Testing of an integrated regime for effective and sustainable control of invasive Crofton weed (Ageratina adenophora) comprising the use of natural inhibitor species, activated charcoal, and fungicide.
Crofton weed is a major invasive species in China. It exhibits superior growth characteristics and can outcompete with native species via allolepathic effects and modulation of the soil fungal microbiome. The simple removal of invading plants will not ensure restoration of the habitat due to the persistence of allelochemicals and viable seeds in the surrounding soil. An orthogonal experimental design was employed to evaluate the effects of three control factors (A, powdered natural inhibitor species to retard growth; B, activated charcoal to absorb allelochemicals; and C, fungicide to reduce fungal modulation effects), applied at three levels, on the growth and competitive ability of Crofton weed against two native species, in a pot-culture experiment. All treatments reduced all measured growth parameters (P<0.05) except for a specific leaf area, when compared with control plants. Furthermore, the competitive capacity of Crofton weed was decreased in the treatments while that of the native species was improved. Application to soil of the powdered natural inhibitor species and of activated charcoal significantly inhibited plant growth and competitive ability of Crofton weed (P<0.05). Application of fungicide was less effective, but significantly reduced the specific leaf area of Crofton weed plants (P<0.05). The specific combination of factors producing the greatest decrease in plant growth and competitive ability (compared with the control) included the addition of Delavaya toxocarpa powder (37.5 g per kg soil), addition of activated charcoal to soil at a ratio of 1:3 (v/v) (62.5 g per kg soil), and application of fungicide (Thiophanate-Methyl) (0.28 g per kg soil).