568 EXPERIIVIENT STATION RECORD. 



differences in tlie susceptibility of different varieties to attacks of this disease. What 

 is beUeved to be the same trouble has been described in Germany as due to tlie fungus 

 Gnomunia erytlirostoma. The rapid spread of this disease is attributed to the over- 

 crowding of fruit trees and too much moisture. As a remedial treatment it is sug- 

 gested that all diseased leaves should be gathered and burned. If this should be 

 continued for a few years the disease would doubtless cease to be troublesome, as has 

 already jiroved the case in Germany. 



Plum-tree canker, F. A. Waugh {Vermont Sta. Rpt. 1900, pp. 370-373, fig. 1) .— 

 Attention is called to a canker of plum trees which is distinguished from gummosis 

 as following and often being the result of that disease. If a wound of a peach or 

 plum tree remains unhealed for some time, either as a result of gum flow or other 

 cause, the surrounding tissues become blackened as if corroded, so that the usual 

 processes of healing do not take place. While the surrounding parts continue to 

 grow the cankered portions remain dead, blackened, and sunken below the green 

 adjacent ])orti(_ins. In extreme cases the branch is finally killed. It is to these 

 blackened, unhealed, and unhealing spots that the term canker is specifically applied. 

 Thus far, neither fungi nor bacteria are known to definitely cause the disease. It 

 frequently begins, however, in the attacks of such fungi as brown fruit rot and the 

 fungus causing plum pockets. Some varieties are much more susceptible than others 

 to injury from this cause. As this disease is not known to be directly of fungus origin, 

 spraying can not be expected to serve as a remedy and the only way to rid the tree 

 after the canker appears is by pruning. Preventive treatment of the canker in arrest- 

 ing the sjjread of the brown-rot fungus and the plum-pocket fungus may be given by 

 spraying witli Bordeaux mixture, which should be applied early in the spring before 

 the buds start. 



Leaf scorch.ing of trees by the •wind, L. R. Jones {Vermont Sta. Rpt. 1900, 

 pp. 281, 382). — About July 1, 1900, there was noticed a sudden and peculiar blighting 

 of the leaves of many trees and shrubs. Phis was first noticed on elderberry. A 

 further observation revealed similar trouble upon a number of other shrubs and trees. 

 The blighting was begun at the tips and margins of the leaves, although in broad 

 leaves like maple dead spots occurred irregular!}^ between the larger veins. Con- 

 siderable injury was done by this leaf scorching. A line of maple trees appeared as 

 if scorched ]jy lire upon one side, while the other was not harmed. The cause of 

 injury is attributed to a peculiar combination of weather conditions. Hot, clear, dry 

 weather was associated with heavy winds, and excessive loss of water through trans- 

 piration is believed to be the cause of the trouble. Trees that were sheltered from 

 the wind escaped, as did many others which wei-e in soil conditions especially favor- 

 able. With tlie exception of trees recently transplanted, it is believed but little per- 

 manent injury will be done. 



Spot diseases of mandarins, Trabut {Bal. Agr. Algerie r.t Tunisie, 7 {1901), No. 

 6, pp. 11..', 1 !■'>). — The author describes the causes of a number of different kinds 

 of spots occurring upon the mandarin. One in which the spots are very numerous 

 and quite small is said to be caused by the orange black scale {Parlaforia zizgjM). 

 A second form of spot is described in which the spots become several millimeters or 

 a centimeter, or more, in diameter, followed by a complete destruction of the skin ot 

 the fruit. This is due to the fungus Septoria glaucescens. This disease is sometimes 

 quite destructive to the fruits. Another form of spot described is due to an acarid. 

 This produces lesions in the skin and makes it possible for the easy attack by the 

 fungus causing the i>reviously described trouble. 



Gooseberry mildew {Jour. Bd. Agr. [London], 8 {1901), No. 1, pp. 1-4, pl- 1)- — 

 A brief popular desciption is given of the gooseberry mildew {Microsphseria grossula- 

 riif) . This mildew is said to be less destructive than the American gooseberry mil- 

 dew {Sparothecn mors-uviv) and its occurrence may be prevented by repeated spray- 



