here. The iliau {Gnomonia iliau Lyon) of Hawaii and Louisiana 

 is still another disease that has not reached the Island. Among nunor 

 maladies are the rust {Uromijcoi Knhnii [Kriiger] Wak. & Went), 

 the smut ( Vstilacjo sacchari Rabenhorst) , an internal rot due to Ceph- 

 alosporium sacchari Butl., black rot {Sphaeronema adiposum Butl.), 

 and a number of leaf spots. No phanerogamic parasites have been 

 collected. 



A plant (juarantiny service was established in 1910 and cane 

 cuttings brought to the Island since that time have been carefully- 

 inspected and treated. Many importations have l)een destroyed or 

 planted in (piarantine for observation. Through the continuance of 

 this service it is hoped that Porto Rico will be spared the necessity 

 of combating any new additions to tlie already long list of sugar-cane 

 maladies. 



DISEASES ATTACKING THE ROOTS AND BASE OF THE STALK. 



THE ROOT FUNGUS (Marasmixs saccJiari). 



Marasmius saccJiari has been collected from practically all parts 

 of Porto Rico, some of the determinations being based only ui)on the 

 vegetative condition, but for the most part upon the fruiting bodies 

 so that the determinations are to be relied upon. The sporophores 

 are found commonly only in the rainy season when the ground and 

 surface layer of vegetable matter are completely soaked. They occur 

 both upon cane trash and upon the lower leaf sheaths of the standing 

 cane. 



This fungus occurs commonly only on fairly heavy or heavy soils, 

 seldom on sandy soils. It is most abundant in low lands that are too 

 heavy to plow with any convenience, or in land that has not been 

 well plowed through neglect or other reason. It is found most abun- 

 dantly in fields of ratoon cane, and the poorer the soil and the culti- 

 vation given, the greater is the damage from this fungus. Fields 

 affected with chlorosis were examined to see if such a condition 

 favored the development of the root fungus. In no case did there 

 seem to be any correlation between chlorosis and Marasmius sacchari. 



Examination has also been made many times of cane stools whose 

 roots were injured by the white grub or the root weevil. Affected 

 roots of this sort also usually show the root fungus. Supposedly 

 the injury would give a free entrance to the fungus, but on the con- 

 trary, it is also true that the root fungus is coimnon on roots not 

 apparently injured by insects. 



In connection with studies of tlie mottling disease, while con- 



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