DISEASES OP PLANTS. 340 



on large apples than on small ones, and that bitter pit is increased by con- 

 tinued heavy irrigation, by continued light irrigation, or by sudden checks in 

 the water supply to heavily watered trees. If a sudden drought comes at mid- 

 season the effects may become more extreme than in typical bitter pit, the 

 fruit developing large dead areas beneath the skin, with a very high coloration 

 on the surface, while the fruit is still green. In such cases drops of sticky 

 exudation often appear on the affected areas and the fruit ripens prematurely. 



Stigmouose is a term used to refer to the response to insect attack, and in 

 the apple one form seems to be closely associated with the occurrence of the rosy 

 aphis. It differs from bitter pit in that it develops earlier in the season, occurs 

 on the fruit in the middle of the tree rather than on the exposed limbs, is often 

 followed by cracking of the fruit and premature ripening, is often accompanied 

 by a gnarled appearance of the apple, the spots are not typically at the end 

 of vasculars, and the brown tissue beneath has more definite margins and is firm 

 rather than spongy. 



Stigmonose: A disease of fruits, M. B. Waite (Ahs. in Phytopatliology, 4 

 {lOlJf), No. 6, p. 402). — The author reports having observed in and under the 

 skin of Japanese plums, pears, and apples a disease which he designates as 

 stigmonose. 



On pears stigmonose forms a hard, sunken, slightly atrophied, greenish spot, 

 and in late pears it may become brownish. In apples a similar sunken, greenish 

 spot is produced, the spot later becoming corky and dry, resembling bitter pit. 

 In plums the spots remain firm and hard, although possibly streaked with 

 brown after the fruit ripens. 



Plant bugs and aphids are considered as having an important part iu the 

 formation of these injuries, and the stigmonose effect has been observed on the 

 apple around curculio feeding punctures and scars made by the ovipositor. 



Common diseases of apples, pears, and quinces, M. T. Cook (Neiv Jersey 

 f>tas. Circ. JfJt, pp. 20, figs. 18). — This is a descriptive list of common diseases of 

 pomaceous fruits, with treatments. A discussion is also given of water core, 

 winter injury, and spray injury, also of spraying, with reference to the organism 

 to be controlled, the material to be used, and tne time of application. A spray 

 calendar is appended. 



Common diseases of the peach, plum, and cherry, M. T. Cook {New Jersey 

 Htas. Circ. 4-5, pp. 16, figs. 10). — Besides a discussion 0^' the most common dis- 

 eases of drupaceous fruits in this State, and treatments so far as known, a de- 

 scription is given of injuries due to cold, sprays, and constriction by label 

 wires, said to cause symptoms like those of yellows. Spray calendars adapted 

 to the ppach, plum, and cherry are also given. 



A preliminary report on twig and leaf infection of the peach by means 

 of inoculations with Cladosporium carpophilum, G. W. Keitt {Ahs. in Phyto- 

 pathology, 4 {1914), No. 6, pp. 4O8, 409).— The author reports successful infec- 

 tion experiments with C. carpophilum taken from leaves and twigs, more than 

 50 lesions being counted on twigs and more than 100 on leaves. On the control 

 plants only one primaiy twig infection developed and no primary leaf infection 

 was found. 



Fungus-host relationship in black knot, E, M. Gilbert {Ahs. in Phyto- 

 pathology, 4 {1914), No. 6, p. 402).— A microscopical study of the formation of 

 black knot gall shows that a considerable portion of the hypertrophy is in 

 regions not directly in contact with the fungus. The continued invasions of 

 • the fungus hyphfe cause a separation of cells into larger and small masses, and 

 during this process some of the cells gradually fill with a granular substance 

 which becomes resinous in nature and is exuded from the mature knot. Other 

 cells disintegrate, the cell walls break down, cytoplasm disappears, and at this 



