ii6 DISEASES OF TREES 



advisable to form the nursery in such a position at the edge of 

 the wood that the west winds that impinge upon it shall first 

 have blown over a wide extent of open country. The seed-beds, 

 which are not to be made too large, should be enclosed on the 

 side towards the wood by a perfectly close board fence 6J feet 

 high. If spruce nurseries are available, containing dense and 

 high beds of plants running from north to south, the pine seed- 

 beds may be laid down between the beds of spruce, so that 

 the latter form a protection against the spores that are borne by 

 the west wind. Burying pines in deep trenches during winter 

 often results in complete smothering of the plants owing to the 

 exclusion of atmospheric oxygen. On the other hand, a light 

 covering of leaves in winter affords good protection against 

 contact with the spores. 



In protecting the areas under regeneration against fungal 

 leaf- shed, regeneration by groups, under certain circumstances, 

 gives the best results. Blanks in close pine woods may be very 

 successfully restocked even where the disease destroys every- 

 thing on larger clear-felled areas. This is undoubtedly due in 

 the first place to the protection afforded against the spore-laden 

 wind. In arranging the direction of felling one must take all 

 possible care to prevent the west wind from blowing over large 

 infected areas before it reaches the part of the wood that is being 

 regenerated. Very extensive seed-fellings, when they adjoin 

 each other, further the epidemic distribution of the disease in 

 any case. Where seed is sown or trees are planted in stripes, it 

 is a good plan to plough the stripes from north to south, and to 

 throw the furrow slice on to the west side. If the furrows run from 

 west to east, the west wind, blowing along them, is sure to carry 

 the spores from diseased plants to sound ones. Where the 

 spruce and Douglas fir thrive, these trees may be planted in 

 stripes running north and south, partly at the edge of the wood, 

 and partly at fixed distances throughout it, to act as screens and 

 prevent the disease spreading. This must be done at least ten 

 years before the final felling of the pine wood. 



Areas that are completely overrun by this disease should be 

 planted with Weymouth pines, or some other disease-resisting 

 species, according to the character of the soil. 



The Weymouth pine suffers here and there from a leaf- 



