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Plantwise Technical Factsheet

canker of tomato (Didymella lycopersici)

Host plants / species affected
Capsicum (peppers)
Solanum lycopersicum (tomato)
Solanum melongena (aubergine)
Solanum nigrum (black nightshade)
Solanum tuberosum (potato)
List of symptoms/signs
Fruit  -  lesions: black or brown
Fruit  -  mummification
Leaves  -  yellowed or dead
Stems  -  discoloration of bark
Stems  -  mycelium present
Whole plant  -  plant dead; dieback
The initial symptom is usually a dark-brown, sunken lesion which eventually may girdle the stem just above soil level (Jones, 1991). Secondary cankers may develop later, higher up the stem. The soft, outer diseased tissue contains numerous conidiomata and, in damp conditions, conidia are extruded in slimy pink masses (Holliday and Punithalingam, 1970).
Prevention and control
Cultural Practices

Avoid wounds and high rates of watering. Remove diseased plants. Debris from the previous season's crop should also be removed and destroyed. In glasshouses the humidity should be kept below 90% RH and the temperature above 15°C (Verhoeff, 1962; Fagg and Fletcher, 1987; van Steekelenburg, 1988). Solarization of soil and of the reed canes (Arundo donax) or Eucalyptus stakes used to support tomatoes reduces disease incidence (Besri, 1983; Cartia, 1989; Besri, 1991).

Host-Plant Resistance

Resistance to D. lycopersici on F3- and Bc1-lines from interspecific crosses of L. esculentum with L. hirsutum and with L. hirsutum f. glabratum is not monogenic and is inherited in a dominant fashion (Boukema, 1982). Tomato grafting on the hybrid KNVF has shown resistance to D. lycopersici (Ginoux et al., 1978) but there is no tomato cultivar with complete resistance to the disease (Fagg and Fletcher, 1987).

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:

Biological Control

Trichoderma harzianum strain VKM F-2477D gives good control of D. lycopersici and results in yield increases (Grin'ko, 1997). Favaron et al. (1993) demonstrated inhibition of D. lycopersici polygalacturonase by Allium cepa and A. porrum extracts.
D. lycopersici occurs sporadically in Europe and New Zealand. Modern techniques used in tomato production (culture in nutrient solutions and rockwool) have eliminated soil as a source of inoculum and have, therefore, reduced disease incidence. Despite this, localized outbreaks do occur: in one glasshouse in West Sussex, UK, 105 basal lesions (affecting 12% of the tomato plants) were recorded in June 1985, 6 months after the plants were established on rockwool (Fagg and Fletcher, 1987).
Related treatment support
Plantwise Factsheets for Farmers
Burgos, O.; Orquera, T.; Balderrama, A.; Villarroel, B.; CABI, 2012, Spanish language
Burgos, O.; Orquera, T.; Balderrama, A.; Villaroel, B.; CABI, 2012, English language
Ding, S.; CABI, 2014, Chinese language
Pest Management Decision Guides
Gekone, J. M.; Too, A.; CABI, 2016, English language
External factsheets
Crop Science Extension & Outreach Factsheets, College of ACES, University of Illinois, Urbana Champaign, USA, 2013, English language
Ohio State University Extension Fact Sheets, The Ohio State University Extension, English language
Ontario CropIPM factsheets, Ontario Ministry of Agriculture, Food and Rural Affairs, Canada, 2015, English language
Ontario CropIPM factsheets, Ontario Ministry of Agriculture, Food and Rural Affairs, Canada, 2015, French language
PlantVillage disease guide, PlantVillage, English language
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