WSEASES OP PLANTS. 44^ 



p. 244), the author gives a detailed account of investigations conducted to 

 determine tlie cause of rlie silver-leaf disease of plums and other fruit trees. 

 His investigations, in which inoculations vpere made with portions of sporo- 

 phores, mycelium, and sinn-es of Stercum purimremn, seem to indicate that 

 this fungus is the active agent which causes silver-leaf disease in England. 



A study of the diseases of apples and pears, E. Griffon and A. Maublanc 

 {Ann. Inst. Aat. Agroii., 2. ser., 10 (1911), No. 1, pp. 69-105, figs. 13).— The 

 results of a study of diseases of apples and pears when gathered, in transit, 

 and in storage are given. A number of diseases due to physiological causes 

 are described, such as the formation of stone cells in pears, water core of 

 apples, and various Ivinds of spotting that are not due to fungi. Among the 

 troubles that are attributed to parasites are rots caused by several molds, 

 brown rot, scab, and bitter rot. In addition notes are given on rots caused 

 by Triclioseptoria fructigena on apples, and DiscocoUa pirina, Lasiostroma 

 pirorum, Aposphceria pomi, and Phoma umbilicaris on i^ears, the last-named 

 being described as a new species which attacks pears about the calyx while 

 they are still attached to the tree. 



Leaf scald or fruit spot, D. McAxpine (Jour. Dept. Agr. Victoria, 9 (1911), 

 iVo. 8, pp. 512-515, pi. 1, figs. 2). — A description is given of the disease caused 

 by EntoDiosporiitm maculatum, whicli has only recently been foiuid occurring 

 on pear trees in Australia. 



A disease of the cultivated fig, F. A. Wolf (Ann. Mycol., 9 (1911), No. 6, 

 pp. 622-624, fig. 1). — The author's attention was called in 1910 to a decay of 

 figs, and an examination of the fruits showed the mycelium of a fungus. This 

 was transferred and grown on various media, and soon pycnidia were pro- 

 duced which were found to contain the spores of a species of Macrophoma. 



The author has compared his fungus with the known species of the genus 

 occurring on figs, and concludes that it closely resembles M. flci. This species, 

 however, has been previously reported as parasitic on the trees, and there 

 seems to be no record of its occurrence in America nor of its presence on the 

 fruit. The disease has been observed only on the purple varieties of figs; 

 hence its early appearance is diflicult to recognize. 



Studies were made to determine how the fungus passed from one crop of 

 fruit to the other, and there were found black pycnidia in the dead bark of 

 branches which were identified by cultures and inoculations as associated with 

 the disease. 



In addition to the Macrophoma there were found on twigs a species of Pleo- 

 spora and also one of Phoma, but attempts to connect these with M. fid by 

 means of cultures indicate that they are not related. 



The author concludes that the fungus is evidently parasitic on the twigs and 

 larger branches and hibernates within the bark, and that if these be cut off 

 early in tlie season little or no infection need be expected. 



Stem-end rot of citrus fruits (Phomopsis sp.), H. S. Fawcett (Florida 

 Sta. Bui. 107, pp. 23, figs. 9). — Stem-end rot of citrus plants is a fungus disease 

 appearing usually in August, causing fruits to drop or to soften at tlie stem end 

 and decay, killing back the twigs and readily attacking wounded branches. 

 Its progress is favored by the presence of scale insects on the fruits, and by 

 warmth, shade, and dampness. The fungus (Phomopsis sp.) lives on dead 

 branches and bark, on the mummified fruit, and in the soil under infected trees. 

 Sound fruit can be infected, whether green or mature. 



Experiments with fungicides have not proved effective in the prevention of 

 this disease. The remedial measures recommended are the destruction of all 

 infected branches and fruit, culling and careful handling, cooling shipped fruit 

 in transit, and spraying against scale insects. 



