Proceedings of the Sixty-first Annual Meeting of the Northeastern ...

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EVALUATING TRIKETONES IN SWEET CORN. R.R. Bellinder and C.A. Benedict,
Cornell Univ., Ithaca, NY.
ABSTRACT
Effective postemergence (POST) weed control is essential when preemergence
(PRE) herbicides fail. New triketone herbicides for use POST are available, but their
effectiveness has not been thoroughly tested. In 2006, five field trials evaluated weed
control and varietal tolerance to mesotrione, tembotrione, and topramezone. Weed
pressure at the time of application was heavy and highly uneven across trials.
Broadleaf weed control was variable based on product and surfactants. Broadleaf weed
control decreased with all three triketones (1X rate) when they were applied without
atrazine. At the 1X rate, tembotrione and topramezone provided adequate control of
redroot pigweed (Amaranthus retroflexus L.), common lambsquarters (Chenopodium
album L.), and common ragweed (Ambrosia artemisiifolia L.). Tembotrione at the 2X
rate provided better broadleaf control than did 2X rates of mesotrione and
topramezone. Foxtail species (Setaria spp.) were common in all trials, but large
crabgrass (Digitaria sanguinalis (L.) Scop.) populations were variable. Mesotrione
inadequately controlled crabgrass in one trial; however control increased with rate and
addition of atrazine. Due to their large size (8-12 in.) at the time of application Setaria
spp. control was inadequate regardless of rate. Weed control was better when MSO
was used with atrazine, topramezone, and UAN than when a non-ionic surfactant was
used. Tembotrione controlled crabgrass adequately at 6 DAT, but control broke at 21
however, adding atrazine increased control with the 1X rate substantially. A field trial
evaluated ten varieties for crop tolerance. Two varieties, 'Argent' and ‘Silverking’
showed initial sensitivity to all three of the triketones, but outgrew this injury. There was
no reduction in weight in any of these varieties. In another trial, there was a decrease in
ear number and total weight with a 2X rate of mesotrione. Ongoing greenhouse trials
are taking a closer look at the application timing of these herbicides for control of annual
broadleaves and grasses. Preliminary results suggest that timing is crucial to the
effectiveness of these herbicides.
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