448 EXPERIMENT STATION RECORD. C Vol. 88 



DISEASES OF PLANTS. 



The relation of some rusts to the physiology of their hosts, E. B. Mains 

 (Amer. Jmir. Bot., 4 (1917), No. 4, pp. 179-220, pis. 2).— The work here outlined 

 was carried on during 1914 to 1916 in order to obtain data regarding the factors 

 which control the obligate condition for parasitism and to determine the sort of 

 substances necessary to such parasiti-sm. 



It is stated that the optimum temperature for Puccinia coronata and P. 

 sorghi is near 20° C. (68° F.) and the maximum for the latter is about 10* 

 higher. P. sorghi is favored by moist soil and humid atmosphere, but it devel- 

 ops also on the host under dry conditions. Neither of these fungi appears 

 to injure directly the cells of the area infected. The surrounding areas ap- 

 pear to suffer starvation owing to the withdrawal of the food material by the 

 infected areas. Depriving the host of various nutritive substances reduces 

 the quantity of rust. The fungus is not starved by deprivation of light, ex- 

 cept as this reduces the carbohydrate supply of the host. I>ack of carbon dioxid 

 has the same effect as darkness in case of P. sorghi. Pure cultures of this 

 fungus can be maintaine<l upon sterile seedlings and upon pieces of Zea mays 

 floated upon carbohydrate solutions, and it also develops and forms spores on 

 seedlings or pieces of corn leaf in the dark when these are supplied with starch, 

 cane sugar, dextrose, maltose, and dextrin ; but it is not able to develop 

 in the dark when the seedlings or leaves are exhausted of carbohydrates and 

 when only miueral nutriment or water is supplied. P. sorghi is not able to 

 Titilize directly a supply of maltose, dextrose, cane sugar, asparagin, leucin, 

 peptone with or without mineral salts, or decoctions of the host. 



The obligate parasitism of the rusts is thought to be explainable by their 

 requirement of some transitory or nascent organic products related to the 

 carbohydrates which they obtain in the living host. 



The origin and development of the galls produced by two cedar rust fungi, 

 J. L. Weimer {Amer. Jour. Bot., 4 {1917), No. 4, pp. 241-251, pis. 5, fig. 1).— 

 The author states that the galls produced by Gymnosparangium juniperi-vir- 

 ginianw and O. globosum on Juniperus virginiana originate as modified leaves, 

 the vascular systems of the galls being composed of the enlarged and modified 

 leaf-trace bundles. 



The genus Citromyces, G. Pollacci {Atti 1st. Bot. R. Univ. Pavia, 2. scr., 16 

 {1916), pp. 121-136, pi. 1). — The author discusses several species of the genus 

 Citromyces which he thinks should be placed in the genus Penicillium. He has 

 renamed C. pfefferianus, which is technically described as P. pfefferianum. 



Mycological notes, A. Lendnek {Bui. Soc. Bot. Geneve, 2. ser., 8 (1916), No. 

 4-6, pp. 181-185, figs. S). — Discussion is given of Pestalozzia briardi (said to be 

 identical with P. monocluutoidea) , which is present but does little damage on 

 grapevines, also of a fungus technically described as a new species {Lophionema 

 chodati) on Pinus sylvestri*. 



Diseases and injuries of cultivated plants during 1912 {Ber. Landw. Rdch- 

 samte Innern, No. S8 {1916), pp. VIII+354).— This report deals with the 

 weather in Germany during the year, with the influence of disease and injury 

 on crops (particularly noting tliose considered as more important), and with 

 the apparatus and materials employed against injurious agencies. 



Grain smut in Java, O. J. J. van Hall {Teysnuinnia, 28 {1917), No. 1, pp. 

 24-27). — Among the diseases which have already appeared on the gi-ains now 

 being tested out with a view to their cultivation in the Dutch East Indies are 

 wheat smut {Ustilago tritici) and barley smut {V. nuda). 



The prevention of bunt, G. P. Darnell-Smith {Agr. Gaz. N. 8. Wales, 28 

 {1917), No. 3, pp. 1S5-1S9). —Tests reported during a series of years are said to 



