The diseases and pests of the rubber tree . Fig. 7.—UstuUna zonata ; mycelium between the wood and the bark, x J. to the same class as UstuKna form black hnes in wood, andthe majority of them are merely saprophytic. 60 THE RUBBER TREE The fructification of the fungus (Fig. 8) is usuallyproduced in profusion at the base of the stem, generallybefore the tree is dead. The fungUs emerges through thebark as a short, white column, one or two millimetres indiameter, and spreads out in all directions flat on the surfaceof the bark, being attached to the bark only at the point oforigin. It thus forms a
The diseases and pests of the rubber tree . Fig. 7.—UstuUna zonata ; mycelium between the wood and the bark, x J. to the same class as UstuKna form black hnes in wood, andthe majority of them are merely saprophytic. 60 THE RUBBER TREE The fructification of the fungus (Fig. 8) is usuallyproduced in profusion at the base of the stem, generallybefore the tree is dead. The fungUs emerges through thebark as a short, white column, one or two millimetres indiameter, and spreads out in all directions flat on the surfaceof the bark, being attached to the bark only at the point oforigin. It thus forms a flat plate about four or five centi-metres in diameter, but several may arise side by side andfuse into a continuous plate covering a large area of the. Fio. 8.—Ustulina zonata; fructification, x J. base of the stem. These plates are at first white and soft,but soon become grey or greenish-grey. In the tj^ical formthey are generally concentrically zoned or corrugated. Theythen harden and become purple-grey, and finally weatherto black ; in these later stages they bear scattered, miuute,black, slightly elevated points. After the plates havebecome hard they are at &st white internally, with a singlelayer of dark, oval, or globose cavities (Fig. 9); later theybecome black internally, and more or less hollow. Whenold they are brittle, and easily crumble to pieces whenhandled. They are usually not more than about two milli-metres thick.
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Keywords: ., bookcentury1900, bookdecade1920, bookidcu3192400285, bookyear1921
