866 EXPERIMENT STATION RECORD. 



an ounce oi iron sulphate per gallon was added, given to the roots of the tree. The 

 following winter the usual dressing of air-slaked lime was given the soil about the 

 trees. The next season the trees seemed to be affected to a greater extent than the 

 previous year but the treatment was repeated with the result that the third year no 

 indication of disease was observed. 



The injury of fungicides to peach foliag-e, S. M. Bain {Science, n. ser., I4 {1901), 

 No. 345, pp. 221, 222). — The author has been conducting investigations for a number 

 of seasons on the injury produced by fungicides to peach foliage, and a preliminary 

 report of his observations is here given. It was found that pure copper hydroxid, 

 copper oxid, or metallic copper placed on leaves is injurious to the foliage of the 

 peach, but without visible injury to that of the apple or the grape. A solution of 

 copper sulphate 0.00005 normal proved fatal to water cultures of the ayjple, while 

 grapes and peaches under like conditions were not seriously injured. Peach foliage 

 protected from rain and dew, as in a greenhouse, sustains no external visible injury 

 from spraying with Bordeaux mixture or copper hydroxid. Under normal (jrchard 

 conditions, leaves sprayed with Bordeaux mixture in situations so as to lie partially 

 protected from rain or dew are the last to show injurious action of the copper salts. 

 The presence of deliquescent salts, such as calcium nitrate and calcium chlorid, 

 appears to accelerate the injurious action of copper hydrate on the foliage of the 

 peach. When grown in saturated atmosphere, peach seedlings were not injured by 

 Bordeaux mixture, and only slightly by pure copper hydrate. Peach leaves growing 

 in such an atmosphere possess a thinner, more easily permeable cuticle than those 

 growing in dry or less moist atmospheres. The presence of a certain excess of lime 

 accompanying the copper hydrate retards or possibly may entiiely prevent the injuri- 

 ous action of the fungicide. This is true of lime applied either as hydrate or as a 

 carbonate. The author is led to believe that the results obtained will serve to explain 

 some of the conflicting testimony of different investigators regarding the effect of 

 Bordeaux mixture upon peach foliage. A practical application of tlie results obtained 

 is suggested in the recommendation that spraying with Bordeaux mixture be fol- 

 lowed with one or more sprayings of milk of lime, thus preventing injury which 

 would otherwise occur. Experiments inaugurated by the author during the present 

 season have thus far showed this method of treatment to be successful; whether it 

 will remain so to the end of the season is yet to be determined. 



Investigations on the mulberry dwarf troubles, U. Suzuki {Bui. Col. Agr. 

 Imp. Unir. Tokyo, 4 {1901), No. 4, pp. 2G7-2^S). — In a previous publication (E. S. R., 

 13, p. 61) the author described the disease of mull)erry, which is said to be the cause 

 of very extensive injury. He has continued his investigations which are reported at 

 some length, the effect of oxidizing enzyms, influence of cutting upon the decay of 

 roots, and the quantity of reserve starch as affecting the disease being reported upon. 

 His former views on the primary causes of the disease are confirmed and it has been 

 shown experimentally that the poor development and ultimate decay of the roots is ■ 

 caused by cutting back the plants during the growing season. The small rootlets 

 which have just begun developing lose their activity and decay, and new ones are 

 not developed for 2 or 3 months after the cutting. The new shoots api>earing depend 

 upon the reserve materials of the roots until that time, and a deficiency of reserve 

 material is not only a result of the disease but is considered the principal cause of its 

 further development. There was observed an abnormal increase of oxidase and 

 peroxidase in the diseased leaves, and at the same time the migration of starch and 

 nitrogenous compounds was greatly retarded. It ia believed that the oxidizing 

 enzyms present exert an inhibiting action upon the diastatic and proteolytic enzyms, 

 and thus become one of the principal causes in the retardation of growth in the 

 diseased plants. A second cause has been lately found to be an insufficient develop- 

 ment of the transportation tissues. These phenomena are analogous to those causing 

 variegation or albinism in plants. The production of oxidizing enzyms in such 



