Vol. 15—1961 - NorthEastern Weed Science Society

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The herbicides were applied on June 6, 1960. All of the plots were
roto-til1ed to a depth of 2 to 3 inches after treaanent with the exception
of the EP-161 treated plots. After roto-tilling, all plots were heavily
watered.
131.
Petunias were transplanted to these plots on different dates following
treatment. Silver Medal, an 11 hybrid multiflora single petunia was
the variety used. These petunias were sown in the greenhouse on April 1,
1960 and transplanted to flats on April 22, 1960. Eight plants were
planted in each plot on the following dates: one day, two days, four days.
one week, two weeks, three "Weeksand four weeks after treatment~ The
plants were all watered at time of transplanting. Rainfall was supplemented
by overhead irrigation.
Rfsults
and Discussion
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The plots were checked for weed prevalence on July 12, and August 18,
1960. which were approximately 5 ~nc1 10 weeks after treatment. The performance
of the various pre-plant herbicides on weed control is summarized
in Table 1. The treatments showing reasonable weed control after 5 weeks
were EPrC at 5, 10 and 20 pounds per ocrc; vapam at 2 quarts per 100 square
feet, mylone at 1/2, 1 and 2 pounds per 100 square feet; aDd Niagara 5996
at 1, 2 and 4 pounds per acre~ After 10 weeks, EPrC at 5, 10 and 20 pounds
per acre and Niagara 5996 at 4 pounds per acre still produced good weed
contro1~
On July 12, 1960, which was apprOXimately 5 weeks after treatment, the
petunia plants were examined for any detrimental effects due to the herbicide
as affected by its rate of application, and also the date of planting
after treatment. Table 2 summarizes the data on the effects of the various
pre-plant herbicides on petunias.
TheEPrC treated plots showed no detrimental effec*s on the growth of
petunias planted on any date following treatment except for the petunias
planted one and two days following treatment in the 10 and 20 pounds per
acre plots. In these four treatments the damage was very slight.
The vapam treated plots showed only a very slight damage to petunias
planted one day a~ter treatment in the 1 quart per 100 square feet plots
and to those planted two days after treatment in the 2 quarts per 100
square feet treatments. MOderate damage was found in petunias planted one
day after treatment in the '2 quarts per 100 square feet treatments. The
petunias in the other vapam-treatad plots exhibited very slight or no
damage at all.
In the mylone-treated plots, moderate or severe damagewas exhibited
in petunias planted one, two and four days after treatment in the 1/2,
1 and 2 pounds per 100 square feet treatments and also in the petunias
planted one week after treatment in the 2 pounds per 100 square feet
treatments. Slight damage was exhibited by petunias planted one week
after treatment in the 1 pound per 100 square feet treatment. The other
plots exhibited either no or negligible damage.