Resumen de Incidencia del saltahojas verde de la caña en siete cultivares de caña de azúcar, Estado Táchira, Venezuela

Humberto Giraldo-Vanegas, Herman Nass, Edith Hernández, Freddy Amaya, Alvaro Vargas, Miguel A. Ramírez Arrebato, Jorge Freddy Ramírez Pérez, Miguel Ramón, José O. Lindarte

• español

  Dada su importancia del saltahojas verde, Saccharosydne saccharivora (Westwood), se decidió establecer la reacción de los cultivares presentes en el Semillero Básico de Variedades Promisorias de Caña de Azúcar del INIA en la Granja Experimental CAZTA, Ureña. El diseño experimental consistió en bloques al azar, 4 repeticiones, 7 tratamientos. Se evaluaron los niveles poblacionales del insecto en los cultivares B 80-529, B 67-49, B 74-118, B 80-549, V 75-6, B 81-494 y V 71-39; mediante evaluaciones semanales, entre enero y abril de 2003, utilizando una escala visual del 0 al 100% correspondiendo el último a la lámina foliar completamente cubierta por las colonias del insecto. Los datos se analizaron estadísticamente con el Programa InfoStat, realizándose un Análisis de Varianza y comparación de medias con la Prueba de Tukey. Se detectaron diferencias significativas (P<=0,05) entre los cultivares, así, B 80-529 presentó los porcentajes más bajos, con un promedio del 10,00% de incidencia, seguida del B 67-49 con 25,46%, mientras que B 81-494 y V 71-39 tuvieron los más altos con 56,12% y 56,33%. Estos máximos niveles ocurrieron el 18/03/2003 con 81,33% y 79,33%, cuando se registraron menos precipitaciones y humedad relativa. Estos resultados sugieren que existe algún factor biótico en B 80-529 y B 67-49 que inhibe el desarrollo del saltahojas, así como un efecto negativo de la lluvia sobre dicha población.

• English

  The green leafhopper, Saccharosydne saccharivora, is the most important pest in the sugarcane crop of San Antonio-Ureña Valley in Táchira State, Venezuela. It is able to affect plants under six months of age, inducing direct and indirect damage. Lately, it was found that the insect is a vector for Yellow Leaf Syndrome. Consequently, a screening of the INIA sugar cane collection at Táchira state for its reaction to the insect was a critical goal to achieve. The collection is located at the experimental farm of the Táchira Sugar Mill (CAZTA) at San Antonio- Ureña Valley and includes cultivars B 80-529, B 67-49, B 74-118, B 80- 549, V 75-6, B 81-494 and V 71-39, which were evaluated. Experimental design was a random block with four repetitions and seven treatments. Eight weekly evaluations of leafhopper populations were conducted on first ratoon three month old plants from February to April 2003 where a scale ranging from 0% (absence of insect) to 100% (the whole leaf cover by leafhoppers) was used. ANOVA and Tukey tests were conducted by Infostat program. Results indicated significant differences (P<0,05) between cultivars for weekly evaluations and total averages. B 80-529 and B 67-49 had the lowest mean incidence (10% and 25,46% respectively) while B 81-494 and V 71-39 resulted with the highest means (56,12% and 56,33%). The highest values for B 81-494 and V 71-39 (81,33% and 79,33%) occurred during the third and fourth week (18/ 03/2003) when the lowest rain and relative humidity levels were observed. These results suggest the existence of a biotic factor in B 80- 529 and B 67-49 which deters leafhopper development as well a negative effect of rain on insect population.