New Yorx AGricuLTuRAL EXPERIMENT Station. 197 
knot. In the central part of Rensselaer Co. we have examined 
the choke cherry, Prunus virginiana L., which grows wild there, 
but found no knots upon it. However, at Washingtonville, Orange 
Co., the latter species is said to be much affected. 
What has been said applies only to old knots. The observa- 
tions furnish no information as to the number of knots produced 
by infections occurring in 1899, for the new knots do not appear 
until late in autumn, after the time when the survey was finished. 
WITCHES BROOMS. 
(Hxoascus cerast (Fckl.) Sadeb.) 
Knowing that this disease is not uncommon in some other parts 
of the State?’ we expected to find it in the Hudson Valley, but 
failed to find a single specimen. 
POWDERY MILDEW. 
(Podosphaera oxyacanthae (D. C.) De By.) 
On July 20, a single bearing cherry tree affected with powdery 
mildew was observed at Delmar, Albany Co. A few leaves at 
the ends of the twigs were affected. 
FUNGUS ON DEAD TRUNKS. 
(Irpex lacteus Fr.) 
On a fruit farm at Middle Hope we observed many dead cherry 
trees bearing numerous pilei of Irpex lacteus Fr.*° The trunks 
were from three to five inches in diameter and in many cases were 
thickly covered with the fungus to a height of from three to five 
feet. The owner explained that the trees were of the variety 
Elkhorn, which is not hardy. Most of the trees had died during 
the past three or four years, apparently from winter injury. 
15 See Fourteenth Ann. Rept. of this station, 1895: 532-533; also, Fifteenth 
Rept., 1896: 459. In May, 1899, we found a single large specimen on an ox- 
heart cherry (Prunus avium), at Sodus Center, in Wayne county, about five 
miles from the shore of Lake Ontario. 
16 Identified by Dr. C. H. Peck. 
