No abstract

Leachates from the landrace sorghum IS9456 were tested on Bidens pilosa emergence and growth at Henderson Research Station in 2018. The trial had six treatments replicated four times. Stover was put in perforated plastic pots suspended on a frame. Watering released leachates, which were received by clay pots under the suspended pots. Atrazine significantly inhibited percentage emergence (P < 0.05) and leaf area (P < 0.001) of B. pilosa compared to leachates from all sorghum plant parts and the negative control. There was no significant effect (P > 0.05) of sorghum plant part as source of aqueous extract, and atrazine on height of B. pilosa. Sorghum stalks, leaves and sorghum stalks combined with leaves significantly (P < 0.05) reduced dry weight of B. pilosa compared to treatments with heads, atrazine and no sorghum herbage. Heads, stalks, leaves and leaves combined with stalks from mature IS9456 have limited allelopathic effect on the emergence of Bidens pilosa compared to atrazine. However, stalks, leaves and leaves combined with stalks can suppress biomass of Bidens pilosa possibly due to high concentrations of water soluble allelopathic compounds. Atrazine can provide early suppression B. pilosa, while allelopathic leachates from sorghum leaves, stalks and leaves combined with stalks can suppress B. pilosa in later growth stages by reducing weed biomass.