To Evaluate Potassium Salt of Phosphonic Acid, Against Late Blight (Phytophthora Infestance) in Potato

Abstract

Potassium salt of phosphonic acid is an elicitorof defence compounds that acts by systemic action for enhancing the plant’s natural defense mechanisms. It is believed to stimulate the production of phytoalexins, which are antimicrobial compounds produced by plants in response to pathogens. Furthermore, phosphonates can interfere with the pathogen\'s ability to infect plant tissues and can inhibit spore germination and mycelial growth of Phytophthora infestans. The study aimed to evaluate the efficacy of the potassium salt of phosphonic acid (trade names: Defend, Sanchar 40), alone and in combination with the ajujuvant in controlling late blight disease caused by Phytophthora infestans in potato cultivar Kufri Ashoka was taken during the Rabi season of 2021-22. The trial was conducted at the Zonal Agricultural Research Station, Chhindwara, M.P., The experiment was laid a Randomized Block Design with seven treatments for bio-efficacy and three for phyto-toxicity, studies, respectively. A total of three foliar applications as well as soil drenching were given at 10-days intervals, thedisease incidence was assessed before and 10 days after treatment.Results indicated significant improvements in disease reduction, plant height and tuber weight with treatments involving Potassium salt of phosphonic acid. The best-performing treatment, PSPA at 2.5 g/lit combined with adjuvant and drenching of Potassium salt of phosphonic acid at 2.5 g/lit, resulted in a minimum percent disease incidence (PDI) of 8.95, a disease control rate of 81.33%, and gave maximum tuber yield of 189.10 q/ha, which was significantly higher than the untreated control. Furthermore, the treatment\'s cost-benefit ratio was notably favourable at 1:3.18. Other treatments with PSPA also demonstrated substantial disease control and yield potential, indicating the efficacy of potassium phosphonate formulations in managing late blight in potato crops. The study highlights the potential of PSPA as an effective tool in management of late blight caused by Phytophthora infestans in potatoes. The significant reductions in disease incidence and the improvements in yield and plant growth observed with various treatments emphasize the valueof PSPA in agricultural practices. Additionally, the better cost-benefit ratio further supports its practicality for use in commercial potato farming. These findings suggest that phosphonate-based treatments, especially when combined with appropriate adjuvants, can serve as a reliable, eco-friendly, and economically viable input for managing late blight and enhancing potato productivity.

Introduction

1. Introduction

Potato (Solanum tuberosum L.) is a vital staple crop globally, particularly in India’s Rabi season. A major threat to its productivity is late blight, caused by Phytophthora infestans, leading to severe yield and quality losses.

To address this, the study evaluates the efficacy of Potassium Salt of Phosphonic Acid (PSPA), a systemic product with both plant defense-activating and antifungal properties. The research explores PSPA’s effectiveness with and without adjuvants and soil drenching, using the Kufri Ashoka variety during Rabi 2021–22.

2. Methodology

• Design: Randomized Block Design (RBD), 7 treatments, 3 replications.

• Application: PSPA foliar sprays (with/without adjuvant), soil drenching, and a PSPA + Mancozeb combo. Three applications were done at 10-day intervals.

• Measurements: Disease incidence & intensity (PDI), plant height, tuber weight & yield, cost-benefit ratio, and phytotoxicity.

3. Key Results

A. Plant Growth

• Best performance in plant height (80.84 cm) and tuber weight (6.13 kg/plot) was from PSPA @2.5 g/lit with adjuvant + drenching.

• All PSPA treatments significantly outperformed the untreated control (64.46 cm, 3.98 kg/plot).

B. Disease Management

• PSPA reduced late blight incidence and intensity significantly.

  • Lowest PDI (8.95%) and disease intensity (3.61%) recorded in the treatment with PSPA @2.5 g/lit (spray + adjuvant + drenching), achieving 81.33% disease control.

  • Control plots had 47.95% PDI and 17.94% disease intensity.

C. Tuber Yield

• Highest yield: 189.10 q/ha gross, 187.31 q/ha marketable (PSPA 2.5 g/lit + adjuvant + drenching).

• Untreated control yielded only 139.24 q/ha gross.

D. Cost-Benefit Ratio

• Best C:B ratio: 1:3.18 with PSPA @2 g/lit + adjuvant + drenching.

• Demonstrated economic viability with higher yields and effective disease control.

E. Phytotoxicity

• No phytotoxic effects observed across all PSPA concentrations.

• PSPA deemed safe for use with potential for repeated applications under high disease pressure

Conclusion

The study demonstrated that the potassium salt of Phosphonic acid is an effective tool for management of late blight (Phytophthora infestans) in potato, The results showed that treatments involving potassium salt of Phosphonic acid, especially when combined with adjuvants for spray and soil drenching, significantly reduced disease incidence and severity, with the best-performing treatment (Potassium salt of Phosphonic acid spray @ 2.5 g/lit with adjuvant and drenching of Potassium salt of Phosphonic acid @ 2.5 g/lit) achieving the maximum height plant disease control rate and a remarkable reduction in disease intensity. This was followed by PSPA concentration of 2g/lit These treatments also contributed to improved plant growth, as evidenced by increased plant height and tuber weight, leading to higher overall yields compared to the untreated control. The maximum yield observed was 189.10 q/ha for the treatment with Potassium salt of Phosphonic acid @ 2.5 g/lit water with adjuvant and drenching, followed by 188.82 q/ha for Potassium salt of Phosphonic acid @ 2 g/lit spray with adjuvant and drenching 2gm / lit water. The cost-benefit ratio was recorded as 1:3.18 for the treatment of 2g/litwhich further underline the economic viability of using potassium salt of Phosphonic acid in managing late blight and making it an appealing option for disease management by potato farmers. No any treatment showed phytotoxic effects at the applied concentrations, highlighting the safety and suitability of the compound in potato farming. In conclusion, Potassium Salt of Phosphonic Acid, particularly when combined with adjuvants for foliar sprays and soil drenching, offers a promising, eco-friendly, and economically viable solution for managing late blight disease in potatoes. This study supports its adoption as part of integrated disease management strategies, contributing to enhanced potato productivity and agricultural sustainability. The studies also highlight that for effective management of Phytophthora in potato results in better tuber yield,when foliar application with soil drenching is supported.

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Copyright

Copyright © 2025 P. M. Kothawade, R. B. Shirode, S. R. Bhonde, S. S. Sonawane. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.