Pseudomonas syringae pv.lachrymans (Smith and Bryan) Yong et al. - Angular Leaf Spot of Cucumber.

Systematic position.

Kingdom Procaryotae, section Gram-negative aerobic rods and cocci, family Pseudomonadaceae, genus Pseudomonas.


Bacterium lachrymans E.F. Smith and Bryan, Bacillus lachrymans (E.F Smith and Bryan) Holland, B. Burgeri Potebnia, Phytomonas lachrymans (E.F Smith and Bryan) Bergey et al., Pseudomonas lachrymans (E.F Smith and Bryan) Carsner.

Biological group.


Morphology and biology.

Bacteriosis attacks cotyledons, leaves, flowers, and fruits. It presents as fine light brown spots on cotyledons. Then this lesion passes to all surfaces of the cotyledon. Infected shoots have spoiled cotyledons which usually perish. The disease is shown on leaves as angular, oily brown spots. Such spots can embrace significant area of leaf surface. The infected tissue is friable and leaves become holey. Bacteriosis causes ulcers on fruits. Young fruits are bent and become deformed. The exudate appears on ulcers in damp weather. Cells P. syringae pv.lachrymans are straight bacilli, usually 0.8-1.0 x 1.0-2.0 mkm, moving by means of 1-5 polar flagella. Gram-negative. Forming levan. Colonies on nutrient mediums are round, albesent, smooth, brilliant, with thin even border. Diluting gelatin. Curtailing and peptonizining milk. Not restoring nitrates. Not forming indol and H2S. Producing acid on media with glucose, fructose, arabinose, xilose, saccharose, and mannitol; not fermenting maltose, ramnose, lactose, raffinose, glycerin, and salicin. Optimum temperature of growth is 25-27°C, minimum 1°C, maximum 35°C. The pathogen primary infection survives in the vegetation residues and in seeds.


Bacteriosis is distributed in all territories of the former USSR where this culture is growing in both open and closed ground.


High temperature (25-30°C) and relative air humidity 90% and higher is favorable for the infection development.

Economic significance.

Pathogen parasitizes on plants of the family Cucurbitae only. Yield losses depend on a cultivated variety and on conditions of cultivation of plants. In the Kaliningrad Region, about 60-65% of plants are diseased. In the Republic of Mordova 30-40 % plants are infected and 14% of fruits are diseased. In Ussuriisk and Chuguevka districts of Primorskii Territory, lesion of plants of early planting reaches 100%; in the Amur Region, lesion of fruits is to 40%; in Sakhalin Region to 90% of plants are diseased. In the Central Black Earth (Kursk and Voronezh Regions), Central (Kaluga and Moscow Regions), North-Caucasian (Krasnodar and Stavropol Territories) zones, and in the Chita Region, about 30-90% of plants are diseased. In Ukraine, 25 to 90% of plants are infected, depending on cucumber variety and area of cultivation. The lesion of plants exceeds 25-35% in Belarus. In Azerbaijan, the bacteriosis attacks 16.6-25.7% of plants depending on a cultivated variety. Amount of diseased plants is 60% and more (at development 16%) in Kazakhstan. Control measures include a complex of various agronomical actions directed at cultivation of healthy plants. These are maintenance of crop rotation, correct entering of mineral fertilizers (with prevalence of potash), pesticide treatment of seeds before sowing, treatment of plants during vegetation by pesticides and by complex of micro-elements, careful destruction of vegetation residues, and selection of resistant varieties.

Reference citations:

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Bushkova L.N. 1962. Pathogen of bacteriosis of cucumbers Pseudomonas lachrymans (Smith et Bryan) Ferraris and its properties. Nauchnye doklady Vysshei shkoly. Biologicheskie nauki 1: 165-169 (in Russian).
Dorozhkin N.A. & Sapogova A.A. 1968. About actions on protection of cucumbers from bacteriosis in the closed ground. News of Academy of sciences BSSR. A series of agricultural sciences. Minsk: Nauka i tekhnika, p. 74-77 (in Belorusian).
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