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. 



Nectria 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 

 microns 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 78 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 somewhat narrower; 12-13x4' 5-5 microns, 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 



x 580. 



FIG. 68 



Natural Size 



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 type 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 106 

 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 

 interned es. 



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



4. The nodes are tinted red. 



5. Numerous aerial roots are formed. 



