4 DAMAGE TO SUGAR CANE BY THE SUGAR-CANE BORER. 



Ill the event of the stalks being broken, however, the damage is 

 very different. In this case the growth of the cane stops, and the 

 buds on the top joints below the fracture sprout and commence to 

 grow. The process of growth draws upon the supply of sugar stored 

 in the parent cane, so that the cane is not only prevented from 

 reaching its fullest maturity, but also stands a very good chance of 

 losing a percentage of the sugar already stored up in the stalk. 



A close examination of a cane field after a heavy wind will show 

 that to borer mjury is directly due the great majority of broken stalks. 

 A cane will seldom break in a wind unless the stem has been phys- 

 ically injured, and examination of broken stalks nearly always shows 

 that the breaks occur at a borer girdle or a large burrow near the 

 surface of the cane. The burrows and tunnels in the stalks frequently 

 concentrate upon a certain jomt, with the result that it will be mate- 

 rially weakened and will snap off at the slightest provocation. Many 

 canes are literally girdled by borers, a tunnel being made just inside 

 the rind completely around the cane and only the center is left to 

 hold up the top. 



To a large extent, also, borers are directly responsible for the spread 

 of fungous diseases in sugar cane. In order that the fungus may 

 enter a plant it is nearly always necessary for the spores to settle on 

 an excision or wound in the rind of the cane. These openings are 

 furnished in great numbers by the borer holes. Dr. C. W. Edgerton,^ 

 in " Some Sugar-Cane Diseases," advises that all "seed" cane showing 

 external evidence of horer injury be thrown out, as a preventive of 

 fungous diseases. L. Lewton-Brain ^, in considering the rind disease 

 i Melanconium sacchari), says: 



Whenever it is possible to trace the discoloration to its starting point, this will 

 always be found to be a wound of some sort. The wound may be a borer hole, a leaf- 

 hopper puncture, or a wound made in stripping, the borer wounds being perhaps 

 most favorable to the fungus, especially in the older parts of the stalk. 



INJURY TO MATURE CANE BY THE SUGAR-CANE BORER, 



AMOUNT OF INFESTATION. 



In order to determine the extent of borer infestation an elaborate 

 examination of canes was made during the fall of 1910. The gen- 

 eral practice was to examine 100 canes across each end of a plat and 

 100 canes across the middle. These hundreds were divided into 4 

 groups of 25 canes each at different points in the row. This plan was 

 modified in varying degrees as circumstances made it necessary or 

 advisable. In all, the infestation was approximately determined 

 in 9 plats planted to cane. Of these 9 plats 3 were in stubble and 6 



' Bui. 120, La. Exp. Sta., p. 12, 1910. 



2 Bui. 7, Hawaii Sugar Planters' Association Experiment Station, 1907. 



