Proteção de mudas de cafeeiro à ferrugem com aplicação de óleo de neem, silício, própolis e Bacillus subtilis

Abstract

Coffee (Coffea arabica) is one of the most important crops for the Gross Domestic Product (GDP) of Brazil. The main coffee disease is rust (Hemileia vastatrix), its control is difficult. The objective of this work was to evaluate the alternative control of coffee rust by neem oil, silicon suspension, propolis ethanolic extract (EEP) and Bacillus subtilis suspension. In vitro experiments with uredospores and in vivo with coffee plants were treated. The experiments were maintained in a completely randomized experimental design with 5 treatments and 4 replications. The treatments used were: suspension of Bacillus subtilis, obtained through the commercial product Serenade® (10 mL diluted in 1.5 liters of water); neem oil obtained from the commercial product Neenmax® 0.12% w/w of Azadirachtin (diluted 10 mL to 1 L of water); silica in pure form (SiO2) and in the 25 µm mixed in proportion 0.2 g in 100 mL;. EEP was prepared using 20% propolis compound Apis mellifera and 80% ethyl grain 70% alcohol; and a control containing only water. In the experiment with coffee plants, the Mundo Novo cultivar was used, which received treatments by spraying, and after 72 hours inoculations with the pathogen. The experiment was carried out in a greenhouse and all the leaves of the seedlings that received the treatments and evaluations for the presence of signs of the disease were considered. No in vitro experiment evaluated the percentage of germinated spores and the size of germ tubes of uredospores admitted to treatments on agar-water medium. The EEP and suspension of Bacillus subtilis promoted a significant reduction compared to control in the number of leaves with signs and number of leaves with pustules. Bacillus subtilis suspension, EEP and neem oil promoted a significant reduction in uredospore germination. Neem oil and propolis ethanol extract showed a significant reduction in the size of germ tubes. The results demonstrated the potential of Bacillus subtilis, EEP and nem oil in the control of coffee rust.