APPLE DISEASES 



489 



ent on the life history of the fungus 

 causing the disease. Since the fungus 

 winters over on the fallen leaves, it would 

 be advisable to destroy all such leaves 

 before blossoming time. The usual recom- 

 mendation is to plow the orchards early 

 in the spring before the trees blossom, in 

 order to bury the leaves in which the 

 ascogenous spore stage is developed. The- 

 oretically, the best way to destroy the 

 leaves would be to rake and burn them 

 before plowing, but pathologists have hesi- 

 tated to make this recommendation on the 

 grounds of impracticability. 



In any case, the trees should be given 

 at least three sprayings during the spring. 

 The first application should be made as 

 the blossom buds begin to separate in the 

 cluster and show color; the second should 

 be applied just after the petals fall, fol- 

 lowed by a third application 10 days or 

 two weeks later. Should the third appli- 

 cation be followed by prolonged rains, a 

 fourth may be found profitable. 



Formerly Bordeaux mixture was used 

 almost entirely as a preventive of scab, 

 but in certain sections of this country, 

 notably under the climatic conditions 

 prevalent in the Northwest, the injury 

 from russeting has been so severe as to 

 make its use prohibitive. On this ac- 

 count lime-sulphur has largely supplanted 

 Bordeaux as a remedy for this disease. 



In the Willamette valley repeated ex- 

 periments conducted under the direction 

 of Prof. A. B. Cordley have shown that 

 lime-sulphur (stock solution 30 degrees 

 Barme) diluted one to 30 with water, 

 app 'ed in three sprayings as recom- 

 mei.'i->(i above, has given excellent results 

 in V\- control of apple scab. This method 

 is ni.-\ nsed by most growers in the Will- 

 amette alley. 



The fall applications of Bordeaux mix- 

 ture recommended for the control of the 

 apple tree anthracnose, will doubtless 

 have a tendency to reduce the spread of 

 the apple scab in the fall and may prove 

 to have a beneficial effect in retarding 

 the development of the ascogenous stage 

 in the leaves which fall to the ground 

 coated with the spray. 



liiblio^^^a])lly 

 1S91. Ohio Experiment Station, Bulletin 



Vol. IV., No. 9. 

 1897. Ohio Experiment Station, Bulletin 



No. 79. 

 1899. Ohio Experiment Station, Bulletin 



No. 111. 



1909. Duggar, Fungus Diseases of Plants. 



1910. Ohio Experiment Station, Bulletin 

 No. 214. 



1912. Montana Experiment Station, Cir- 

 cular No. 17. 



Scurf 



Phyllosticta prunicola Sacc. 



The branch scurf fungus is believed to 



occur in Ohio. This causes roughening 



of the bark, but no statements can now 



be made as to its possible seriousness. 



A. D. Selbt 



Shot-hole Fungus. See Leaf Spot. 



Silver Leaf 



Stereum purpureum, Pers. 



Attacks a variety of plants in Europe 

 and reported in 1910 from Nova Scotia. 

 Trees affected may be cherry, plum, al- 

 mond, apple or pear. The leaves have a 

 peculiar silvery appearance or milky- 

 white gloss on the upper surface which 

 appears brittle when bent. Branches 

 attacked die after one or two years. The 

 whole tree eventually succumbs. 



Remedy 



Cut off affected branches as fast as they 

 appear and burn. Paint all wounds with 

 white lead. 



Soft Rot (Sclerotinia fructigina). See 

 Brown Rot. 



Sooty Blotch and Fly Speck 



Leptotherium Pomi (Mont. & Fr.) Sacc. 



The sooty blotch and the fly speck of 

 the apple were formerly thought to be 

 caused by two different fungi, but a re- 

 cent writer* claims that one fungus is 

 responsible for the two diseases. The 

 names given to these two effects charac- 

 terize their appearance. The former pro- 

 duces blotches one-eighth to one-half inch 

 in diameter on the fruit (Fig. 1) and the 



• B. F. Floyd in Dueear's Fundus Diseases of 

 Plants. 



