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Page number:191 
Remarks (internal):This causal organism of Sharp Eyespot of cereals is in the literature commonly indicated as Rhizoctonia solani Kühn, the well-known mycelial state of Thanatephorus cucumeris (Frank) Donk [Check-list 2a in Neth. J. Pl. Path. 82: 210-211. 1976]. Comparative cultural studies, however, have convinced us that it represents a separate fungus. to be differentiated from R. solani by i. its relatively slow radial growth (on PDA in the dark at 23°C: 4.8-7 mm/day), ii. the sclerotia which are at first white-yellow and iii. the presence of only two nuclei in the hyphal cells [compare Parmeter, Whitney & Platt in Phytopathology 57: 218-223. 1967].
The common Rhizoctonia solani without doubt also occurs on cereals and grasses [see Richter & Schneider in Phytopath. Z. 20: 167226. 1953, 'Gruppe C°, and Parmeter. Sherwood & Platt in Phytopathology 59: 1270-1278. 1969, 'Group AG 4'], but in western Europe R. solani is not known as an important pathogen of Gramineae; compare Smith, Fung. Dis. Turf Grasses ed. 2 [revised by Jackson & Smith], 85. 1965. For the symptoms of sharp eyespot of cereals in comparison with the more serious Eyespot disease caused by Pseudocercosporella herpotrichoides (Fron) Deighton see the descriptions in Advis. Leafl. Minist. Agric. Fish. Fd 321. 1972 [revised ed.]. See further the studies on sharp eyespot disease of cereals by Pitt in Ann. appl. Biol. 54: 77-89. 1964; 58: 299-308. 1966.
Description type:Original description 
Description:Rhizoctonia cerealis van der Hoeven spec. nov.
On PDA (2% Difco), the colonies grow comparatively slowly and are colourless to dirty white with little white aerial mycelium. The main hyphae are 3.8-6.2 µm wide, side branch hyphae 5.1-8.7 µm and aerial hyphae 2.8-5.3 µm. The hyphae generally branch at right angles, with a constriction at the point of origin and the first septum placed a few microns beyond this. The hyphal branches sometimes anastomose. All hyphal cells are binucleate. Monilioid hyphae of irregular length, consisting of doliiform cells, 17-30 x 7-15 µm. Sclerotia produced after 10 days on PDA are at first white to yellow, later brown, globose to irregular, 0.3-1.2 mm in diameter. They consist of loosely arranged doliiform cells with a little differentiated superficial layer. In older cultures aggregations of dark brown sclerotia occur -. All commonly grown varieties of rye, wheat, oats and barley are attacked, and according to Pitt in Ann. appl. Biol. 54: 231-240. 1964, some grasses can also become infected.
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