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Disease Note.

Phytophthora nicotianae var. parasitica, a Pathogen of Pepper in Tunisia. M. B. Allagui, Laboratoire de Cryptogamie, INRAT. Rue Hedi Kar-ray. 2080 Ariana, Tunisia. J. Tello-Marquina. INSPV Ctra. de La Coruna, Km 7,5. 28040 Madrid, Spain. Plant Dis. 80:344. Accepted for publication 16 January 1996. Copyright 1996 The American Phytopathological Society. DOI: 10.1094/PD-80-0344C.

Blight of sweet and hot pepper (Capsicum annuum L.) results in severe losses in the main areas of production in Tunisia. The disease appears in crops grown both in the field and greenhouse, but it is more important in the field. Symptoms are similar to those of the stem blight caused by Phytophthora capsid Leonian. The crown and roots of diseased plants show a conspicuous browning that reaches the cortical cylinder. This discoloration can progress along the stem but never extends to the first lateral branch. Leaves and fruit have a normal appearance until the vascular system is affected by the rotting of crown and roots. Then, the whole plant wilts without prior yellowing. Leaves and fruit remain attached to the wilted plant, and the immature fruit take on a reddish color. Phytophthora nicotianae Breda van Haan var. parasitica (Dastur) G. M. Wa-terhouse was consistently isolated from diseased plants. The identification was made according to the criteria of Stamps et al. (1). Healthy plants of local pepper cultivars were inoculated at the floral bud stage by depositing 250,000 zoospores in the crown of each plant. Isolation of the fungus from wilted roots confirmed the role of P. nicotianae var. parasitica as the causative agent of disease. This species of Phytophthora is cited for the first time as a pathogen of pepper in Tunisia. To date, we have not isolated P. capsici from the diseased plants, even though this pathogen has been associated with pepper diseases in the rest of the world.

Reference: D. J. Stamps et al. CAB Int. Mycol. Inst. Mycol. Pap. 162:1, 1990.