POTASSIUM PEEMANGANATE. 191 



tioas ; the effect is produced instantaneously. But as permanganate 

 solutions cannot penetrate into the organs of plants to destroy the 

 mycelium which vegetates in and between the cells, permanganate finds 

 no application except to destroy fungi, the mycelium of which live 

 on the surface of the plant, that is to say Erysi])he and Cajmodium. 



Action on Insects. — The action of permanganate is weak and 

 sometimes nil. Perroncito immersed the eggs of Bomhyx Mori, L. (silk- 

 worm) in a 1 per cent solution. After twelve hours the action was nil ; 

 only after twenty-four hours' immersion were the greater part of the 

 ■eggs destroyed. Trials made in 1872 (Samal process) to destroy the 

 phylloxera of the vine by watering the stocks with a 0-06 per cent 

 solution failed because the permanganate was decomposed before 

 reaching the roots infested with this aphis. However, Stengele recom- 

 mends a 1"25 per cent solution of permanganate to kill infallibly the 

 vyoolly aphis. 



Use. — -Erysiphe communis, Wal. (mildew of the pea). — Douaire 

 simultaneously tried sulphur and permanganate of potash against this 

 parasitic fungi, the mycelium of which lives on the surface of the 

 diseased plant, and he obtained the best result with the latter. Used 

 at the rate of 1 lb. in 100 gallons of water permanganate completely 

 stopped the invasion of this fungus. A few days after this treatment 

 the less-attacked leaves had become green again, whilst those which 

 were greatly attacked bore black spots in the places where the epi- 

 dermic cells had suffered from the fungus. To obtain a definite result 

 spraying must be done carefully so that both surfaces of the leaves are 

 moistened. This treatment only produces a curative effect, never a 

 preventive one. It can in no way prevent a fresh invasion by spores 

 coming from elsewhere. 



Oidium Tuckeri, Berk, (oidium of the vine). — Of all the fungi the 

 mycelium of which live on the exterior of the diseased plant the most 

 formidable is the oidium of the vine, which, if very resistant to copper 

 salts, may be easily contended against by sulphur and soluble sulphides. 

 Permanganate of potash has also been recommended to kill this para- 

 site. Guocdenovic tried a O'l per cent solution of permanganate 

 which proved entirely satisfactory. Kulisch repeated these experi- 

 ments to compare the results with sulphur. He used solutions made 

 at the rate of lj-2^ lb. per 100 gallons of water. He found perman- 

 ganate produced good results, but the good effect was purely local, and 

 to obtain a complete result it was necessary to reach the whole surface 

 of the plant by spraying. On the other hand, sulphur, which acts by 

 the vapours which it disengages and which penetrate everywhere, pro- 

 duces complete disinfection without it being necessary to cover the 

 whole surface of the vine with sulphur. It has been seen that it is 

 sufficient when the temperature and the atmospheric conditions are 

 favourable to deposit the sulphur at the foot of the stocks to destroy 

 the oidium completely. The advantage of permanganate of potash lies 

 in the fact that it can be mixed with cupric bouillies without losing 

 its properties. Added to bouillie bordelaise one can contend in a single 

 treatment against oidium, mildew, and black rot, which is a great 

 economy of time. 



