La peca amarilla (Passalora koepkei U Braun & Crous comb nov) se ha presentado en Venezuela en las regiones cañeras con alta precipitación causando pérdidas económicas importantes en variedades susceptibles. Los síntomas se caracterizan por puntos cloróticos amarillos que crecen en forma redondeada y con el tiempo coalecen y se tornan rojizos. El objetivo de esta investigación fue estudiar el desarrollo de la enfermedad, la incidencia y la severidad en diferentes edades, época y conocer el comportamiento de la enfermedad en plantas con diferentes edades. Se utilizó la variedad de caña de azúcar V 84-19 susceptible a la enfermedad de la peca amarilla (Biosensor). Las diferentes edades de las plantas se obtuvieron mediante podas mensuales de 12 parcelas distribuidas en un diseño de bloques al azar con tres repeticiones sembradas en la estación Local Yaritagua del INIA Yaracuy. La severidad de la enfermedad fue evaluada mensualmente en la hoja TVD así como las dos superiores y las dos inferiores a ésta, con una escala diagramática. Los resultados indican, que la peca amarilla afectó el cultivo durante todo el año con una severidad variable, presentándose con mayor incidencia y severidad en los meses de Mayo a Octubre independientemente de la edad de la planta, siendo las hojas más afectadas las hojas inferiores a la TVD. Los análisis estadísticos indican que las hojas recomendadas para hacer evaluaciones de incidencia y severidad de la peca amarilla en la Caña de Azúcar, son la TVD y la inmediata superior e inferior.

The Sugar cane yellow spot (Passalora koepkei U Braun & Crous comb nov) occurs in Venezuela in areas with high relative humidity, causing serious losses when susceptible varieties are planted. Its symptoms are characterized by chlorotic yellow spot that increase their size becoming relish and coalescing. Economic losses may be between 10 to 40%, depending on the environmental conditions and the variety planted. The objective of the research was to study the epidemiology of this disease to provide information on disease incidence and severity on different leaves of the plant on susceptible sugar cane variety V 84-19. A randomized complete block design with three replications planted at INIA,s research station in Yaritagua, Venezuela was used. The different ages of plants were obtained through monthly pruning of the 12 plots. A diagrammatic scale was used to rate monthly damage on the TVD leave and two leaves located above and under it. Results indicate the disease occurs during all year, having its highest incidence and severity rates from May to October. Yellow spot symptoms were observed on all plant ages, affecting with higher severity the TVD leaf and the leaves immediately above and under it.

Em um latossolo, com teor de P disponível entre baixo e médio foi instalado um ensaio destinado a comparar a eficiência de um fosfato natural parcialmente acidulado (FAPS) com a do super simples (SS) e a do fosfato de Araxá (FA) original, na cultura da cana-de-açúcar (cana-planta). Os dados obtidos mostraram que: (1) o FAPS deu uma produção que não diferiu estatisticamente da obtida com o SS, sendo superior ao FA como fonte de P2O5; (2) os dados de diagnose foliar sugerem que o FAPS e o SS funcionam como fonte de P e de S; (3) o teor de açúcares redutores no caldo aumentou em consequência da adubação fosfatada; (4) o FAPS, na dose mais alta, elevou o teor de sacarose do caldo.

The relative efficiency of a partially acidulated and granulated rock phosphate, FAPS, containing 26% total P2O5, 10% citric acid soluble P2O5, 13% ammonium citrate soluble P2O5, 27% total CaO and 7% total S, was compared with that of both simple superphosphate (SS) and ground rock phosphate (FA). The experiment with the sugar cane variety NA 56-79 was set in a red yellow latosol, pH 5.1-5.5, low in P (4 ppm), and with and average available sulphur content (5 ppm as sul fate). The main conclusions were as follows: a) FAPS gave the same yield results provided by SS when used at the same rates based on total P2O5 content; b) sucrose content in the juice was increased by the highest level (16a kg P2O5 of application of FAPS; c) leaf analyses data suggest that FAPS has incre ased yield by supplying both P2O5 and S to the sugar-cane crop.