Vegetable growing is an important part of the country's food complex. The changes taking place in the food culture and the modern increase in the standard of living of the population contribute to an increase in the consumption of vegetable products. Onions are always in great demand among the population. When growing it, close attention is paid to protective measures. A program for the protection of onion crops has been developed, research on which has been conducted in conditions characterized as arid. The studied drugs significantly reduced the incidence of pathogenic microorganisms in plants. When using fungicides, compared with production control, the yield of onions increases 2-3 times. The expedient sequence of application of fungicides allowed to improve the quantitative indicators of the harvest – the average diameter of the bulbs increased by 20-49%, the average weight of the bulbs – by 30-60%. The rational use of plant protection products at the optimal time, taking into account their mechanism of action, should be considered as a factor in increasing the effectiveness of protective measures and reducing the consequences of the risk of a chemical control method.