286 Studies in Forestry [CHAP. xm. 



2. Chrysomyxa abietts, Ung., the Spruce needle-rust or 

 blight. 



Pale yellow spots break out here and there on the needles 

 of one-year-old shoots about the end of May or the beginning 

 of June, which increase and become of an intense yellow whilst 

 the uninfected parts remain normally green. Towards autumn 

 brown longtitudinal marks make their appearance along the 

 underside of the needles on both sides of the midrib, which 

 become ruddy and slightly swollen during the autumn. These 

 beds of Teleutospores become enlarged in the following spring ; 

 the epidermis bursts along the middle of the swelling in April 

 or May ; and the spore-bed makes its appearance as a velvety, 

 bright orange pustule, which scatters its spores about the 

 middle of May over the new flush of needles. The green 

 parts of the foliage attacked soon withers, and the needles fall 

 off in June and July. 



This fungus only attacks the young needles, hence one-year- 

 old or older needles are exempt ; and the upper portions of the 

 crown are much less liable to the disorder than the central 

 and lower portions. Spruce plantations of from ten to twenty 

 years of age, in damp, close situations with southern and south- 

 western exposures suffer most, although the disease is also 

 found in woods of thirty to forty years old. Its spread is said 

 to be much more prevalent on limy than on other soils. 

 Warm, damp spring weather favours its increase, whilst all 

 atmospheric influences checking the early flush of the foliage 

 militate against it. The direct injury done to the plantations 

 is only considerable when the disease has obtained a foothold 

 on the foliage for several successive years ; but indirectly it is 

 of real importance, as it vastly increases the danger of attacks 

 from Bark-beetles. The only means of preventing attacks is 

 to avoid planting Spruce in pure forests on wet soils and close, 

 confined situations ; whilst remedial measures are confined to 

 the removal of all twigs infected, and to the regular conduct 

 of thinning operations. 



