244 Summary of Agricultural Experiments, [june, 



Weeds and Insect and Fungus Pests. 



Destruction of Charlock by Chemical Means (Mitt eilun gen der Deut. 

 Landw. Gesell., April 29th, 191 1, Flugblatt, No. 11). — The destruction 

 of charlock (Sinapis arvensis, L.) and wild radish (Raphanus Raphan- 

 istrum, L.) is most effectively carried out by mechanical means, e.g., 

 harrowing. Where such methods are inapplicable, or where they have 

 not proved successful, the German Agricultural Society recommends the 

 eradication of. the weeds by chemical means. The method which has 

 been found in Germany to be the best and cheapest is to spray the weeds 

 with a solution of sulphate of iron at the rate of about 54 gallons of a 15 

 to 20 per cent, solution (£ cwt. to 1 cwt. sulphate of iron) per acre. 

 Smaller quantities will not ensure success, but larger quantities will do 

 no harm. The addition of 5 per cent, of molasses is also recommended 

 as causing the solution to adhere to the weeds more firmly. Care should 

 be taken in the choice of a sprayer and the regular cleansing of the 

 same. 



Sulphate of iron applied in the form of a powder, whether as crystals 

 or dried, is also effective if sufficient quantities are used (say 90 lb. per 

 acre of the dry form, or 180 lb. per acre of the crystalline form), if the 

 powder is evenly distributed, and if it is applied when the leaves are wet 

 with dew. Its application is therefore only possible in the early morn- 

 ing in calm weather. Distribution by hand is difficult, and manure 

 distributing machines should be used. Nitrate of lime is also effective 

 in destroying charlock, but on account of its cost it should only be used 

 where the crop under cultivation needs nitrogenous manuring. It should 

 be applied at the rate of 90 lb. per acre. 



All cereals may without hesitation be sprayed or powdered with 

 sulphate of iron. The slight damage apparent at the commencement is 

 unimportant, and as a rule further growth is favourably influenced. 

 Clover, lucerne, and seradella sown among the grain crops will also 

 stand the treatment. On the other hand, roots, potatoes, beans, 

 vetches, and yellow and white lupins are injured, but peas and blue 

 lupins are more resistant. Flax can also be sprayed if about 4 in. 

 high. 



The success of the treatment depends upon the time of spraying. 

 The standing stems of the older weeds and their buds are not destroyed, ' 

 and treatment should therefore take place before the appearance of the 

 buds about the time the fourth leaf develops. Spraying should not be 

 carried out when the plants are wet with rain or dew, or when rain is 

 expected, but otherwise it may be undertaken at any time of the day, I 

 though cold or windy weather is prejudicial to the effectiveness of the 

 operation. 



Remedies for Apple Sucker. — In addition to the methods recom- 

 mended in Leaflet 16 to be employed against Apple Sucker (Psylla malt), 

 one of the Board's inspectors has found two remedies very useful during 

 the last few years. These are respectively a nicotine wash of strength 

 about 0*075 P er cent., and a lime-and-salt wash containing 20 per cent, 

 of lime and 2 per cent, of salt. 



The nicotine wash has proved superior to paraffin emulsion, and is 

 absolutely innocuous to leaves and flowers. It should be used after 

 the young begin to hatch out. A solution of this strength was found 



