Mycoherbicide potential of Alternaria alternata (Fries.) Kiessler and its formulations on the host weed Xanthium strumarium L.

This study evaluated the mycoherbicidal potential of Alternaria alternata(Fries.) Kiessler on cocklebur (Xanthium strumarium L.), a noxious weed in Algeria. Conidial suspension, a rapeseed-oil-based liquid formulation and a sodium-alginate-based solid formulation, all with 10(6) conidia/ml, as well as the herbicide (Mustang(R)) at a reduced dose (0.45 L/ha) were compared. Inoculum was applied on detached leaves of cocklebur under laboratory conditions and on 4-5 leaf stage cocklebur seedlings in pots in a greenhouse and in the field. Disease severity was highest following application of the liquid formulation in the detached leaf assay (95.5%) as well as in the pot (80%) and field (43%) experiments. Similarly, the oil-based liquid formulation reduced cocklebur height, root length and dry weight by up to 50%, 27% and 58%, respectively in pot trial and 40%, 51% and 45%, respectively in the field experiment. The conidial suspension ranked second in efficacy, followed by the solid formulation. Mustang(R) showed the highest herbicidal effect. None of the crops tested for host specificity including tomato, wheat, faba bean and zucchini was susceptible to the fungus. Our findings suggest that A. alternatahas potential as biocontrol agent of cocklebur especially when applied in an oil-emulsion-based formulation.