Vol. 16—1962 - NorthEastern Weed Science Society

Ratings at the time of'gJ;Vllst; although generally higher,
showed little change in the relationship of treatments.
319
Teat U: ,All the nutpat. weedcont17O-1i' ratings of comparable
treatmentBrecord~d 'in th:l.superiment wereb,l8her than those found
in Test 1. This was part:LallY'attdbuted ti).' ehe less severe ahd
less uniform nutgrass infestation found in this field. The area
in which Test II was conduct;ad:was lower: :Lnorganic matter than
that of Test 1 which would condition the results to be expected
from both chemicals. ' :
!l
Three pounds of Atrazine." pre-emergence or post-emergence,
were effective in controlling nutgrass in this test. Granular:
Atrazine, however. gave 1e.8cuns:Letent and-slightly less
effective control than liquid application8., .
Four pounaof EPTCgave.exce11ent earlt' control and highly
effective controL throughout the season. The nutgrass growth,'
such as that observed later in the summer in Test 1, could have'
been suppreseed in Test 11 by the shading effect of the tall
broad1eaves growing in the EPTCplots. Granular and liquid
EPTCapplications were equally effective. EPTCcorn injury
symptoms, twisting of about 10 percent of the plants, were
observed in all plots.
Summary
Nine pounds of Atrazine were required for complete control
of nutgrass in field corn. Three pounds were sufficient for
effective control in one test area; ho~~ever, six pounds were
needed in another test area. Four pounds of EPTCprovided
effective nutgrass control, but corn injury symptoms were recorded
in both tests.
The time of application (pre- vs. post-emergence) of Atrazine
was less important than the rate of application.
Granular Atrazine gave slightly less effective and less consistent
control than its liquid counterpart. No important differences
were observed between granular and liquid EPTCtreatments.