ABSTRACT
Excessive use of chemicals in papaya (Carica papaya L.) crops puts the efficacy of fungicides at risk because of the resistance problems of pathogens to these products, besides the possibility of toxic residues endangering the human health and the environment. Therefore, the present study aimed to evaluate the efficacy of natural products in controlling Colletotrichum gloeosporioides in vitro and in vivo. In the in vitro assay, the evaluated products were aqueous extracts of clove (Syzygium aromaticum) and cinnamon (Cinnamomum zeylanicum) at 1.5% and chitosan at 4%, separately, and the association of these plant extracts with 4% chitosan, as well as the fungicide prochloraz (100 mg L-1), added to PDA culture medium; they were evaluated for their effect on the mycelial growth of the fungus, maintaining a control without addition of products. The treatment with aqueous extract of clove at 15% and its association with chitosan inhibited mycelial growth. Association of chitosan with aqueous extract of cinnamon was more effective in reducing mycelial growth than the two products used separately. In the in vivo test, papaya ‘Formosa’ fruits were subjected to the following treatments by immersion: 1 - control (distilled water); 2 - control - fungicide prochloraz (Sportak® 450 EC) at a concentration of 0.75 mL L-1; 3 - chitosan (4%); 4 - aqueous extract of clove (10%); 5 - aqueous extract of cinnamon (30%); 6 - aqueous extract of clove (10%) + chitosan (4%); 7 - aqueous extract of cinnamon (30%) + chitosan (4%). After 24h, fruits were inoculated with C. gloeosporiodes and evaluated for the disease severity at every two days. Only in the third evaluation, treatments with fungicide and aqueous extract of cinnamon at 30% associated with chitosan at 4% reduced the disease severity, compared to control. The area under the disease progress curve indicated that the treatment with aqueous extract of clove was also effective in reducing the severity of anthracnose in fruits.
Keywords
Carica papaya L.; Colletotrichum gloeosporioides; alternative control
