Root and Foot Rot on Tomato Caused by Phytophthora infestans Detected in Belgium

In January 2003, a severe root and foot rot was observed on 2-month-old wilted tomato (Lycopersicon esculentum Mill.) plants in a large-scale (2.5 ha) commercial greenhouse setting in Belgium. Tomato plants (10%) produced from healthy nursery-grown seedlings and planted to new, clean rockwool and drip irrigation with UV-disinfected water developed symptoms. Symptom development was restricted to lower plant parts with severe rotting of the entire root system and dark lesions girdling the stem base. No symptoms of disease were observed on the foliage or upper stems. Cross sections of the stem base revealed brown discoloration of internal tissue, including the vascular tissue and pith. Dark brown lesions also occurred on the roots. Sections of the stem base, the upper roots (sampled near to the stem base), and the lower roots (sampled on roots deeper in the rockwool) were plated separately on corn meal agar. The oomycete pathogen Phytophthora infestans (Mont.) de Bary was identified in each sample on the bas...