C ASS AV A {Manihot util issi ma). 



. WiT,HERTii' (Gloeosporium maniJiot Earle). — In one locality a 

 ;sweet (non-poisonous) variety of cassava was suffering- severely from 

 die back induced apparently by poor soil, and prolonged drouth, aided 

 hy the fungus in question. There was a characteristic withering and 

 ■dying of the leaves which remained hanging at the tips of the twigs. 

 The twigs and even the branches died back for a considerable dis- 

 tance, at times nearly to the ground level. Examination of the under- 

 ground portions of the plants revealed no indications of disease. Oji 

 the dead twigs the fungus formed small black fruiting pustules. 

 Under favorable conditions this disease probably will give no trouble, 

 though removal of diseased portions and cultivation should suifice to 

 check it if it should by any chance get a start. 



Leaf Spot (Cercospora henningsii AUesch.) — The characteristic 

 leaf spots due to this fungus are conunon but of no great importance. 

 They are angular, small (seldom over one-eighth inch in diameter), 

 iind dull white or gray in color, with a definite reddish-brown margin. 



Rust [Vromyces janiphae [Wint.] Arthur.) — Not common, pro- 

 ducing brown, powdery pustules on the under sides of the leaves. 

 A root rot has also been reported (8) on this host. 



Chayote {Sechh(7n edule) . 



Tiie chayote is very subject to one or more leaf diseases which 

 v^ery often completely destroy the plant, frequently before any fruit 

 "has been produced. Spraying with Bordeaux mixture has not given 

 satisfactory results in so far as observations have been made, nor 

 ■do published records report any success along this line (5). 



Miss Young (7) describes one type of leaf spot due to PhyUosficta 

 iSechii. The spots caused by this fungus are said to be amphigenous. 

 more or less irregular, often confluent, varying in size from two to 

 twelve millimeters and dull white in color. Minute dark brown or 

 black pycnidia are produced in the center of the spots on the upper 

 surface of the leaves. 



A second and much more virulent type of leaf spot occurs. This 

 is due to an apparently undescribed species of Cercospora or prefer- 

 ably UelminiJiosporium. The spots are angular, up to ten milli- 

 meters in diameter, dull brown above, lighter below, sometimes be- 

 coming a dull white at the center in old spots, margins definite, 

 fruiting on both surfaces. The leaf area between the numerous spots 

 speedily dies and the leaf withers and drops. This disease presents 



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