Abstract1. Gummosis of sugar cane is a bacterial disease, caused by Bacterium vascularum (Cobb) Grieg Smith. 2. The organism lives in the tracheary tissues of the fibro-vascular bundles. Sometimes it dissolves the cell walls and spreads into the surrounding tissues of susceptible canes and into young tissues of somewhat resistant canes. 3. The organism produces a gum which oozes out of the cut ends of the infected canes. 4. The disease kills many young canes and causes a reduced yield, varying with the susceptibility of the variety and the severity of the attack. 5. The gum also interferes with the crystallization of the sugar in the mills. 6. The percentage of infection is higher on plant than on ratoon cane but in all cases that have come under our observation, the yield on the ratoons was reduced. 7. The leaf symptoms are more pronounced during wet than during dry weather. 8. Many of our best varieties in Porto Rico are immune or highly resistant. Therefore, the disease is not a serious problem if these varieties are used. 9. Immune or resistant varieties should be used in Porto Rico. Infected cane should never be used for commercial planting.
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