Mil. A, 4 Reinking: Philippine Economic-Plant Diseases 213 



the upper surface is red-brown with concentric dark brown lines. 

 It is smooth with concentric grooves parallel to the outer edge. 

 The lower surface is covered with minute pores, the spore- 

 bearing surfaces, and at first is orange; but later, when old, 

 is red-brown. 



Control. — The disease as a rule cannot be detected until the 

 tree is about to die; consequently remedial measures must be 

 practiced that will prevent the fungus attack. Land cleared 

 for rubber plantations should have the old jungle stumps removed 

 and burned as completely as possible down to a depth of at 

 least half a meter. Preferably the land should be cleared, 

 cleaned, and planted to a cultivated crop two years before planting 

 the rubber. This will give time for the complete removal and 

 burning of all stumps. 



Dead rubber trees must be dug up with all roots and burned. 

 Since the disease frequently occurs in patches, these patches 

 may be isolated by digging a trench, about 45 centimeters deep, 

 around the affected trees. Quicklime should be scattered over 

 the ground and in the trench. This will prevent the fungus 

 from spreading through the ground to healthy surrounding 

 trees. All dead stumps should be removed and the infected 

 spot dug up so as to destroy as many of the roots as possible. 

 Frequently newly infected trees near affected spots can be saved 

 by removing all dirt from the tap roots and cutting out the 

 affected portions. If the roots are too severely diseased, the 

 tree must be dug up and burned. It is absolutely necessary to 

 remove all dead stumps so as to prevent the spread of the disease 

 by the mycelium growing through the ground, and to prevent 

 the production of fruiting bodies, which produce spores that 

 spread the disease. An efficient drainage system should be 

 provided for poorly drained regions. 



SPOTTING OF PREPARED PLANTATION RUBBER: SAPROPHYTIC FUNGI 



Symptoms. — Prepared plantation rubber when produced under 

 improper conditions may, during drying, become spotted with 

 b;"ight red, pink, reddish yellow, dark blue, bluish green, bright 

 yellow, black, or clear spots. The colors can be more easily ob- 

 served by holding the sheets of rubber up to the light. These 

 spots may extend through the entire sheet, or they may be con- 

 fined to the upper or the lower surface. They range from mere 

 specks, 1 to 2 millimeters in diameter, to blotches, 15 centimeters 

 in width. When the spots are abundant, a mottling of red or 

 yellow may be produced. The color usually fades slightly after 

 several weeks, but it has been observed to last for an indefinite 

 period. 



