RUBBER (HEVEA) DISEASES 11 
RED STRAND-ROT 
The red strand-rot fungus (Poria vincta (Berk.) Cke.) was found 
fruiting on the lateral roots of living Hevea stumps at Colonia de 
Onteiro (PL V, B). The decay affected the lower half of the root 
and extended about 6 inches beneath the soil. At the root collar 
the decay had spread over an area of about 8 square inches and had 
caused shrinkage and death of the cortex, with checks in the outer 
bark. Smooth, tough, dark-red rhizomorphs were distinguishable 
as small irregular patches between the bark and wood. These rhizo- 
morphs were of the color of dried blood, and in some case: u n e 
dark brown or black with age. They occurred chiefly as flat anasto- 
mosing bands of irregular breadth, becoming whitish fimbriate at 
their extremities. The fimbriate condition was more pronounce 1 
on the wood longest in decay and took the form of a thin white 
silky sheet radiating in a fanlike manner (PI. V, B). These become 
brownish with age. The hyphse may coalesce and re-form as red 
rhizomorphs. 
In cavities produced by shrinkage of the wood the rhizomorphs 
become rounded and more cordlike. Cross sections of these strands 
showed an outer compact layer of deep-red thick-Availed branching 
hypha? of irregular dimensions, with conspicuous lumina presenting 
a pseudosclerenchymatous appearance. Deep-red cystidia of irregu- 
lar shape and of a sclerotic effect were occasionally observed in this 
tissue. The outer layer surrounded a parenchymatouslike central 
core of hyaline thinner walled hyphse of great irregularity in size 
and shape. Sometimes there were two layers of the hard red outer 
hyphse separated by a layer of less dense and slightly yellowish tissue. 
Under the microscope the upper free surface of the rhizomorphs 
may be slightly tomentose. 
These strands were also discernible in the irregularities of the bark 
beneath the subiculum of the fungus, but in no case either between 
the bark and wood or beneath the subiculum were they abundant. 
They rarely occurred on the outer surface of the bark not overrun 
by the fructification. Several collections of the fungus on dead wood 
of various trees had developed the rhizomorphs imperfectly, or they 
were entirely absent. Most of these collections, however, were past 
their prime, and the rhizomorphs, if present, were largely discolored 
or disintegrated. This fungus has been repeatedly collected in the 
West Indies and Brazil in recent years, and on the subiculum and 
substrata of some of the specimens remnants of these rhizomorphs 
still persist. 
The under side of the mature fructification, which may be irregu- 
larly raised from the substratum, is smooth, horny, and of a dried- 
blood color. In a young growing stage the under side may be of a 
brighter red. Occasionally the outer layer of the wood is stained 
faintly reddish, becoming brownish with age. Faint reddish lines 
may irregularly penetrate the wood, or the stain may develop be- 
tween two annual rings. The presence of the red color in the wood 
is but temporary, and it usually disappears altogether or remains as 
a faint rustiness. In diseased wood of long duration all evidence 
of a red color has disappeared. Since the red color in the wood is :; 
temporary condition, it should not be used as a reliable diagnostic 
character for the species. The reason for this lies in the fact that a 
