424 The Philippine Journal of Science 1023 
Scaly bark; undetermined. Old neglected trees are subject 
to a rotting of the bark and a consequent sloughing of the dead 
parts. The trouble is only serious in older, poorly kept or- 
chards. It is not a typical bark rot. 
Septobasidium albidum Patouillard. A thick, brown, leath- 
ery growth of Septobasidium albidum Pat. may be produced 
over stems attacked by scales. Usually no damage is done by 
the fungus. 
Sooty mold; Meliola citricola Sydow. A black mold may de- 
velop on leaves and stems, especially in the presence of scale 
insects. The trouble is not serious. 
Witches’ broom; nonparasitic. In poorly kept, improperly 
pruned orchards, witches’ broom may develop on the branches. 
The trouble is not serious. 
Yellowing, or chlorotic condition; nonparasitic. During the 
extreme dry season, the trees may look sickly, being yellowed. 
This condition is commonest where irrigation is not properly 
practiced. The Nakorn Chaisri seedless pummelo is not a 
hardy, robust tree; consequently it is easily weakened by un- 
favorable conditions. Often, due to neglect, the trees are old 
at ten years of age. Well-kept orchards have healthy trees, 
free from the majority of serious plant pests, and produce fruit 
for thirty years. The age of the tree is frequently dependent 
upon the care given it and upon the extent of the dry season. 
Healthy trees produce most abundantly between eight and fifteen 
years of age. In poorly kept orchards, during the extreme dry 
season, the trees are sickly, the leaves wilt and drop, and. there 
is a die-back of the branches. The trees will not stand flooding. 
The greater number of seedless pummelo trees in the Ban Mai 
section that have died were lost either through lack of attention 
or through heavy floods. The owners do not replant with the 
Kao Pan trees, because they are delicate and require a good deal 
of attention. They recognize the hardiness of the Kao Phuang 
pummelo and are planting this variety. 
On dead branches the following may develop: Schizophyllum 
commune Fr., Tryblidiella rufula (Spreng.) Sacc., and Hetero- 
chaete tenuicula (Lev.) Pat. 
INSECTS 
Insect attacks may cause great losses. The leaf miner, the 
flea beetle, ants, and scale insects do the most damage. The 
insects listed are those most generally found and, consequently, 
those that may cause the greatest amount of destruction. 
