Guava Wood Vinegar Controls Black Dot Disease in Potatoes and Tomatoes

Introduction

Black Dot Disease on Potato

Black dot disease, caused by Colletotrichum coccodes, is a persistent problem in potato and tomato cultivation, leading to significant yield losses and deterioration of tuber quality. This study evaluates the antifungal efficacy of guava (Psidium guajava) wood vinegar (WV), derived from guava tree wood, against C. coccodes and its impact on potato plant growth and yield.

Experimental Design and Application

Various concentrations of guava WV—0%, 0.25%, 0.50%, 1%, 2%, and 3% (v/v)—were tested against C. coccodes to determine their impact on mycelial growth.

Key Findings

Fungal Growth Inhibition

  • The highest concentration (3%) achieved complete (100%) inhibition of C. coccodes.

Disease Suppression in Greenhouse Trials

  • Guava WV at 2% and 3% significantly reduced disease severity compared to untreated plants.
  • The 3% WV treatment reduced stem colonization to 21.91% in 2022 from 73.15% in untreated controls.

Enhancement of Plant Growth and Yield

  • Foliar application of guava WV improved plant height, stem diameter, and tuber yield per plant.
  • The 3% WV treatment resulted in the highest tuber yield, reaching 281.72 g per plant in 2022.

Implications for Sustainable Agriculture

Gas chromatography-mass spectrometry (GC-MS) analysis identified phenols, esters, organic acids, antioxidants, and alcohols as key bioactive compounds in guava WV. These compounds are known to exhibit antifungal properties.

Beyond disease control, guava WV appears to promote plant growth, likely through biostimulant effects.

Conclusion

Guava wood vinegar demonstrates strong potential as a natural fungicide against C. coccodes, significantly reducing disease severity while enhancing potato and tomato plant growth and yield.

Future research could focus on isolating the specific bioactive compounds responsible for these effects and optimizing application protocols for commercial use.

Article based on: Fungicidal Effect of Guava Wood Vinegar against Colletotrichum coccodes Causing Black Dot Disease of Potatoes