464 



The Museum Gazette 



FUNGUS DISEASES OF VIOLETS. 



A note upon this subject seems desirable, as from many 

 districts we have received complaints of violets suffering from 

 " disease," some gardeners asserting that it is almost impos- 

 sible to grow them. The term "disease" is a vague one, 

 and probably often includes several parasites, though as far 

 as Haslemere is concerned, all diseased violets brought to 

 the Museum for inspection, have been infested with the Spot 

 Disease (Cevcospom viola). There are three fungi parasitic 

 on cultivated violets, and three on wild ones. These we will 

 very briefly allude to. 



Violet Spot Disease. 



Cercospom 1 viola, Saccardo. — Causes dry whitish spots on the 



leaves of the sweet violet, Viola odorata, especially when grown 



under glass ; but we have seen it in great plenty in gardens 



in the west of England, and it is very prevalent around 



Haslemere. Treatment : spray with dilute Bordeaux mixture. 



Water ... ... ... ... ... 50 gallons. 



Copper sulphate ... ... ... 6 lbs. 



Unslaked lime ... ... ... 4 lbs. 



For adhesive properties add 6 lbs. of soft soap. 



When grown under glass, great care should be observed to 



keep the houses or frames clean, and to select for the cutting 



bed only strong and vigorous plants entirely free of disease. 



American Violet Spot Disease. 



(Altemaria viola) causes greenish or yellowish- white spots, 

 or even pure white ones, on the leaves of cultivated violets. 

 In the very young state it resembles the bite or sting of an 

 insect, at maturity the ring is J inch in diameter with a 

 central light-coloured spot, with more or less numerous 

 alternate rings of dark and light tissue. It is the presence 

 of this central spot which superficially separates this disease 

 from the ordinary violet spot of this country. 



Excessive cultivation in all probability produced a weak 



1 To this genus belong the "shot-hole " fungi of the leaves of celery, and 

 peach, apricot, &c. 



