DISEASES OF SUGAR CANE 305 



up of the conidia cemented together by mucilage. The conidia 

 are unicellular, pale brown, cylindrical, straight or curved, 14-15 

 X 3.5-4 microns. 



The infested cane dries up and becomes very light. 



Pineapple Disease of Cuttings. 

 History and Distribution. 



This disease, caused by Thielaviopsis paradoxa (De Seynes) v. 

 Hohn. was described by Went in Java in 1893. He gave it 

 the name Pineapple Disease owing to the smell, resembling that 

 of a ripe pineapple, noticed when a cane containing the fungus 

 in a fresh and vigorous condition is split open. The fungus 

 would seem to occur in all cane-growing countries, and, from its 

 invariable appearance when conditions favour it, would seem 

 to be universally distributed on sugar estates in the West Indies. 

 It is a somewhat curious coincidence, considering the name 

 given to the disease on sugar-cane, that the fungus has since 

 been found to be the cause of several diseases of the pineapple. 

 It occurs also on coconut and banana. 



Causative Fungus. 



The fungus was discovered by De Seynes in 1886 in France, 

 and again by Went in Java in 1893 in connection with the disease 

 under consideration. W^ent gave it the name Thielaviopsis 

 ethaceticus, under which it has become generally known, but in 

 accordance with the rules of priority the earlier specific name 

 must be adopted. The fungus grows and fruits in the interior 

 tissues of the cane. The abundant mycelium produced in the 

 cells is at first hyaline but turns brown or nearly black as it 

 matures. Two forms of conidia are produced from the hyphae 

 within the tissues, sometimes one, sometimes the other pre- 

 dominating. The macro-conidia are black, thick-walled, oval, 

 produced in a chain by septation at the tip of a hypha ; the 

 micro-conidia are short, hyaline, cylindrical or oval, formed by 

 the sub division of the internal contents of a hypha and pushed 

 out successively from its open end. No other form of fructifica- 

 tion is known. 



Nature of the Attack. 



When trouble is experienced from this fungus it is in nearly 

 all cases connected with the infection of planted cuttings, 

 which takes place from the cut ends in a manner strongly sug- 

 gesting infection from the soil. It is, however, to be noted that 

 unplanted cuttings, set aside in moist air or transported to a 

 distance involving close packing for several days, are also very 

 liable to be attacked. The fungus usually involves the centre 



X 



