Herbicides

Glyphosate

On all Pacific Northwest grapes, glyphosate was applied to 29,674 acres (23,434 base acres) for control of annual and perennial weeds. This included 12,669 acres (10,991 base acres) of juice grapes, 245 acres (90 base acres) of Idaho wine grapes, 6,645 acres (4,968 base acres) of Oregon wine grapes and 9,779 acres (6,949 base acres) of Washington wine grapes.

If glyphosate were unavailable, paraquat applications would replace 70% of the acre treatments of glyphosate, and glufosinate would replace 10% of the acre treatments.

Glufosinate is a nontranslocated herbicide similar to paraquat, but is not a restricted-use pesticide. Relative use of glufosinate would probably increase as growers become more familiar with it.

Paraquat and glufosinate would be imperfect substitutes for glyphosate, because they do not kill perennial weeds. Also, they are most effective under warm temperature conditions in the summer, while glyphosate is normally applied in the spring (before budbreak) and fall. Acres treated with paraquat and glufosinate would suffer a slight yield loss (1%) due to increased weed competition. Two applications of paraquat or glufosinate would be needed to replace one application of glyphosate. Mechanical cultivation would replace 20% of the acre treatments of glyphosate. Growers would need to cultivate six times per season to replace glyphosate. Because cultivation is difficult between vines, a 1% yield loss would occur on these acres due to increased weed competition. The overall cost (replacement compounds, increased applications, and yield loss) of replacing glyphosate with paraquat, glufosinate, and mechanical cultivation would be $1.89 million ($80 per base acre) on all Pacific Northwest grapes. Cost would be $976,000 ($89 per base acre) on juice grapes, $34,000 ($65 per base acre) on Idaho wine grapes, and $540,000 ($78 per base acre) on Washington wine grapes. See also Table 13.

Table 13. Economic assessment for glyphosate on Pacific Northwest wine and juice grapes.
Active ingredient	Target pest	Acres treated	Base acres	Rate lb ai/A	Treatments per year	Cost/A/ application	Alternatives	Rate lb ai/A	Cost/A/ application1	Æ2 Control costs (1000$)	ÆYield %	Æ Yield ($)	Total impact3 (1000$)	Impact/A4 ($)
Idaho wine grapes
glyphosate	annual, perennial weeds	581	526	1.0	2.7	$13.75	paraquat glufosinate cultivation	1.25 2.00 6x	$18.00 24.38 8.50	25	1	9	34	65
Oregon wine grapes
glyphosate	annual, perennial weeds	6,645	4,968	1.0	1.3	$13.50	paraquat glufosinate cultivation	1.25 2.00 6 x	$18.69 28.88 8.50	213	1	122	335	67
Washington wine grapes
glyphosate	annual, perennial weeds	9,779	6,949	1.0	1.4	$12.91	paraquat glufosinate cultivation	1.25 2.00 6x	$19.47 32.50 8.50	294	1	246	540	78
Juice grapes		12,669	10,991	1.0	1.2	$12.91	paraquat glufosinate cultivation	1.25 2.00 6 x	$19.47 32.50 8.50	763	1	213	976	89
Pacific Northwest totals		29,674	23,434		1.3					1,295	1	590	1,885	80
1Costs shown are for the pesticides only. Labor and equipment costs are about $6 per acre for each application. 2 Æ is a symbol that means "change in." 3Total impact is total cost to the growers, figured by adding Æ control costs and monetary Æ yield. A positive number is the cost to the grower. A negative number indicates a positive impact to growers. 4Total impact per base acre is the change in cost per acre to acres that have the pest problem and require use of the current pesticide."

Oryzalin

On all Pacific Northwest grapes, oryzalin was applied to 8,746 acres (8,731 base acres) in the spring and fall mainly for control of annual grasses (it also controls some species of annual broadleaves). This included 6,023 acres (6,023 base acres) on juice grapes and 2,172 acres (2,157 base acres) on Washington wine grapes.

If oryzalin were unavailable, glyphosate and mechanical cultivation would each replace 20% of the acre treatments of oryzalin. Simazine would replace 15% of the acre treatments; paraquat, napropamide, and diuron would each replace 10% of the acre treatments; and trifluralin, norflurazon, and pronamide would each replace 5% of the acre treatments.

Acres treated with glyphosate, paraquat, or mechanical cultivation would suffer a slight decrease in yield (1%) due to increased weed competition. Simazine, diuron, and norflurazon tend to leach, so they might cause phytotoxicity in some vineyards, leading to a 5% yield loss. This loss would decrease over time as growers learn on which soils they can and cannot apply the more leachable herbicides.

With three exceptions, all the alternatives would need to be applied only once to replace one application of oryzalin. Exceptions include glyphosate, which would need to be applied twice per season, paraquat, which would need to be applied three times per season, and mechanical cultivation, which would be required six times per season. The overall cost (replacement compounds, increased applications, and yield loss) of replacing oryzalin with glyphosate, mechanical cultivation, simazine, paraquat, napropamide, diuron, trifluralin, norflurazon, and pronamide would be $2,03 million $233 per base acre) on all Pacific Northwest grapes. Cost would be $578,000 ($96 per base acre) on juice grapes, and $1.45 million ($672 per base acre) on Washington wine grapes. See also Table 14.

Table 14. Economic assessment for oryzalin on Pacific Northwest wine and juice grapes.
Active ingredient	Target pest	Acres treated	Base acres	Rate lb ai/A	Treatments per year	Cost/A/ application	Alternatives	Rate lb ai/A	Cost/A/ application1	Æ2 Control costs (1000$)	ÆYield %	Æ Yield ($)	Total impact3 (1000$)	Impact/A4 ($)
Washington wine grapes
oryzalin	annual weeds	2172	2157	2.0	1	$40.37	diuron norflurazon glyphosate cultivation napropamide paraquat pronamide trifluralin	2.40 2.36 1.00 6 x 2.0 1.25 2.50 1.50	$19.20 55.49 12.91 8.50 62.50 19.47 121.50 12.37	1,298	0-5	152	1,450	672
Juice grapes
oryzalin	annual weeds	6023	6023	2.0	1	$40.37	diuron norflurazon glyphosate cultivation napropamide paraquat pronamide trifluralin	2.40 2.36 1.00 6 x 2.0 1.25 2.50 1.50	$19.20 55.49 12.91 8.50 62.50 19.47 121.50 12.37	345	0-5	233	578	96
Pacific Northwest totals	annual weeds	8746	8731		1					1,645	0-5	385	2,030	233
1Costs shown are for the pesticides only. Labor and equipment costs are about $6 per acre for each application. 2 Æ is a symbol that means "change in." 3Total impact is total cost to the growers, figured by adding Æ control costs and monetary Æ yield. A positive number is the cost to the grower. A negative number indicates a positive impact to growers. 4Total impact per base acre is the change in cost per acre to acres that have the pest problem and require use of the current pesticide."

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