Rodent Injury to Trees. 445 



RODENT INJURY TO TREES. 



Cause, Prevention, and Repair. 



By W. F. ScHLUPP, B.Sc. (Agr.), Entomologist, School of 

 Agriculture and Experiment Station, Potchefstroom, Transvaal. 



Rodent injury to trees is of frequent occurrence in certain parts of 

 the Union. In this article the various ways and means of dealing 

 with the problem are discussed. The farmer or fruit grower can 

 select the method best suited to his own particular case. 



The trees most commonly injured are those of the orchard, but 

 occasionally shade trees and plantations are damaged. This article 

 deals principally with the protection of fruit trees, but some of the 

 methods described are adaptable in other cases. 



The rodents responsible for the damage are hares, field mice and 

 rats. In addition to rodents, small antelopes sometimes do much 

 injury. 



Cause of Rodent Injury. — The damage is nearly always done in 

 winter and spring, and the immediate cause is a lack of green plants 

 and other food. However, in most of the cases that have come to the 

 notice of the writer the primary cause has been neglect of the 

 orchard. By allowing a rank growth of grass and weeds to spring 

 up, favourable conditions for rodents are produced; the vegetation 

 affording the animals a shelter from hawks, owls, and other natural 

 enemies 



Preventive Measures. — The best preventive measure is clean 

 cultivation. By this we mean keeping the orchard free of weeds, 

 etc., during the dry season, as it is in dry winters and springs that 

 the trees are generally attacked. During the wet summer season a 

 cover crop may be grown, but at the end of the rainy season this, 

 should be ploughed under and not allowed to remain on the ground 

 over winter. Grass and other vegetation growing around trees should 

 be destroyed. In addition to sheltering rodents, rank vegetation may 

 sometimes increase the chance of damage by insects and fungi. 



When all that is desired is protection of the trees from a few( 

 rodents that occasionally enter the orchard, the winter prunings are 

 sometimes left lying on the ground until spring, in order that the 

 animals may feed upon these instead of upon the trees. A few 

 cabbages, mangels, etc., could also be placed about the orchard. This 

 is sometimes successful in preventing injury, but is only a com- 

 promise measure and may at times result in attracting a few more 

 rodents to the vicinity. 



Fencing. — Rat and mouse proof fences are practically out of the 

 question. For hares, poultry netting with l^-inch meshes is suitable. 

 A height of 3 feet is suggested, although 2^ feet or even 2 feet would 



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