DOUGLAS-FIR BLIGHT. 



461 



14. Botritis Douglassii, Tubf. 



This fungus, termed Douglas - fir blight, and known 

 for several years, as attacking 2 6 years old Douglas firs, 

 in 1895, was found on young Scots pine in Holland (Kitzema 

 Boos). Wellingtonia seedlings have also been attacked at 

 Kew. 



The needles, especially the upper ones, wilt, and the 

 whole plant's growth is weakened. A brownish grey mycelium 

 appears on the upper shoots, which become curved and die, 

 the needles falling off. Conidia form on the fallen needles 

 and minute black sclerotia on the dead branches. The latter 

 produce conidia if the air be moist. Young plants are 

 frequently killed. Nisbet states that this fungus is identical 

 with Sclerotinia 



I 



fuckeliana, De Bary 

 (J5. cinerea), the vine 

 pest. This, how- 

 ever, appears to be 

 doubtful. 



Spray with Bor- \I H ft 41* a 



deaux mixture and 

 burn affected plants. 



C. Needle-fungi. 



15. PeridermiumPini 

 acicola, B. Hrtg. 



(Pine Needle-rust.) 



During April and 

 May, on the one-year 

 or two-years needles 

 of young pines of 

 different species, 

 orange - yellow blis- 

 ters appear, about the size of a mustard seed, often several of 

 them being in a row on one or both ides of the needles. When 

 ripe, they turn brown and split, emitting their spores and 

 leaving on the needles blackish spots with lighter borders. 

 The mycelium is perennial on the needles, and without killing 



Fig. 223. Peridermium Pini acicola, R. Hrtg., on 

 Scots pine needles, a Burst sporoearps. 



