Relevance. The yield of watermelon fruits and seeds depends on many factors, one of which is the phytosanitary condition of the crops. Weather conditions during the growing season at the beginning of flowering contributed to the infection of plants with bacteriosis and Alternaria.Methodology. The experiments were carried out in the central zone of the Krasnodar Territory in the department of vegetable and potato growing of the Federal State Budgetary Scientific Institution "Federal Research Center of Rice" at the seed-growing site of the watermelon variety Nitsa. The work was carried out in accordance with generally accepted guidelines. Results were obtained on the use of fungicides Metabacterin and Plantare on seed crops of the Nitsa watermelon variety.Results and discussion. Double treatment with drugs significantly limited the spread and damage of plants by bacteriosis and alternaria. The phytotoxicity of Plantarel for harmful pathogens was higher than that of Metabacterin, which was reflected in an increase in fruit yield – by 7.8 t/ha, fruit marketability – by 8% and seed yield – by 57 kg/ha more, in comparison with the control option. The effect of treating watermelon plants with Metabacterin on yield indicators is less significant in comparison with Plantarel but higher than in the control variant. 4.2 t/ha more fruits were collected, with a 5% higher yield of marketable fruits and a 5 kg/ha higher seed yield than from watermelon plants without protective measures. The use of drugs contributed to the preservation of a larger number of plants in the variants (compared to the control), and ensured a high accumulation of dry soluble substances in the fruit pulp. Bacteriological and mycological analyzes showed that there are no pathogenic microflora on seeds from fruits from plants treated with Plantarel and Metabacterin. Both drugs have a growth-stimulating effect. Soaking the seeds before sowing in a solution of preparations contributed to the emergence of vigorous shoots three days earlier than when soaking in water.