Seeking natural herbicides that could reduce weeds in croplands without exerting negative effects on the environment, Nigerian researchers recently investigated fungal strains commonly found in agricultural soils. The University of Ilorin research team discovered two particular fungi – one of which is a cousin of the Penicillium fungi used to make the antibiotic penicillin – that could complement synthetic herbicides. They published their study in the Albanian Journal of Agricultural Sciences.

• Researchers collected soils from four separate farm sites – Kogi, Kwara, Niger, and Benue – in Nigeria’s Southern Guinea Savanna (SGS) agro-ecological zone. Using the soil dilution method to isolate fungi from the soil, they determined the presence of 21 fungal isolates.
• Fungal strains were screened for herbicidal properties. The foliage of the common weed Amaranthus hybridus served as a target. Herbicidal effectiveness was determined using leaf necrosis assay. Strains were also rated according to their prevalence in the soil.
• The predominant fungal strains per site were Aspergillus sydowii (43.47 percent) and Alternaria alternata (30.43 percent) at the Kogi site;  Aspergillus tereus (53.85 percent) and Aspergillus ustus (23.08 percent) at the Kwara farm; Aspergillus niger (44.44 percent) in the Niger location; and Aspergillus tereus (33.33 percent), Penicillium marneffei (58.06 percent) and Fusarium vertilliodes (25.81 percent) in soils from Benue.
• Varying degrees of herbicidal properties were shown by a very large percentage (80 to 85 percent) of the 21 fungal isolates.
• The Aspergillus fumigatus and Penicillium citrinum strains caused the largest necrotic lesions to form on A. hybridus foliage.

The full version of the study can be found here.

The researchers recommended further investigations of A. fumigatus and P. citrinum as potential bio-herbicides, in particular, the secondary metabolites generated by their functions as well as their effects on certain weeds.

Journal Reference:

Fawole OB, Yahaya JU. OCCURRENCE OF FUNGAL STRAINS WITH HERBICIDAL POTENTIALS IN AGRICULTURAL SOILS OF SOUTHERN GUINEA SAVANNA AGRO-ECOLOGY OF NIGERIA. Albanian Journal of Agricultural Sciences. 2017;16(4): 143-150.