1922.] 



Spraying of Cornfield Weeds. 



1113 



the abnormally dry conditions of 1921, and further trials are 

 necessary to see if the spray is more effective in a normal season, 

 as was the case in Herefordshire in 1920. 



Other Buttercups, named " Crazies " locally, included the 

 Creeping Buttercup (Ranunculus repens), the Upright or ordinary 

 Field Buttercup (R. acris), etc. In these cases all leaves which 

 the spray hit were badly scorched, bat after about three weeks 

 a good proportion showed signs of recovery. 



Dandelion (Taraxacum Dens-leonis, Desf .). — All leaves hit with 

 the spray were badly burnt, but, like buttercups, many recovered 

 after about three weeks. 



Broad Dock (Rumex obtusifolius, Linn.). — In some of the corn- 

 fields selected for spraying, docks were fairly common. The 

 spray was very severe on the leaves, and growth was temporarily 

 checked ; but after a few weeks the docks began to produce new 

 growth. 



Common Field Thistle (Carduus arvensis, Curt.). — In this case, 

 wherever the " spray " hit the leaves they were badly scorched, 

 and where thistles had been damaged previously either "by the 

 horses' feet, or the cart wheels, they appear to have been killed 

 outright, but the others recovered after two or three weeks. 

 Group III. — Almost Ineffective in 1921 . 



Black Mustard (Sinapis nigra, Linn.). — This weed appeared to 

 be confined to the cornfields in one parish near Aylesbury. Only 

 one field containing it was sprayed and that after the plants had 

 come into flower. At this stage the plant was tall and possessed 

 long tough stems bearing few leaves. The flowers are small and 

 yellow. The spray fluid burnt the leaves somewhat, but did not 

 destroy the flowers or prevent seeding. Further trials are 

 required to see if the spray will destroy this plant in its early 

 stages of growth. 



Black Bindiveed (Polygonum Convolvulus, Linn.) and Milk or 

 Soiv Thistle (Sonchus arvensis, Linn."). — The spray does not 

 appear to injure these plants. 



Stimulating Effect of the Spray on the Cereal Crop.— At one 



centre, viz., Saunderton, Nr. Princes Bisborough, a patch of 

 spring oats, containing Wild White Mustard, was sprayed as 

 follows : — Plot 1 . No spray. Plot 2. 1 cwt. sulphate of ammonia 

 dissolved in water and made up to 60 gal. Plot 3. 2 cwt. sulphate 

 •of ammonia made up to 60 gal. 



The stronger solution (Plot 3) was much more effective in 

 destroying the mustard than the weaker solution on Plot 2, and 

 this in turn compared very favourably with Plot 1. 



