558 EXPERIMENT STATION RECORD. 



rosette, while briefly described, has so far not been demonstrated to 

 exist in Ohio. The twig - disease described, which is accompanied by 

 an exudation of gum, affects the twigs, branches, and even the trunks 

 of the trees. There are no evidences of previous perforations of the 

 bark as when attacked by some bark beetle. A sectional examination 

 of diseased branches shows a dead or injured area. The author enu- 

 merates various hypotheses as to the possible cause of this disease, but 

 does not believe that the true cause is known. He believes, however, 

 that some impairment of vigor or interference of normal life activities 

 is a partial, if not complete, explanation of the cause. The disease is 

 of a progressive nature and ultimately destroys the trees, and on this 

 account infected ones should be quickly destroyed. 



Dropsical swellings of the twigs and branches and twig spots are 

 briefly described. ISTo fungus or other organism has so far been found 

 which is the probable cause of these affections. The nature and cause 

 of crown gall does not admit of precise statements. The growth of 

 the galls are usually soft, corky, or spongy upon the various parts 

 of the tree. Below ground they are renewed on the peach each 

 season, the old galls falling away and decaying, while the new ones 

 are formed. By many authors the chief cause of these galls has 

 been attributed to nematodes, but the author thinks this hypothesis is 

 hardly warranted by the facts as observed. Experiments with lime, 

 sulphur, and wood ashes have failed to cure any trees affected by 

 crown gall, and the author suggests that any tree showing rough gall 

 growths should be thrown out and burned. 



Among the fungus diseases of the peach described are the peach rot, 

 peach scab, brown or pustular spot, anthracnose, peach mildew, leaf 

 curl, leaf spots, a constriction disease of the stem and branch, which is 

 said to be due to Phoma persicce, twig blight, twig spots, and a root 

 rot. These diseases are more or less briefly characterized and so far as 

 known remedies are suggested. 



The diseases due to animal organisms, as nematodes, root borers, and 

 root lice are briefly described. 



Experiments in spraying peach trees (pp. 237-260). — The author reports 

 a series of experiments which have been carried on for 3 years in the 

 commercial spraying of peach orchards. These experiments are said to 

 have fully demonstrated the practicability of spraying peach trees with 

 Bordeaux mixture for the prevention of leaf curl, scab, and pustular 

 spot diseases. In spraying for the prevention of leaf curl the applica- 

 tion seemed to have a cumulative effect. The disease on trees sprayed 

 in 1897 which had been sprayed the two previous seasons amounted 

 only to 8 per cent. 



Three applications of the fungicide reduced the amount of spotted 

 peaches to 1 per cent, and 2 sprayings reduced the pustular spot disease 

 to 2J per cent, while unsprayed trees bore 16 per cent of affected 

 peaches. For the early spraying of trees the author recommends a 



