14/4/2010
Abstract
Leaf and crown wart, marbled or beet root tumour are some of the common names given to a disease of sugar beet (Beta vulgaris) caused by Urophlyctis leproides(formerly Physoderma leproides ). It was first reported in Algeria in 1894 (Trabut, 1894). Since then, the disease has been recorded in Argentina, Italy, Spain, United Kingdom, Palestine and theUSA (Whitney, 1971). In Egypt, the disease was observed during harvest (2003, 2004, 2005) at three locations in the Nile Delta (Behira, Gharbia and Kafr El-Sheikh) on a range of sugar beet cultivars (Gloria, Kawmera, Oscar poly, Othus poly and Pleno). Disease incidence (DI) was less than 1% in 2003, 1–2% in 2004 and 3% in 2005. Although the DI is currently low, if the trend observed over the last few years continues, the disease could reach epidemic levels in the near future. The disease exhibited typical symptoms on root crowns and occasionally on petioles and leaf blades. Galls on leaf blades and petioles are greenish brown and have a rough appearance. Affected leaves are malformed. On the crown, galls range in size from 1 cm to (most commonly) 8–10 cm. These galls are spherical, rough and are attached to the host by a narrow base. Gall colour was variable, ranging from shades of green through yellow to brown depending on the age of plant cultivar. Galls occurred singly or coalesced to form complexes. Sections made spores) surrounded by thickened wall. Sporangia were light brown, spherical to ovoid or concave (25 ± 5 × 40± 5?m) in diameter (Ruppel, 1995). As the gall decomposes, resting sporangia are released into the soil. Soil surveys were carried out in the affected areas and detected resting Twenty seedlings of B. vulgaris cv. Gloria were inoculated with 10 5 resting spores mL ?1and incubated 22 ±2 ° C in continuous fluorescent light for 48 h, followed by 14 h light and 10 h dark. Uninoculated plants were used as a control. Symptoms appeared on the test plants after 11 days and sporangia were reisolated from the mature gall tissues (Mahmoody et al ., 1997). No symptoms were observed on uninoculated controls.This is the first report of sugar beet crown wart disease (U. leproides)affectingB. Vulgaris in Egypt. sporangia.
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