1909.] 



Dry Scab of Potatoes. 



31 



half or one-quarter grown, at a time when the corn crop is 

 not too tall to prevent the solution duly wetting the poppy 

 plants. Further, although a single application of a 2 per 

 cent, solution has not proved successful, two applications of 

 a 3 per cent, solution with an interval of a few days might 

 have the desired effect. 



Maier states that the common scarlet poppy is very sensi- 

 tive to a 13 to 20 per cent, solution of sulphate of iron, and 

 as a 15 per cent, solution has been found to do no permanent 

 harm to the cereal crop when destroying charlock by this 

 method, a solution of this strength might be tried. 



To make a 2 per cent, solution of copper sulphate, 8 lb. 

 should be dissolved in 40 gallons of water; for a 4 per cent, 

 solution, 16 lb. in 40 gallons of water. To prepare a 15 per 

 cent, solution of sulphate of iron, 60 lb. must be dissolved 

 in 40 gallons of water. In either case 40 gallons of solution 

 will suffice for an acre of the cereal crop. To dissolve the 

 sulphates of copper or iron the powdered material should be 

 placed in a bag and suspended in the water by tying the top 

 of the bag to a rod placed across the mouth of the barrel or 

 tub containing the water. Warm water and frequent move- 

 ment of the bag will aid solution. 



References : — 



The Studenfs Flora of the British Islands. Sir J. D. Hooker. 

 Agricultural Botany. John Percival, 1907. 



Journal of the Royal Agricultural Society of England, 1 902, p. 360. 

 Des Plantes Veneneuses. Ch. Cornevin, 1887. 



Poisonous Plants in Field and Garden. Rev. Professor G. Henslow, 1901. 

 Poisonous Plants of all Countries. A. Bernard Smith, 1905. 

 English Botany, Vol. 8 } p. 645. Smith & Sowerby, 1799. 

 Die Bekampfttng der Acker- Unhrduter. Fr. Maier, 1908. 



The Kew Bulletin (No. i, 1909) contains an account 

 of a disease caused by a parasitic fungus named 

 Spondylocladium atrovirens, Harz. 

 Dry Scab of This has been known on the Con- 

 Potatoes, tinent since 1871, and under the name 

 of Phellomyces sclerotiophorus, Frank, 

 is stated by Professor Johnson to be the cause of serious 

 trouble to the potato crop in Ireland. It also occurs in the 

 United States. 



Recently three samples of diseased potatoes were sub- 



