Competition of Common Milkweed with Sorghum¹

Abstract

Common milkweed (Asclepias syriaca L.) is a deep‐rooted perennial weed that has increased in occurrence in recent years and has caused much concern among landowners. Because it occurs frequently in dryland sorghum [Sorghum bicolor (L.) Moench], a 3‐year competition study using paired plots was conducted to determine the degree of yield loss caused by common milkweed. Sorghum yield and number of heads per hectare were significantly reduced by common milkweed competition each of the 3 years. Common milkweed reduced average yield by 21% and number of sorghum heads per hectare by 14%. Even low populations (less than 12,000 plants/ha) of common milkweed resulted in severe yield losses. Grain weight per head was significantly reduced by common milkweed competition in 1970 and 1972 but not in 1971. Competition had no effect on sorghum 500‐ seed weight in 1971 or 1972. Percentage protein (Kjeldahl method) of sorghum grain was significantly increased by competition in 1972 but not in 1971.

Conservation tillage systems for sorghum production under semi‐arid conditions in India

“…Perhaps the higher rainfall in 1981 resulted in a greater abundance of perennial weeds, which were not adequately controlled with atrazine. This is in agreement with Evetts and Burnside (1973) who found that common milkweed (a perennial) reduced yields of sorghum by 21 %. T-8, which simulates the most common tillage and weed control practices carried out by peasant farmers, had the lowest weed weight and the highest fodder and grain yields in both years.…”

Herbicidal Control of Common Milkweed (Asclepias syriaca)

“…In the U.S., this species caused yield loss in heavily populated areas in dryland sorghum [Sorgbum bicolor (L.) Moench.] of 18 to 25% (10,11).…”

Integrating Insect, Resistance, and Floral Resource Management in Weed Control Decision-Making

“…(19%), oats (Avena sativa L.) (26%), sorghum [Sorghum bicolor (L.) Moench ssp. bicolor] (29%), and wheat (Triticum aestivum L.) (47%) (Cramer and Burnside 1982;Evetts and Burnside 1973;Yenish et al 1997a). Milkweed is problematic in no-till and reduced-tillage agricultural systems and does not persist in frequently mowed or cultivated systems (Bhowmik 1994;Yenish et al 1997b).…”