Grasshoppers
are a “risk” insect when cotton is in the seedling stage. With today’s seed and
technology costs at planting, we must manage this risk just as we manage our
in-season insects. I do not know of any established thresholds. This problem is
much greater in reduced tillage in the central and southern areas of Alabama.
The immature stage of grass hoppers are much easier to control in March and
April than the adults will be in May. Most all labeled cotton insecticides, at
the lower labeled rates, give good control of immature grasshoppers. Control can
be achieved for as little as 50 cents to $1.00 per acre with some chemistries
by mixing with the burn down herbicides. If that window is missed, broadcast
applications behind the planter would not be too late if planting in April.
The
addition of Dimilin, at 2 oz. per acre, would give residual control when
applications are made in March or early April. Dimilin would provide control of
later emerging grasshoppers or those that might migrate from field borders.
No
highly effective controls have been found for adult grasshoppers that may be
present in May. Cotton is susceptible to grasshopper chewing on the stalk, just
above the soil line, until plants reach the fifth to seventh true leaf stage.
More comments about early season thrips control will follow in a week or so.
More comments about early season thrips control will follow in a week or so.
Follow me on Twitter for updates throughout the season @Ron_Smith23