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Agronomic Row Crops
Hot Tips for Flame Weeding
In-Field Tips
Once you’ve got the hardware, focus on hitting weeds early. Flaming
can set back larger weeds, but zapping weeds as tiny seedlings or
before they have three or four leaves is best. Killing small weeds,
you will have more predictable success at field speeds and fuel
use competitive with mechanical or herbicide passes. For guidelines,
flaming experts say
 Don’t
burn weeds. If weeds are toasted, you’re wasting fuel.
Energy-efficient flaming will have little immediate visible effect
but will cause weeds to droop and wilt within a few hours. You
want to travel as fast as possible, using the lowest gas pressure
(hence the least amount of fuel) that kills weeds.
Timing
is everything. In stale-seedbed flaming, growers cultivate
the growing area to stimulate surface weed-seed germination, with
weed flushes controlled one or more times to deplete weedy competitors.
When weed pressure and planting schedules allow, delay the final
broadcast flaming until just before transplanting vegetable crops
or planting quick-germinating, direct-seeded crops. This gives
the crop the least weed competition during its most vulnerable
stage.
Early postemergence flaming works, too, for crops that send up
early leaves before their growing point emerges. Even if the young
leaves are singed, these crops will bounce back as long as the
growing point survives. (See de Wilde)
Once the growing point emerges, allow substantial growth before
flaming stalks.
Run
when it’s hot and dry. Band flaming for between-the-row
weeds—just like cultivating or rotary hoeing—is most effective
at killing weeds in the heat of day with a gentle drying wind,
not the cool dewy morning when it’s more comfortable for the driver
or in the evening when visible flames make it more dramatic. The
more you want a drink of lemonade, the more you need to be out
flaming weeds.
Adjust
for accuracy. For flaming between rows of emerged crops,
leave time for careful adjustment of burner height and angle (both
vertical and horizontal), fuel pressure, tractor speed and regulator
setting. Take time to carefully examine young crops for flame
damage to stems buds or leaves. Quick test: firmly squeeze a plant
leaf between thumb and forefinger. Let go. If you see a finger
print where you squeezed, the heat has burst cell walls and the
leaf will wither.
End
the fireworks. Yellowish flecks or bands within the flame
indicate foreign material within the combustion zone or blockage
at the burner. Carefully clean out nozzles each year to remove
carbon and rust that can flake off the inside of the steel pipe
that leads to the burners. A bluish center flame is desirable.
Protect
crops with water shield. Spraying a thin layer of water
over the plants with flat-fan nozzles helps protect them from
the flame’s heat. The sensitive plant parts of cotton, string
beans and other crops can be protected with a wall of mist.
Maximize
the benefits of beneficials. Researchers notice that
ladybird beetles survive higher temperatures than do tarnished
plant bugs, a serious cotton pest. The beneficial beetle preys
on the pests in both their larval and adult stages. Further, the
tarnished plant bug appears at about the same time that cotton
plants can first tolerate flaming.
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