abstracts: phytopathology 563 



other hand, is generally not of sufficient intensity to be injurious to the 

 causal organism, and potatoes grown on the Washburn loam are very 

 often infected with the common scab. L. J. G. 



PHYTOPATHOLOGY. — Irrigation experiments on apple-spot diseases. 

 Charles Brooks and D. F. Fisher. Journ. Agr. Res. 12: 109- 

 138, pis. 2-5, figs. 1-10, tables 1-11. January 21, 1918. 

 The writers point out the distinguishing characteristics of a number 

 of different spot diseases of the apple, including bitter pit, Jonathan 

 spot, and drouth spots of various kinds, but the paper is devoted mainly 

 to experimental data on the relation cf the soil-water supply to the 

 occurrence of these various troubles. In the experimental work the 

 amount of soil water was controlled by the duration and frequency of 

 irrigation and was determined from soil samples taken at various depths. 

 Bitter pit was found to be greatly increased by heavy irrigation, par- 

 ticularly when applied late in the season. It was decreased by heavy 

 irrigation followed by light. It was in general worse on large apples 

 than on small ones, but heavy irrigation caused practically as great 

 increase of the disease on small and medium sized fruit as on the large. 

 Drouth spot were found to be produced by sudden shortage of water. 

 Certain kinds of drouth and cork were apparently correlated with 

 particular soil types. C. B, 



PHYTOPATHOLOGY.—^ lea/blight of Kalmia latifolia. Ella M. 

 A. ExLOWS. Journ. Agr. Res. 13:3. April 15, 1918. 



The disease was found on mountain laurel in the vicinity of Wash- 

 ington. It is characterized by a blight or dry rot involving large 

 areas of the leaf blade or the entire leaf. Later it extends through the 

 petioles into the stems and may eventually kill the entire plant. The 

 causal fungus is a new species: Phomopsis kalmiae, its parasitism hav- 

 ing been demonstrated by successful inoculations into healthy plants. 



Pycnidia are readily produced on diseased leaves placed in damp 

 chambers. Sclerotia-like bodies and pycnidia are produced in large 

 numbers in most of the ordinary culture media. The sterile bodies 

 are undoubtedly potential pycnidia as shown by the production of 

 pycnospores after transplanting portions to fresh culture media. 



E. M. A. E. 



