Resumo -O objetivo deste trabalho foi avaliar o efeito de indutores de resistência abióticos no controle da fusariose (Fusarium guttiforme) do abacaxizeiro na fase pré-colheita, em área de ocorrência natural da doença, e verificar se promoveram alterações físico-químicas e bioquímicas nos frutos. Os produtos testados foram fosfito de potássio, fosfito de cálcio, fosfito de cobre, Agro-Mos, silicato de cálcio, Biopirol e Bion pulverizados em campo, nas dosagens recomendadas pelos fabricantes. Fosfito de potássio, Biopirol e fosfito de cobre foram os mais eficientes na redução da incidência da fusariose do abacaxizeiro em campo, com 91,67, 70,01 e 67,68% de controle, respectivamente. As análises físico-químicas mostraram que os tratamentos não promoveram alteração no pH, nos sólidos solúveis totais e na acidez total dos frutos, enquanto, nas análises bioquímicas, apenas a β-1,3-glucanase apresentou menor atividade em relação à testemunha (água destilada esterilizada), com exceção do tratamento com fosfito de potássio. Assim, a adubação foliar com fosfito de potássio e fosfito de cobre, assim como o tratamento com o Biopirol, podem auxiliar no controle da fusariose do abacaxi.Termos para indexação: Fusarium guttiforme, Agro-Mos, Bion, fosfitos, silicato. Abiotic resistance inducers for control of pineapple fusariosisAbstract -The objective of this work was to evaluate the effect of abiotic resistance inducers on the control of pineapple fusariosis (Fusarium guttiforme) in the pre-harvest period, in an area with natural occurrence of the disease in the field, and to check for any physicochemical and biochemical changes in the fruits. The products tested were potassium phosphite, calcium phosphite, copper phosphite, Agro-Mos, calcium silicate, Biopirol, and Bion sprayed on the field, at the dosages recommended by the manufacturers. Potassium phosphite, Biopirol, and copper phosphite were the most effective in reducing the incidence of pineapple fusariosis in the field, with 91.67%, 70.01%, and 67.68% of control, respectively. The physicochemical analyses showed that the treatments did not promote change in pH, total soluble solids, and total acidity of fruits, while, in biochemical analyses, only β-1,3-glucanase showed lower expression compared with the control (sterilized distilled water), except for the treatment with potassium phosphite. Therefore, foliar fertilization with potassium phosphite and copper phosphite, as well as the treatment with Biopirol, may aid in the control of pineapple fusariosis.

No abstract

To study the effects of resistance inducers used to control fusarium wilt in tomatoes due to the fungus Fusarium oxysporum Schlecht f. sp. lycopersici, we evaluated the effects of ASM (acibenzolar-S-methyl), Agro-Mos, chitosan, Biopirol and neem oil on F. oxysporum f. sp. lycopersici mycelial growth and sporulation and systemic resistance in tomatoes. In vitro experiments comprised evaluations of the products’ effects on the mycelial growth and sporulation of the PDA (potato dextrose agar) growth medium-cultured pathogen. In vivo experiments included product application to tomato plants of the Santa Cruz cultivar that were grown for 25 days on autoclaved soil, followed by determinations of disease severity and peroxidase, polyphenol oxidase and Beta-1,3-glucanase enzyme activity levels, which are related to the process of resistance induction. Pathogen inoculation occurred after 5 days at a concentration of 106 conidia/mL. We evaluated the disease according to a rating scale. Enzymatic activity was determined according to specific protocols. Neem oil controlled pathogen mycelial growth and sporulation, while ASM influenced sporulation. The products reduced the severity of wilt in the plants. We highlight neem oil, Agro-Mos and Biopirol due to their ability to induce significant peroxidase, polyphenol oxidase and Beta-1,3-glucanase expression, respectively.

The objective of this work was to evaluate the effectiveness of seed treatment with fresh suspensions and powder formulations with Bacillus methylotrophicus to promote plant growth and induction of resistance against fusarium wilt (Fusarium oxysporum f. sp. lycopersici) in tomato plants under greenhouse conditions, verifying the occurrence of morphological and biochemical changes in the evaluated plants. Powder formulations based on Cassava (Manihot esculenta), Arrowroot (Maranta arundinacea) and sodium alginate containing Bacillus, in addition to the commercial product Quartz®, were used to microbiolize the tomato seeds of the cultivar Santa Cruz. The formulations promoted plant growth, with a seedling vigor index greater than 50% for all treatments containing B. mthylotrophicus, in addition to a significant increase in total dry matter. The treatments induced systemic resistance, controlling the fusarium wilt with a 75% reduction of the disease and activation of enzymes such as peroxidase and polyphenoloxidase, only β-1,3-glucanase presented less activity than controls (treatments without B. mthylotrophicus). Thus, the use of formulations containing Bacillus are efficient in promoting plant growth of tomato plants and in inducing resistance to the control of fusarium wilt.

One of the bottlenecks to heliconia production is leaf diseases, which have the main characteristic of forming necrotic spots, that can reduce photosynthesis, damage the heliconia bracts and make the flowers unsuitable for commercialisation. The objective of the present study was to identify inducers capable of inducing resistance in H. psittacorum cv. Golden Torch, assessing by enzymatic action the reduction in the severity of the fungus complex associated to the cultivation of this species and verifying the action of the severity in relation to the net photosynthesis rate of the plants. The inducers were applied to the plants using a back spray and during application the plots were protected to prevent the products from drifting. The concentrations applied were Agro-Mos® (10 ml L-1), Bion® (0.5 g L-1), Quartz® (40 ml L-1), potassium phosphite (3 g L-1) and calcium phosphite (3 g L-1). During the experimental cultivation, the severity caused by the fungus complex and the photosynthetic rate of the plants were assessed and plant material was collected to analyse the enzymatic activity. The results indicated that the inducers Bion® and the phosphites applied reduced the fungus complex severity, increased the activity of peroxidase, polifenoloxidase and β-1.3 gluconase but did not cause alterations in the net photosynthesis rate of the plants. The value found for β > 1 suggested that the visual estimation of the fungus complex severity is a good visual indicator of the effect of the plant pathogens on the host photosynthetic rate. The results are concrete responses to producers in the sector on management alternatives for diseases associated to heliconia cultivation.

No abstract