Potassium phosphite is emerging as a vital fungicide in agriculture practices. It is a reduced form of traditional fertilizer phosphate.Being a systemic fungicide, it works effectively against oomycetes and fungi. Itis known to induce defence responses in plants against certain diseases.Phosphite works by boosting the plant's own natural defences and thereby allowing susceptible plants to survive. It moves through the plant fast, both by basipetal and acropetal transport. Potassium phosphite is a fungistatic molecule with low risk of pathogens developing resistance, and it is an environmentally acceptable active material. Its results can be enhanced by combination with other fungicides.Thus use of Potassium phosphite is an effective way of prevention as well as curative mode and indirectly for yield of crops.