Diseases

Alternaria solani (Ell. et Mart.) Sor. - Early Blight of Tomato

Systematic position.

Division Ascomycota, order Dothideales, family Pleosporaceae, genus Alternaria.

Synonym.

Macrosporium solani Ell. et Mart.

Biological group.

Facultative parasite.

Morphology and biology.

Leaves, petiole, stems and fruits of tomato are affected. Infection begins on the lower leaves in form of large dark brown spots that are 5-15 mm in diameter; the spots are well pronounced and covered with brown velvety bloom of sporification. In damp weather the spots coalesce, and leaves die off. Lengthened dark spots with velvety bloom are formed on petioles and stems, and black concave blooming spots on fruits. Conidiophores reach up to 110 microns in length, 6-10 microns in thickness. Conidia are dark, obclavate, multi-cellular, with transverse and longitudinal septa, 90-140 x 12-20 microns in size. The infecting agent also affects potato, eggplants, and other solanaceae family cultivars.

Distribution.

The disease was revealed for the first time in the former USSR in the Kursk Region in 1901. Now it is distributed everywhere in zones of tomato cultivation. The greatest harm occurs in the Far East, on Sakhalin, in Eastern Siberia, and also in Byelorussia, Moldova, Ukraine, Tambov, Orel, Belgorod, Smolensk, Volgograd, Rostov, Saratov, Astrakhan Regions, Kabardino-Balkaria, and Uzbekistan. Everywhere the infection of plants reaches 100%, and reduction of yield is up to 50%.

Ecology.

Mycelium and conidia are sources of infection; they stay on affected vegetation residues in ground. Optimum temperature for the fungus development is 24-30.C. Incubation period is 3-4 days. The disease development is promoted by an alternation of hot dry weather and rains or night dews.

Economic significance.

Owing to premature drying and dropping of leaves the yield of tomatoes is sometimes reduced by 20-50%. Control measures include the destruction of vegetation residues; deep autumn plowings after harvest; maintenance of crop rotation with the return of tomatoes to the field after at least 3 years; disinfection of ground in hotbeds; spraying of plants by fungicides if necessary; cultivation of resistant varieties.

Reference citations:

Hawksworth D.L., Kirk P.M., Sutton B.C., Pegler D.M. 1995. Ainsworth & Bisby.s Dictionary of the fungi. CAB International. 616 p.
Kulakov L.F. 1963. Pests and diseases of potato and tomatoes. In: Kulakov L.F., ed. Pests and diseases distribution on agricultural crops in Tuva ASSR in 1962 g. and the forecast of their appearance in 1963. Kyzyl: Tuva Publishing House. 35-36 p. (In Russian)
Natalenko G.S., Sorokina V.K. 1966. Pests and diseases of tomatoes. In: Sorokina B.L., ed. Pests and diseases distribution on agricultural crops in Rostov Region in 1966 and the forecast of their appearance in 1967. Rostov-na-Donu: RostovSTAZR, Don NIISKH. 46-47 p. (In Russian)
Osnitskaya E.A. 1968. Diseases of vegetables. In: Polyakov I.Ya., Chumakov A.E., eds. Pests and diseases distribution on agricultural crops in RSFSR in 1967 and the forecast of their appearance in 1968. Moscow: Rosselkhozizdat. 120-125 p. (In Russian)
Osnitskaya E.A. 1969. Diseases of vegetables. In: Polyakov I.Ya., Chumakov A.E., eds. Pests and diseases distribution on agricultural crops in RSFSR in 1968 and the forecast of their appearance in 1969. Moscow: Rosselkhozizdat. 137-144 p. (In Russian)
Osnitskaya E.A. 1970. Diseases of vegetables. In: Polyakov I.Ya., Minkevich I.I., eds. Pests and diseases distribution on agricultural crops in RSFSR in 1969 and the forecast of their appearance in 1970. Moscow: MSKH RSFSR, VIZR. 252-263 p. (In Russian)
Osnitskaya E.A. 1971. Diseases of vegetables. In: Polyakov I.Ya., Minkevich I.I., eds. Pests and diseases distribution on agricultural crops in RSFSR in 1970 and the forecast of their appearance in 1971. Moscow: MSKH RSFSR, VIZR. 187-198 p. (In Russian)
Pavlov N.K. 1973. Pests and diseases of vegetables. In: Pavlov N.K., ed. Pests and diseases distribution on agricultural crops in Smolensk Region in 1972 g. and the forecast of their appearance in 1973 and their control. Smolensk: SmolenskSTAZR. 45-54 p. (In Russian)
Poliksenova V.D. 2001. The retrospective review of tomato diseases in Byelorussia and prospect of development phytopathologic situation. In: Soroka S.V., ed. Plant protection on a boundary of XXI century. Materials of scientific practical conference devoted to 30 anniversary of BelNIIZR. Minsk: Belbiznespress. 225-228. (In Russian)
Saichuk A.I. 1989. Estimation of harmfulness of Alternaria solani on initial selection tomatoes. In: Ershova V.L., ed. Selection, agriculture and irrigation of vegetable cultures. Kishinev: Shtiintsa. 114-117 p. (In Russian)
Shapova A.P. 1966. Alternaria on tomatoes in conditions of Uzbekistan and its control. PhD Thesis. Tashkent: Tashkent GU. 20 p. (In Russian)
Verderevskii D.D., Kuporitskaya K.I., Stanko A.I., Okhova V.P. 1968. Tomato diseases. In: Verderevskii D.D., ed. Reference book for agronomists on plant protection. Kishinev: Kartya Moldovenyaske. 305-326 p.
Zarutskii M.M. 1972. Biological features of agents of macrosporiosis and septoriosis of tomatoes and their control in condition of Byelorussia. PhD Thesis. Minsk: BelNIIZR. 20 p. (In Russian)

© Khlopunova L.B.