448 Journal of the Department of Agriculture. 



Repellent Washes. 



Repellent washes can be recommended, but it must be 

 remembered that they are not absolutely infallible ; occasionally they 

 fail to save the trees from injury. They are applied to the trunks 

 with a brush, and deter animals from gnawing the bark because of 

 an objectionable taste or odour. A great variety of substances are 

 used. Some are without any real value, but others are distinctly 

 useful and generally fulfil their purpose. 



Aloes and other bitter substances do not afford sufficient protec- 

 tion, as many rodents do not object to bitterness. 



Coal-tar dips, carbolic acid, etc., lose their effectiveness very 

 quickly, and have to be renewed at short intervals. Moreover, if used 

 too strong thej will injure tender young tissue. They cannot be 

 recommended, except perhaps for emergency use. 



Stockholm tar and coal-tar, though effective, should not be used, 

 as they are very injurious to young trees. The effect does not always 

 show at once. In the writer's experiments, tar preparations w^ere 

 applied during the last week of August, 1918, to seedling peach trees 

 about the thickness of the thumb. The trees came into leaf and 

 showed no injury for several weeks, but they died before autumn. 

 Young shoots were killed very quickly. Even tarred roofing paper 

 is said to produce severe injury to young trees. 



Limewash has some merit, but it is not so effective as certain 

 other washes, and it does not stick well. Salt is sometimes added to 

 make it more adhesive, but on the farm Turffontein, Welverdiend, 

 where it was tried, the hares injured the treated trees badly. The 

 salt seemed to att^-act the rodents. The addition of soot does not appear 

 to make much difference in effectiveness. Carbide lime soon loses 

 its characteristic odour, and does not seem to be very much superior 

 to ordinary lime. The Minnesota Station recommends that limewash 

 be coloured a deep blue by the addition of copper sulphate (blue- 

 stone), but, as will be seen later, such a wash did not prove to be 

 very adhesive at Potchefstroom. 



Blood has given very good results against hares. Judging by 

 the antipathy that cattle have for it, blood should also be an excellent 

 thing for use when fruit trees are attacked by buck. Probably the 

 effectiveness could be increased by mixing it with water in which a 

 little glue is dissolved, in order to make it more adhesive. If the 

 trees are to be protected from mice, blood must not be used, as it 

 attracts these pests instead of repelling them. 



Sulphur is used in many storehouses as a repellent for rats and 

 mice., The value of lime-sulphur spray has already been discussed. 

 Everything considered, a tree paint containing sulphur seems to be 

 the most promising deterrent for general use. Such paints are stated 

 to have given good results in oversea countries. Aside from effective- 

 ness, sulphur has the advantage of being beneficial rather than harm- 

 ful to the tree. 



Experiments with Repellent Washes. 



With the object of finding a wash that was sufficiently adhesive, 

 experiments were conducted by the writer for the past three seasons 



