233 
Oidium , 223. 
In Now Zealand, 200. 
Oidium Tuckerii identical with TJncinula spiralis , 
46. 
Onion disease, 102,178. 
Oogonium of TJromyces poce, 44. 
Oospores of Cystopus, 167. 
Paper for spore collection, 163. 
Paraphyses of Sclerotinia vaccinii, 40. 
Peach blight, 123,130,131. 
Cause of, 130. 
Connection with rot, 131. 
Varieties most subject to, 131. 
Peaches: 
Cracking of, 33. 
Infected by Monilia spores, 125. 
Pot induced in, 131. 
Rot of, 33. 
Shipments in 1888, 126. 
Spotting of, 32. (See Oladosporium carpophi- 
lum.) 
Peach-rot: 
Conditions necessary for, 132. 
Destructiveness of, 123. 
How carried over winter, 129. 
How communicated, 128. 
In Chesapeake peninsula in 1SS8,125,126. 
Induced by cracking of fruit, 33. 
Influence of rain-fall on, 128,129. 
In market, 124. 
Losses from, 33,126,127. 
More destructive to early varieties, 124. 
On twigs, 130. 
Other fruits subject to it, 131. 
Prevented by destroying diseased fruit, 132. 
Treatment for, 132,133. 
Varieties most subject to, 124. 
Pear blight, 176. 
Pears, cracking of, 33. 
Peas, attacked by powdery mildew, 214. 
Peck: 
On Bolcti of the United States, 220. 
Reports of, 78. 
Perithecia: 
Of Ascomycetes, 53. 
Of Black-rot, 45. 
O t'Cucurbitaria jAatani, 181, 183. 
Of Cytispora platani, 115. 
Of Macrosporiurn parasiticum, 102. 
Of Spheerotheca phytoptophila, 86. 
Wrong use of term, 223. 
Peronospora. (See Downy mildew.) 
On Boston Ivy, 202. 
On succulent hosts, 10. 
On cucumber, 168, 201. 
On squash, 201. 
On violet, 202. 
Peronosporece: 
Iu Iowa in 1887 and 1888, 6. 
In New Jersey iu 1889, 201. 
Prevalence of, in wet and dry seasons, 6. 
Peziza tuberosa-. 
Germination of nscospores of. 224. 
Mycelium of, 224. 
On Anemone, symptoms of, 224. 
Peziza tuberosa —Continued. 
Relation to P. bulborum, 225. 
Sclerotia of, 224. 
Phalloidei: 
Attractions of, for insects, 169. 
Dispersion of spores, 168. 
Phylophthora, a new American, 221. 
Phytophthora infestans. (See Potato rot.) 
Phytoptus galls: 
Favorable to development of fungi, 85, 134. 
Spheerotheca on, 85, 134, 177, 209. 
Platanus. (See Sycamore.) 
Pleospora herbarum, forms of, 102. 
Plowright, C. B., on British Zfredinece and Ustil- 
aginece, 103. 
Plum: 
Black knot, not in Europe, 176. 
Leaf-blight, treatment for, 38. 
Monilia laxa on, 222. 
Podosplicera tridactyla on, 223. 
Rot induced in, 131. 
Pores, spiny, in Mucronoporus 28, 90. 
Potassium permanganate used for smut, 89. 
Potassium sulphide: 
For apple scab, 35, 36, 37, 210, 212. 
For bitter-rot of apple, 37. 
For gooseberry mildew, 33. 
Strength of, 210. 
Potato: 
Diseases of, 178. 
Nematodes in, 178. 
Potato-rot, 7, 178: 
An experiment in preventing, 158. 
In New Jersey in 1889, 202. 
Treated with copper salts, 227. 
Varieties subject to, 202. 
Potato-scab diminished, 160. 
Powdery mildew: 
On peas and beans, 214. 
Sulphur for, 214. 
In New Zealand, 200. 
Preliminary report on smut in oats, 218. 
Prevalence of ergot in 1889, 203. 
Prillieux, M., on a disease of apple and chestnut 
leaves, 106. 
Promycelia of TJstilago boutelouce. , 13. 
Propagation and prevention of smut in oats and 
barley, 42. 
Prunes: 
' Monilia laxa on, 222. 
Podosplicera tridactyla on, 222. 
Pucciuia: 
Hetercecismal, 167. 
Identity of different species, 217. 
Pumps: 
Lewis combination force, 37. 
Little Gem force, 35. 
Pycnidia: 
Doubtful in Macrosporiurn parasiticum, 102. 
In Protobasidiomycetes, 99. 
Of Ascomycetes, 53. 
Of black-rot changed into perithecia, 45. 
Of Cucurbitaria platani, 181. 
Of Cytispora plztani, 114,119. 
Of Discula platani, 57. 
