I 5 o DISEASES OF TREES 



The shape of the gonidia makes it probable that the parasite is 

 a species of Nectria. A few days after being sown in a gelatine 

 extract of fruit they produce a luxuriantly branching mycelium, 

 whose hyphae are much septated and anastomose irregularly 

 (Fig. 84, b\ This mycelium produces either similar gonidia, or 

 such as are somewhat smaller, less bent, and possessed of fewer 

 cells. 



On being transferred to black bread the mycelium grew so 

 vigorously that the large glass jar in which the culture was 

 conducted was completely filled with a white growth. In the 

 flower-pots also, in which the infected conifer seedlings were 

 growing, the mycelium developed so luxuriantly in the soil as 

 to find its way out at the hole in the bottom and to form a dense 



mass between the pot and the table. 

 This proves conclusively that the 

 fungus, like most species of Nectria, 

 can also exist as a saprophyte, and 

 as such may live in the soil. 



Unfortunately I have not been 

 successful in reproducing the peri- 



FIG. 86. -Immature, ripe, and thecium form of the fungUS. On 



germinating gonidia. a slide numerous spheroid bodies 



which were the first stages of peri- 



thecia or pycnidia formed in the mycelium, but they always 

 failed to mature. On this account I am unfortunately still 

 unable to refer the fungus to a species. 



As regards measures that may be instituted with the view of 

 preventing the spread of the disease, attention should in the first 

 place be directed to the diminution of surplus moisture. If 

 such are present, we should also remove all objects such as latticed 

 frames, branches, &c., that have been laid down to shelter the 

 plants. As it is certain that the fungus remains in the ground 

 from one year to another, one must take care, in laying down 

 new seed-beds, to avoid situations where the disease was 

 prevalent in the previous year. If this cannot be done, one 

 should interstratify the upper nine inches of soil with brush- 

 wood, dry turf, or some such material, and roast it, or at least 

 raise its temperature to such a pitch that any spores present in 

 it may be killed. Herr Mantel related to me how he had heated 



