18 



Where 1 lb. of the Paris green was used to 500 gallons of liquid, 

 little or no injury to the foliage was noticed. 



The effects of the above injury to the foliage must be to seriously 

 weaken the vigor of the tree and it is probable that the scab fungus, 

 under the same conditions of moisture and temperature, would 

 develop most rapidly where the trees have the less vigor. 



EXPERIMENT NO. 4. 



KEROSENE FOR THE PLUM WART. 



For several years past experiments have been made in this division 

 to find a remedy for thc^^lum wart (Plowrightia [Sphoeria] morbosa) 

 and we have reported in previous bulletins on the efficacy of 

 kerosene. 



The past season a more extensive use of this remedy has been 

 made and we are able to report our trees which have been treated, as 

 almost entirely free from this pest. 



In its application we have found that unless used with great care, 

 the smaller branches were destroyed. The past season we have 

 overcome this difficulty by applying the kerosene mixed with some 

 pigment to form a thin paste so that it would not spread over the 

 branches. If some bright colored pigment be used for this purpose 

 it enables the person making the application to see at a glance, 

 whether the wart has been previously painted or not and whether the 

 remedy has been effectual. 



When applied in the earlier stages of growth the wart is stopped 

 at once and no disfigurement of the tree is noticed, while, at the same 

 time, none of the summer spores are scatteied, but when the wart 

 becomes fully grown, the disfigurement will not be removed by the 

 treatment, and the early summer spores will have already been 

 scattered to other branches. 



To he effectual, tiiis application must be made as soon as the wart 

 begins to enlarge, which is shown by a swelling on or under the bark, 

 generally of a light browu color when the bark first bursts open, but 

 becoming darker as it increases in development. 



The kei'osene paste is best applied with a small pointed paint brush 

 and should be used on the wart only. 



Examination of the trees must be made at intervals of from two 

 to four weeks, according to the state of the weather. 



If the weather be dry and clear few warts will be started, while if 

 moist and warm they develop more abundantly. 



