295 
673. [Editorial.] The two puzzles. Pear blight. <^Cult. and Country Gent., 61st 
year, Albany, Dec. 3, 1891, p. 976, | col. 
Refers to peach yellows and pear blight and concludes only method of eradication is to 
cut oil'and burn diseased parts. Mentions cutting out of diseased wood of pears and ad¬ 
vantage resulting from better cultivation of remainder of orchard in producing better fruit. 
(J. F. J.) 
674. [Goethe, K.] Einige Ursachen durftigen Wachsthums der Obstbaume. <^Ber. K. 
Leliranst. fur Obst- und Weinbau zu Geisenlieiin am Rhein, fin* d. Etatsjahr 
1889-90, Wiesbaden, 1891, pp. 38-40, fig. 1. 
As a cause of stunted growth of young nursery trees gives the differences existing be¬ 
tween stock and scion. Recommends selection of seed for stocks from vigorous parents and 
the rejection of all stunted stocks. A common cause of stunted growth is too deep planting. 
Such deeply set trees are not only stunted, but were liable to diseases and to attacks of in¬ 
sects. Mentions that deep-set trees are more likely to have “Krebs” or in case of stone 
fruits “gummosis.” Such plants also suffer first from frost. Even if plauted only 5 cm. 
too deep the tree suffers. One may suppose the injurious effects of deep planting are due to 
the injurious effects of the soil moisture on the bark of the buried portion, or that they are 
due to the hindering of respiration of this portion of the bark, causing stagnation of the sap. 
One thing is certain, the flow of sap is hindered through the buried stem and causes the 
production of watersprouts and roots here. Lack of moisture may also be the cause of the 
trouble. (W. T. S.) 
675. “Indigator.” Die-back. <[Fla. Disp., Farmer and Fruit Grower, new ser., 
vol. hi, Jacksonville, Jan. 29,1891, j). 85. 
Gives analyses of soil upon which die-back of orange does and does not exist, showing 
that soil where it exists has more organic matter and more phosphoric acid than the one on 
which it is not known. (D. G. F.) 
676 . JGnsson, Bengt. Om brannflackar pa vaxtblad. <^Bot. Notiser. Lund, 1891, 
pp. 1-16, 49-62, pi. 2. 
Burnt spots on leaves of plants, which are kept in green or hot houses, have been recorded 
in the oldest phytopathological literature. Several theories have been given to explain their 
origin, and the author shows by experiments that the oldest theory, that the burnt spots 
are caused by the action of the sun’s rays through air-bubbles in the glass, is entirely 
correct. Among the different theories, enumerated and discussed by the author, the fol¬ 
lowing might be mentioned; De Candolle (Physiologie v6getale, hi. p. 1113) thought that 
the water might soften tlxe tissue of the leaves and then by being heated in the sun prevent 
the evaporation and produce burnt spots. Sorauer (Pflanzenkrankheiten, 2nd ed., i. p. 456) 
says that when drops of water are left upon leaves of plants in hothouses without draught 
and exposed to the"sun, they cause burnt spots. Other authors, Neumann (Adansonia, vol. 
ii, 1862) and Frank in part (Die Krankheit. d. Pflanzen, 1880, p. 174) believed that the drops 
of water merely by their own heat could produce the burning, but Frank was not un¬ 
willing to suppose that the drops might also have the same effect as lenses. Hoffmann 
(Sameubruch bei der Weinbeere, Bot. Ztg., 1872, p. 113) had observed that grapes upon 
which drops of water had been left became burnt, and he thought that the drops had really 
acted as lenses, concentrated the sunlight and produced the burning, and this theory has 
also been given by Yon Thiimen (Ueber den Sonnebrand der Rebenblatter, Die Weinlaube, 
1886 pp. 409-410). The author has now examined these different theories and he has proved 
that drops, fallen upon leaves, are unable to burn, since they represent but half a lens, 
and they are not able to burn by their own heat, since this is far from being strong 
enough to disturb the tissues. The only acceptable explanation is that poor glass with 
air bubbles produces the burning, although he is not quite unwilling to see some cause in 
drops of water which are hanging down from the inside of the glass. (Theo. Holm.) (See 
Bot. Gaz., vol. xvn, Mar. 17. 1892, pp. 89-91.) 
677 . May, Walter. Die Rohrzucker-Culturen auf Java undihre Gefahrdung durchdie 
Sereh-Krankheit. <^Bot. Zeit. 49 Jalirg. Leipzig, Jan. 2, 1891, pp. 10-15. 
After giving a general account of the soil and climatic conditions in Java in reference to 
thecultureof sugarcane, the author describes the Sereh-disease. It appeared in Java in 1879- 
1880 but did not cause much damage until five years later, when it spread rapidly over 
almost the entire island, causing immense loss. Since then the disease has prevailed to 
greater or lesser extent every year. The outer symptoms of the disease are given thus: The 
stems remain short, the leaves are crowded, many branches and aerial roots are produced; 
the diseased plants do not develop a tall-upright stem, but form a small fan-shaped tuft of 
leaves. In the worst cases no cane is produced, only leaves; certain tissues of the dis¬ 
eased plants become reddened, and cuttings taken from such plants show an increased 
redness and finally decay. The checked growth of the diseased plants brings about a 
diminished sugar content and the sugar present is difficult to secure. As to the cause of 
the disease no generally accepted explanation has been put forth. Nematodes, bacteria 
and even methods of culture newly introduced have been supposed by different writers to 
be the cause. The best means of combating the malady at present known is to obtain sets 
from Sereli-free regions such as Borneo. (W. T. S.) 
678. McC allan, C. W. [and Howard, L. O.]. The Bermuda peach maggot and orange 
rust. <Insect Life, vol. hi, Washington, Nov., 1890, pp. 120-121. 
Describes disease of oranges. Trees die from limb to limb in one year. New shoots also 
die rapidly and in three or four years the tree is entirely dead. This is said to be die-back. 
Disease yields to treatment with carbolic or creosote washes “provided the existing cause is 
removed, and this latter is variously ascribed to over-fertilization, deep planting and im¬ 
perfect drainage.” (J. F. J.) 
