Flame cultivation is a nonchemical method of weed control where target plants are damaged or eradicated by brief exposure to high temperature. The utility of flame cultivation on perennial weeds in cranberry (Vaccinium macrocarpon) systems is currently being investigated to determine if it could be a useful practice for cranberry weed control. Our work is focused on evaluating the use of flame cultivation as a spot-treatment for control of dewberry (Rubus spp.), sawbrier (Smilax glauca), dodder (Cuscuta gronovii) and rushes (Juncus spp.). In addition to collecting efficacy data, we wanted to determine and compare the cost of using hand-held flame cultivators (FC) to the conventional management of using glyphosate wiper applicators. Three hand-held FC were considered in this comparison: infrared (IR), infrared with spike (IRS), and open flame, (OF).

The hourly costs of operating any of the 3 torches tested was comparable to the hourly cost of weed wiping (i.e., using a hockey stick applicator) with glyphosate. Labor costs were assumed to be $12 per hour and the impact of weed patchiness across the farm was assumed to affect each weed control method equally. The equipment costs of the hand-held FCs are very similar to one another; the weed wiper is much less expensive ($200 to $250 for the torches compared to $40 for the weed wiper). The cost of fuel expended for 1 hr of torch operation was comparable for the three FCs but the cost of the herbicide that would be used in 1 hr of wiper application was $7 to $8 more than the propane to run the FCs. 

A square meter was selected as the base unit area by which to calculate the costs associated for the treated area for all management options. Actual management costs would most likely vary due to factors such as operator skill, patchiness of the weeds (i.e., how far would one need to walk between applying a treatment), how much fuel or herbicide a person might use on any particular weed or location, etc. Any deviations from assumptions could be inserted into our formulas to recalculate the actual cost to a grower on their particular farm.

            As a spot-application on cranberry farms, use of the OF is comparable economically to the standard weed management practice of spot-applications of weed wiping with a hockey stick applicator. Our research showed a dose response (increased control with increased duration), so we would likely recommend growers use at least the medium (6 sec), if not the high (9 sec) duration for weed management with the OF hand-held applicator. At the medium OF duration, costs are equivalent with glyphosate applications ($0.37 vs. $0.32 per m², respectively). Use at the high duration would still be competitive ($0.56 per m²). The IR and IRS are more expensive relative to both the OF and the wiper applicator. At the long duration for the IR flame cultivators (45 sec), the costs are 8 times higher ($2.60 per m²) than both OF at medium duration and the glyphosate wipes.

 

 

hsandler@umext.umass.edu