Vol. 15—1961 - NorthEastern Weed Science Society

75.
Results
The delay in application time undoubtedly had an important inUuence in
the results because the weed 4nd crop seeds were actively geminating alJnost
immediately. At the time ot th~ August 5 application many seedlings were at
or near the soil surface. Chemicals which have contact action were favored
when applied at this date. Conversely, chemicals which act as gemination
inhibitors were undoubtedly penalized.
A few of the data obtained on crop response are presented in Table 1.
From them several important facts can be noted. When Solan is applied to
sprouting crops it can be very toxic. Carrots show good tolerance to Solan
i~, mixtures. It is also apparent that CIPC in the cotnbination was likely
to be somewhat toxic, except possibly to lettuce. This trend has been noted
by the authors in seeded crucifer experiments, not reported here. The most
favorable combination. seemed to be CDro and CDAA.
Weed.control was generally good in these tests. The most speetaclar
results were obtained with the Solan combinations. Here both contact and
preventati va type chemicals were involved and the plots stayed weed free the
remainder of the season.
CDAAplus CDS::Test
Since response of crops and weed control were rather good with CDECplus
CDAAcombinations, it was decided to give them detailed testing by means of
specific dosages on a series of plots.
An area was fitted, seeded, and treated August 24. Plots were 6 1 x 15:(
and each contained two rows of tomatoes, cabbage, broecoli, spinach, lettuce,
carrots, and beets. Good moisture prevailed because of irrigation and rain.
Crop growth was generally good. '''eed populations were heavy and. consisted ~
of crabgrass, barDY&rd grass, red root pigweed, and purslane. Information
on chemicals, rates, crop response and weed control are presented in Table 2.
However, flea beetles damaged the crucifer seedlings so severely that data
from these two crops are omitted from the table.
Indi vidual crops responded somewhat differently. Tomatoes and spinach
were quite tolerant of practically every dosage and combinati,on of CDAAand
CDS::• Carrots and beeta were severly stunted by the highest combinations;
somewhat less stunted by high single treatments or moderate· combinations.
Neither crop was injured by the lower combinations or single treatments.
Lettuce was the.1I1ost sensitive of any crop to high 'or intermediate rates of
CDAA. Injury was much greater when CDIDwas applied in combination with CDAA.
Only at the loWest rates did CDAAalone or in· combination with CDECfail to
injure lettuce.
One of the most striking features of this test was the enhanced kill of
weeds that was obtained by combinations of CDro and CDAAas compared to
either chemical applied singly. It can be seen in Table 2 that even as much
J.l8 Aiglrt pounds of CDAAgave poor control. of broadleaves and a similar rate