Sensibilidade de espécies de Colletotrichum associadas à antracnose do maracujazeiro utilizando o controle químico e biológico

Abstract

Passion fruit (Passiflora spp.) is one of the main fruit trees cultivated in Brazil, which is the largest producer in the world. Anthracnose, caused by species of the genus Colletotrichum, is one of the main factors that point to a reduction in production. Knowing the importance of this pathogen for culture and the great diversity of species of this fungal genus is essential to develop specific techniques to control the disease. Therefore, the objectives of this study were to evaluate in vitro and on passion fruit seedlings the effects of the fungicides Difenoconazole, Pyraclostrobin, Flutriafol and Azoxystrobin + Difenoconazole, and the microorganism Trichoderma harzianum on Colletotrichum plurivorum, C. brevisporum, C. theobromicola, C. tropicale and C. fructicola. In the in vitro evaluation of the sensitivity of Colletotrichum spp. For fungicides, the pathogens were inoculated in PDA culture medium supplemented with the concentrations established for each fungicide. In in vivo evaluations, healthy cerrado passion fruit seedlings were used in preventive and curative treatments. In the preventive treatment, the fungicide was sprayed and after 48 hours the Colletotrichum isolates were inoculated, while in the curative treatment the seedlings were inoculated with the pathogen and after the lesions appeared, the fungicide was sprayed. Evaluating Trichoderma in the pairing test, filter paper discs were used moistened with a suspension of Colletotrichum spores (2x106 conidia/mL) and placed on the edge of Petri dishes containing synthetic Potato-Dextrose-Agar (BDA – Kasvi) culture medium. After 72 hours, the same procedure was performed using Trichodermil SC 1306 ® (T. harzianum), at concentrations 0.5; 1.0 and 1.5 L/ha, placing the moistened paper disc in the opposite direction to the phytopathogens. The control was composed only of the plate with the Colletotrichum species. To evaluate the action of metabolites, plugs containing structures from each Colletotrichum species were placed in the center of Petri dishes, separately. After 48 hours, Trichoderma harzianum plugs were placed in plates containing synthetic PDA medium. The bases of the plates inoculated with antagonist and the bases with Colletotrichum spp. phytopathogens were overlapped, joined and sealed. For control, an inoculated base was superimposed with a disc with the pathogen structures and the other containing only a disc of PDA culture medium. To verify the difference between the treatments tested in chemical and biological control, the mycelial growth index (IVCM) and the percentage of mycelial growth inhibition (PIC) were estimated. In general, the fungicide pyraclostrobin was the most efficient both in vitro and in vivo in controlling Colletotrichum species. Furthermore, T. harzianum is a promising species for reducing anthracnose of species associated with anthracnose in passion fruit crops. Keywords: Biofungicides; Phytopathogens; Fungicides; Passionflower.