Abstract

Since there is considerable use of preemergence herbicides in the containerized nursery industry, a study was conducted to determine if they affect the ability of plants to cold acclimate. Six preemergence herbicides with different modes-of-action were chosen for the study, and were applied to a Kurume type azalea (Rhododendron x hybrida ‘Tradition’) on October 8, 2004. Laboratory cold hardiness evaluations were conducted at 10, 17, and 24 weeks after treatment (WAT) to both stems and leaves. None of the preemergent herbicides tested caused a significant trend in cold acclimation with either stems or leaves when compared over all sampling dates and temperatures. However, some preemergence herbicides caused a significant increase or decrease in cold acclimation of stems and leaves at selected sampling dates and temperatures.