86 TBINIDAD AND TOBAGO BULLETIN. \XIX. 1. 



Where the disease has become established the following routine 

 is recommended by the United States Department of Agriculture- 

 (Bnllefin 829):— 



" It is suggested that the following schedule of inspection and 

 roguing be put into operation: In the spring, just as soon as all the 

 plants have sprouted, the field should be inspected by passing up and 

 down the rows. All diseased stools should be pulled out of the ground 

 and c:ist down between the rows. If this first inspection is carried out 

 in a thorough manner the field will be completely freed from the disease 

 provided no secondary infections are going on. Since there are as yet' 

 no certain means of determining the latter fact, a second inspection is 

 essential. It sliould be made from 25 to 30 days after the first, a lapse 

 of time sufficiently in excess of the incubation period for mosaic to- 

 insure recognition of the disease in plants inoculated prior to the first 

 inspection. If no diseased plants are found during the se 'ond inspection,, 

 it can be assumed that secondary infection is not in operation and 

 that the remaining plants will continue In althy. If diseased i^lants 

 are found, however, it establishes the fact that secondary infections- 

 are going on. The field should be rogued as before, and a third 

 inspection made after the same interval, i.e. 25 to 80 days. If the 

 carriers remain active it may be necessary to repeat the process- 

 several times, and owing to the impossibility of recognising the 

 disease in inoculated plants before the end of the incubatijn period 

 it is certain tbat plants which have become infected just before the 

 inspection is made will escape detection. This emphasizes the- 

 necessity for making the first inspection early, preferably before 

 the leaf-hoi:)pers or other sucking insects have appeared on the plants. 



"This procedure may result in perfect control or eradication of the 

 disease, or in partial control, the element of unceriain'y buing due to 

 our inability to control the carriers. By it their activity can be rendered 

 less effective by reducing the sources of inoculation to a minimum. 

 It has effectually halted the progress of the disease into new territory 

 in Porto Rico. 



"In badly infected sections the problem is manifestiv complicated. 

 "Where 25 to 60 per cent, or more of the plants in large fields are 

 diseased, roguing is obviously out of the question. 



" Such planting should be allowed to mature. Every stalk of it 

 should be ground, however, and the stubble plowed up and killed." 



BuUclin No. 22. Porto Rico Department of Agriculture (received 

 April 10, 1920) by F. S. Earle, Expert in Cane Disease, gives the 

 experience gained during 1919 in eradicating the disease : 



" The results have uniformly been very favourable and they have been 

 obtained at moderate cost. The object of this publication is to record 

 these facts and bring them to the general knowledge of cane planters 

 not only in Porto Rico but in other cane-growing countries, for it isi 

 now known that this disease exists in Santo Domingo, Hayti, Cuba 

 Louisiana and all of the other cane-growing districts of the United 

 States, besides Argentina, Egypt, Hawaii and all parts of the far East. 



" The method of eradication consists in doing just two things, and of 

 those one is equally important as the other. If seed muat be taken 



