1908.] Wart Disease (Black Scab) of Potatoes. 671 



y%d. to a fraction over 8%d., which is less than half that of the 

 ducklings. But for spring killing, the latter are much more 

 valuable. 



A comparison of the two lots is given in Table VI : — 

 Table VI. 



Lot I. Lot II. 



Soft Food. Dry Mash. 



Total food consumed 2 cwts. 2 qrs. 6 lb. 8 oz. 2 cwts. 2 qrs. 9 lb. 8 oz^ 



,, cost of food .. ... ^14^.11-89^. ... £1 5 s. 4 "j6d. 

 Weight of food consumed for 



each lb. gained 4' 5 lb. ... 4 '68 lb. 



Average cost of food per bird... is. 2'g8d. ... is. 3'2$d. 



Cost of increased weight per lb. 4. yd. ... 5* 06a?. 



Total gain in weight 63 lb. 10 '88 oz. ... 60 lb. 2*88 oz. 



Average gain in weight ... 3 lb. 2*94 oz. ... 31b. 0*14 oz. 



,, weight, 9 weeks ... 3 lb. 5 oz. ... 3 lb. 2 '2 oz. 



These experiments enable us to estimate the cost of producing 

 breeding ducks at, say, six months old, for which purpose 

 experiments have been made with older specimens. From 

 nine weeks onwards the birds were fed on the B mixture. 

 During the next five weeks each bird had consumed an average 

 of 14 lb. of food, by which time they had increased in weight 

 to an average of 5 lb., though four specimens weighed 6 lb. 

 each. During the next ten weeks the average consumption of 

 food was 35-J- lb., making 49^ lb. in all, the value of which is 

 35. 2d. If to this is added the cost of the duckling at nine 

 weeks, the total expense in hatching and rearing a duck to 

 twenty-four weeks is brought up to nearly 5s., which shows 

 that the opinion generally held, namely, that the rearing of 

 ducks for winter marketing is less profitable than the breeding 

 of spring ducklings, is justified. 



WART DISEASE (BLACK SCAB) OF POTATOES.* 

 The disease known as Wart Disease, Cauliflower Disease, 

 Canker, " Fungus " or Black Scab, Chrysophlyctis endobiotica, 

 Potter (doubtfully of Schilbersky), attacks the tubers and 

 haulms of potatoes, giving rise to large and irregular out- 

 growths which resemble pieces of cauliflower covered with mud. 

 Warts or wrinkles appear at first near the eyes of the young 



* This memorandum is issued as Leaflet No. 105, and copies can be obtained 

 on application at the offices of the Board. 



