762 EXPERIMENT STATION RECORD. 



{DelavMTe Sta. Rpt. 1899^ 2'P- 37-30, (Icjm. 1). — In eontinuatiou of 

 previous investigations, the fourth year's report is given of spraying 

 experiments conducted on Winesap and Strawberry apple trees. Bor- 

 deaux mixture, composed of 6 lbs. of copper sulphate, 6 lbs. of lime, 

 and 50 gals, of water, was applied to the trees, the first application 

 being made when the buds were swelling, the second just after the 

 petals had fallen, and the third at the time the fruits were about the 

 size of peas. At the third spraying 4 ozs. of Paris green was added 

 to each barrel of fungicide. 



The effect of the spraying, as shown by the yield of Winesap apples, 

 is reported, the Strawberry apple trees not having produced any fruit. 

 At the close of the season the Strawberry apple trees had produced 

 an abundance of fruit buds, with good foliage, while the unsprayed 

 trees had lost their leaves and were in poor condition. The 3neld of 

 the Winesap apples is tabulated, from which it appears that the trees 

 receiving 3 sprajdngs bore- 68.2 per cent first class, 16.6 per cent sec- 

 ond class, and 15.2 percent third class fruit which were badly scabbed, 

 while the unspra^'ed trees produced 11.7 per cent first class, 33.1 per 

 cent second class, and 52.2 per cent third class fruit. 



Peach-leaf curl, its nature and treatment, N. B. Pierce {U. S. 

 Dtjif. -b/''-. Division of Yc'ijctalAr IVrys/o/ogy <ind Pathology Bui. 20, 

 J)]). 20Jf^ ph. 30, figs. 10). — The authors investigations show that peach- 

 leaf curl has a widespread distribution and in humid localities is a 

 hindrance to peach culture. The disease is caused l)y the parasitic 

 fungus, Exoascus defonnans, the ravages of which are largely depend- 

 ent upon the atmospheric conditions prevailing while the trees are 

 leafing out. Rains and cold weather at that time increase the severity 

 of the disease by favoring the growth of the parasite. For this rea- 

 son, orchards near large bodies of water and in low, damp situations 

 are more subject to leaf curl than those in dry regions or elevated 

 situations. An extensive account is given on the life history of the 

 fungus causing the disease. The mycelium of diseased leaves is found 

 to be connected through the leaf petiole with the mycelium of the 

 infected limb. Much of the spring infection probably occurs through 

 the wintering mj-celium of the branch, but this is not considered the 

 common mode of infection of the leaves. It seems that most of the 

 spring infections of the peach occur from spores that winter on the 

 tree and about the newly formed buds, and most of the infected leaves 

 fall off without infecting the branch which bears them. The mycelium 

 of badly infected leaves sometimes passes into the l)ranch and this 

 mycelium in some instances may follow the branch for 1 or, at most, a 

 few internodes and possibl}^ infect some adjoining buds. Badly infested 

 branches usually die during the year, while in a comparatively few 

 instances they ma}' support a li\ing mycelium capable of inducing 

 spring infection upon opening buds. Most of the spring infections 



