Crepe jasmine, Tabernaemontana divaricata (L.) R. Br. ex Roem. & Schult. (Apocynaceae), is a popular flowering shrub in South Florida. A native of Southeast Asia, it is one of approximately 100 ornamental species in the genus. In December 2007, rust was observed on the leaves of landscape plants in Key West and Miami. The rust has become prevalent and severely affects young and old leaves of plants in the landscape and in commercial nurseries. Leaf lesions begin as chlorotic flecks that expand into necrotic spots with orange-to-reddish brown, subepidermal uredinia; brown telia develop on the abaxial side of leaves. Urediniospores are one-celled, initially hyaline, minutely echinulate and spherical, turn dark orange, and measure (22) 24 to 29 (32) × (19) 21 to 24 (26) μm. Teliospores are (26) 29 to 36 (38) × (20) 22 to 26 (28) μm, two-celled, ellipsoidal to ovoid, echinulate, constricted at the septum, reddish brown, and have 0.8-μm thick spore walls; pedicels are 25 × 5.6 μm, persistent, and hyaline. Attributes for urediniospores are consistent with those from the original description of Uredo manilensis Syd. & P. Syd. on T. coronariae in Manila (2); however, there are no reports of a telial stage for this rust. Attributes for urediniospores of the South Florida fungus were also consistent with those on herbarium specimens of U. manilensis from the U.S. National Fungus Collection, also collected in Manila but from T. polygama (BPI Accession Nos. 0155269 and 0155270). Notably, these specimens contained telia that matched those found in South Florida. Subsequent comparisons were made with herbarium specimens of the three Puccinia spp. that have been reported on Tabernaemontana spp. (the U.S. National Fungus Collection or the Arthur Herbarium, Purdue University, West Lafayette, IN). Puccinia engleriana (five specimens from India, New Guinea, and the Philippines) differs from the BPI specimens of U. manilensis and the South Florida fungus by its bigger teliospores (32) 35 to 41 (45) × (21) 22 to 24 μm. P. tabernaemontana (six specimens from Uganda) has bigger urediniospores ( 34 to 41 ×  26 to 32 μm) and yellow-brown, poorly echinulated to almost smooth teliospores. The revised material of P. morobensis (type) was poor, but according to the original description (1) and notes found in the herbarium specimen, the teliospores (24 to 29 × 33 to 45 μm) and urediniospores are larger (23 to 28 × 29 to 35 μm) and the teliospores walls are finely and sparsely echinulated to sometimes smooth, and the pedicels are very short and fragile. A specimen of the South Florida fungus was deposited with the U.S. National Fungus Collections (BPI Accession No. TBA). To our knowledge, this is the first report of U. manilensis in the Western Hemisphere and the first time a telial stage (provisionally P. manilensis) has been recognized for the fungus. This disease has become a concern in South Florida for gardeners as well as producers who must now treat the crop with fungicides.
References: (1) G. B. Cummins. Mycologia. 33:148, 1941. (2) H. Sydow, and P. Sydow. Ann. Mycol. 8:36, 1910.