Field Application of Chitosan and Moringa oleifera Extracts as Fungicides Alternatives to Control Early Blight and Improvement Growth and Yield Quality of Potato

Abstract

© 2016 Riad S.R. El-Mohamedy etal. Objective: The study was carried out to evaluate the efficiency of Moringa oleifera seed oil (MSO), leaves extract (MLE) and chitosan (CH) alone or in combined treatments as fungicides alternatives in control of early blight disease of potato plants caused by Aiternaria soiani. Materials and Methods: Different concentrations of MLE, MSO and CH against linear growth and spore germination of A. soiani were carried out on PDA medium in vitro. Under field conditions, the promising/effective single or combined (mixture) concentrations of MLE, MSO and CH treatments were applied as foliar applications during two season 2014 and 2015. The beneficial effects of such treatments on control of early blight, plant growth, total tuber yield as well as enzymatic actives (chitinase and p-1, 3-gluconase) were evaluated. Duncan's multiple range test was used for means separation. Results: In vitro, chitosan at 4.0 and 6.0 g L -1 , MSO at 3.0%, CH+MSO at 1 g L -1 +1.5% or 2 g L -1 +1.0% and mixture of CH+MLE+MSO at 2 g L -1 +20%+1.5% resulted in complete reduction of linear growth and sporulation of A. soiani. Under field conditions, combined treatments of CH, MLE and MSO successfully suppressed early blight of potato plants during 2014 and 2015 seasons. The highest records of disease reduction was obtained with the mixture of CH+MLE+MSO (1.0 g L -1 +20%+1.5%) followed by CH+MSO (2.0 g L -1 +1.5%) and CH+MLE (2.0 g L -1 +20%) treatments, which reduced the early blight disease severity by 94.4, 88.2, 84.4% and 92.8, 85.2, 80.8% during two growing seasons, respectively. Such treatments resulted increasing of tuber yield and chitinase and p-1, 3-gluconase enzymes activity compared with untreated plants. Conclusion: Chitosan (CH), Moringa oleifera seed oil (MSO) and leaves extract (MLE) resulted in complete growth reduction of A. soiani and successfully control the early blight disease and improved the growth and tuber yield of potato under field conditions. Chitosan and M. oleifera extracts may be used for controlling early blight disease of potato plants under field conditions as natural fungicide substitute of chemical fungicides.