Efficacy and Duration of Control using Indaziflam during Containerized Plant Production Varies with Formulation and Application Rate

Weed control during containerized plant production continues to be a serious challenge, especially in light of current economic and labor restraints.  The purpose of this experiment was to determine the relative length and degree of control of a grass and a broad leaf weed using three indaziflam formulations applied at three application rates compared to untreated control treatments.  Nursery containers filled with a mix composed of pine bark:new peat:sand (6:4:1 by vol.) were treated with one of two granular formulations or a liquid formulation (SC) of indaziflam applied at the rates of 0.022, 0.034, or 0.045 lb a.i./acre.  Seeds of large crabgrass [Digitaria sanguinalis (L.) Scop.] and spotted spurge [Chamaesyce maculata (L.) Small] were sown in different sets of containers at 0, 14, 28, 42, 56, 70, or 84 days after treatment.  For both weeds, control generally increased linearly with increasing application rates for all three formulations of indaziflam.  The rate effect was more apparent at the later weed seed sowing dates.  There was little difference in the performance between the two granular formulations; however, the SC formulation provided better control than the granular formulations at several evaluations, predominately in comparisons of the lowest indaziflam application rate.  Weed control from the 0 and 14 days after treatment sowings was mostly good to excellent for three months even for the low and middle application rates suggesting that indaziflam sensitive plants could potentially be treated at reduced rates and still provide acceptable weed control.