On Idaho wine grapes, carbaryl was applied annually to an average 479 acres (430 base acres) in the spring and summer for control of leafhopper. If carbaryl were unavailable, dimethoate would be used on 85% of the base acres currently treated with carbaryl, and imidacloprid would be used on the remaining 15% of the acres. One application of any of the alternatives would replace one application of carbaryl, but where carbaryl is applied more than once, one application of dimethoate or imidacloprid would suffice. No change in yield or quality would occur where any of the alternatives are used. The overall cost (replacement compounds) of replacing carbaryl with dimethoate or imidacloprid would be $1,000 ($2 per base acre).
On Washington wine grapes, carbaryl was applied annually to an average 1,701 acres (1,660 base acres) in the spring and summer for control of leafhopper and cutworm. About 70% of these treatments were primarily for leafhopper, and 30% were primarily for cutworm.
If carbaryl were unavailable, the alternatives would depend on the primary target pest. Where leafhopper is the primary target, imidacloprid applications would replace 75% of the acre treatments of carbaryl, dimethoate applications would replace 15% of the acre treatments, and applications of malathion-methoxychlor and endosulfan would each replace 5% of the acre treatments. One application of any of the alternatives would replace one application of carbaryl, but where carbaryl is applied more than once, one application of imidacloprid or dimethoate would suffice. Where cutworm is the primary target pest, chlorpyrifos applications would replace 100% of the acre treatments of carbaryl. On acres where carbaryl is applied more than once for cutworm control, one application of chlorpyrifos would suffice.
No change would occur in yield or quality where any of the alternatives are used. The overall cost (replacement compounds) of replacing carbaryl with imidacloprid, dimethoate, malathion-methoxychlor, endosulfan, and chlorpyrifos would be $65,000 ($39 per base acre).
Chlorpyrifos
On all Pacific Northwest grapes, chlorpyrifos was applied annually to an average 2,425 acres (2,387 base acres) in the spring. The primary target pests were cutworm and mealybug. Cutworm infestations occur in localized areas of vineyards, so the low usage figure does not reflect the true importance of chlorpyrifos to individual growers.
Washington growers used chlorpyrifos for several years under an emergency
exemption (Section 18). They use it now under a Special Local Need (24 c)
registration. If chlorpyrifos were unavailable, carbaryl and methomyl applications
would each replace 50% of the acre treatments of chlorpyrifos. Three applications
of carbaryl or methomyl would be needed to achieve the same control as one
application of chlorpyrifos. An estimated 5% yield loss would occur where
these alternatives replaced chlorpyrifos due to cutworm damage. The overall
cost (cost of replacement compounds, increased application costs and yield
loss) of replacing chlorpyrifos with
carbaryl and methomyl would be $2.92 million ($1,223 per base acre). See
also Table 6.
On juice grapes, chlorpyrifos was applied to an average 1,075 acres (1,073 base acres) annually in the spring. The primary target pests were cutworm and mealybug. If chlorpyrifos were unavailable, carbaryl and methomyl applications would each replace 50% of the acre treatments of chlorpyrifos. Three applications of carbaryl or methomyl would be needed to achieve the same control as one application of chlorpyrifos. An estimated 5% yield loss would occur where these alternatives replaced chlorpyrifos due to cutworm damage.
The overall cost (replacement compounds, increased application costs and yield loss) of replacing chlorpyrifos with carbaryl and methomyl would be $1.37 million ($1,277 per base acre).
On Washington wine grapes, chlorpyrifos was applied to an average 1,349 acres (1,314 base acres) annually in the spring. The primary target pests were cutworm and mealybug.
If chlorpyrifos were unavailable, carbaryl and methomyl applications would each replace 50% of the acre treatments of chlorpyrifos. Three applications of carbaryl or methomyl would be needed to achieve the same control as one application of chlorpyrifos. A 5% yield loss would occur where these alternatives replaced chlorpyrifos due to cutworm damage.
The overall cost (cost of replacement compounds, increased application costs and yield loss) of replacing chlorpyrifos with carbaryl and methomyl would be $1.55 million ($1,179 per base acre).
Endosulfan
On Washington wine grapes, endosulfan was applied annually to an average 1,851 acres (1,740 base acres) in the spring and summer for control of leafhoppers and thrips. About 80% of these treatments were primarily for leafhoppers, and 20% were primarily for thrips.
If endosulfan were unavailable, the alternatives used would depend on the primary target pest. On acres where leafhopper is the primary target, imidacloprid applications would replace 75% of the acre treatments of endosulfan, and dimethoate applications would replace 15% of the acre treatments. Carbaryl and malathion- methoxychlor applications would each replace 5% of the acre treatments. One application of imidacloprid, dimethoate or malathion-methoxychlor would replace one application of endosulfan, but where endosulfan is applied more than once for leafhopper, one application of imidacloprid or dimethoate would suffice. About 1.2 applications of carbaryl would be needed to replace one application of endosulfan.
Questions remain about the efficacy of imidacloprid on thrips; dimethoate applications would replace 100% of the acre treatments of endosulfan on acres where thrips are the primary target. Imidacloprid might be an alternative in the future if it proves to be effective against thrips. Where endosulfan is applied more than once for thrips, oneapplication of dimethoate would suffice. No change would occur in yield or quality where any of the alternatives are used. The overall cost (replacement compounds) of replacing endosulfan with imidacloprid, dimethoate, carbaryl, and malathion-methoxychlor would be $52,000 ($30 per base acre). See also Table 7.
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