Diseases

Colletotrichum glycines Hori (C. truncatum (Schw.) Andrus et W.D. Moore, C. dematium (Pers. ex Fr.) Grov var truncatum (Schw.) Arx) - Anthracnose of Soybean

Systematic position.

Class Deuteromycota, superorder Ceolomycetes, order Melanconiales, family Melanconiaceae, genus Colletotrichum

Biological group.

This is a saprobiont.

Morphology and biology.

The fungus Colletotrichum glycines Hori causes damage to all plant organs. Sowing of infected seeds causes a significant part of the sprouts in ground to perish. Brown depressed ulcers form on cotyledons. Dark brown spots or strips appear on root neck, on radical part of stem. The fungus spreads later to young petioles and stems, forming oblong cracking spots with sporification. Breaking of petioles and stems is sometimes observed at places of affection. On beans the spots are small in the beginning, bordered with brown limbs, then going deep, increasing in size, and merging. Valves of beans are destroyed, and the disease affects seeds. Conidial sporification of the fungus is visible on all affected organs, forming small spots with numerous black setae. Affected seeds are covered with dense gray bloom of mycelium and sporification, having no setae. Pads are cream-colored, with numerous dark-brown pointed setae reaching 300 microns in length. Conidia are colorless, slightly bent, lanceolate, 18-30 x 3-4 microns in size. Sources of the infection are infected seeds and vegetation residues keeping mycelium, chlamydospores, and conidia of the fungus. In the cycle of fungus development its local populations only have conidial stages. Several generations of conidial sporification develop during a season.

Distribution.

The Anthracnose of Soybean is distributed in Japan, China, India, USA, Brazil, Columbia, France and Moldova. In Russia it is found in the Far East and the Krasnodar Territory.

Ecology.

Rainy weather in spring and summer promotes high severity of the Anthracnose to Soybean. Optimum temperature for growth of mycelium and formation of conidia is 28-30.C.

Economic significance.

The fungus can infect Phaseolus vulgaris (L.) Sav., Lotus spp., Medicago sativa L., and Trifilium pratense L. in addition to soya. The Anthracnose can cause reduction of weight of plants, amount and weight of beans and seeds down 2 times and more. Qualitative characteristics of soybeans are worsened; content of oil and protein is reduced by 1.8-2.1%. Control measures include crop rotation, autumn plowing along with burying of vegetation residues, seed dressing, fungicide spraying of plants during vegetation period, use of resistant cultivars, duly mode of irrigation.

Reference citations:

Pidoplichko N.M. 1977. Fungal parasites of cultural plants. Guide. V. 2. Kiev: Naukova Dumka. 299 p. (In Russian)
Podkina D.V. 1986. Harmfulness of Anthracnose of Soybean. Scientific and technical bulletin VNII oil-bearing crops. Krasnodar: VNIIMK. Issue 4 (95): 41-42. (In Russian)
Prostakova Zh.G., Ganya A.I. 1983. Fungal diseases of soybean and their control. Kishinev: Shtiintsa. 35 p. (In Russian)
Zaostrovnykh V.I. 2005. Diseases of soya. Zashchita i karantin rastenii (Moscow) 2: 49-53. (In Russian)
Zhukovskaya S.A., Serebrennikova N.I., Kulikova L.S. 1990. Diseases of soya in the Far East. Zashchita rastenii (Moscow) 10: 42-45. (In Russian)

© Kungurtseva O.V.