Carbohydrate Response of Bermudagrass, Dallisgrass, and Smutgrass to Atrazine, Bromacil and MSMA

Abstract

Analysis for total carbohydrate content was made on oven dried bermudagrass [Cynodon dactylon(L.) Pers.] dallisgrass (Paspalum dilatatumPoir.) and smutgrass [Sporobolus poiretii(R. & S.) Hitchc.] storage tissue collected at 2, 4, 6, or 36 weeks after fall treatment and at 2, 4, or 6 weeks after fall and spring treatment with three herbicides at varying rates. Those species that survived either fall or fall and spring herbicide application exhibited an initial reduction in carbohydrate content, but it returned to a level comparable to that in the untreated plants in most instances within 6 weeks after treatment. Atrazine [2-chloro-4-(ethylamino)-6-(isopropylamino)-s-triazine] at 4.48 and 8.96 kg/ha and bromacil (5-bromo-3-sec-butyl-6-methyluracil) at 2.24 and 4.48 kg/ha resulted in carbohydrate reduction in bermudagrass and dallisgrass for no more than 6 weeks except where both fall and spring treatments were used. Smutgrass was controlled with these two herbicides within 2 weeks so that not enough live tissue was available for analysis. There was no carbohydrate reduction in bermudagrass with the 2.24, 4.48, or 8.96 kg/ha rates of MSMA (monosodium methanearsonate) beyond 2 weeks following treatment. The carbohydrate content of smutgrass was reduced up to 6 weeks after treatment with MSMA, and dallisgrass was controlled at all rates so that no carbohydrate analysis could be made.