APPENDIX 293 



The first principle of crop sanitation is to avoid planting 

 infected bulbs, which invariably give rise to diseased 

 plants. The necessity for selecting healthy bulbs for 

 planting cannot be too strongly impressed upon banana- 

 growers. 



When a diseased individual is detected in the field, it 

 should be immediately rooted out and destroyed by 

 burning; otherwise it becomes a menace to surrounding 

 plants, on account of the production and dispersal of 

 disease-producing spores. Heedless neglect of any such 

 diseased plant is bound to produce a harvest of new cases. 



Eradication of the organism in the soil by allowing the 

 land to remain fallow, rotation of crops, disinfection of 

 the soil, mulching, flooding, and other methods, have been 

 tried, but none has yet been found effectual. 



The longevity of the organism is not definitely known, 

 but it has been isolated from land which had not been 

 planted to bananas for five years. 



It has been found in studies on this disease that steam 

 sterilization of the soil was very effective, but it is needless 

 to say that under plantation conditions this method is 

 impracticable. 



4. Immunization. The conclusion is arrived at that 

 there is only one solution to the problem of the control 

 and final eradication of the disease, and that is by the 

 development of resistant strains of desirable varieties 

 of banana. 



Experiments have been started in this direction at the 

 Porto Rico Agricultural Experiment Station. Although 

 it is too soon to make definite statements as to the results, 

 the indications point to a successful issue. It has been 

 observed that an occasional plant growing in badly infected 

 areas would resist the disease and produce good bunches 

 of fruit, and give rise to healthy suckers. Such healthy 

 plants had been surrounded by diseased ones for many 

 generations. Suckers of these healthy plants have been 

 removed to a specially prepared field artificially inoculated 

 as heavily as possible. The progeny of any plants that 



