DISEASES OF PLANTS. 553 



as a saprophyte on dead Hevea stems; (2) on caeao, causing a dry canker on 

 the larger branches or killing back the twigs, or on diseased cacao pods which 

 have been attacked by Pliytophthora ; (3) on Castilloa, in previously formed 

 wounds on the stem; (4) on dead pa paw stems as a saprophyte; (5) on wounds 

 on the stems of old dadaps and on decaying dadap logs; (6) as a saprophyte on 

 stems of Ficus elastica ; (7) on pruned stems of A. inoluccana, which it enters 

 through the cut surface and kills down to the base; (8) on tea, which it enters 

 through the roots and gradually kills; and (9) on roots of coconuts killed by 

 the root disease fungus (Fomes lucidus). 



An extensive defoliation of the older Hevea trees in low country districts is 

 also noted, and is attributed to an abnormal rainfall. 



A bark disease of Hevea, tea, etc., T. Fetch (Cii-cs. and Agr. Jour. Roy. Bot. 

 Gnrd. Ceylou. J, (1909), No. 21, pp. 189-196).— A detailed description is given of 

 the gross characteristics, damage, and probable source of infection of the bark 

 disease (Corticium javaniciim) of Hevea, tea. and other crops in Ceylon. 



On Hevea brasiliensis the disease usually originates at a fork of the tree, and 

 appears as a superficial pink incrustation on the bark which gradually spreads 

 until the whole circumference of the tree and the bases of the adjacent branches 

 are covered. Meanwhile, the hyphte from the older parts of the superficial area 

 penetrate into the bark and gradually kill it. This dead bark splits and finally 

 peels away from the wood. The spread of the fungus is governed largely by 

 the moisture conditions, while the amount of damage done before the disease is 

 noticed depends upon the size of the trees. Young two-year-old stems are 

 quickly encircled and ringed, while the older trees are not so readily damaged. 



On six-year-old Hevea in the wetter rubber districts the fungus grows con- 

 tinuouslj^ and kills off the bark uniformly, while the side branches at the point of 

 attack are ringed and killed and the bark on the main stem peels off in large 

 patches. The disease usually appears toward the close of the southwest mon- 

 soon rains, and is conveyed from tree to tree by wind-blown spores which are 

 produced in large numbers on the surface of the pink incrustations. One and 

 two-year-old trees when attacked should be cut back below the point of infec- 

 tion. In older trees the diseased area may be cut out and the wounds tarred. 



On tea the growth of the pink fungus on the smaller twigs is the first sign of 

 the disease. From these it spreads down to the thicker branches, which soon 

 lose their leaves and die back either over the whole bush or on only one side. 

 In many cases the fungus grows along only one side of a branch, usually the un- 

 der side. In such cases the bark is killed only where the fungus grows, and the 

 subsequent ingrowth of living bark produces a canker in which the dead bark 

 is not shed, but remains ragged and fibrous on the younger twigs, or smooth 

 and blackened internally on the larger branches. 



The more important fungus diseases of deciduous trees, G. Kock (Sep. 

 from Landes Arntsbl. Erzherzogt. Ostcrr. iinter drr Enns, 1909, No. Jf-5, pp. 36, 

 fiyti^ 6). — Descriptions are given and methods suggested for the control of some 

 of the more important diseases of maple, locust, birch, beech, alder, ash, linden, 

 poplar, sycamore, plane tree, horse chestnut, elm. and willow. 



Arsenical poisoning of fruit trees, W. P. Headden ( Colorado Sta. Bui. 151, 

 pp. 3-56, figs. 8).— Further investigations on the arsenical poisoning of fruit 

 trees by the use of insecticides containing certain forms of arsenic ( K. S. R., 20, 

 p. 452) are reported. 



Three forms of this trouble are recognized, viz, corrosive arsenical, systematic 

 arsenical, and arsenic-lime poisoning. The trouble is said to be very general 

 throughout the vState, and occurs in all kinds of soils, which fact is thought to 

 eliminate the question of seepage and, to a large extent, that of alkalis. 



The conclusions reached are practically the same as heretofore reported. 



