412 DISEASES OF CULTIVATED PLANTS 



chlorospora, better known as Fusicladium dendriticum^ occur- 

 ring on diseased apple twigs, but the perithecia were always 

 associated with the Fusicladium stage of the fungus, producing 

 its well-known conidia. The habit and general appearance 

 of the American fungus seems to suggest the idea of its being 

 identical with our apple scab. In the United States, or in 

 those particular States where apple blotch is predominant, is 

 the Fusicladium stage arrested, and the Phyllosticta stage alone 

 produced ; in Europe we know the opposite is the case. A 

 similar condition of things is known to exist in the case of 

 other parasites. 



Spraying with Bordeaux mixture is recommended, of 

 strength 4, 4-6*50. First application, just before blossoms 

 open. Second, immediately after the petals fall. Third, 

 three or four weeks after the petals have fallen. Fourth, 

 eight or nine weeks after the petals have fallen. Fifth, two 

 to three weeks after the fourth. Sixth, three weeks after the 

 fifth spraying. This treatment is also said to cover bitter- 

 rot. Remove diseased twigs and wounds in the bark of 

 larger branches. 



Scott, W. M., and Rorer, J. B., U.S. Dep. Agric., Bur. PL 

 Ind., Bull. No. 144 (1909). 



Phyllosticta cannabinis (Kirch.) forms more or less circular, 

 tawny, then pale spots on the upper surface of hemp leaves, 

 and when present in quantity the plants are seriously 

 injured. 



The perithecia forms small blackish dots on the bleached 

 spots. Conidia hyaline, elliptical, sometimes slightly curved, 

 4-6X2-2-5 p. 



Violet disease (Phyllosticta violae, Desm.) forms more 

 or less circular bleached spots on the leaves ; these gradually 

 increase in size and often run into each other, forming 

 irregular blotches which show equally on both surfaces of the 

 leaf. At a later stage the fruit of the fungus, under the form 

 of minute black dots on the bleached spots. 



Perithecia minute, dark coloured, with a small pore or 

 ostiolum at the apex; conidia hyaline, subcylindrical, 10 // 

 long. 



Spraying with potassium sulphide checks the spread of 

 the pest, if begun at an early stage. To ensure strong, 

 vigorous plants, a period of rest in a cool frame is necessary. 



