STEM AND LEAF DISEASES 149 



penetrates and kills the bark and frequently enters the wood, 

 in which case a sudden wilting of the leaves may be observed. 

 In the case of lime trees the affected branches are visible from an 

 elevation scattered amongst the healthy foliage. The pink layer 

 is the fruiting part of the fungus, and produces the spores upon its 

 surface. One or more pink fungi which are harmless occur on the 

 bark of trees, and are liable to be mistaken for this species. 



A second stage of the fungus, originally described as Necator 

 decretus, Massee, occurs together with or in succession to the 

 Corticium stage, often on wood killed by the fungus. This 

 consists of orange-red pustules about 3 mm. in diameter, made 

 up of irregularly shaped thin -walled spores. This stage has not 

 so far been recognised in West Indian examples. 



Treatment. 



The simplest and most effective way to treat the disease is to 

 cut off the branch on which it occurs at its junction with the 

 next older branch or with the stem, taking care to cut well 

 below the affected part. The branch removed should be burned 

 or buried, with as little handling or transportation as possible, 

 and the bark for some distance below its point of origin disinfected. 

 General spraying with Bordeaux mixture or lime-sulphur mixture 

 has given satisfactory results on citrus trees in the Philippines, 

 the latter being preferable owing to its lesser effect in protecting 

 scale insects. No such measure has yet been needed in West 

 Indian cultivations. 



Thread Blight. 



Thread BUght is the name commonly given to affections of 

 shrubs and trees in which white to dark brown compact strands of 

 fungus mycelium run along the twigs, and send out branches to the 

 leaves, on the blades of which they ramify, or spread out into a 

 thin web, generally white in colour. 



Distribution. 



Diseases of this nature occur widely over the world, especially 

 in humid situations in the tropics. In the Lesser Antilles 

 thread blights have been found on various forest trees, and on 

 cultivated plants have been most noticed on cacao, coffee and 

 nutmeg. There are in various parts of the tropics several 

 Basidiomycetes which have scandent whitish mycelium of the 

 general type under discussion. 



Corticium Stevensii, Burt {Hypochnus ochroleucus, Noack). 



The common thread blight which occurs in humid situations 

 in these islands on cacao, nutmeg, and numerous other plants has 

 been identified by E. A. Burt as due to the fungus above named, 

 which was first described from Brazil, and later as the cause of a 



