Sugarcane smut development models. 2. Polyetic curves of disease progress
1991
Amorim, L. (Sao Paulo Univ. (Brazil). Dept. of Plant Pathology) | Bergamin Filo, A.
Sugarcane smut progress was evaluated for five consecutive years on inoculated and non-inoculate cultivars 'NA56-79', 'SP71-799', 'SP71-1406', 'SP71-6163', and 'SP70-1143'. The evaluation of disease progress was always conducted starting from stool sprouting and proceeded, at regular intervals, during the whole crop cycle, when the cumulative number of apical whips and the total number of tillers of each plot were counted. With the data generated in these evaluations, polyetic curves of disease progress were constructed using the highest cumulative value obtained in each year of observation. The curves relating to the control treatment showed a constant increase in disease amount between plantcane and third ratoon and a decrease between the third and fourth ratoons. The tillering curve showed a similar behavior during the same period. In the treatment with inoculation, the decrease in disease incidence was observed as early as the second ratoon on cultivars SP, although the tillering curve exhibited an ascending slope in that same period. The maximum number of whips produced in the inoculated cultivars represents the constant asymptote of each cultivar, and is associated with the resistance of these materials
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