238 THE PROTECTION" OF WOODLANDS. 



during wet weather spore-producers are formed in 3 or 4 days from first 

 signs of infection. Hence infected seedlings should be removed and 

 burned before the disease gets epidemic, and infected seed-beds should 

 be used as transplant lines for next 2 or 3 years, and preferably for some 

 other kind of tree than that already attacked. 



Remedy. To prevent the disease spreading the seed-beds should be 

 watered with a solution of 4| Ibs. blues tone (copper- vitriol) and 1 quart 

 ammonia in 50 gallons water. Men working on infected beds should be 

 told to wipe their boots before working in other parts of nursery. 



Cercospora acerina causes a similar disease among Maple and Sycamore 

 seedlings in wet seasons, the cotyledons, primary leaves, and stalks 

 becoming spotted or blackened and withering, and conidia-bearers appear- 

 ing, while the mycelium assumes a thread-like dormant form and resumes 

 activity next spring. 



* The Oak- seedling Fungus, Rosellinia quercina, attacks and kills the 

 roots of 1- to 3-year-old Oak in nurseries during damp warm weather ; 

 but plants are attacked up to about 10 years old, the terminal leaves of 

 infected plants gradually wilting and dying. Roots infected become 

 covered with finely-woven mycelium, the bark turns brown, and small, 

 round, black pustules appear, especially where the first side-roots branch 

 off. From these pustules fine thread-like rhizomorphs, whitish then 

 brown, spread from root to root (as in Agaricus melleus, see p. 251), while 

 the mycelium sometimes also grows above ground and produces conidia 

 which germinate. By means of these small black pustular fruits (sclerotia) 

 the fungus outlives periods of summer drought, and when the air becomes 

 damp again they develop a whitish-grey, mould-like mycelium producing 

 brown rhizomorphs which enter the unprotected tips of rootlets. 



Remedy. In nurseries diseased plants should be removed and burned, 

 and beds used for other plants : in young plantations or natural regener- 

 ations the infected area should be isolated by a trench about 1 ft. deep 

 to prevent rhizomorphs spreading. 



* The Pine leaf -shedding disease, Lophodermium pinastri, is caused by 

 a saprophyte on dead Conifer foliage, that can become parasitic, and 

 chiefly on young 1- to 6-year-old Pine and other evergreen Conifers, to 

 which it is very destructive (damage on old plants being slight). 

 Seedlings and transplants in nurseries are thereby rendered useless. 



During late summer and autumn the needles become speckled with 

 reddish - brown spots, containing the mycelium, and in the following 

 March or April the leaves wither, turn red or brown, and die off, the dead 

 1-3-year-old leaves usually adhering to the young shoots, while the older 

 needles generally fall off ("leaf-shedding"). If the winter has been 

 mild, open, and followed by a wet spring, black fruits (apothecia) appear 

 early, and burst and scatter their spores, but the disease is chiefly spread 



