HOT WATER SPRAYING AGAINST MILDEW. 37 



guy, and E. Salomon confirm the results obtained. This method is 

 currently used to-day. Not only does it cause no prejudice to slips 

 catching root, but it seems, on the contrary, to facilitate it. And the 

 importance of this treatment is so much the greater as it follows from 

 determinations made in Algeria (1885), in Champagne (1890), and in 

 Lorraine (1894), that new phylloxera hot-beds have no other origin 

 than plants coming from countries infested with this formidable insect. 

 G. Couanon and J. Michon resumed the same experiments and ex- 

 tended them to rooted plants which are most frequently used in the 

 reconstitution of vineyards. Eooted Noah plants, dipped for three, 

 four, and five minutes in water at 53° C. (127-4° F.) (51° C. at the 

 exit, 123-8° F.), were planted at the same time as test samples. They 

 took root completely, as well in the greenhouse as in the open air, and 

 the vines grew very finely. Dipping in water at 53° C. (127-4° F.) 

 is thus a practical and economic method for disinfecting vines, rooted 

 or not, for it kills at the same time both the insects and their eggs. 

 It has also the advantage over the sulphocarbonate treatment recom- 

 mended by Mouillefert, that it does not require, like this latter, two to 

 three hours, and has no injurious action on the plants (Balbiani). 

 Disinfection by hot water gives very satisfactory results ; the same pro- 

 cess has been used for other fruit trees intended for sale, and cochineals, 

 the woolly aphis, and other injurious insects, have been simultane- 

 ously destroyed. According to Danesi, all fruit trees, the peach excepted, 

 stand very well being dipped for five to ten minutes into water at 

 53° C. (127-4° F.). To ensure complete disinfection the whole plants 

 must be entirely dipped into the water at 53° C. (127-4° F.), and dried in 

 the air on a copper grating. They can then be packed in disinfected 

 moss and despatched. 



Bruchus Pisi, L. (pea-weevil). — To kill this insect Fletcher recom- 

 mends the following method : A vessel is taken which is half-filled 

 with the infested peas, and boiling water poured on until they are 

 entirely submerged. The vessel is then filled with cold water, and 

 left to stand for twenty-four hours. The peas which do not suffer from 

 the treatment and which are entirely freed from the insects they 

 sheltered can then be sown. De la Bonnefon advises to drop the 

 peas into water and leave them there for some hours. The peas which 

 remain at the bottom are put into an oven the temperature of which 

 is 60° C. (140° F.). After some time they are taken out and then 

 sown. 



Hot Water Spraying. — Spraying plants with hot w^ater has not 

 only been used to destroy injurious insects, but also to cause certain 

 fungi to disappear, such as the Erysiphece. or mildews, which crawl on 

 the surface of the epidermis without ever penetrating into the interior 

 of the tissues. It is owing to this peculiarity that they can be destroyed 

 by hot water. The leaves of plants stand without injury sprayings of 

 77°-85° C. (170-6°-185° F.), whilst at that temperature the mildews 

 disappear entirely. The roots alone of the plant must be protected, 

 because they suffer from contact with water at that temperature. 

 Hot spraying has been used against the following mildews : tlncmula 

 Americana, How. (oidium of the vine) ; Sjyhaerotheca pannosa, Lev. 



