190 ^^6 Philippine Journal of Science lais 



witches'-broom effects and a more or less complete rosette of 

 the leaves (Plate III, fig. 1). 



Causal organism. — The disease is a nonparasitic one/ being 

 due to some disturbance of the normal physiological activities 

 of the plant. It is not transmitted from one plant to another. 

 Sometimes in marcotting, the disease is produced on branches 

 the bases of which have been encircled with a bamboo tube or 

 a coconut husk containing earth. 



Control. — Since the disease is little understood, no definite 

 control can be given. Badly affected trees should be removed, 

 for they are stunted and will never produce healthy fruit. 



PINK disease: CORTICIUM SALMONICOLOR berk. ET BROOME 



Symptoms. — This disease may be severe during the rainy sea- 

 son in poorly kept orchards. The fungus is a common one, 

 producing disease on other woody plants. Infection starts on 

 the trunk or branches usually in some damp pocket. It is first 

 noticed by the production of cracks and by an exudate of gum. 

 As the fungus penetrates into the bark, it spreads under the 

 surface and causes a more or less cankered condition. In the 

 latter stages the bark cracks and dries up. The fungus may 

 penetrate through the bark into the cambium and wood. When 

 a branch or trunk of a small tree is girdled by the fungus and 

 the xylem is invaded, the upper parts of the plant gradually 

 die, due to starvation. Diseased trees are easily discovered by 

 reason of the dead branches. The diseased area in certain stages 

 of development, especially during the rainy season, is covered 

 with a mass of pink mycelium that often extends over the bark 

 in strands. During drier weather the mycelium dries consider- 

 ably and is not so evident, as it changes to a dirty white or gray. 



.Causal organism. — No detailed work has been done with the 

 fungus. It grows in pure culture, producing a matted mass 

 of pinkish mycelium. The complete life cycle of the fungus 

 has not been worked out. 



Control. — Since healthy, vigorous trees are less liable to attack, 

 proper cultural methods should be practiced. Spraying healthy 

 trees as in the case of citrus canker will exclude the fungus. 

 Once the fungus has gained entrance into and under the bark, 

 spraying will do no good. Young infections may be removed 

 by cutting out all the diseased portions well down into the healthy 

 wood and painting the wound with a creosote paint or white lead. 

 All badly diseased branches should be pruned out and destroyed 

 by burning. These branches should be cut out 15 to 20 centi- 

 meters below the visible extent of the disease, for the mycelium 



