Efeito de produtos químicos e biológicos sobre a mancha bacteriana, flora microbiana no filoplano e produtividade de pimentão

Abstract

Effects of chemical and biological products on bacterial spot, microbial flora and yield in bell pepperThe effect of weekly sprayings with streptomycin sulfate + oxytetracycline (0.8 g ia L -1 ), copper oxychloride (2.4 g ia L -1 ) and Agrobio fertilizer (5%) plus a control (water) was evaluated in the control of bacterial spot, the microbial flora in the phyloplan, and over yield in three bell pepper cultivars (Magda, Cascadura Itaipu and Magali R). The study was carried out under field conditions from May to December 2002. A randomized complete block experimental design was used with four replications in a 4 x 3 factorial design. Weekly assessments were made for plant height (cm); number of stems; total number of leaves; number of fallen leaves; number of leaves with visible symptoms; damaged leaf area (severity), and yield (t ha -1 ). The microbial population resident in the phyloplan and fruits was quantified at the same time. There was no effect of treatments on yield, but an effect was observed on plant growth, on leaf spot and on the microbial flora. Copper oxychloride inhibited plant development, reduced number of fallen leaves and decreased the bacterial flora. Agrobio stimulated plant growth and, like streptomycin sulfate + oxytetracycline, inhibited the bacterial population, except Bacillus sp., and fungi, except Cladosporium sp. in the phyloplan. Among the genotypes, the hybrid Magali R was significantly superior in plant vigor, yield and resistance to bacterial spot. The results suggest bactericidal activity of the Agrobio under field conditions.

Resistência à mancha-bacteriana e características agronômicas de linhas recombinadas de Capsicum annuum L.

“…No entanto, para a área abaixo da curva de progresso da doença, estes valores estão de acordo com os apresentados por Silva et al (2006), que encontraram CV acima de 30% para avaliação da mancha-bacteriana em pimentão. A abscisão foliar, provocada pelo rápido avanço da doença, observada em algumas plantas suscetíveis, impossibilitando as avaliações subsequentes, e a segregação observada em algumas linhas, podem ter sido responsáveis por esse valor.…”

“…Os antibióticos, apesar de serem recomendados no início de ocorrência da doença, contribuem para a seleção de populações bacterianas resistentes aos princípios ativos dos produtos, para o aumento do risco de contaminação ambiental e do consumidor e oneram o custo de produção Cuppels et al, 2006;Silva et al, 2006;Marcuzzo et al, 2009).…”

Resistance to Xanthomonas spp. in Tomato: Diallel Analysis and Gene Effects Estimative in a Breeding Programme Carried out in Brazil

“…(Schaad and Stall, 1988; Jones et al., 1995, 1998, 2004; Hert et al., 2005), one of the main diseases of tomato. It can affect all above‐ground plant organs at any development stage while the field control is difficult (Lobo et al., 2005; Silva et al., 2006).…”

“…The economic losses caused by the disease could be minimized with the use of chemical products. However, there are several reports on the low efficiency of chemical substances, be it antibiotics or copper‐containing products, which is related with the emergence of new bacterial races (Gore and O’Garro, 1999; Lopes and Quezado‐Soares, 2000; Carmo et al., 2001; Aguiar et al., 2003; Quezado‐Duval and Camargo, 2004; Silva et al., 2006) or the development of bacterial strains tolerant to copper (Martin and Hamilton, 2004; Basim et al., 2005).…”

“…Genetic resistance is therefore the most appropriate alternative for controlling the bacterial spot (Berry et al., 1992; Lobo et al., 2005; Silva et al., 2006) and classical breeding for disease resistance has an important role to play in this issue (Strange and Scott, 2005), either by itself or associate with biotechnological approaches. The great genetic diversity of the causal agents of bacterial spot is the main problem to the development of tomato varieties with durable resistance (Quezado‐Duval and Camargo, 2004).…”