Research in Kansas from 1983 to 1986 evaluated early preplant (30 to 45 days) and late preplant (10 to 14 days) herbicide treatments for weed control before ridge-till planting in a soybean and sorghum rotation. Control of fall panicum and common lambsquarters at planting time averaged at least 95% for all early preplant and 92% for late preplant treatments. Where no preplant treatment was used, heavy weed growth in spring delayed soil dry-down, which resulted in poor ridge-till planting conditions and reduced plant stands, and ultimately reduced sorghum grain yields by 24% and soybean yields by 12%. Horsenettle population declined significantly, and honeyvine milkweed population increased. Smooth groundcherry populations fluctuated from year to year with no overall change.

Horsenettle was described quantitatively in two grazed bermudagrass pastures for two years. Six times from April through October, plants were counted, phenologically documented, and tops were harvested for estimation of above-ground phytomass. Roots were sampled for carbohydrate, N fraction, and macronutrient analyses. Top growth, flowering, fruiting, and chemical composition were similar between sites within years, but differed between years. Starch and total non-structural carbohydrates in roots increased following reproductive periods both years. Root concentrations of protein and non-protein N increased and concentrations of P decreased in August and September in one year only. Analysis of the relationship between seasonal trends in carbohydrate fluctuation and pasture management practices suggests that systemic herbicide application in mid-summer may lead to more effective control than application in spring.

Continuous corn was grown for 5 consecutive yr using conservation tillage methods in the Maryland Piedmont. Herbicide treatments were applied annually at common usage rates and were compared for their effects on weed cover, species stability, and grain production. Weed flora dominance shifted from giant foxtail the first year to smooth pigweed the following year. Smooth pigweed then dominated the flora for the duration of the study. Horsenettle was ubiquitous in all treatments but never became competitive. Canada thistle occurred in measurable densities in all plots that had not received atrazine applied preemergence. Grain yields were correlated negatively with densities of smooth pigweed in 1983 (r = −0.58, P = 0.01), and Canada thistle in 1983 and 1984 (r = −0.63 and −0.62, respectively; P = 0.05). Grain yields were correlated positively with midseason precipitation (r = 0.85, P = 0.01).