Rate ranges of graminicides
Post emergent grassy weed control (including volunteer corn) in the bean crops has begun, and as labels are reviewed questions arise over rate ranges. Both of ADAMA’s Eastern Canada graminicide products (clethodim in ARROW ALL IN® and quizalofop-P-ethyl in LEOPARD®) have rate ranges, but when is it best to use lower vs higher rates?
Weed size is a big driver for product rate. Graminicides target the growing point, which is generally only a small fraction of the total plant, and as the grassy weeds get larger the percentage of meristematic tissue decreases further. Given that control is only achieved when a lethal dose of ai gets into the growing point, larger grasses need higher rates to overcome the dilution that occurs via increased biomass. And it is important to remember that once a seed head forms there really isn’t any longer a growing point to target – the products will no longer work.
Differences in susceptibility amongst grasses also exists. Certain weeds (i.e. Crabgrass) are more challenging to control than other grasses of similar size, so higher rates will be needed. Perennial grasses (i.e. Quack grass), with meristematic tissue in their rhizomes, require the maximum label rates to ensure enough ai gets down to these root based targets.
Tank mix partners can also impact optimal rates. Burning type products (group 6 or 14) can damage the cuticle of the grassy targets, which can impair graminicide uptake. Split applications are the best course of action, but increasing the rate of the graminicide can help maintain efficacy1. Mixes with synthetic auxins (Enlist or Xtend based platforms) can also decrease graminicide efficacy. Again split applications are best, but graminicide rate adjustments can help (please note that Enlist and ‘fop’ products have very strong antagonism that even rate adjustments rarely overcome).
For more information on the graminicide products offered by ADAMA, and their associated rate ranges, please visit our website links below, or reach out with any questions.
ARROW ALL IN® | ADAMA East Canada
*** always read and follow the label***
Referenced Literature:
1 Evaluation of quizalofop tank-mixtures for quizalofop-resistant rice - ScienceDirect
