Weed Suppression Potential of Ailanthus altissima Compost: Effects on Germination and Emergence

The Tree of Heaven (Ailanthus altissima (Mill.) Swingle), originally from Southeast Asia, is considered an invasive alien plant in many countries. It produces a strong allelochemical called ailanthone, and this phytotoxic quassinoid inhibits the germination of seeds and/or suppresses the growth of other plants. This study aimed to determine the applicability of plant biomass of the Ailanthus as a raw material to prepare various compost types. The compost treatments were composed of the biomass of A. altissima alone, the biomass of A. altissima+chicken manure, and the biomass of A. altissima+cattle manure. Weed seeds in the mixtures were kept for 7, 14, 21, and 28 days in the composts during the summer and autumn seasons, and the effect of these durations on the viability of the weed seeds was determined by a 28-day petri experiment. The percentage of decayed weed seeds (DSP) placed in the compost increased over time. The decayed seed percentage for Sorghum halepense (L.) Pers. (Johnson grass) in summer-prepared compost was higher than that in autumn-prepared composts, whereas seasonal differences were insignificant for Convolvulus arvensis L. (Field bindweed). Additionally, increasing mulch thickness reduced weed emergence, indicating that a mulch layer of at least 5 cm is necessary for effective weed control.