Antagonist Testing in Soybeans.

Development of new and novel crop protection products rely on screening currently used tankmix combinations to rule out adverse effects of performance. Tankmix applications of herbicides and plant growth regulators (PGR) or crop biostimulants (CBS) can lead to antagonistic impacts of herbicide efficacy. Field trials were conducted screening 15 new PGR and CBS products for potential antagonistic effects with glyphosate. Applications were made to actively growing soybean stands inter-seeded with dense weed populations to track antagonistic impacts on weed efficacy. Experimental products were compared to a glyphosate alone and glyphosate plus MAX-IN^® Calcium, a known antagonist for glyphosate. Weed efficacy ratings were taken 7,14 and 21 DAT to evaluate weed control. Tissue samples were also collected two times from the soybean canopy; either prior to applications for baseline nutrients concentrations and again 7 days after application to monitor nutrient uptake for the PGR and CBS products. Overall performance of the experimental products was related to inclusion with glyphosate and results showed varying degrees of antagonistic effects. Reduced weed efficacy was a direct result for inclusion of experimental products in with glyphosate. Experimental uptake by soybeans was also reflected in tissue sample collections.