1112 



Spraying of Cornfield Weeds. 



[Mar. 



smothering effect of the cereal crop therefore was not so apparent 

 and this gave the weeds a unique opportunity of reviving, where 

 they were not absolutely killed out. 



Effect of Sulphate of Ammonia Spray on Various Weeds in 

 Bucks. — The spray fluid was 2 cwt. of sulphate of ammonia 

 dissolved in water and made up to 60 gal. 4 



Group I. — Spray Effective in 1921. 



Charlock (Sinapis arvensis, Linn.). — This particular weed was 

 not very common in spring-sown cereals during the past season 

 in Bucks, although one very like it in many respects was abun- 

 dant, as is explained below. However, at those centres where it 

 was present, the spray destroyed the charlock satisfactorily. 5 



Wild White Mustard (Sinapis alba, Linn.). — This plant is easily 

 confused with ordinary charlock in its earlier stages of growth ; 

 but the pod is very distinctive. The beak of the pod is longer 

 and broader than the rest, whereas in charlock the beak is 

 shorter than the rest of the pod. This was the prevailing corn- 

 field weed in the Chiltern Hill district. It was sprayed at some 

 centres immediately it came into rough leaf, whereas in others 

 it had got into full flower. However, the leaves were badly 

 burnt, the flowers destroyed and seeding very largely prevented. 

 At both stages the spray was most effective. 



Ivy Ijeaved Speedwell (Veronica hedera 'folia, Linn.). — This 

 weed was common in some of the cornfields in the Vale of 

 Aylesbury. On account of its spreading habit it tends to smother 

 the young cereal plants. The spray appeared to destroy this 

 weed completely. 



Sheep's Sorrel (Rumex AceioseUa, Linn.) was only common in 

 one or two centres. The spray fluid appeared to be quite effective 

 in destroying it. . 



Group II. — Partially Effective in 1921. 



Corn Buttercup or Starveacre (Ranunculus arvensis, Linn.). — 

 This weed was fairly common among winter wheat on the stretch 

 of land extending from Stony Stratford to Chaddington. It grows 

 up to 18 in. high, has a smallish yellow flower and black spinous 

 fruits. In Herefordshire these black fruits are called " harvest 

 lice," and the spines do undoubtedly suggest legs. 



When these plants were sprayed during the earlier stages of 

 growth, 6 the leaves were withered up and it appeared for two or 

 three weeks that the plants were quite destroyed, but after this 

 time a proportion of the weeds recovered, and ultimately pro- 

 duced seeds. The spray, therefore, was not quite so effective under 



