Diseases
Distribution and severity zone of Spring and Summer Black Stem and Leaf Spot of alfalfa (Ascochyta imperfecta Peck. =Phoma medicaginis Malbr. et Roum. var. medicaginis; Phoma herbarum West. var. medicaginis West. et. Rab.).
Object description Download GIS-layers
Authors:
Specialists-biologists T.I. Ishkova & E.I.Gultyaeva, GIS-specialist M.I.Saulich.Date of creation:
03.08.2004.Scale:
1:20 000 000.Accuracy of map:
It is created on materials of map of natural scale 1: 12 000 000 and 1: 33 000 000.Projection:
"Alber's Equal Area Conic for the USSR", 9, 1001, 7, 100, 0, 44, 68, 0, 0.Basic contents:
Vector map. It consists of two layers characterizing disease distribution and severity on alfalfa.Accuracy of the classifier:
Severity zone has been allocated in the former USSR in limits of alfalfa ascochytosis distribution zone. Regions have been included, where the disease distribution can exceed 15% with the disease severity more than 3-4 points (point 3 means that 25 to 75% of leaf surface is affected; point 4 . leaves wither) (Salunskaya, 1959; Nigmanova, 1967; Kobakhidze, 1977).Procedure of map drawing:
In published materials the Spring and Summer Black Stem and Leaf Spot is described as a widespread disease of alfalfa in all region of the crop cultivation. Zones of severity have been determined in regions where the disease causes significant losses. In Georgia the alfalfa affected in moderate and high severity can lose biomass by 25-55%, and seed yield by 46-62%. Under Middle Asian conditions the percent of defoliation increases with increasing point of the disease severity, reaching 63% at 4th point. After defoliation and shoot death the alfalfa hay yield can decrease by 27.5% on average. Seeds of diseased plants have low germinating ability, i.e., 65% on average. Definition of the disease distribution has been carried out on vector layer of alfalfa growing regions. The blank map with outlines of area and severity zone has been scanned. Registration and vectoring of raster map have been performed by standard tools of current GIS-technologies.Related references:
Dorozhkin, N.A., Pekel.naya, Т.S. 1985. Biology of Ascochitosis caused agent on alfalfa in BSSR. Doklady Akademii nauk BSSR 29(11): 1039-1041 (In Russian).Ganzhina, T.S. 1979. Ascochitosis and common leaf spot of alfalfa in Byelorussia. Abstracts of repots of science-practical conference "Ways of future improving of plant protection in Byelorussia and Baltic republics. Minsk, 27-28 February, 1976. Part 1. Minsk: 86-87 (In Russian).
Kabakhidze, P.A. 1977. Study of harmfulness of alfalfa ascochitosis in Georgia. Proceedings of abstracts of 8th Transcaucasian council session for coordination of research in plant protection. 14-16 December, 1977. Erevan: 39-40 (In Russian).
Karimov, M.A. 1980. Regularities of development of fungus fodder alfalfa diseases in dependence on ecological factors. Collection of scientific works of Tashkent Agricultural Institute. Diseases and pests of agricultural crops and protection measures. V. 89. Tashkent: 52-63 (In Russian).
Kovalenko, N.M. 1985. Alfalfa black stem in Stavropol Territory. Mikologiya i fitoptologiya 19(2): 150-153 (In Russian).
Nigmanova, S. 1965. Biology of Ascochitosis caused agent on alfalfa in Uzbekistan and protection measures. Abstact of PHD thesis.. Tashkent: Nauka (Uzbek SSR). 16 p. (In Russian).
Salunskaya, N.I. 1959. Ascochitosis of alfalfa in the USSR. Collection of scientific works of Ukrainian Research Institute. Diseases of agricultural crops. Kiev: Ukrainian Academy of Agricultural Sciences: 83-97. (In Ukrainian).
Salunskaya, N.I. 1976. Ascochytosis of alfalfa plants. Mikologiya i fitoptologiya 10(1): 37-41 (In Russian).
Samersova, V.A. 1982. Reaction of different alfalfa varieties to ascochitosis and common leaf spot in Byelorussia. Collection of scientific works of Byelorussian Research Institute of Plant Protection. Plant protection. V.7. Minsk: Urozhai: 127-140 (In Russian).
Strukchinskas, M. 1971. Caused agents of fungus alfalfa diseases in Lithuania and some other USSR republics. Materials of 1st conference for sporous plants of Ukraine (September, 1969). Kiev: Naukova dumka: 231-232 (In Russian).