PORTO RICO EXPERIMENT STATION. 461 



leaf tissues, causing the death of irrcoulur ureas 1 to 2 centhueters 

 in diameter. When several of these dead areas occur on each leaf, as 

 is often tlie case, the reduction of active leaf surface is so o-reat as to 

 seriously derange the nutrition of the plant. No natural enemies of 

 this pest were o])served. The larva' are so protected, owino- to their 

 foedin*^- on the iimer tissues of the leaf, that applications of insecti- 

 cides would be useless. The only possible remedy that suggests itself 

 is the laborious one of hand picking and burning the infested leaves. 

 At first thought this would seem impractical)le with a crop like coffee 

 on account of the expense. It is probable, however, that thorough 

 work contiimed for a single season would so nearly exterminate the 

 pest as to give practical inummity for a number of years. If so, the 

 expense would l)e amply repaid by the increased yields of successive 

 crops. The mature insect is so small that it is not likely that it flies 

 far, and an estate once thoroughly cleaned up would be only slowly 

 reinfested. This method of treatment is at least promising enough to 

 deser\'e a practical test. A thorough stud}' of the habits of the adult 

 moth might suggest some means by which the insect could be more 

 clioai)ly conil)ated while in this stage, but in the al)sence of this knowl- 

 edge no plan of attack can be suggested. The injury done b}" this 

 insect is serious enough to demand a thorough investigation of its 

 habits and life history. 



Stllh(()ti leaf spot {StilhuDi fiavidimi). — In moistcr locations, and 

 especially where ovcrshaded, coft'ee leaves arc also nuich spotted l)y 

 this fungus. The Stilbum s})ots can easily be distinguished from 

 those caused l)y the leaf miner by their lighter, nearly white color and 

 regularly rounded outline. They are usually about 1 centimeter in 

 diameter. The leaf miner spots are brown and irregular in outline. 

 At certain times the fruiting bodies of the fungus can be seen with 

 the naked eye abimdantly scattered o\er the spots. They consist of 

 minut(% i)ale, yellow stalks, 2 to 8 millimeters high, ending in a small 

 enlargement or knob. AMiile the Stilbum disease is rather troul)le- 

 some under present conditions it is not to be specially feared, since it 

 only occurs where there is too nmch shade and moisture. It can be 

 completely controlled by a proper thinning of the plantations and the 

 cutting out of excessive shade. 



SclerotiK)!! il) Jeafhiight. — A peculiar disease of cofi'ee foliage was 

 obser\ ("d at one spot on the Carmelita estate. The above name is pro- 

 visionally suggested for it. although no true Sclerotia were found. - 

 The underside of the leaves were covered by a thin weft of delicate 

 white mycelium. On the petioles and twigs this myceliiun was gath- 

 ered into thick, tough i)rownish strands that advanced rapidly up the 

 stems, spreading out again into a delicate white weft as each leaf 

 was reached. No spore forms were ol)served, the fungus having the 

 appearance of the mycelium of some of the hymenomycetes. The 



