1920.] MOSAIC DISEASE OF SUGAR CANE. 37 



from a field that is partially diseased, then the selection must be made 

 before the top is cut off. Once the leaves have been removed it is 

 impossible to distinguish the earlier stages of the disease. Inspecting 

 and sortiag over the piles of cut seed is absolutely useless as far as this 

 ■disease is concerned. Second, when the young cane is a foot high, the 

 fields should be carefully inspected and all plants showing signs of 

 ■disease should be pulled out. These may be either from overlooked 

 infected seed or they may be incipient secondary infections. This 

 inspection should be repeated at intervals of about ten days until -no 

 more cases are found. Most ])lanters make the mistake of delaying 

 this first inspection much too long, and of not repeating it sufficiently 

 frequently. When the disease is active, success will depend entirely on 

 the promptness and thoroughness with which this work is done. 

 Every day that a dise^ised cane stands in the field adds to the chance of 

 ■secon;lary infection. Then too, when a small cane is pulled the vacancy 

 may be easily filled by planting a new seed piece. When the cane 

 gets larger replanting must be done by dividing stools and this is much 

 more expensive. Mter the cane closes further inspection is practically 

 impossible. 



" Ratoon fields should be treated exactly like new plantings. 

 Digging out diseased stools is more expensive than pulling up recently 

 planted seeds. When ratoon fields do not show more than 20 or 25 per 

 cent, of infection if otherwise in good condition, it will pay to clear 

 them up and replant them. 



" Ordinarily if the percentage of disease is greater than this it will 

 be best to plow them up and make a new planting. Whether to clean 

 out a fiel I of infected ratjons or to plow it up will naturally depend 

 on the team force and seed cane available for making new plantings. 

 Fields can often be seen with old diseased stubble sprouting and 

 growing on the banks between the rows of young cane. The best 

 possible seed will inevitably soon become infected under these 

 conditions." 



There is no doubt that the disease is a serious one, and if allowed 

 to spread unchecked may cause enormous losses to the island. If taken 

 in time, however, by the methods outlined above, it may be kept within 

 bounds or even perhaps exterminated, and it is hoped that farmers, 

 overseers and managers will do all that they can without delay to assist 

 in preventing the spread of the disease and in destroying the centres of 

 infection already unfortunately present. 



July, 1920. 



