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ResumoO objetivo deste estudo foi avaliar o efeito da adubação fosfatada, com e sem aplicação foliar de zinco na produção de alface americana. O experimento foi conduzido no Instituto Federal do Triângulo Mineiro (IFTM), campus Uberaba, em área de campo. O delineamento experimental foi de blocos casualizados, em esquema fatorial 5 x 2, com quatro repetições. Foram avaliadas cinco doses de fósforo (50%, 75%, 100%, 150%, 200% da quantidade recomendada de P 2 O 5 ) com ou sem aplicação foliar de zinco (0,5 kg.ha -1 ). Houve efeito signiicativo para as características massa fresca total e massa fresca comercial da planta apenas em relação ao fator doses de fósforo. Conclui-se que para a alface americana, cultivar Lucy Brown, cultivada na região de Uberaba-MG não se recomenda a utilização de adubo foliar à base de zinco, já que este não proporciona diferenças signiicativas na produtividade da cultura e deve-se aumentar a adubação fosfatada em 50% da dose atualmente recomendada. Palavras-chave: Adubação; Lactuca sativa L.; Massa fresca AbstractPhosphorus doses for producing iceberg lettuce with and without foliar application of zinc. This study aimed to evaluate the effect of phosphate fertilization, with and without foliar application of zinc for producing iceberg lettuce. The experiment was conducted in the Federal Institute of Triângulo Mineiro (IFTM), campus Uberaba, in the ield area. The experimental design was randomized blocks, in a 5 x 2 factorial scheme with 4 replications. Five phosphorus doses were evaluated (50%, 75%, 100%, 150%, 200% of the recommended amount of P 2 O 5 ) with or without foliar application of zinc (0.5 kg.ha -1). There was a signiicant effect for the characteristics total fresh mass and commercial fresh mass of the plant only regarding the factor phosphorus levels. We conclude that for iceberg lettuce, Lucy Brown cultivar, grown in the region of Uberaba, Minas Gerais, Brazil, it is not recommended to use a zinc-based foliar fertilizer, since this does not provide signiicant differences in crop yield and phosphate fertilization must have a 50% increase in the currently recommended dose.

Lettuce (Lactuca sativa) is among the most widely cultivated leafy vegetables. Its production is in continuous expansion, with an increase of 491,000 tonnes, on average, in recent years (FAOSTAT, 2020). However, Bremia lactucae, the causal agent of lettuce downy mildew (LDM), considered one of the main leaf diseases of lettuce in the world, can infect any stage of plant development and cause extensive production losses (Spring et al., 2018;Van Hese et al., 2016).In Brazil, losses due LDM can reach up to 70% under conducive weather (author's unpublished observations). Disease symptoms include development of light green to yellow areas on the upper side