Métodos de inoculação de fusarium spp. e uso de indutores de resistência “in vitro” para controle da fusariose do abacaxizeiro ornamental

Abstract

The fusarium rot, a disease caused by the fungus Fusarium sp., Is present in the main producing regions of ornamental pineapple (Ananas spp.) And its efficient control requires the integration of control methods like cultural, chemical, genetic, alternative, gaining prominence induction resistance. So, the objective of work was to evaluate methods of inoculation of Fusarium spp. and performing in vitro tests of resistance inducers for the control of Fusarium ornamental pineapple. Six isolates of Fusarium spp. were utilized from seedlings of ornamental pineapple. First was performed by testing the pathogenicity in the concentration of 1 x 105 conídios/mL at two methods: wounds in roots and 'dipping' pathogen inoculum; and inoculum injection in the lap region of the plant. For germination and mycelial growth resistance inducers (treatments): 1- BION (0.2 g/250 ml); 2- AGRO MOS (200 μL/250 ml), 3- ECOLIFE (200 μL/250 ml) and 4- FERTSILÍCIO (200 μL/250 ml) were placed in erlenmeyer flasks, containing 250 ml of PDA (potato dextrose agar) autoclaved. The witnesses consisted in incorporating the fungicide Thiabendazole (1400μL/250 ml) (positive control), and only the BDA (negative control). To test the mycelial growth were made from the isolates discs (3 mm diameter) and deposited in the center of each petri dish. The experiment was conducted in incubator BOD at 28°C. The observation of the effect of the treatments was performed by measuring the mycelial growth in two diametrically opposite directions (referred to as "a" and "b"), with the aid of a millimeter ruler. For the germination test were obtained culture medium + discs treatments (set), with the aid of a punch 15 mm. The assembly was placed in sterile glass microscope slides. Later drops were added 20μL of the conidial suspension of each fungal isolate. The slides were kept in a humid chamber, which consisted of gerbox boxes with paper towel moistened with sterile distilled water. The set was incubated at 25°C, for 6 h in the clear. After this period, the germination was stopped with the addition of two drops of Aman dye, containing lactophenol. Evaluating the disease severity index the inoculum injection method was efficient unlike the method for dipping. The Fertisilício inductor was not efficient in controlling mycelial growth of Fusarium spp. in vitro, unlike the inductors AgroMos, Ecolife, Bion. The Fertisilício and Ecolife inductors were not effective in controlling Fusarium spp. germination in vitro, unlike the Bion inductors and Agro-Mos.