NOTES AND ABSTRACTS. 



279 



these characters are derived from the paternal or maternal side. 

 The reciprocals differed from one another, having some characters 

 more like the seed parent, and various hypotheses as to the reason 

 for this variation are considered. The hybrid is infertile but seed has 

 been obtained from the hybrids by the use of pollen from the two 

 parents. — F. J. C. 



Diseases of Plants, International Campaign against. By Giuseppe 

 Cuboni (Rev. Hort. Beige, No. 23, p. 370, Dec. 1, 1912). — A plea for 

 some sort of combined international action in preventing the spread 

 of plant diseases by infected nursery stock. It is suggested thai 

 an International Convention formed for this purpose might also do 

 valuable work in encouraging and subsidizing a more scientific study 

 of all the preventable diseases. — Af. L. H. 



Diseases, The Influence of Environmental Conditions upon the 

 Development of Plants. By J. M. Reed {U.S.A. St. Bd. Hort., 

 Missouri, 4th Ann. Rep., 1910, pp. 138-154). — Fungi and bacteria 

 are the principal causal organisms of disease in plants, and light, 

 water supply, temperature etc., play an important part in their 

 development and considerably affect the ability of the best plant 

 to resist invasion (p. 139). Soil conditions are an important factor, 

 the root rot of tobacco, for instance, being much more serious in an 

 alkaline soil, while the use of acid fertilizers is effective in controlling 

 the disease. The contrary is the case with club-root in the cabbage 

 family and with the root rot of beets, both of which can be prevented 

 to a great extent by liming (p. 141). In the case of asparagus rust 

 an ample water supply causes such vigorous growth in the host that 

 it can resist invasion by the rust, but a moist atmosphere and heavy 

 dews aid spore germination and the growth of the mycelium of the 

 fungus (p. 142). Carnation rust is much favoured if the leaves are 

 wetted in the process of watering for the same reason. Infection 

 by various green rusts is specially favoured by humid, showery, 

 sultry days followed by damp nights, but where irrigation is practi- 

 cable and there is an absence of dew, rust never causes serious injury 

 to cereals (p. 144). Similar observations have been made with the 

 black rot of grapes, the brown rot of stone fruits, the black rot of 

 cabbage, the late blight of potatos, and larch canker (pp. 143-8). 



The influence of temperature upon different diseases varies very 

 much, the bitter rot of apples becoming a serious menace to the 

 apple crop in very hot weather in the southern portions of the apple 

 belt, and being soon checked by a period of cool weather, while peach- 

 leaf curl is much more prevalent after a cold spell, and the germina- 

 tion of various rust spores has been found to be considerably aided 

 through being subjected to cold for some hours. Chilling also favours 

 infection, radish plants inoculated and then chilled for ten hours 

 showing over 95 per cent, of infections, while only a small number of 



