DISEA8ES OF I'L.W 473 



j rospora melonis, and the resultsof various methods of treatment for its prevention 

 are Btated. 



The treatmenl of the soil by watering every fourth day with a solution of copper 

 sulphate was tried, and while at first it seemed successful, later the plants were 

 badly attacked by the fungus, and those which had been treated seemed particularly 

 susceptible to the red spider. \ second series of experiments was inaugurated, in 

 which the plants were treated with a copper sulphate solution and with ammonium 

 copper carbonate, but from the results obtained it seems that the use of copper 

 fungicides does nol offer any very satisfactory method of combating this disease. 



The most hopeful method of treatment the author believes is the utilization of 

 •disease-resistant varieties. Where forcing houses have become badlj infested with 

 the fungus some other crop should be grown for a number of years. 



A mushroom disease {Jour. Bd. Agr. [London], 12 (1905), No. /. pp. 

 fig. t). An account is given of a disease of cultivated mushrooms which is due to 

 the parasitic fungus Hypomyces perniciosus. 



This fungus attack- parasitically the mycelium of the mushroom, causing it to 

 become distorted and resulting in curious malformations of the spore-bearing form 

 of the mushroom. On account of the rapid growth of the parasite all beds should 

 be removed before spores arc produced, others isethe houses may become thoroughly 

 infested. 



If this should occur the houses in which mushrooms are grown should be com- 

 pletely emptied ami thoroughly sprayed at intervals of LO days with a strong solu- 

 tion of copper sulphate. '.'> or 4 applications being given. At the same t hue the house 

 should lie kept warm ami moist to favor the germination of the spores of the para- 

 site, which are destroyed by the treatment suggested. 



Some of the results of three years' experiments with crown gall, G. «■. 

 Hedgccm k Science, n. ser., 22 I 1905 . No. 552, pp. 120-122).— k summary is given of 

 the author'- experiments on crown gall, \\ inch is found on the almond, apple, apri- 

 cot, ash, blackberry, chestnut, cherry, grape, hop, oak, peach, pear. plum, prune, 

 poplar, quince, raspberry, rose, walnut, and willow. 



A number of forms of the disease are recognized, some of which arc little known. 

 Those occurring <>n the apple, pear, and quince are said to be quite similar and have 

 not yet been proven to be contagious. Those occurring on the almond, apricot, 

 blackberry, cherry, peach, plum, prune, and possibly the chestnut and walnut are 

 similar in nature and origin and are often very contagious. Those on the grape and 

 rose appear to be slightly contagious, bul can not be classed with either of the preced- 

 ing groups, as far as presenl information goes. The crown gall on the hop is caused 

 by a slime mold resembling Pla&modiophora brassicse, the cause of club root in crucif- 

 erous plants. 



Experiments with apple, quince-, and pear seedlings grown under sterilized condi- 

 tions show that the apple and pear crown gall of the ordinary type, in which there 



IS an absence of Bide roots or hairy roots, is nol contagious. In experiment- carried 



on for '2 years the average result obtained from inoculation of selected apple nursery 



Stock was LO per cent of diseased plants, with 15 per cent of the control plants 



affected. 



The author states that the apple crown gall is of 2 types, one a more or less woody 

 ,L r all with few or no roots growing from it, while the other form is commonly called 

 hairy root from the numerous Bide root- that are put out. Galls may or may not 

 occur in connection with this form, and for the presenl it is considered a distinct 

 disease. 



Careful cross-inoculation experiments show that the crown gall of peach, plum, 



cherry, raspberry, al nd, and apricot are identical. The peach and raspberrj are 



most susceptible to wound inoculation, hut also become diseased through infected 

 soil, it has been impossible to transfer this disease to the apple, pear, or quince. 



14462— No. •")— 00 5 



