Ascochyta pisi Lebert., Ascochyta pinodes (Berk. et Blox.) Jones - Ascochyta Blight of Peas.

Systematic position.

Class Deuteromycetes (Fungi imperfecti), group of orders Coelomycetes, order Sphaeropsidales, family Sphaeropsidaceae, genus Ascochyta.


Teleomorph Mycosphaerella pinodes (Berk. et Blox. Stone) Vest. = Didymella pinodes (Berk. et Blox.) Petr.

Biological group.


Morphology and biology.

Ascochyta pisi, the agent of pale-spot blight, damages mainly beans and seeds, less often stalks and leaves. Rounded or oblong depressed spots are formed on beans, stalks, and leaves, having light centre and dark-brown edging. A. pinodes, the agent of dark-spot blight, damages all parts of plant. On leaves the fungus causes convex dark brown spots of various size and shape. The spots have no dark edging, and the centre is darker. Stalks have fine, dotty or lengthened ulcers. On beans the spots are dark brown, convex. Damaged root collar is brownish, having rot tissues. Both species form numerous pycnidia in the center of spots. Pycnidia are spherical, flattened, dark-brown, 143 to 287 microns in size. Pycnospores are colorless, oblong (A. pisi) or cylindrical (A. pinodes), with rounded apices, bicellular; their size is 9.6-19 x 3.3-6 microns in A. pisi, and 10-21 x 2.7-6.1 mkm in A. pinodes. The agent of A. pisi forms asci, and A. pinodes forms dark-brown pseudothecia with asci. Asci are club-shaped or cylindrical (50-75 x 11.5-13.5 mkm). Each ascus has usually 8 colorless roundish-elliptic bicellular ascospores. Diseased seeds and infected vegetation residues are the main source of the infection.


Ascochyta Blight is distributed everywhere on peas. It harms in Europe, in eastern parts of Canada and USA, in Japan, Morocco, Southern Africa, New Zealand, and Australia. In the former USSR it is harmful in Black Earth Zone, in southern and northwestern regions, in the Volga Basin region, and Siberia.


Infection of plants occurs at temperature 4.C and higher and at humidity 90% and higher. High development of the disease is observed at plentiful precipitations and temperature 20-25.C. The incubation period can vary from 2 to 4 days depending on temperature and species of the disease. At alternation of damp and dry weather the development of the disease slows down, and it stops completely at temperature higher than 35.C. The A. pisi disease incidence depends more on amount of the precipitations, and humidity 78-86% is sufficient for development of A. pinodes disease. The Ascochyta Blight of Peas is restricted to areas with sufficient or superfluous humidifications.

Economic significance.

The disease damage peas mainly. Harming activity is expressed in deterioration of germinating state of seeds and taste property of green peas, loss of shoots, and reduction of yield. The fungus can infect Lathyrus pratensis L., Cicer arietinum L., Pisum arvense L., Vicia sativa L., Lens esculenta Moench., Phaseolus vulgaris (L.) Sav., and others in addition to host plant. Control measures include sowing of healthy seeds in optimum terms, presowing seed dressing, fungicide treatments during vegetation, maintenance of crop rotation (return of peas in 3-4 years), use of grain predecessors, duly harvesting of seed crops, deep autumn ploughing, cultivation of resistant varieties.

Related references.

Balashova, N.N. 1964. Ascochyta blight of garden peas in Moldavia and its control. Kishinev. 18 p. (in Russian).
Bondartseva-Monteverde, V.N. & Vasil`evskii, N.V. 1937. Ascochyta blight of peas. Leningrad and Moscow: AN SSSR. 88 p. (in Russian).
Chumakov, A.E., Fratkin, A.B. & Vlasov Yu.I. 1962. Pests and diseases of the legumes. Leningrad and Moscow: Sel'khozgiz. 85 p. (in Russian).
Makasheva, R.Kh. 1973. The pea. Leningrad: Kolos. 312 p. (in Russian).
Mikheeva, R.I. 1976. Ascochyta blight of peas. Leningrad: Kolos. 53 p. (in Russian).

© Kungurtseva O.V.

Photo Kungurtseva O.V.

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