Resumen

JIMENEZ, O; CONTRERAS, N  y  NASS, H. Xanthomonas albilineans causal agent of sugarcane (Saccharum sp) leaf scald disease in states Lara and Yaracuy. Rev. Fac. Agron. [online]. 2004, vol.21, n.3, pp.233-245. ISSN 0378-7818.

In experimental and commercial fields of Lara and Yaracuy states were observed symptoms of leaf scald: Chlorotic leaf striation, straights lines with defined borders, variable thickness and red discoloration of vascular bundles in longitudinally split stalks. Isolations were made from this material, resulting in yellow bacterial colonies, rounded with uniform margin, gelatinous consistence and shining appearance. The pathogenicity test inoculations were made in healthy stocks. Two methods were compared: Internal stalks injection, and infiltration cotton using suspension bacterial, resulting the last methods mentioned, positive. Five days after the inoculations was observed internal red discoloration in stalk. In the reisolation identical colonies like the original ones were obtained. The bacteria isolated was: Gram negative, and seen through the optic microscope had a rod shape. It grew yellow in the cultures AN, YDC, YCA, AS, YSP, MW, XAS and D5. In D2, D3 and D4 the bacteria did not grow, it turned to be aerobic, basic reaction in red phenol dextrose agar, positive oxydase, positive catalase, negative nitrate reduction, tolerated concentrations of 0,5-1% NaCl, negative starch hydrolysis, positive growth at 35ºC-37ºC-, positive esculin hydrolysis, negative dihydrolase arginine, urease's production negative, partially liquated gelatin, indol's production negative, positive sulfide acid production, positive carbohydrate reduction of glucose and mannose and negative of arabinose, trehalose and cellobiose. The bacteria was identified as Xanthomonas albilineans.

Palabras clave : Sugarcane (Saccharum sp.); identified bacterial pathogen; Xanthomonas albilineans.