroll; TODD, J - UNIVERSITY OF GEORGIA; CULBREATH, A - UNIVERSITY OF GEORGIA; MULLINIX JR, B - UNIVERSITY OF GEORGIA

Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/8/1996
Publication Date: N/A
Citation: N/A

Interpretive Summary: Field studies were conducted from 1990 through 1992 to determine the incidence of tomato spotted wilt virus (TSWV) and population dynamics of thrips on seven warm season weeds and three crops. Weeds were sicklepod, coffee senna, smallflower morningglory, pitted morningglory, prickly sida, Florida beggarweed, and common cocklebur. Crops were peanut, tobacco, and bell pepper. All of the weeds were native to the region and all crops wer commercially produced in the vicinity of the test site. Most of the weeds were closely related to species identified as hosts of TSWV. Virus was not consistently detected in any of the weed species throughout the study, while TSWV incidence in all crops increased at a linear rate throughout the growing season. Order of TSWV incidence in crops was peanut>tobacco>bell pepper. Generally, thrips species diversity differed among weeds and crops. The most common vector of TSWV in the southeastern coastal plain is tobacco othrips, which was rarely found on weeds in our study, but was numerous on peanut. While these weeds were susceptible to TSWV, they were not preferred hosts for vectors of the virus. TSWV in weeds is likely due to random feeding by the vector. Vectors of TSWV are attracted to susceptible crops, especially peanut. It is unlikely that these warm season weeds contribute to the epidemiology of TSWV.

Technical Abstract: Field studies were conducted from 1990 through 1992 to determine the incidence of tomato spotted wilt virus (TSWV) and population dynamics of thrips on seven warm season weeds and three crops planted in microplots. Weeds were sicklepod [Senna obtusifolia (L.) Irwin and Barneby], coffee senna (Cassia occidentalis L.), smallflower morningglory [Jacquemontia tamnifolia (L.) Griseb.], pitted morningglory (Ipomoea lacunosa L.) prickl sida (Sida spinosa L.), Florida beggarweed [Desmodium tortuosum (Sw.) DC.], and common cocklebur (Xanthium strumarium L.). Crops were peanut (Arachis hypogaea L.), tobacco (Nicotiana tabacum L.), and bell pepper (Capsicum frutescens L.). All of the weeds were endemic to the region and all crops were commercially produced in the vicinity of the test site. Most of the weeds were closely related to species identified as hosts of TSWV. Virus was not consistently detected in any of the weed species throughout the study, while TSWV incidence in all crops increased at a linear rate throughout the growing season. Order of TSWV incidence in crops was peanut >tobacco>bell pepper. Generally, thrips species diversity differed among weeds and crops. The most common vector of TSWV in the southeastern coastal plain is Frankliniella fusca (Hinds) which was rarely found on weeds in our study, but was numerous on peanut. While these weeds were susceptible to TSWV, they were not preferred hosts for thrips vectors of the virus. TSWV in weeds is likely due to random feeding by the vector. Thrips vectors are attracted to susceptible crops, especially peanut. It is unlikely that these warm-season weeds contribute to the epidemiology of TSWV.