15(1 FUNGOID PESTS OF CULTIVATED PLANTS. 



In this stage it is more likely to submit to treatment by fungicides 

 than in the more mature or resting condition. 



S . Syll. iv. 988 ; Sacc. F. Ital. t. 1006 ; Mass. PI Dis. 107. 



Ripening fruits are liable to attack from Oidium Balsami, already 

 v/r, p. 84). 



Strawberry-leaf Blight. 

 Spharella Fragaria (Sacc), PI. XII. fig. 42. 



When a spot first appears on a young leaf it is brownish or reddish, 

 l hen becomes circular with a dead white centre (3-6 mm.) and broad 

 purple border. Subsequently conidia are produced as already described 

 (Bamularia Tulasnei), which for some time are produced in succession 

 in mi the same threads. If these conidia fall on a fresh leaf surface they 

 germinate in a few hours. In the latter part of the season the mycelium 

 becomes compacted into sclerotia, which are capable of germinating and 

 producing a crop of conidia in the spring. 



Perithecia are developed in late autumn, but are not matured until 

 the spring, upon the white centre of old spots. Asci are produced within 

 tin se perithecia, each containing eight oblong colourless two-celled 

 sporidia (15 x8 4 /<). 



The fungus passes the winter under three forms : (1) as mycelium in 

 the leaves, \'1\ as sclerotia developed from the mycelium, (3) as ascospores 

 produced in the perithecia. 



The remedies suggested are a solution of sulphide of potassium one 

 ouuce to eight gallons of water. Also the copper solutions. Burning of 

 il spotted leaves which may carry the disease over to the spring. 



Known in Europe- — in France, Germany, and Italy — as well as in the 

 United States. 



U.S.A. Exp. St, i. Cornell, xiv. Dec. 1889 ; Sacc. Syll. i. 1951 ; Mass. 

 PI. Dis. 107, fig. is ; Tubeuf, Dis. 215, fig. 



S'ri;\\\ l;i;i;l;\ MlhDKW . 



Spharotheca Humuli (DC). 



A while mould on Strawberries was recognised by Berkeley in 1854, 

 when be imagined il was the same species as bad been Known on Turnips. 

 AJterwardf th< occurrence <>f the same mildew in America led to its 

 further in tion, and it was discovered at Length to be none other 



than ;i form of the will -known mildew of the Hop. In this country only 



th< conidia! condition had been seen, which was a simple Oidium, some- 

 what Like that of the Vine. <>n the other hand the perfect fruit was 

 found in America, so thai between L892 and 1898 it became established 

 that the fungus of the Strawberry mildew was thai known as Sphcsroth 



Humuli (or, as formerly termed, Sphorotheca CtUtCtgnei), the cause of the 

 Hop mildew. (Pig. 21.) 



In the firsi stage il attacks the leaves, causing them to curl, so as to 

 appear as if Buffering for lack of water. At this time the mycelium 



