| Nematode management relies heavily on the use of nematicides, such as
aldicarb (Temik 15G), applied at-planting or preplant soil fumigation
with 1,3-dichloropropene (Telone II). Usually growers apply a uniform
rate of one of these nematicides across an entire field or even farm.
However, nematodes are not uniformly distributed within fields and uniform
nematicide applications therefore result in nematicides being applied
in areas with and without nematodes infestations. Nematicide applications
that are properly matched to spatial distributions of nematodes would
be advantageous, reducing environmental contamination, chemical inputs
and expenditures. GPS-based equipment for controlling the rates of Telone
II and Temik 15G to match the spatial distribution of nematodes were developed
and tested under actual field conditions. Tests were conducted during
2002 in a 10-acre field, naturally infested with Columbia lance nematode,
to compare efficacy of variable-rate vs. uniform-rate nematicide applications.
Both variable-rate applicators closely followed the recommended nematicide
application-rate maps. All rates of nematicides increased the cotton yield
compared to no-nematicide treatment. The yield increase in the sandy portion
of the field was significantly higher than the clay areas. The variable-rate
Temik 15G system resulted in 5% higher yield and 34% lower nematicide
usage compared to a single rate application. Variable-rate Telone II applications
increased lint yield by 5% with a 78% reduction in nematicide usage compared
to a single rate application. |
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