A number of growers have turned to backpack or tractor-drawn flamers to perform weed management tasks on the farm. Flamers are propane fueled and are used to pass heat quickly over small weeds. Weeds are killed not so much by being burned as "boiled" - water in cells boils and bursts the cells as the flame touches the leaves. Weeds begin to wilt and die within a few minutes after flaming.
Backpack units can be constructed from parts purchased by the grower or purchased completely assembled for slightly more than $100. Backpack flamers consist of a propane tank which is carried in a backpack, a wand and hose to carry the fuel, and a shielded torch. Weight of the entire unit, including a full tank of propane, is around 45 lbs. These units are best for small jobs around the farm killing weeds in drive rows, wheel marks, or in small areas missed with herbicides or cultivators. The advantage of this type of unit is that it is quick and easy to use.
Tractor-drawn flamers must be custom-built from parts purchased from specialty manufacturers. Propane companies will occasionally give assistance to growers assembling flamers. Tractor-drawn flamers are most often used for "stale seedbed" weed control - the flame is passed over small weeds which have emerged in a fully-prepared bed. The bed can then be planted. Weeds will still emerge, but in small numbers. Alternatively, the crop can be planted and the flamer can be used just before crops emerge. Some growers will also flame over the top of young corn and onion plants.
The main disadvantage of flamers is that they do not kill grasses, particularly crabgrass, very well. If you do decide to use a flamer on grasses, try driving slower or flaming with a little more heat and wait until the seedlings are in the two-to-four leaf stage. In small grass seedlings, the growing point is often below the soil or protected within the plant's stem. Waiting until this growing point has emerged will give you better kill.
A video on weed management tools, produced by UMass and University of Vermont (UVM) Extension, features three farmers discussing backpack and tractor-drawn flamers. The video also discusses a number of types of cultivation tools which may be used on vegetable farms. It can be purchased for $10.00 from Extension Publications at UMass or from UVM at: The Center for Sustainable Agriculture at UVM, 590 Main Street, Burlington, VT 05405-0059.
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