Description

Abstract: North Carolina peanut growers have seen an increase in the amount of tomato spotted wilt virus (TSWV)

over the past five years. TSWV is transmitted by thrips as they feed on the peanuts. Both in furrow and

foliar insecticides are quite efficacious in controlling thrips, but often have only a limited impact on the

incidence of the disease since the virus may be transmitted to peanut before the thrips die. There are no

known controls measures for TSWV, but several cultural practices are available to help reduce the incidence

of the virus. Research in NC and VA has looked at using multiple applications of foliar insecticides as an

additional approach to reduce the amount of TSWV. Field studies were conducted in 2003 and 2004 in Bertie County, NC and Suffolk, VA. Plots were 2 rows wide (1.8 m) and 40 feet long (12.2 m). VA98R peanuts were planted in Bertie County, NC on 9 May in 2003 and 10 May in 2004. VA98R peanuts were also planted in Suffolk, VA on 7 May in both 2003 and 2004. Plots were established using Temik 15G at 1.0

lb ai/A in-furrow and Thimet 20G at 0.4 lb ai/A in-furrow. Plots were treated with acephate 97S at 0.36 lb

ai/A at 2, 4, and 6 weeks after planting. Thrips damage ratings were taken prior to each foliar application.

Results indicate no significant difference between the at-plant, in-furrow treatments versus plots treated with

multiple applications of acephate in reducing the number of thrips. TSWV ratings were also taken during the

growing season and at harvest and these results indicate no significant reduction in the amount of TSWV

with multiple acephate foliar sprays. There was no yield difference between the standard in-furrow treatments and those treated with multiple foliar sprays. Management of TSWV remains focused on options

such as variety selection, planting date, plant population, insecticide selection, and tillage practices rather

than multiple insecticide applications. All of these production practices play a vital role in minimizing the

amount TSWV in peanuts and multiple insecticide applications increase cost of production with no documented benefits.