586 Journal of Agriculture, Victoria. [15 Oct., 1919. 



In tlie case of pear trees attacked by Koot Borer, one of the worst, 

 if not the worst of orchard pests, their natural resisting power is con- 

 siderably lessened by the wet conditions due to improper drainage, which 

 has impaired the trees' root system. It is found that where a favourable 

 soil condition obtains pear trees, even when attacked by this pest, will 

 show great resisting power and probably remain productive for manj 

 years after being infected. 



The Root Borer thrives in compact and impervious soil and clay, 

 which allows of its free tunnelling through the soil without the tunnels 

 collapsing as in the case of the more friable conditions produced by 

 proper drainage. 



Plate 18a.— Shovring hard, lumpy condition of soil due to 

 improper drainage. 



Influence of Good SoiI=Tilth and Aeration on Trees. 



By tilth is meant the ideal soil condition making for the growth of 

 trees, as when the soil particles are comparatively fine and easily broken 

 up, rendering the soil capable of retaining sufficient moisture for use of 

 trees and allowing free access of air deeply into soil. These factors of 

 comparative looseness of soil, moisture, and air mean an ideal environ- 

 ment for growth of trees, providing sustenance for them during times 

 of heavy and continual cropping, and enabling them to better withstand 

 effects of drought. In fact, without such conditions continual cropping 

 would be out of the question, for after a. heavy crop it would probably 

 take the trees a season or two to recuperate and build up their fruit buds 

 for another crop. It is this attention to the soil, together Avith scientific 

 pruning and manuring, that enables some orchardists to obtain regular 

 and heavy crops of pears, whilst others can claim only very intermittent 

 cropping for their trees. 



