Diseases

Phyllosticta mali Prill et Del - Brown Spot on Leaves of Apple

Systematic position.

Division Deuteromycota, class Coelomycetes, order Sphaeropsidales, family Sphaeropsidaceae, genus Phyllosticta.

Biological group.

This species is a biotroph.

Morphology and biology.

The fungus over-winters on fallen leaves in teleomorph stage; in spring, conidia of the fungus disperse, causing primary infection of leaves. The primary infection is visible in the second half of May. Small at first; later indistinct brownish spots with dark brown limb appear on apple leaves. At the end of summer the center of the spot brightens; the tissue becomes thin and black pycnidia develop there (90-130 x 60-90 microns), forming conidiospores (cylindrical or ovoid, small-sized, unicellular, colorless, 5-8.5 microns long and 3-4.5 microns wide). Infection of various parts of apple tree can occur during the entire vegetation season.

Distribution.

The disease is widely distributed in all fruit-growing regions of the Russian Federation and other countries of the former USSR; but the disease does not demonstrate levels of harmfulness in all areas. Epiphytotic development of the Brown Spot of Apple (were infection reaches 50-100% one time every 2 years,) is observed in the Krasnodar and Stavropol Territories, in the Black Sea zone, Kabardino-Balkaria, Chechnya, Ingushetia, Alania. Moderate development of the disease (where infection reaches 30-50% one 1 time every 3 years) occurs in Byelorussia and some areas of Moldova. Low development (where infection reaches 10-30% one 1 time every 5 years) of the disease develops in the northern zone of Moldova, in the Far East.

Ecology.

The fungus develops under high levels of air humidity and at temperatures of 14 to 29.C. The optimum temperature for the fungus is 22-26.C. Mild winters promote good survival of the fungus; warm and wet summers strengthen the severity of the disease.

Economic significance.

Disease results in premature yellowing and falling of leaves. Photosynthetic activity of affected plants is reduced greatly during the seasons of maximum disease development. Methods of protection include the use of less susceptible plant cultivars, agronomical measures, and chemical control (fungicides).

Reference citations:

Ablakatova A.A. 1965. Mycoflora and the main fungal diseases of fruit plants in the south of the Far East. Moscow-Leningrad: Nauka. 146 p. (In Russian)
Byzova Z.M., Vasyagina M.P., Deeva N.G., Kalymbetov B.K., Pisareva N.F., Shvartsman, S.R. 1967. Flora of spore plants of Kazakhstan. V. 5. Part 1. Sphaeropsidales. Alma-Ata: Nauka. 339 p. (In Russian)
James P.W., Hawksworth D.L. 1971. Ainsworth & Bisby.s dictionary of the fungi. 6th Edition. Kew: CAB International. 663 p.
Koropatyuk E.E. 1974. Brown Spot on leaves of apples. Sadovodstvo, vinogradarstvo i vinodelie v Moldavii (Kishinev), 3: 36-38. (In Russian)
Kuntsevich L.V. 1976. Spot of apple. Fruit cultures. Minsk: Urozhai. 262-268 p. (In Russian)
Sevryukova M.V. 1980. Epiphytoty of Brown Spot of apple. Sadovodstvo, vinogradarstvo i vinodelie v Moldavii (Kishinev), 2: 47-48. (In Russian)
Sheliya T.G. 1954. Spots of apple leaves. Works of experimental station of orcharding. V. 3. Tbilisi: AN Georgian SSR. 249-255 p. (In Russian)
Smolyakova V.M. 1970. About harmfulness of phyllostictous spots of apple in Kuban region and features of construction of its control. Problems of a gardening of Northern Caucasus (abstracts of conference). Krasnodar: SZNIISV, KKNTOSKH. 161-163 p. (In Russian)
Smolyakova V.M. 2000. Fungal diseases of fruit trees of South Russia. Krasnodar: Vesty. 192 p. (In Russian)
Zhukova V.D. 1964. Brown Spot of Apple and measures of its control. Works of Krasnoyarsk research institute of agriculture. V. 2. Krasnoyarsk: Krasnoyarsk Publishing House. 163-164 p. (In Russian)

© Bilder I.V.