Abstract
Southern corn leaf blight (SCLB) is one of the most important corn leaf diseases. Appropriate management strategies and the use of resistant cultivars allow disease control. Therefore, knowing the aspects related to the pathogen and the response of hosts makes it possible to design efficient strategies for selecting genotypes resistant to this disease. In this sense, the objective was to carry out the Bipolaris maydis isolate characterization, evaluating the pathogenicity in different popcorn lines and the symptoms generated in the host after inoculation. The isolate characterization consisted of the macromorphological evaluation of the colonies and the micromorphological evaluation of the conidia in the PDA medium. An experiment was carried out in a greenhouse to evaluate the pathogenicity of the isolate, using 20 inbred lines of popcorn in a randomized block design with four replicates. Inoculation was carried out by spraying leaves, with a suspension containing 1.0 x 104 conidia.ml-1 of the CF/UENF 501 isolate of B. maydis. An incidence assessment and three assessments of disease symptom severity were performed, with seven days intervals between evaluations. The morphological characterization data of the isolate were analyzed using descriptive statistics, and for disease severity, the linear regression model was applied the first-degree model. The variance analysis was performed for the linear and angular coefficients obtained for each treatment. When a difference was found, the Scott-Knott clustering algorithm at 5% significance was applied. The isolate had gray-green colonies, a cottony appearance, and an irregular shape. The lines L353, L354, and L624 show more resistance at the beginning and throughout the evaluations. The high virulence of the CF/UENF 501 isolate made it possible to differentiate the lines in terms of disease intensity and the pattern of symptoms presented.
Highlights
IntroductionThe species Bipolaris maydis [(Nisikado and Miyake) Shoem] (teleomorph: Cochliobolus heterostrophus) causing southern corn leaf blight disease (SCLB) is an important pathogen that affects the Zea mays species in warm, humid regions of the world (White, 1999)
The species Bipolaris maydis [(Nisikado and Miyake) Shoem] causing southern corn leaf blight disease (SCLB) is an important pathogen that affects the Zea mays species in warm, humid regions of the world (White, 1999)
This study aimed to characterize the CF/UENF 501 isolate of B. maydis regarding its morphology, pathogenicity in different popcorn lines, and the symptoms generated in the host after inoculation
Summary
The species Bipolaris maydis [(Nisikado and Miyake) Shoem] (teleomorph: Cochliobolus heterostrophus) causing southern corn leaf blight disease (SCLB) is an important pathogen that affects the Zea mays species in warm, humid regions of the world (White, 1999). The yield loss occurs due to leaf surface lesion increase, compromising the photosynthetic area of plants (Agrios, 2005). When favorable environmental conditions provide the multiplication of pathogens, the yield of susceptible maize genotypes can be reduced by more than 70% (Ali et al, 2011). Utilizing chemical control and resistant genotypes are the primary forms of control (Pate et al, 2017). The high cost of fungicides and the problems they can cause to the environment point out the use of resistant cultivars as the best control disease measure. It is noteworthy that there are no registered products for the control of B. maydis
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