Tomato Spotted Wilt Virus: TSWV of Peanut: Factors
TSWV of Peanut
Insecticide Use
Control of thrips with insectides typically has not resulted in control of spotted wilt. Use of phorate insecticide in-furrow at planting has been a major exception, and is an important part of an integrated spotted wilt management program.
At-Plant Insecticide Use
Phorate InsecticideAlthough TSWV is vectored by thrips, the use of insecticides to control thrips in general has been ineffective for suppressing spotted wilt. While providing good control of thrips damage to plants, insecticide applications have been ineffective in preventing plant feeding and inoculation by viruliferous thrips that have migrated from areas outside the field. Despite the overall disappointing results with insecticides, phorate has provided consistent, low-level suppression of TSWV.
The mechanism of disease suppression has no direct link with thrips control, since phorate typically offers no better control than other insecticides. Phorate is phytotoxic, and often causes marginal chlorosis and necrosis on peanut leaves (shown above). This effect on young plants may induce a host defense response, or serve in some other way to inhibit virus replication or movement. The effect of this systemic insecticide may be worthy of investigation in the future as being a potential inducer of systemic acquired resistance. Regardless of the mode of action, in-furrow application of phorate at planting provides control of thrips and a low to moderate level of suppression of spotted wilt in peanut.
At-Plant Insecticide Use
If root-knot nematodes are a problem in a field, take steps to manage them FIRST! Phorate does not provide nematode control. Do not make insecticide choices solely because of effects on spotted wilt.