Comparison of methyl bromide and herbicide effects on endomycorrhizal formation,seedling production,and weed control in sweetgum seedbeds

Sweetgum seedlings were grown in fumigated and nonfumigated nursery plots where equal portions were treated with a preemergence application of 1.1 kg/ha of trifluralin and a postemergence application of 1.7 kg/ha of napropamide. Methyl bromide at 478 kg/ha significantly decreased average root dry weight. Endomycorrhizal formation on one, two, and three month-old seedlings was not significantly decreased by fumigation or herbicide application. Weeding times for herbicide plots were less than half that for fumigated plots. These results show that herbicides can provide better control of annual weeds and produce better sweetgum seedlings than fumigating with methyl bromide.