FUNGOUS DISEASES IN SHIPMENTS OF SUGAp CANE. 7 



genus as the fungus causing rind disease of cane. There should be 

 no confusion in distinguishing the two diseases in the field, the one 

 being a vigorous parasite attacking only young shoots, while the 

 other is a saprophyte found on cane killed from some other cause. 

 The spores are formed in pustules usually within the tissue of the 

 stem or the inner leaf sheaths and are not released until the stem 

 disintegrates. So long as the shoot remains dry the pustules remain 

 intact, but when moistened the sheaths loosen and the spores are 

 freed. 



The disease flourishes only (hn-ing damp, cool weather and then 

 only on young shoots. Fields in which the cane is more than half 

 grown are not affected, the disease being confined in that case to the 

 young shoots or suckers. 



Inspection of seed sugar cane for this disease would be inadequate, 

 since the disease is usually not evident on mature cane. S]:)ores of 

 the fungus might be carried on the surface of the lower portions of 

 the stalks which had outgrown the disease or might find lodgment 

 on healthy cane coming from infected areas and the disease be thus 

 carried. 



Control. — Thorough preparation of the soil previous to planting is 

 recommended in controlling the disease, since an exposure of the 

 spores and mycelium to the sun for a fe\y hours effectually destroys 

 them. 



GUMMING. 



Gumming {Bacterium vascular^im (Cobb) Greig-Smith) , a disease of 

 the fibrovascular bundles of sugar cane, was first described in 1893 

 by Dr. N. A. Cobb ^ from the Clarence River district of Australia. 

 It is also present in Mauritius, Java, and Brazil. TVTiile this trouble 

 has so far been easy to control in infected regions it might become 

 far more serious if introduced into a new habitat. 



The disease is characterized ^ by a dying of the cane tops, a rotting 

 of the tissues at the base of the "arrow," and the production of a 

 yellowish gmmny substance in the bundles of the stem. Gmmning 

 is propagated through diseased sets. The bacterial organism ad- 

 vances in the bundles of the stem along with the growing plant. In 

 severe cases the plants are dwarfed, attaining in a year's growth only 

 a third or half the size of healthy plants. Occasionally the young 

 plants are killed before they have had time to push through the 

 ground. If a diseased stalk is cut crosswise, a sticky yellowish sub- 



1 Cobb, N. A. Diseases of the sugar-cane. Agricultural Gazette of New South Wales, v. 4, pt. 10, p. 

 777-833, 46 fig., 1893. 



2 Cobb, N. A. Third report on gumming of the sugar eano. Report of Work of the Experiment Station, 

 Hawaiian Sugar Planters' Association. Division of I'utliology and Physiology, Bulletin 3, 40 p., 12 fig., 

 2 pi., 1905. 



[Cir. 126] 



