Manejo ecológico de fitopatógenos em sementes de pimentão

Abstract

The association of phytopathogenic fungi in seeds is harmful in all phases of crop production, as it compromises both sanitary and physiological quality. Chili (Capsicum annuum L.) is susceptible to various diseases caused by fungi such as anthracnose, a highly destructive disease caused by Colletotrichum gloeosporioides (Penz). The objective of this research was to evaluate the sanitary and physiological quality of pepper seeds, the reduction of phytopathogens and the control of anthracnose with the use of thermotherapy, plant extracts and chemical and biological products. The experimental design was completely randomized for all experiments and in the statistical analysis the means were compared by the Tukey test (p <0.05). In the in vitro tests, the physiological and sanitary quality was performed according to the Rules for Seed Analysis. In the trials with chemical products (Thiophanate Methyl, Tebuconazole, Carbendazin and Azoxystrobin + Thiram) and biological (Quality® - Trichoderma asperellum and Rizos® - Bacillus subtillis), the seeds were treated according to the manufacturer's recommendations in seven treatments and five replicates. In the termotherapy, the seeds were immersed in a water bath with six different combinations of time and temperature in seven treatments and five replications. In the aqueous extracts of plants: neem (Azadirachta indica A. Juss), eucalyptus (Eucalyptus citriodora L.), cinnamon (Cinnamomum zeylanicum Blume) and basil (Ocimum basilicum L.), the seeds were immersed for ten minutes in five treatments and five replications. (Bacillus cereus), B47 (B. methylotrophicus), B22 (B. polymyxa), B7 '(Bacillus sp.) And B22' (B. pentothenticus) isolates in six treatments and five replicates. Soon after the treatments, the seeds were plated, incubated and evaluated after seven days. The in vivo experiment was conducted in a greenhouse with treatments with the highest reduction in seed phytopathogens: thermotherapy (45 ° / 25 min.), Aqueous extract of basil, 5%; Bacillus methilotrophicus; Quality®; Methyl thiophanate. After 30 days of planting the treated seeds, the pepper seedlings were inoculated with the pathogen C. gloeosporiodes. To evaluate the severity of the anthracnose, a specific notes scale was adopted for the pathosystem. Seed germination was observed to be within commercial standards. In the reduction of phytopathogens in the seeds, without interfering in the germination, the aqueous basil extract had a lower incidence of fungi, with 0.19 pathogens / treatment. In the thermotherapy was the treatment with 45 ° C / 25 '. In the use of the chemicals, the Methyl Thiophanate and, in XIII the biological, the Quality® (Trichoderma asperellum). In biological control, isolate B47 (B. methylotrophicus). In the management of the anthracnose, the results were significant in the control of the disease, in which the aqueous extract of 5% basil, the B47 isolate and the Quality product promoted a better response in reducing the severity of the anthracnose in the sweet pepper.