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Species Page

bacterial speck

Pseudomonas syringae pv. tomato
This information is part of a full datasheet available in the Crop Protection Compendium (CPC). Find out more information on how to access the CPC.
©CAB International. Published under a CC-BY-NC-SA 4.0 licence.


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Host plants / species affected

Main hosts

show all species affected
Solanum lycopersicum (tomato)

List of symptoms / signs

Fruit - lesions: scab or pitting
Leaves - abnormal colours
Leaves - necrotic areas


Young leaf, stem, floral and fruit tissues are most susceptible. On leaves, stems, petioles, peduncles and pedicels, round spots develop which are dark brown to black with a narrow yellow halo. Spots on stems, petioles and peduncles are oval to elongated in appearance. Spots tend to aggregate towards the tip of the leaf. On fruit, very small black specks develop that are slightly raised. When small fruit are infected, the specks may be sunken.

Prevention and control

Cultural Control and Sanitary Methods

1. Disease-free seed should be used to reduce primary inoculum (seed treatment should be routine procedure);
2. Produce transplants in locations removed from production sites to reduce likelihood of inoculum introduction from old fields;
3. Do not plant in the same field two successive years;
4. Avoid clipping transplants or take extreme care to avoid secondary spread when thinning seedlings;
5. Do not work in fields when plants are wet;
6. Keep all production fields free of weeds and tomato volunteers following production season.

Chemical Control

Due to the variable regulations around (de-)registration of pesticides, we are for the moment not including any specific chemical control recommendations. For further information, we recommend you visit the following resources:


Bacterial speck is a significant source of economic loss in the tomato industry. Lesions may make fruit unfit for fresh market. On tomatoes for processing, lesions may be deep enough to cause considerable grading or loss in quality (Goode and Sasser, 1980). The severity of bacterial speck of tomato is closely related to weather conditions in the field. The disease develops and spreads only at temperatures between 13 and 28°C and at high relative humidity when there is free water on the leaves. In the field, yield losses varied from 75% in plants infected at an early stage of growth to 5% in plants infected later in the season (Yunis et al., 1980).

A serious outbreak of a leaf spot disease was observed on tomato transplants grown in commercial seedling companies in southwestern Turkey (Antalya) during the springs of 2002 and 2003. Disease incidence was more severe in the western mediterranean region of Turkey. Occurrence of the outbreak resulted in approximately 20 and 25% seedling losses in 2002 and 2003, respectively. In addition, in 2003, the disease incidence was approximately 5% in 142 commercial greenhouses. Tomato production was unaffected as significant outbreaks did not occur on greenhouse plants (Basim et al., 2004).