Alguns fungos da mandioca. II

Diseases of Cassava (Manihot esculentaCrantz)

“…have been reported (Sydow, 1913;Vincens, 1915;Reinking, 1919;Viegas, 1943a;CIAT, 1972) as inducing the same disease syndrome. Vincens (1915) first described the causal agent as Haplographium maníhoticoJa Vincens, but the pathogenicity of this fungus was later questioned by Viegas I 1943a) .…”

“…During rainy seasonS and when the temperature is below 22°C, this disease may cause severe defoliation of susceptible varíeties, finally resulting in die-back of the plants. The disease has also been reported to Qccur on Manihot heptaphy/Ja, M. dicho toma IReinking, 1919, Viegas, 1943a and M. aipi ISpegazzini, 1913;Viegas, 1943a) …”

“…occurs through stomatal cavities and invasion of the tissues through intercellular spaces. In warm, humid conditions infection usually occurs within twelve hours (Wallaee, 1931;Cilerri, 1933, Viegas 1941, 1943a, 1943bChevaugeon, 19561. When these lesions mature, conidiphores are produced from the sto mata. Secondary disease cycles are repeated throughout the rainy season whenever conidia are carried to new sites of infection by wind or rain.…”

“…Significant differences in varietal resistance have be en reported in Africa (Chevaugeon, 1956;Umanah, 19701. Brazil (Viegas, 1941, 1943a and in the extensive eolleetion 01 eassava varieties at CIAT, Colombia (CIAT, 19721. White leaf·spot (e. canbaea) is commonly found in the humid but cooler cassava-growing regions and has been reported in certain areas of Asia, North America, tropical Africa, and Latín America (Viegas, 1941;Viennot·Bourgin andGrimaldi, 1950, Chevaugeon, 1956;Castaño, 1969;CIAT, 1972).ln these areas this pathogen may cause considerable defoliation of susceptible varieties of M. escu{enta, the only reported host species (Viegas, 1941;Chevaugeon, 19561. C. caribaea forms slight stromata in infected leaves from which conidiophores are produced in loase fascicles. The conidiophores which emerge through sto mata are usually olivaceous brown, uniform in colour and width; rare!y branched, 1-15 genicu!ate, sub-truncate al the1ipwith a fair!y !arge spore scar and measure 3-5 x 50-200 ¡l.…”

Alguns fungos do Brasil: XIII - Hifomicetos

“…VI eretos, isolados ou em grupos, 0-1 septados, de base fusca, cilíndricos, 40-80 x 4-5 [x, simples ou ramificados. Conídias obclavuladas, septadas, lisas, hialinas, [28][29][30][31][32][33][34][35][36] x 8 -9 [x, Ã base, as conídias trazem um apendículo típico, portador da cicatriz de inserção. 32 -Sobre Stenotaphrum glàbrum Trind., (grama inglesa), leg.…”