546 EXPERIMENT STATION RECORD. 



In conclusion the author calls attention to the fact that the immunity which 

 a host plant enjoys from mildew may be due largely to environmental conditions. 

 From a large number of experiments he has carried on he has reached the con- 

 clusion that water supply, nutrition, relative abundance of spores, etc.. play an 

 important part in the susceptibility or immunity of a particular plant to fungus 

 parasites. 



Notes on some apple diseases, F. A. Wolf {Proc. Ala. State Eort. Soc, 9 

 (1912), pp. 69-75). — Popular descriptions and methods for control of the bitter 

 rot and rust of apples are given. 



Canker diseases of apple trees, Pbobst (Oartcnwelt, 16 {1912), No. 21, pp. 

 284-286). — The author discusses the difference in susceptibility of different 

 varieties of apple trees to canker, due to Ncctria dnnabarina, and the relation 

 of the fungus to frost and other injuries of the trees. 



The fungus is considered a wound parasite. The cankers are said to be more 

 liable to appear on trees in poor dry soils and in soils in which the water table 

 is near the surface. Planting in such situations should be avoided, and espe- 

 cially susceptible varieties should not be employed in setting orchards. Where 

 cankers are found upon the trees they should be carefully cut out from the 

 trunks and larger limbs and the wounds covered with coal tar. When on 

 smaller branches the whole branch should be cut off and burned. 



Two apple cankers, H. S. Fawcett (Mo. Bui. Com. Mart. CaL, 1 (1912), No. 7, 

 pp. 2-'i7-2Ji9, figs. 2). — Descriptions are given of 2 forms of apple canker, due 

 to Nectria ditissima and N. dnnabarina. 



Apple scab infection as correlated with maturity of ascospores, weather 

 conditions, and development of fruit buds, E. Wallace (Abs. in Phytopath- 

 ology, 2 (1912), No. 2, pp. 9Jf, 95). — From observations covering a period of 3 

 years in New York it is concluded that if the weather conditions are favorable 

 the primary spring infection usually occurs about the time the ascospores 

 mature, that is, usually about the time the apple blossoms are ready to open. 

 There is believed to be little probability of serious infection earlier than this, 

 whatever the weather conditions may be. Later secondary infections were 

 studied, and the date of attack and relation of rain to infection were determined. 



Frost injuries to apples, A. Naumann (Reprint from Ztschr. Obst u. Oar- 

 icnbaii [19111, No. 2, pp. 4, figs. 2). — This is a brief discussion with illustra- 

 tions of conditions observed to follow low temperatures on young fruits, includ- 

 ing invasions by fungi, etc., favored by such injuries. 



Gum diseases in citrus trees, H. S. Fawcett (Mo. Bui. Com. Hort. Cah, 1 

 (1912), No. 5, pp. I.'i7-15G, figs. 5). — Descriptions are given of a number of dis- 

 eases of citrus trees in California, and comparisons made with similar diseases 

 in Florida. The diseases described are gummosis or lemon gum disease; scaly 

 bark of California, which is said <,o be the same as psorosis in Florida ; foot rot 

 or mal di gomma, which is common in Florida and rare in California ; root rot, 

 due to some of the higher fungi ; and Diplodia gumming and Florida scaly bark, 

 both of which are present in Florida but thus far have not been reported in 

 California. 



A new species of Pyrenomycetes, N. Naoumow (Bui. Trimest. Soc. Mycol. 

 France, 28 (1912), No. 1, pp. 55, 56, fig. 1).—A description is given of a new 

 fungus, Pleospora batumcnsi.<i n. sp., which was found attacking the petioles of 

 orange leaves in the south of Russia. 



The treatment of downy mildew, black rot, and powdery mildew, J. I.erou 

 (Rev. Vit., 37 (1912), No. 957, pp. 526-528) .—The author describes methods for 

 combating the above diseases that have been repeatedly tested with success by 

 growers. 



