THE PESTS AND DISEASES OF THE CANE 



167 



Figs. 68 and 69 show, after Butler, a piece of cane infected with this 

 disease and also the'spores. 



Nedria laurentiana (Marchal).— Stroma somewhat broad, convex, superficial 

 1-2 m.m. diam. seated on a hyaline slender cottony, evanescent, at first free, later 

 confluent white parenchyma ; perithecia densely caespitose, globose or ovoid, 250-350 

 niicrons diam., strongly rugulose, even subsquamulate, ferruginous, glabrous, ostiole 

 slightly dark, somewhat broad, membranaceous ; asci, 8-spored, oblong cylindrical, at 

 lower end subsessile 60-70 x 7-8 microns ; aparaphysate ; spores in one series, oblong, 

 equal-sided straight, at bottom end obtuse acute, '2-celled, constricted in the middle.' 

 rarely the lower end somew-hat narrower; 12-13 x 4- 5-5 niicrons, epispore rarely 

 subasperulate. 



Diseases classed as Pathological Conditions. — Specific organisms have 

 not been connected with two of the most important of cane diseases, as is 



^ X 250 



Fig. 67 



oa^^ 





FiG. 68 



Natural Sue 



Fig. 69 



also the case with " top rot, ' already described. The two conditions 

 described below are known as " sereh " and as the " yellow stripe disease." 



Sereh. — This disease was first recognised as such in 1882 in Java, where 

 it has done much harm. In the typical form of sereh the stool of cane 

 consists of a number of short stalks with very short joints ; the buds, 

 especially those below, sprout, whereby results a bundle of short stems 

 hidden in a mass of leaves. The whole stool bears a resemblance to lemon 

 grass {Andropogon schcenanthus) , the Javanese term for which is " sereh." 

 In a second tj'pe one or two stalks may grow to a fair size, with very many 

 short joints in the upper part. Above all is a fan-shaped crown. Many of 

 the eyes, especially those below, sprout and form small branches. Benecke^''^ 

 has given the following symptoms of the disease : — 



1. A low, shrubby growth, often only from 3-4 centimetres. 



2. A fan-shaped arrangement of the leaves arising from a shortening of the 

 intemodes. 



3. The intern odes are only from a half to two-thirds of an inch long. 



4. The nodes are tinted red. 



5. Numerous aerial roots are formed. 



