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Strategies to improve native grass establishment
Abstract
Big bluestem (Andropogon gerardii Vitman), indiangrass (Sorghastrum nutans (L.) Nash), and switchgrass (Panicum virgatum L.) are native warm-season tallgrasses that are important in rangeland improvement and grassland restoration programs in the Great Plains of North America. Weed interference is an important constraint to establishment of these grasses. Once weed interference is alleviated other constraints must be overcome to increase probability of successful establishment including planting grasses before periods of adequate precipitation. Four experiments were conducted to determine the influence of herbicides and spring planting date on establishment of 'Pawnee' big bluestem, 'Holt' indiangrass, and 'Trailblazer' switchgrass. Grasses were planted at 330 pure live seed m$\sp{-2}$ at about 26-d intervals from mid-March to early June 1996 at sites near Mead and Clay Center, Nebraska and at about 17-d intervals from late March to late June 1997 at sites near Clay Center and Lincoln, Nebraska. Imazapic $\{(\pm$)-2- (4,5-dihydro-$ 4$-methyl-4-(1-methylethyl)-5-oxo-1H-imidazol-2-yl) -5-methyl-3-pyridinecarboxylic acid$\}$ and imazethapyr $\{(\pm)$-2- (4,5-dihydro-4-methyl-4-(1-methylethyl)-$ 5$-oxo-1H-imidazol-2-yl) -5-ethyl-3-pyridinecarboxylic acid$\}$ were applied at 70 g active ingredient ha$\sp{-1}$ within 40 d of planting. Weed control and yields, seedling density, stand frequency, and yields of the planted grasses were measured. Imazapic provided better control of annual broadleaf and grass weeds than imazethapyr in each experiment. By 60 d after the last planting date, big bluestem and indiangrass yields were usually greater where imazapic was applied than where imazethapyr or no herbicide were applied, regardless of planting date. In experiments initiated in 1996, yields of these grasses were the same where imazapic and imazethapyr had been applied the year of planting and often superior to yields where no herbicide was applied by 15 months after the last planting date. Switchgrass seedling density or stand frequency were adversely affected by imazapic in two experiments. However, across all experiments and planting dates, the seedling density of all planted grasses exceeded 10 plants m$\sp{-2},$ which is considered the threshold for successful establishment of warm-season perennial grasses. Based on results from this study, big bluestem, indiangrass, and switchgrass were successfully established when planted between mid-March to mid-June as long as weed interference was reduced by imazapic or imazethapyr applied shortly after planting.
Subject Area
Range management|Environmental science|Soil sciences|Botany|Ecology
Recommended Citation
Rivas-Pantoja, Fernardo Antonio, "Strategies to improve native grass establishment" (1998). ETD collection for University of Nebraska-Lincoln. AAI9838602.
https://digitalcommons.unl.edu/dissertations/AAI9838602