Leaf Spot and Blight of Strelitzia reginae (Bird-of-Paradise) Caused by Xanthomonas campestris

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Abstract
A newly described bacterial leaf spot disease of Strelitzia reginae (bird-of-paradise) is caused by a strain of Xanthomonas campestris. Angular, yellow to reddish brown lesions were found on all ages of leaves and petioles. Lesions were frequently bordered by leaf veins and remained less than 1 mm in diameter or length, although lesions coalesced to give leaves a blighted appearance. A strain of X. campestris caused these symptoms on bird-of-paradise and S. nicolai (bird-of-paradise tree) but not on Heliconia spp., Musa acuminata (blood banana), Ravenala madagascariensis (traveler''s palm). Moderate symptom development occurred between 21 and 27 C, with optimal development at 24 C. Pathogenicity tests with strains of known pathovars of X. campestris showed the bird-of-paradise pathogen to be distinct from X. c. pv. dieffenbachiae (Araceae), X. c. pv. hederae (Araliaceae), X. c. pv. malvacearum (Malvaceae), and X. c. pv. poinsettiicola (Euphorbiaceae) but not distinct from strains of X. campestris isolated from Ficus (Moraceae) or Pellionia and Pilea (Urticaceae).