|Abstract or Summary
- Norbak, Dacagin, and Vistik, when mixed with a spray solution,
each have the unique property of increasing the viscosity of
that solution. This property has been used commercially for the
reduction of spray drift.
Studies were made of the drift control adjuvants to determine
the following: (1) the effect of the adjuvants on the phytotoxicity of
selected herbicides to several crops, (2) the effect of the adjuvants
on the herbicidal efficacy of paraquat, (3) the effectiveness of the
adjuvants in reducing spray drift under field conditions, (4) the effect
of the adjuvants in preventing amitrole-T from being washed off
plants with simulated rainfall, and (5) the ability of the adjuvants to
reduce vapor loss of 2,4-D ethyl ester when applied in combination
to plant surfaces.
Field experiments in which adjuvants were sprayed in combination
with 2,4-D amine on wheat and corn, dicamba on barley, and
MCPA on red clover, indicated that only in the case of Vistik applied
with MCPA at rates of 1.0 and 1.5 lbs./A. was there a reduction in
herbicidal selectivity. This reduction was very slight.
The adjuvants were each very effective in reducing spray drift
in paraquat field studies. Injury to test plants 50 feet from the
spray swath was less than five percent for the paraquat solution containing
an adjuvant as compared to 20 percent for the solution without
Studies were conducted to determine whether the adjuvants
would substitute for the wetting agent X-77 in paraquat applications
under field conditions. Thirty-two plant species were sprayed in
each plot and visually evaluated several weeks later for injury. Results
showed that the adjuvants were not effective substitutes for
X-77. On the other hand, the addition of Dacagin or Vistik to the
paraquat solution did not decrease the herbicidal efficacy when X-77
was used. Norbak decreased the herbicidal efficacy of paraquat with
or without the addition of X-77.
A study to determine the effectiveness of the adjuvants in preventing
amitrole-T from being washed off plant surfaces was conducted.
Tomato plants were sprayed with an amitrole-T solution
containing adjuvant and washed with simulated rainfall at various time intervals following the spraying. The adjuvants proved ineffective
in preventing the amitrole-T from being washed off the
In another experiment bean plants were sprayed with a 2,4-D
ethyl ester solution in which adjuvant was mixed. These plants were
placed in a plastic bag enclosure with untreated bean plants to study
the effectiveness of these adjuvants in reducing vapor loss of 2,4-D
from the treated beans. Results suggested that only Dacagin had
properties that reduced vapor loss, and this reduction was slight.
Throughout the above experiments Norbak noticeably decreased
the efficacy of the herbicides. This decrease is attributed
to the reduction in the number of spray droplets per unit area in
the spray swath.