Antifungal Activity of Organic Manure Extractsagainst Exerohilum Turcicum, Causal Agent of Helminthosporiasis of Maize (Zea mays L.)

Helminthosporiosis of maize (Zea mays L.) is one of the cryptogamic diseases of maize, causing enormous yield losses. Chemical fertilizers and fungicides are most often used for soil fertilization and disease control. Inorder to develop ecologically acceptable alternative methods, several results were reported on the antifungal potential of compost juice or tea. The overall aim of this study was to evaluate the antifungal activity of four types of organic manure extracts against Exerohilum turcicum, the causal agent of maize helminthosporiosis. Two batches of aqueous organic manure extracts (sterilized and non-sterilized) at concentrations C1= 0.375 μL/mL; C2= 0.75 μL/mL; C3= 1.5 μL/mL and C4= 3 μL/mL were used. These organic manures consisted of extracts from beef manure (EBM), household waste (EHW), pig manure (EPM) and poultry manure (EPTM). The chemical fungicide (FONGI) Ridomil Gold plus 66WP was used as a negative control. Radial growth inhibition rates of the pathogen as a function of extract concentrations were evaluated. The results showed that unsterilized extracts had a high inhibitory power compared with sterilized extracts. Non-sterilized household manure extracts showed the highest inhibition rate (IR (EHWM)= 77.32%) at concentration C4= 3 μL/mL, and very low inhibition (IR (EHWMS)= 0.34%) at concentration C1= 0.375 μL/mL in sterilized household waste manure extracts, compared with the negative control, which had an inhibition rate of 100%. Principal component analysis (PCA) showed a wide variability in the inhibitory power of the extracts. In addition, high pathogen inhibition rates were obtained at high concentrations (C3= 1.5 μL/mL and C4= 3 μL/mL). Fresh organic manure extracts are said to contain substances that inhibit the mycelial growth of Exerohilum turcicum. This antifungal potential of organic manures can be integrated into biological control methods against Helminthosporiasis of maize.