IK) INSECTICIDES, FUNGICIDES, AND WEED KILLERS. 



Buffum aud Arthur against this parasite of the strawberry to prevent 

 its too great extension. 



Guignardia Bidwellii, Viala et Eavaz (black rot). — Galloway ob- 

 tained satisfactory results with Q-l per cent solutions of liver of 

 sulphur: blank vines 65-64 per cent of sound grapes; vines sprayed 

 six times, 75-17 per cent of sound grapes. This treatment cannot 

 compete with that of copper salts, because notwithstanding its less 

 efficacy it is not quite harmless to the vine leaves. 



Septoria Piricola, Desm. (spotting of the leaves of the pear). — , 

 Duggar used potassium sulphide with success, but found it less 

 efficient than bouillie bordelaise. 



Gladosporium fnlvuvi, Cooke (tomato disease). — The mycelium, 

 which extends between the cells of the parenchyma, cannot be reached, 

 but the conidiophores may be destroyed. Liver of sulphur acts better 

 than sulphur in this instance (Mohr). 



Gloesporiuin frutigenum, Berk, (bitter or tardy rot of fruit). — To 

 prevent this, Galloway and Nijpels spray the apples before maturity, 

 in August, with a 0-4 per cent solution. 



Fusicladimn dentriticum, Fuckel (apple scab) ; Fusidadium iiiri- 

 niuii, Fuckel (spots of the pear). — Gatf found that on apple-trees 

 frequently sprayed with 4 per cent solutions of liver of sulphur from 

 the birth of the leaves, and renewed after each heavy rain, the amount 

 of diseased apples is appreciably diminished. 



Use against Insects. — Potassiurn sulphide may be used as a 

 caustic against delicate insects. It also destroys the tissues protecting 

 grubs. 



Acridides. — Dubois observed the great sensitiveness of grasshoppers 

 (Locusta) and their eggs to potassium sulphide. These eggs touched 

 by solutions of potassium sulphide do not hatch. Watering the soil 

 with potassium monosulphide on the spot where the Acridides have 

 laid their eggs may suffice to impede the invasions of the Acridimn 

 migratorium so formidable in Algeria. 



Ertocampa adumbrata, Kl. (the pear-tree saw-fly). — Taschenberg 

 recommends powdered fresh liver of sulphur spread like sulphur on 

 the trees. Solutions of the sulphide are used with success against the 

 caterpillar protected by a silky tissue which render them inaccessible 

 to ordinary aqueous insecticides. Potassium sulphide by its caustic 

 action softens and finally decomposes the tissues, and penetrates to the 

 caterpillar which then dies owing to the sulphuretted hydrogen dis- 

 engaged. 



Conchylis ambignella, Hubn. (cochylis of the vine). — Schmidt- 

 Achert recommends as very efficacious against this caterpillar a 2-5 

 per cent solution of liver of sulphur sprayed on the flowers and on 

 the crapes ; Schafer, on the other hand, did not obtain good results by 

 this treatment. 



Hypommeuta Malindla, Zell. (hyponomeute of the apple-tree). — 

 iiach found a bouillie made with 1200 grammes of soft soap and 200 

 grammes of liver of sulphur in 100 litres of water (say 12 lb., and 2 lb. 

 Tn 100 gallons of water). This bouillie can be used with success 

 against all caterpillars that live in company in a spun refuge.^ 



