A COMPARISON BETWEEN MCPA AND PESCO is-I5 FOR THE ...

TABLE 3
CROP HEALTH SCALE
Crop stand as healthy as that of weeded plot
Slight stunting or delay in development
Slight necrosis of leaves, chlorosis or reduced vigour of
crop
Considerable leaf scorch, chlorosis or considerable reduction
in vigour of crop.
Crop severely damaged, stunted or deformed
Crop killed.
The results of the scoring taken at 3 different times in the life of the crop are given in Table
4 below:
Pre-em. MCPA 3ptsjacre
Pre-em. MCPA 5ptsjacre
Pre-em. Pesco 18-15 3ptsjacre
Pre-em. Pesco 18-15 5ptsjacre
Post-em. MCPA 3ptsjacre ..
Post-em. MCPA 5ptsjacre ..
Post-em. Pesco 18-15 3ptsjacre
Post-em. Pesco 18-15 5pts/acre
Hand Weeding
No Weeding ..
TABLE 4
SCORE FOR CROP HEALTH
The immediate effect of the herbicide on the
development of the crop was evident soon
after application, during the germination of
the seed. The seedlings that emerged from
the seed in the pre-emergence treatment plots
were all unusually yellow and were considerably
deformed. The extreme effect of the
herbicides on the seedlings at this stage is
evidently due to the fact that the spray fell
more or less directly on the seed. Perhaps
when the seed is dibbled or drilled at depth
the adverse effect will not be so drastic.
By the 4th of November, 12 days after pre-
"mergence application, when the first scoring
was done, the figures (table 4) indicate that
the crop still showed a severe check in growth
from the pre-emergence application. Recovery
to normal growth was rather slow with
all pre-emergence treatments, except with
the lower level of MCPA at 3pts/acre. In this
case recovery was fairly quick and by the 18th
of November, 26 days after application, the
crop had almost completely recovered.
Growth was normal under all other treat .•
ments except in the 'hand weeded' plots. In
these plots growth and establishment
deteriorated a bit after the first scoring. This