Crop and Pest Management Guidelines

A Cornell Cooperative Extension Publication
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6.3 Effective Use of Herbicides

Most herbicides are degraded in the soil by microbes. Repeated use of the same herbicides, or those with similar chemistry, can lead to a buildup of tolerant weeds, development of resistant biotypes, and more rapid microbial decomposition that can reduce the length of time soil active herbicides are effective. Although herbicide options in vineyards are somewhat limited, weed management programs should not rely on the repeated use of the same herbicide modes of action or weeds will develop resistance. See Table 8.1 for a listing of herbicide mode of action group numbers from the Weed Science Society of America.

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Table 6.3.1 Acres of vineyard sprayed at different row and spray band widths to equal one acre of land surface sprayed.

Width of Spray Band

Distance between rows

8 ft

9 ft

10 ft

30 inches

3.2

3.6

4.0

36 inches

2.7

3.0

3.3

42 inches

2.3

2.6

2.9

48 inches

2.0

2.3

2.5

Example 1: When a 36-inch (3 foot) undertrellis spray band is treated and vineyard rows are 9 feet apart, 3 acres of vineyard are equivalent to 1 sprayed acre.

3' treated band ÷ 9' row width = 0.33 x 3 acres of vineyard
= 1 acre surface sprayed.

In Example 1, a 60-acre vineyard block would require sufficient herbicide to treat 20 acres of land surface:

60-acre vineyard block ÷ 3 acres = 20 acres of land surface treated.

If you choose to apply Acme Weed Killer at a rate of 4 lb product per acre surface sprayed, this 60-acre vineyard block would require 80 lb of Acme Weed Killer.

4-lb product per acre surface sprayed x 20 acres of land surface treated
= 80 lb of Acme Weed Killer.

Example 2: When a 42-inch (3.5-foot) undertrellis spray band is treated and vineyard rows are 9 feet apart, then 2.6 acres of vineyard are equivalent to 1 sprayed acre.

3.5' treated band ÷ 9' row width = 0.39 x 2.6 acres of vineyard
= 1 acre surface sprayed.

In Example 2, a 60-acre vineyard block would require sufficient herbicide to treat 23 acres of land surface:

60-acre vineyard block ÷ 2.6 acres = 23 acres of land surface treated.

If you choose to apply Acme Weed Killer at a rate of 4 lb product per acre surface sprayed, this 60-acre vineyard block would require 92 lb of Acme Weed Killer.

4-lb product per acre surface sprayed x 23 acres of land surface treated
= 92 lb of Acme Weed Killer.

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