Glomevella cingulata (Stonem.) spauld. et v. schrenk. F. SP. phaseoli N.F., fase ascógena do agente causal da antracnose do feijoeiro

Abstract

This paper deals with the perfect stage of Colletotrichum lindemuthianum (Sacc. et Magn.) Scribn. Two isolates which formed fertile perithecia when paired were used to determine some enviromental conditions favorable to sexual reproduction; perithecia were formed in a semi-synthetic medium contaniming glucose, Ca (N0(3)) 2. 4H(2)0, MgSO4. 7H(2)0, KH2PO4, agar (20g/l) and water (1 liter); the favorable quantity of glucose and Ca(NO3)2.4H2O was, respectively, 4-10 and 0,15-0,60 g/ 1, maintaining a C/N ratio between 29,8:1 and 89,6:1; when vitamins were added to the medium, the favorable quantity of Ca(NO3)2.4H(2)0 varied from 0,3 to 1,0 g/1, maintaining the quantity of glucose and the C/N ratio approximately the same; the most favorable quantity of KH2PO4 and MgSO4.7H2O, were, respectively, 0,1-0,5 and 0,5-1,0 g/1; light was inhibitory to sexual reproduction, fertile perithecia being obtained only in conditions of continuous darkness or when the periodo of light do not exceed the first 3 days of incubation; the pH range favorable to fertile perithecia formation was 4,0 to 6,0; high humidity was important for beaked perithecia formation and for ascospores ejection. In paired cultures, the conidial isolates behaved as heterothalic, fertile perithecia being formed only in determinate matings; some matings resulted in few fertile perithecia; others gave rise to perithecia with asci only, or to protoperithecia only. Morphologically the ascogenous stage of C.lindemuthia num fell into the broad description of Glomerella cingulata. Since C.lindemuthianum is pathogenic only to Phaseolus spp.it is proposed for the perfect stage the name Glomerella cingulata (Stonem.) Spauld. et v.Schrenk. f.sp.phaseoli n.f.