Bacterial Canker of Tomato, Bacterial Canker of Tomato

Abstract

Bacterial canker, caused by Clavibacter michiganensis pv. michiganensis, is a damaging disease of greenhouse-grown tomatoes in British Columbia. It affects both tomato seedlings at the propagation stage and tomato plants in the greenhouse. Since bacterial canker is very difficult to control once the symptoms are expressed it is important to monitor for early signs of the disease, get a proper diagnosis, and implement control strategies immediately if it is found in your greenhouse. Although tomato is the primary host of C. michiganensis pv. michiganensis the bacterium has also been reported to cause symptoms on sweet pepper, eggplant, and many weed species belonging to the family Solanaceae. Symptoms Seedlings – If tomato seedlings are infected during the propagation stage, symptoms may develop as cream-to-white, raised blisters or pustules on leaves and stems. These symptoms may resemble oedema, a physiological condition. However, in many cases, symptoms on infected seedlings go unnoticed (non-symptomatic) during propagation if the growing conditions are unfavourable for the pathogen. Under humid, hot conditions, wilting of infected seedlings (especially grafted seedlings) can be observed. Plants – Initial symptoms may appear as interveinal, pale-green water-soaked areas on leaves which quickly turn into yellow-brown to brown necrotic areas, resembling sun-burn. Infected plants begin to wilt, often just the lower leaves or just above the area of the stem/vascular tissue that is infected. It may look like the leaflets on only one side of a leaf are affected. Wilted leaves