— 195 — 



gei'ous enemy, if we may judge from the experience in England 

 and France. 



An important link in its liistorj', its mode of passing the winter, 

 has not been definitel)' ascertained. Beside the conidial spores, 

 which are ephemeral, it produces rarely "oospores," or spores 

 which will live over winter in the dead tissues of the onion-leaf. 

 But these are probably not the active propagators of the disease. 

 The}' rather ensure the species against complete extinction at any 

 time. 



Mr. Goodrich and others have found the onion bulbs in the 

 spring affected, apparently by this fungus. We have examined 

 the tissue of fresh leaves growing on diseased plants in October 

 and November, and found vigorous mycelium among the cells, 

 although there was no external sign of the fungus, nor was there 

 any disposition to send out fruiting branches when the onion plant 

 was brought into a warm room. If the mycelium hibernates in 

 the leaves or bulbs and begins to fruit in the spring from this 

 source, it is possible our future observations may ascertain the 

 fact. 



No remedy has been tried. But the success in France of the 

 copper fungicides in the treatment of a related parasite, the Po- 

 tato-rot, — (see repetition of this important experiment, appended 

 below), justify us in hoping they will protect the onion also. No 

 bulbs from a crop diseased the previous year should be set out ; 

 and the English are in the habit of sowing the onion seed in the 

 fall, thus enabling the j'oung plant to get a good start before the 

 possible advent of the fungus in the spring. 



Note : The Prevention of Potato Rot. 



Col. A, W. Pearson of Vineland, N. J., in "Garden and For- 

 est" Dec. 4, iSSg, reports almost completely successful experi- 

 ments during 1889, against the common Potato Rot {Phytophthora 

 infestans) by the use of either of the following copper solutions : 



(i). The Bordeaux Mixture. The particular formula employed was as 

 follows : (^a) Sulphate of copper (pulv.j, 6 pounds, in 4 gallons of hot water, 

 (b) Fresh Lime, 4 pounds in 4 gallons of cold water. Mix (a) and (b) slow- 

 ly and thoroughly and dilute to 22 gallons. 



(2). Ammotiia Solution of Copper, (a) Carbonate of copper, 3 oz, (b) 

 Ammonia liq., i quart. Dissolve (a) in (b) and dilute to 22 gallons. 



He reports experimenting on two plats of Peach-blow Potatoes, 

 growing side by side, under the same conditions, and equal in 



