and tomato. It lias been found causing a damping off of citrus seed- 

 lings and doubtless attacks a range of other hosts here, many otliers 

 being reported from the Southern United States. 



As a disease of cane Sclerotium Rolfsii was first studied and de- 

 scribed from Java by Kriiger (53). Howard (4-1) has reported it in 

 Trinidad and Longfield Smith (70) in St. Croix. Mention of its 

 occurrence is also made by Home (39) in Oiba and Ashliy (3) in 

 Jamaica. The senior author has seen it in abundance in Florida, 

 Georgia, Louisiana, and Texas. 



Porto Rico. — On cane, Hormigueros, July 17, 1911, 4070; Rio 

 Piedras, September 18, 1915, 3078, June, 1917, 6560. Observed in 

 all sections of the Island. Also collected on Lycopi rsicum esculentum, 

 Capsicum annuum, Solanum melongetia, Citrus sp. (PI. XXV, fig. 3.) 



THE EYE-SPOT OP THE LEAF {HelmintJiosporiuni sacchari). 



The leaf blades of the sugar cane are subject to a number of 

 diseases, so commonly in fact, that a field of mature or nearly mature 

 cane that does not show a large per cent of infected leaves is a rarity. 

 Several fungi are concerned in producing the spotting, some more 

 common in one section, others in other parts of the Island. Certain 

 districts suffer much more than others, the Fajardo area for instance 

 being much more free of leaf disease than some others. It is difficult 

 if not impossible to make any statements as to the losses occasioned 

 by these diseases since their effect is indirect. There is undoubtedly 

 some loss due to the destruction of leaf surface, the amount varying 

 with the per cent of infection, and the age of the cane when attacked. 

 The exact relationships of the various fungi and resulting leaf spot^ 

 have not been completely worked out, but such notes and observations 

 as their economic importance warranted have been made. 



One of the common types of leaf -spot is that called by some workers 

 the ' ' eye-spot. ' ' Several varying forms have been encountered, doubt- 

 less due to the varietal differences of the host or environmental factors. 

 That most generally noted was one encountered very commonly in 

 studies of the mottling disease in the Arecibo-Aguadilla region. The 

 spots were a medium to dark brown in color, with definite margins, 

 much longer than broad, from one to five millimeters in breadth, from 

 one to five centimeters in length, very numerous, often coalescing, 

 and very often the apparent cause of death of the leaf. In other 

 instances the spots are elongate-oval not coalescing, or causing death 

 of the leaf, medium brown in color, 2-4 mm. by 8-15 mm. Still a 

 further type was encountered in which the spots were oval, about 

 one by two centimeters, distinctly zoned, with a rather indefinite 



202 



