Vol. 16—1962 - NorthEastern Weed Science Society

Heights of barley were significantly reduced by silvex containing
the paraffinic carriers at rates of 1/2 and more. These
formulations had no such effect on wheat.
That the two experimentaitormulatiotls'bt silvex were more
phytotoxic to barley than the-commercial fOZlDlulation is furthe~
evidenced by the yield data, Notwithstanding that commercial
silvex reduced yields, the reduotions were not as great as those
from the two experimental formulations. Rates above 1/4 pound
of all preparations significantly reduced barley ~ ields. On
the other hand, wheat yields were not reduce4 significantly be-,
low the check by any rate or formulation.
From the data on kernel weights it can be seen that this"
quantitative response was somewhat related to tiller formation.
Greater decreases in kernel weight resulted from the formulat1Pns
containing the paraffinic fractions than from the commercial
formulation. This decrease was greatest with the formulation
containing the fast-breaking emulsion. The same was true for
tiller formation. The interaction of formulation x rate was
also statistically significant for kernel weights. As with
tiller production, increas£s in rate of all formulations effected
corresponding increases in kernel weight. The reverse,
relationship of tillers to kernel weight might be suspected.
The explanation is easily made. Since the high rates of herbi~
cides tended to check the development of the main culms and
often prevented the formation of heads, the ones that did form
were larger in size and weight. It is known that checking the
development of main culms results in the format~on of more
tillers. No such response or relationship was noted on wheat.
373
From the data and discussion it can be seen that herbicidal"
activity and general phytotoxicity of silvex was greatly enhanced
by using paraffLnic fractions, in aqueous dispersions, as carriers
for this herbicide. Of the two experimental formulations,
the one containing the slow-breaking emulsion was slightly more
effective on dog fennel than the one containing the fast-breaking
emulsion. The same generally was true with regard to their effects
on certain yield components of small grains. There were
instances when the reverse was noted. Additional work is
needed to determine whether the latter is mo'reapparent than
real.
Summary
(1) Two formulations of silvex using high boiling paraff~c
fractions as carriers were compared tQ"a commercially
available formulation of silvex for dog fennel control in barley
and Wheat.
(2) In addition to weed contrOl, the effects of all herbicidal
treatments on tiller production, plant heights, yield,
and kernel weights were made.
(3) The two experimental formulations were more phytotOXic
to dog fennel and on certain Yiel~ c?~ponents of the small grains