68 A PLANT-DISEASE SURVEY IN TEXAS. 



EUONYMUS. 



Anthracnose {Colletotrichum griseum Heald and Wolf, 32). — This 

 is one of the most common diseases of Euonyrrms japonlcu^ Thunb. 

 for this region. It forms on the leaves indefinite-margined, yellow 

 blotches 1 to 4 mm. in diameter. These increase in size until the 

 diseased areas are sometimes 8 to 10 mm. across; a definite, brown, 

 elevated border is formed, and the center of the spot becomes gray. 

 Scattered over this gray area are numerous black acervuli, either 

 zonate or more or less scattered, usually concentrically arranged. 

 Often the spots are marginal, or the disease may apparently work 

 back from the tip of the leaf. (PI. XII, fig. 2.) 



The twigs and larger branches are also affected, resulting in the 

 formation of gray cankers 1 to 8 mm. in diameter. 



These gray patches drop away, leaving the brown, cankered area 

 exposed. The acervuli are immersed, varying in shape from globular 

 to quite flat, 250 to 300 n in diameter, the margin of the opening be- 

 ing set with numerous brown setse, 40 to 60 by 5 /x, quite uniform in 

 diameter or sometimes taper pointed. (PI. VI, figs. 1, 2.) The 

 spores are straight or only slightly curved, hyaline, densely granular, 

 or with several guttulse, 14 to 17 by 4 jn, and rarely marked by a single 

 transverse septum which does not divide the cell into equal halves. 

 (PI. VI, fig. 1.) 



Specimens collected: Austin, 1280 (type specimen) ; San Antonio, 1404; Lock- 

 hart, 2110 ; Georgetown, 2353, 2376. 



Leaf -spot (Exosporium concentricum Heald and Wolf, 32). — This 

 fungus produces on the leaves circular areas 0.5 to 2 cm. in diam- 

 eter which may show concentric zonation. This zonation is due to 

 concentric regions of brown and grayish yellow. The acervuli are 

 confined to the grayish-yellow regions. In other cases the spots may 

 be uniforml}^ grayish yellow with a narrow brown border. Usually 

 only one spot is present on each leaf, but occasionally there are 

 several, which fuse. (PL XII, fig. 1.) The affected leaves may 

 show considerable yellowing beyond the diseased areas, and in severe 

 cases much defoliation follows. 



The acervuli, 100 to 150 /x in diameter, are dark and either con- 

 centrically arranged or scattered. They are at first covered and at 

 length protrude, causing that portion of the leaf to become grayish 

 because the rupture of the epidermis has admitted the air. The 

 spores are nearly hyaline, clavate cylindrical, 25 to 45 by 2.5 to 3 /i, 

 one to several septate. (PI. VII, fig. 5.) 



Specimens collected: San Marcos, 2129; Georgetown, 2375; Austin, 2867 (type 

 specimen). 

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