Skip to main content
link to fruits section
->Home > publications > grapeman

Grape IPM in the Northeast

Economics of Under-the-trellis Weed Management

Research conducted by staff at the Lake Erie Regional Center for Grape Extension and Research, Fredonia, New York, has shown a marked response to good weed control versus none under the trellis. The response on Concord included nearly double pruning weights and up to a 67 percent increase in yield. A study on Delaware showed a reduction in yield of 20 to 30 percent (1 ton/A) due to competition from plantain in the unsprayed and Karmex treatments.

Costs and returns of various levels of under-the-trellis weed management are illustrated below. First, the most dramatic example: no weed control versus a high level of control. This example is meant to prove a point: growers can afford a high-cost, under-the-trellis weed management program if needed.

NO WEED CONTROL

HIGH LEVEL OF CONTROL

Costs

Returns

Costs

Returns

0

0

Solicam

$27.00

3 tons ($170/ton) = $510

 

 

Princep

2.90

 

 

Roundup + Adjuvant

11.50

4.5 tons base yield X 1.67
(67 percent increase in yield)
= 3-ton increase

 

 

Equipment

5.00

 

 

Labor 1.2 hrs.

9.60

 

 

Total

$56.00

 

Benefit/Cost Ratio = $510/$56 = $9.11

This means that growers will get back over $9 for every $1 spent on this high-cost weed control program. Another way to look at this is that a grower using this weed control program has obtained an 811 percent return on his investment!

Competition from plantain under the trellis can cause a one-ton per acre crop loss. Diuron (Karmex) is the most widely used preemergence herbicide, but it doesn't control plantain. Simazine (Princep) does a good job controlling broadleaf weeds such as plantain. Using both herbicides in a tank mix can be very cost effective because only one application is needed, and most weed species are controlled. Benefit/cost ratios of a single Karmex application and a tank mix of Karmex and Princep are compared in the table below.

SINGLE KARMEX APPLICATION

TANK MIX KARMEX AND PRINCEP
(FULL RATES)

Costs

Returns

Costs

Returns

Karmex

$6.13

12.5% increase in yield.  Use 4.5 ton base yield.  4.5 tons X 0.125 = 0.5625 X $170/ton = $95.63

Princep

 $5.80

1-ton increase. 1 ton X $170 = $170

Equipment

$2.50

Labor

$5.60

Total

$14.23

Benefit/Cost Ratio $95.63/$14.23 = $6.72

Benefit/CostRatio $170/$5.80 = $29.31

The single Karmex treatment is worthwhile, but not as cost effective as the "deluxe" weed management plan in our first example. Adding Princep gave us the highest benefit/cost ratio. For every dollar spent on Princep, a grower would receive over $29 back! Adding Princep raises the overall benefit/cost ratio to $13.26 [($95.63 +$170)/($14.23 +$5.80) = $265.63/$20.03 or 13.26], which is higher than that of the deluxe weed management plan. For good reason, a tank mix of diuron and simazine is the industry standard preemergence weed management strategy.

Author: Barry Shaffer