Manejo da podridão-de-Sclerotium em pimentão em um argisolo no Amazonas

Abstract

Southern blight is a common disease in plants belonging to the Solanaceae family in the Amazon. To compare southern blight management strategies for bell pepper (Capsicum annuum, L. Solanaceae) a field experiment was conducted in a split plot design with main plots arranged in randomized blocks, with six replicates for each treatment, in a red-yellow Argisol (Ultisol) artificially infested with Sclerotium rolfsii. The main factor was soil cover (sawdust mulch or bare soil) The secondary factors were the incorporation to the soil: 1) compost (3 L by planting hole), 2) rice colonized by Trichoderma harzianum (90 g by planting hole, with ≈ 1.4 x 10(9) conidia g-1) and 3) compost and T. harzianum in the same proportion described previously; 4) control. All plants were fertilized with 1.5 L of compost by planting hole except those in the treatments with 3 L of compost by hole. The main plot had three rows with ten bell pepper plants (0.50 x 1.0 m) and the subplot, three rows with five plants. Southern blight incidence was accessed twice a week. The sawdust mulch increased the disease incidence significantly. In the mulched plots the disease intensity, expressed as the area under disease progress curve (AUDPC), increase 35.5% compared with bare soil. Trichoderma harzianum or the increase in the amount of compost (1.5 L to 3 L by planting hole) reduced the AUDPC by 38.1% and of 37.5%, respectively. Furthermore T. harzianum or the increase in the amount of compost, even with sawdust mulch added, reduced the AUDPC by 52.8% and in 55.1%, respectively, in comparison with mulch alone. These results suggested that the utilization of T. harzianum or the increase in the amount of compost by planting hole are viable strategies to southern blight management in bell pepper. The sawdust surface mulch is not recommended in an S. rolfsii infested area.