Cucumber Leaf Spot Research Articles

Control of Angular Leaf Spot of Cucumber by Suppressing the Relative Humidity in the Plastic House

Control of Angular Leaf Spot of Cucumber by Suppressing the Relative Humidity in the Plastic House

Ｎ‐アシルアミノ酸エステルの植物病原菌生育阻害作用

Nα-cocoyl-L-arginine ethyl ester DL-2-pyrrolidone-5-carboxylic acid salts (abbreviation: CAE) was prepared by neutralization with pyrrolidone carboxylic acid after condensing fatty acids of coconut oil and L-arginine ethyl ester. Tests for protection of plant pathogens were performed because of wide antimicrobial action of CAE. As the results of investigation in laboratory, CAE in the medium had shown remarkable antimicrobial effects to anthracnose of banana, rust of broad bean, sheath blight of rice plant, black spot of pear respectively. Field tests were carried out and growth inhibitory actions to plant pathogens were clearly shown at such concentration as 500 μg/ml to chocolate or red spot of broad bean, 70 μg/ml to black spot of pear and scab of pear, 150 μg/ml to rust of pear, and 500 μg/ml to bacterial leaf spot of cucumber and downy mildew of cucumber. A slightly inhibitory action to powdery mildew of cucumber was also found.

Marginal Blight of Cucumber Caused by a Strain of Pseudomonas marginalis (Brown) Stevens

A bacterial disease was found on matured lower leaves of cucumber grown under vinyl house conditions in winter of 1974. The disease rarely occurred on inmature leaves soon after unfolding. The disease usually started from leaf edges near hydathodes and quickly enlarged to form V-shaped lesions frequently surrounded by chlorotic areas. These lesions finally coalesced to form the severe blight along the whole margin of the leaf. From these symptoms, “marginal blight of cucumber” was proposed as the disease name. The cultural and biochemical characters of the pathogen were compared with those of Pseudomonas lachrymans, the pathogen of angular leaf spot of cucumber. These two bacteria differed in the important characteristics such as production of fluorecin, degree of gelatin liquefaction, levan formation, margarine hydrolysis, arginine dihydrolase reaction, potato rot, and utilization of sucrose, sorbitol and tartarate. The marginal blight pathogen was rather close to soft-rotting pseudomonads in bacteriological properties. Although the similarity was not complete, therefore, we are inclined to identify the present bacterium as a strain of Pseudomonas marginalis (Brown) Stevens based on the detailed survey of pathological, cultural and physiological characteristics. The isolates of P. lachrymans used in the study showed also some conflicts in physiological properties with the description of the type culture suggesting the presence of strains in this bacterium.

Effectiveness of copper fungicides and streptomycin to the angular leaf spot of cucumber

Effectiveness of copper fungicides and streptomycin to the angular leaf spot of cucumber

Alternaria cucumerina . [Descriptions of Fungi and Bacteria

Abstract A description is provided for Alternaria cucumerina . Information is included on the disease caused by the organism, its transmission, geographical distribution, and hosts. HOSTS: On Citrullus lanatus, Cucumis melo, C. sativus, Cucurbita spp. DISEASE: Leaf spot of cucumber and melon (watermelon, musk melon, cantaloupe). Symptoms begin as yellow-brown flecks, 0.5 mm diam., on the upper surface of usually the crown leaves. They have a light green halo and gradually enlarge, becoming coalescent, with concentric ringing more commonly on the upper surface. Death of the leaves can be followed by lesions, several cm diam., forming on ripe fruit. These become covered with a dark, olive-green, conidial mass; they may be sunken and also show the concentric zonation. Infection of fruit in the field may be aggravated by exposure to sunlight (10: 431). Infection of stems or petioles does not occur. The pathogen can also cause decay in transit and storage, especially of melons and squash. GEOGRAPHICAL DISTRIBUTION: Arabia, Australia, Canada, Chile, Cuba, Cyprus, England, France, Japan, Kenya, Libya, Mozambique, New Zealand, Nigeria, Rhodesia, Rumania, Sierra Leone, South Africa, Sudan, Thailand, Trinidad, U.S.A., Venezuela, Zambia. TRANSMISSION: Seed may become contaminated with conidia. Survival from season to season is probably through mycelium in host debris. No air dispersal studies have been reported.

Pseudomonas lachrymans . [Descriptions of Fungi and Bacteria

Abstract A description is provided for Pseudomonas lachrymans . Information is included on the disease caused by the organism, its transmission, geographical distribution, and hosts. HOSTS: On Cucumis sativus and C. anguria . It may also attack C. melo var. inodorus (26: 140) and some other cucurbits. Elliott (31: 105) lists 10 hosts, all in the Cucurbitaceae . DISEASE: Angular leaf spot of cucumber. Small water-soaked spots appear on the leaves, petioles, stems, and fruits. On leaves they enlarge and become angular as they are delimited by veins They become tan to brown and the necrotic centres may fall out. On petioles, stems, and fruit spots develop white crusty bactenal exudate. A fruit rot develops if the bacteria penetrate deeply. GEOGRAPHICAL DISTRIBUTION: North and parts of Central America, most of Europe, U.S.S.R., China, Japan, W. Australia, Israel, southern Africa. (CMI Map 355, ed. 2, 1964). TRANSMISSION: The pathogen is seed-borne and infects the cotyledons dunng germination. It can overwinter on infected crop residue in the soil and has been found viable in dry leaf matenal after two and a half years (36: 677). The bacteria are carried from plant to plant within a crop by rain splash and probably by insects (Carsner, 1918; 31: 272). Workers can also spread the disease, particularly when foliage is wet with rain or dew (35: 810).

Corynespora 菌によるキウリ褐斑病について (予報)

Corynespora 菌によるキウリ褐斑病について (予報)

Occurrence and its control of angular leaf spot of cucumber

Occurrence and its control of angular leaf spot of cucumber