Oil
On Idaho wine grapes, superior-type oil was applied to 311 acres (311 base acres) for control of mealybug, cottony maple scale, and other pests. If superior-type oil were unavailable, growers would use methomyl instead. Two applications of methomyl would be needed to replace one application of oil.
No yield loss would occur where methomyl is used, but replacement of superior oil with methomyl would result in an estimated 5% quality loss.
Because methomyl is less effective than oil on mealybug and scale, honeydew and sooty mold would be more likely to appear on harvested fruit if methomyl replaced superior oil.
The overall cost (increased applications plus quality loss) of replacing superior-type oil with methomyl would be $24,000 ($77 per base acre). See also Table 8.
Carbofuran
On juice grapes, carbofuran was applied annually to an average 181 acres (181 base acres) in early summer for control of black vine weevil. Following treatment of a vineyard with carbofuran, the black vine weevil population takes at least 5 years to build up again to economic threshold levels. Because of this, the low usage figure for carbofuran underestimates the true importance of the compound to individual growers.
No registered alternatives exist for carbofuran. If carbofuran were unavailable, the effects of the chemical not being used would be negligible for the first year. Black vine weevil populations would gradually build up in older vineyards (more than 10 years old), which comprise about 70% of total juice grape acres. Yields in these vineyards would decrease by an estimated one-sixth to one-third. Fruit quality would remain uncahnged. The overall cost (yeld loss) of losing carbofuran would be $1 million to $2 million per year ($1,105 to $2,210 per base acre). See also Table 9.
As the Washington wine industry ages, black vine weevil may eventually become a significant pest of Washington wine grapes. In at least one Washington wine grape vineyard, black vine weevil has reached economically damaging levels.
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