434 PROTECTION AGAINST FUNGI. 



may be attacked from four to a hundred years old, but especi- 

 ally between four and fifteen years. In dense sowings and 

 multiple plantings the disease is at its worst, especially when 

 the wood was originally stocked with broadleaved trees on 

 which the fungus is saprophytic, such as beech, oak, horn- 

 beam, birch, species of Pyrus and Primus,* etc. The stumps 

 of broadleaved trees left in the ground of a plantation form 

 nurseries which propagate the fungus. The fungus also 

 attacks timbers of bridges and other forest- works. 



Plants which are attacked generally die either between 

 April and July, or from the middle of October to the end of 

 November, and frequently the healthiest and most flourishing 

 plants succumb. It is difficult to recognise plants which are 

 attacked until the year before they die, when their needles 

 turn pale and their shoots are stunted. 



In older crops of trees, bark-beetles frequently come with 

 the fungus ; it is not yet decided whether the fungus is always 

 the primary cause of injuries in such cases. 



In Kussia, the fungi are collected for food, and spores may 

 easily escape from the sacks in which the fungi are trans- 

 ported, and spread the disease. Attacks of bark-beetles 

 frequently accompany the fungus in Eussia. 



c. Protective Rules. 



i. All stumps and roots of broadleaved trees should be 

 thoroughly extracted before plantations of conifers are estab- 

 lished on the site of a broadleaved wood, and where the 

 disease has once appeared dense sowings of conifers and 

 multiple planting should be avoided. When the disease shows 

 itself- 



ii. All plants which are attacked must be dug up with all 

 their roots and the rhizomorphs and burned. Should this 

 produce a blank, the ground must be thoroughly trenched and 

 all strands of rhizomorphs extracted before it is replanted, and 

 then it is best to plant broadleaved species. 



* A. mellea, Vahl., is said bj Hartig to be sometimes parasitic on species of 

 Prunvs. Mr. C. G. Rogers reports that a sycamore, forty years old, was killed 

 by this fungus in 1897, at Hartley, near Plymouth. 



