16 BULLETIN 44, U. S. DEPARTMENT OF AGRICULTURE. 
turing, or heating, or both. Viable spores from pure cultures re- 
cently isolated from arbor vite were used. No results were ob- 
tained. While the fungus is presumably parasitic in nurseries under 
some conditions, the amount of damage it has caused is unknown. 
Spraying with fungicides before infection takes place should pre- 
vent damage by it. 
OTHER NEEDLE DISEASES. 
Various fungi which have been very little studied in this country 
cause needle diseases in American forests. Though none have yet 
been reported as causing disease in our nurseries, there can be little 
doubt that some of them have made, or at least will soon make, trouble 
in nurseries in this country. Much of the comparative freedom from 
needle diseases of American nurseries, even those in the more moist 
regions, has probably been due to the fact that most of our nurseries 
are not in forests. So far as needle diseases are concerned, it will be 
best to avoid forests of the same species as will be grown in the 
nursery in choosing sites for new nurseries. Of the fungi mentioned 
in the literature on needle diseases, which is mainly European, the 
following species will especially bear watching: Lophodermium 
macrosporum Kk. Hrtg. on spruces, Lophodermium nervisequium 
D. C. on firs, Lophodermium laricinum Duby on larches, and Lopho- 
dermium brachysporum Rostr. on white pine. Lophodermium 
brachysporum has been reported by Spaulding? as parasitic on 
needles of young white pines in Maine. Other species of this genus 
and species of Hypoderma and Sphaerella are also likely to prove 
more or less parasitic. It is probable that there are parasitic strains 
of needle fungi in foreign countries which if brought into this coun- 
try will damage our nursery stock more than any of the fungi we 
now have. No practicable quarantine or inspection system will be 
able to keep out these diseases entirely. Nurserymen should avoid 
bringing in foreign pests by using home-grown stock as far as pos- 
sible. So far as is now known seed may safely be imported, but 
bringing in growing stock should be discouraged. 
The Atlantic seaboard and portions of the extreme western and 
northwestern sections of the country, where the climate is especially 
moist during parts of the year, are the most lkely to suffer from 
needle diseases. In the Middle West, where atmospheric conditions 
are relatively dry, past experience indicates little trouble with needle 
parasites in unmulched beds. It is presumable that other needle para- 
sites, like the one causing needle-cast, will be found to be preventable 
by spraying before infection takes place. 
1 Spaulding, Perley. The present status of the white-pine blights. U. S. Department 
of Agriculture, Bureau of Plant Industry, Circular 35, p. 10, 1909. 
