2 



In Europe the resting-spore condition of this fungus has only 

 been met with on the Covcberry—Vaccinmm Vili*-ldaea, L. In 

 addition to this host it also occurs on V. Myrtillus, L., and 1 . 

 Chandl<>>% Jepson, in the United States. It has been recorded as 

 occurring on Salix in the United States, but an examination of the 

 specimen in the Kew Herbarium on which this report was 

 founded, shows that the plant is Vaccinium VHis-Idam, L. 



The "cluster-cup" stage occurs spontaneously on the Silver 

 Hr— Abies pectinate, DC, and on A. Nordmanniana, Spach. 

 Infection experiments have shown that the fungus will also de- 

 velop on Abies nob His, Lindl., A. magnified, A. Murr., A. concolor, 

 Lindl., A. balsamea, Mill., A. Fraseri, Lindl., A. ceplmloniea, Lonrt.. 

 A. cilicica, Ant. & Kotschy, A. Pietita, Forbes, A. Pinsapo, Boiss., 



and A. Veitehii, lindl. 



On the other hand Tsuga canadensis, Can*., and T. Douglaxii, 

 Carr., have resisted all attempts at infection. 



The appearance presented by Cowberry plants when diseased 

 is very striking. All the branches grow perfectly erect, the 

 entire plant grows much taller than uninfected plants, and the 

 leaves are much stunted. The fungus attacks the stem, which 

 becomes much swollen and spongy in texture. The colour of the 

 swollen stem is at first clear pink, gradually changing to brown and 

 finally almost to black. The resting-spores or teleutospores of the 

 fungus are produced in the epidermal cells of the swollen stem, 

 and in the spring following the period of infection, germinate in 

 situ and send delicate threads through the epidermis of the host- 

 plant into the air. These threads bear very minute secondary spores, 

 which are scattered by wind. Some of these spores alight on the 

 stems of other Cowberry plants, and the same cycle of develop- 

 ment is repeated. If young conifers happen to be growing near 

 a diseased Cowberry plant, and the spores from the latter settle 

 on the conifer leaves, the "cluster-cup" stage of the fungus 

 develops and the spores it produces can infect neighbouring 

 Cowberry plants, but cannot directly infect another conifer. 



The Silver fir— Abies pectinate, DC, suffers most from the 

 disease in this country, and also on the Continent; diseased 



specimens of A. Nordmanniana, Spach, have also been received 

 from Wales. 



In conifers the leaves only are attacked. About a month after 

 infection two rows of white, cylindrical " cluster-cups,' 1 about half 

 a line m length, appear on the under surface of the leaf ; these 



cluster-cups" orperidia are the fruit of the fungus and are filled 

 with minute orange spores. Infection usually occurs in May, and 

 by the middle or end of July diseased leaves have become yellow 

 and soon fall. After the spores have been blown away, the 

 suvery-white empty '-cluster-cups" resemble the eggs or empty 



mistaken 8 ° me minute insect ' for which thev are frequently 



ri;£o!I ent T Ve D ? ea » ures are alone of service in combating this 



™2Z'J n * el * c } xn % a s ' tef °r a seed be.l or nursery, it is im- 



? th n^T a i m £* c 110 di8eased Cowberry plants are growing 



n- arZS b T 1 r a - , Such Can be re;i ' lil > *'tecte«l when grow- 

 ing amongBt healthy plants from the description given above. 



