Friday, July 8, 2011

A Few Tomato Diseases Seen at the U of I Plant Clinic this Week and How to Manage Them.

We confirmed 2 tomato samples from Cook County Illinois with TMV (Tobacco Mosaic Virus).  More information about this disease can be found at:  TMV -

How to manage TMV:
Rouge out the affected plants and sterilize pruning equipment. The virus is soil-borne, so crop rotation should be used to reduce the levels of inoculum. Avoid planting tomatoes, potatoes, peppers, and other solanaceous crops in the affected area for several years. Control solanaceous weeds, including jimpson weed as well as nightshade. Resistant varieties of tomato are available.

Septoria leaf blight is one of the most common diseases of tomato.  I have also two samples of tomatoes infected with this disease this week.  A University of Illinois publication about this and other tomato leaf diseases can be found at Tomato leaf diseases -  

How to manage Septoria leaf blight:
Due to the wet weather earlier this season, Septoria leaf spot has been particularly severe. To control Septoria leaf spot in the current growing season, remove infected plant parts and consider spraying weekly with an approved fungicide (or just accept losses). Be sure to avoid overhead irrigation which spreads disease, and stake plants to improve air circulation within the canopy. At the end of this season destroy all plant material. Rotate to a non-host crop next year. Products containing chlorothalonil (Bravo or Terranil, or others), copper, mancozeb (Dithane or pencozeb), or maneb are registered for use on tomato. Be sure to abide by the label you choose, especially the days between spraying and harvest.  Additionally, saving seed from season to season may increase disease because seed infection is possible with Septoria lycopersici.

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