1922.] 



Spraying of Cornfield Weeds. 



1115 



ducting tubes and nozzles with lead or tin, although a harder 

 metal would be required for the wearing parts of the pump. 



Daisies in Lawns. — At one centre, sulphate of ammonia 

 spray (11 lb. to 3 gal.) was used in order to see if it would 

 destroy daisies. The spray was applied with a " Four Oaks " 

 knapsack sprayer, and it appeared to be quite capable of 

 destroying a very large proportion of the daisies present. 



Notes. 



(1) A 4 per cent solution of copper sulphate is generally recommended. 

 See the Ministry's Leaflet No. 68. 



(2) "Copper sulphate lias no effect upon Corn Crowfoot (Buttercup)'' 

 (Worcs.). 



(3) " Field trials were carried out (in Worcestershire) on Corn Crowfoot 

 (in autumn-sown corn) against which sulphate of copper is ineffective, and 

 from the results the following is recommended : 



Strength : Sulphate of ammonia 1| cwt. in 40 gallons of water. 

 Amount of solution per acre : GO gallons " (Worcs^). 



(This is nearly 2 cwt. in GO gallons). 

 If the operation is well carried out in favourable weather at least 75 per 

 cent, of the corn crowfoot will be killed and most of the remainder so damaged 

 that they will have insufficient vigour to produce seed (Worcs.)." 



(4) "In the course of spraying experiments with sulphate of ammonia 

 (in Worcestershire) it was discovered that it had injurious effects upon a much 

 wider range of plants than has sulphate of copper. At the above strength 

 and rate per acre it will exterminate almost completely ivy-leaved speedwell r 

 large field speedwell and corn spurrey or dither if young (the latter at half 

 strength) ; c]iarlock, radish, common hemp nettle, and many other annuals are 

 also destroyed to the same extent as corn crowfoot, the spray thus being iq the 

 case of these plants not quite so deadly as sulphate of copper. Peas, beans, 

 vetches and potatoes are all severely injured and clover seedlings are killed. 

 The operation must not therefore be carried out in the case of corn which has 

 been seeded out with clover. " 



(5) As regards the comparative efficacy of sulphate of ammonia and sulphate 

 of copper against charlock the following are the conclusions of the Bangor 

 report : — 



(a) Spraying Charlock with 4 per cent, sulphate of copper solution is 



much more effective than with concentrated solution of sulphate 

 of ammonia. 



(b) The effect of sulphate of copper is more immediate, and, whereas 



sulphate of ammonia solution only attacks the leaves and to a lesser 

 extenL the flowers, sulphate of copper destroys the leaves, flowers 

 and stem. 



(c) Sulphate of ammonia solution of strengths 2 cwt. or H cwt. to 60 



gallons, causes beans to wither. 



(d) Sulphate of ammonia solution is capable of destroying Charlock if 

 the spraying is done sufficiently thoroughly to cover the whole 

 of the plant. This is not necessary with sulphate of copper 

 spraying. 



