DISEASES OF CULTIVATED PLANTS 439 
Rose Mildew is attributed to the fungus (Zrysiphe 
pannosa Lev.) whichis commonly prevalent in rosehouses; 
it is also found occasionally out of doors. This mildew 
is, for the forcing house, largely diagnostic, indicating, 
when prevalent, uneven temperatures. Proper attention 
to the matter of heat is the best preventive. Sulfur is 
often sprinkled upon plants and is frequently used upon 
the steam pipes, but it is not clear that the influence is 
very great. 
Nematodes. Among the most serious of the rose 
diseases is that caused by the eelworms or nematodes 
which attack the roots. As with cucumbers, these 
parasitic worms induce the growth of small bead-like 
galls upon the roots of the rose. The leaves dry up 
from the margins, 
the plants generally 
turning yellow and 
breaking down as 
the outcome of this 
interference with the 
proper work of the 
roots. This subject 
Fig. 88. Branch of rose of nematodes is dis- 
root with Nematode Galls, cussed at length in 
Bulletin 73. No suc- 
cessful remedy has been found for plants once 
attacked. The method of prevention con- 
sists, as inthe case of cucumbers already 
cited, in the proper steaming and treatment 
of the soil designed for use in the rose 
benches. 
Rust (Phragmidium subcorticium 
Schrank.). This is occassionally met and 
proves very disfiguring. As yet we can ad- 
vise nothing more than the choice of rust 
resistant sorts. 
RUTABAGA 
Rutabaga is attacked by the same 
diseases as attack turnips. 
RYE 
Rye Anthracnose. This new disease was 
very serious upon rye in 1908 and was surely 
prevalent in 1907. The spores are carried 
by adhering to the seed grain and can be 
discovered in centrifuge separations of grain Fig. 89, Head and upper portion of 
washings. In rye fields the anthracnose stem or rye attacked by anthracnose, 
attacks both the ‘heads and the lower ‘The point of attack upon the head is 
portions of the culms. The localized attack eae eg aa 
upon the head (rachis) kills all that portion te dark spots are the acervuli of the 
of the spike above the point of attack and the anthracnose. From Bulletin 203. 
grain is but partly deqeloped. See Fig. 90. 
Upon the bases of the stems, including the roots, the fungus develops its dark 
masses often closely packed together and dotting both stem and sheaths (see 
figure). In 1908 the loss of yields in rye were from 25 to 60 percent of the total crop. 
