{"id":4626,"date":"2011-03-21T10:10:18","date_gmt":"2011-03-21T14:10:18","guid":{"rendered":"http:\/\/extension.umaine.edu\/ipm\/"},"modified":"2021-08-31T16:18:45","modified_gmt":"2021-08-31T20:18:45","slug":"5088e","status":"publish","type":"page","link":"https:\/\/extension.umaine.edu\/ipm\/ipddl\/publications\/5088e\/","title":{"rendered":"Septoria Leaf Spot of Tomato"},"content":{"rendered":"

\n \n \"Print\n <\/a>\n <\/div><\/h3>\n

Pest Management Fact Sheet #5088<\/h3>\n

Authors: Dr. Alicyn Smart, Dr. Bruce Watt, and Abigayl Novak<\/em><\/p>\n

For information about UMaine Extension programs and resources, visit extension.umaine.edu<\/a>.
\nFind more of our publications and books at extension.umaine.edu\/publications\/<\/a>.<\/strong>
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Pathogen:<\/strong>\u00a0Septoria lycopersici<\/em><\/h4>\n

Introduction<\/h3>\n
\"Infected<\/a>
Figure 1. Infected fruit. Fruits are rarely infected. Photo by Dr. Bruce Watt.<\/figcaption><\/figure>\n

Septoria leaf spot is one of the most common foliar diseases of tomato in Maine. It can be highly destructive, given the proper conditions and has been known to cause complete crop failure. Although the causal fungus will not directly infect the fruit, losses are the result of defoliation, which can lead to the failure of fruit maturation and sunscald of exposed fruit.<\/p>\n

The disease usually begins to be seen in early to mid-August when the foliage has become sufficiently dense, restricting air movement within the canopy. After canopy closure, the humidity remains high, and any free water on leaf surfaces tends to dry more slowly. Infection can occur when the relative humidity has been at 100% for more than 48 hours. These conditions are cumulative and can be spread over several days. The optimal temperature range for Septoria<\/em> is between 68\u00b0F and 77\u00b0F. The disease usually starts on the lowest leaves where the humidity tends to be the highest and where the fungal spores are most likely to land.<\/p>\n

Septoria survives the winter on infected plant debris, including tomato and related plants. The fungus may also be transmitted by infected seed and spores can be present around growing facilities such as greenhouses, cold frames, flats, etc. Where spores have survived the winter, initial infections may begin early in the year. Otherwise, infection is delayed due to the fungus not sporulation below 59\u00b0F. Spores are splashed by rain, blown by the wind, or carried by insects and other animals (including humans) and once the initial infection as started the fungus can produce new spores which rapidly increases the rate at which the disease spreads.<\/p>\n

Host Plants<\/h3>\n

Tomatoes, ground cherries, and some Solaneceous weeds<\/p>\n