30 



THE AGRICULTURAL NEWS. 



Jaxuaey 15, 1916. 



PLANT DISEASES. 



NOTES ON BURGUNDY MIXTURE. 



In continuation of tlie article on Burgundy mixture 

 given on page 414 of Volume XIV of this Journal, the 

 following notes embodj' the results of trials that have been 

 made of certain modifications and adaptations of the mixture. 



ADHESivES. In the article referred to, the addition of 

 milk for the purpose of increasing the adhesion of the mixture 

 is mentioned. The use of resin soap for a similar purpose in 

 connexion with the s})raying of trees exposed to heavy rains 

 in India was described on page 270 of the same volume. 

 .A comparison of the two methods in application to 

 Burgundy mixture has recently been made by the writer. 

 In the one case milk was added at the rate of 8 oz. to the 

 -.gallon; in the other, resin soap at the rate of J-pint to the 

 igallon. The resin soap was made by boiling 2 B) of resin 

 ■and IB), of washing soda in 1 gallon of water until a clear 

 compound was obtained. 



The mixtures were applied with a knapsack sprayer, 

 using a Vermorel nozzle with a small aperture to give 

 a misty spray, to a variety of plants including rough and 

 smooth-leaved types. It was found that the resin mixture 

 had the better covering quality, the smaller tendency of the 

 droplets to run together resulting in a smoother and more 

 uniform coating on the leaf. 



The sprayed plants have since been subjected to daily 

 drenching with a garden hose with an ordinary rose attach- 

 ment, and have been exposed to a number of heavy showers. 

 At the end of a fortnight the deposit is not noticeably 

 affected, and there is nothing to choose in respect of the 

 adhesion obtained by the two methods. The superiority 

 of both to the plain mixture in this respect is very marked. 

 Tor general purposes it would appear that the choice between 

 these adhesives may be governed entirely by consider- 

 ations of cost and convenience, though in dealing with 

 foliage with water-repelling qualities it seems probable that 

 the resin mixture will have a decided advantage. 



The relative cost depends on local and individual 

 circumstances. In Barbados resin costs from 6 to 12c. 

 per lb., .soda 2i to 4c. according to quantity, so that the 

 i:ost of the resin soap for 1 gallon of the Burgundy mixture 

 Tvould be from '6 to l'2c. Separated or skimmed milk 

 3nay be used where it is available, in which case little will be 

 added to the cost of the original mixture. 



PRESERVATiVE.s. As stated in the previous article. Bur- 

 gundy, like Bordeaux mixture, should be applied as fresh as 

 possible, since the gelatinous precipitate first formed is totally 

 changed in a few hours to a heavy crystalline precipitate 

 with very inferior adhesion. It has appeared during 

 experiments recently made by the writer that this change 

 may be very considerably delayed in two ways; (1) by the 

 addition of milk as described above for improving the 

 adhesion, and (2) by the addition of a small excess of soda. 

 The latter, contrary to a statement made by E. Bourcart 

 {Insecticides, Fungicides and Weedkillers, London, 1913, 

 p. 278), has been found to prevent the change for at least 

 several days. There does not seem to be any practical 

 application for these observations, for thers should be no 

 difficulty in making the approjiriate quantity of mixture at 

 the time when the spraying is to be carried out. 



BUR<:uNi)Y p.vsTE. A mixture of creamy consistency, 

 suitable for painting over wounded surfaces on trees, the ends 

 of cutting.s, etc., may be prepared by using the following 

 proportions: — 



Copper sulphate 4 oz. in 1^ pints of water 

 Washing soda 5 oz. in 1 pint of water 

 Milk 1 pint 



A similar paste may be obtained by evaporating, by- 

 exposure, the ordinary milk or resin Burgundy until the 

 required consistency is obtained. 



STOCK .SOLUTION. 



Owing to the slowness with which copper sulphate 

 dissolves, it is convenient, where Burgundy mixture is in 

 frequent requisition, to make up a stock solution at the rate 

 of I ft), of copper sulphate to 1 gallon of water. Care 

 must be taken before this solution is measured out to make 

 up any loss by evaporation. The soda is best kept in 

 solid form. 



W. N. 



PHYSIOLOGICAL EFFECTS ON HEVEA 



BRASILIENSIS PRODUCED 



BY TAPPING. 



In the i)revious number of the Agricultural New, 

 a summary of results and conclu.sions drawn from experiments 

 carried out at the Experiment Station, Peradeniya, during 

 191 1-13, in tapping rubber trees on one-third circumference, 

 and published in Bulletin No. 19 of the Department of Agri- 

 culture, Ceylon, was given. In the present number, the 

 summary of results and final conclusions in regard to tapping 

 on alternate days, and pricking methods, obtained from the 

 same source, are presented. 



With regard to tapping on alternate days rersus daily 

 tapping on alternate months, experiments were carried out ou 

 four groups of trees, as follows: — 



87 E. — Half herring-bone on one-quarter of the tree's 

 circumference. Four cuts one foot apart to the left of the 

 channel tapped on alternate days. 87 B. — Four cuts one 

 foot apart on the half herring-bone system over one-ijuarter 

 of the tree's circumference daily in alternate months. 

 87 I). — Two cuts on the full herring-bone system one foot 

 apart on half the tree tapped on alternate days. 87 C. — 

 Two full herring-bone cuts one foot apart over half the tree. 

 Tapping carried out daily in alternate months. The results 

 are summarized as follows: — 



87 E. 'When examined there were bridges of untapped 

 bark 3 to 4 inches broad between tlie tapped area. Though 

 tapping had apparently no considerable effect on the amount 

 of reserve starch in the regions vertically below, or 

 horizontally to the side of, the tapped portion, two out of 

 three of the untapped bridges between the four tapped areas 

 did show considerable evidence of depletion of starch. It 

 may be concluded, therefore, that had tapping been continued 

 over those untapped bridges, the bark renewal at least would 

 have been poor.' 



87. B. 'In this case the effects of tapping appeared to be 

 absolutely localized. The bridges of untapped bark between 

 the tapped areas, though narrower than in the case of 87 E, 

 were not deficient in reserve starch to the same extent.' 



87 D. 'There was no lack of starch in either the bark 

 or the wood of the untapped bridge between the tapping 

 cuts. There was, as usual, a paucity of starch in the 

 renewing bark and the wood behind it. In sections taken 

 just below the lowest tapping cut, the bark vertically below 

 the right-hand arm of the \' showed rather less than the 

 normal quantity of starch, whilst that below the left hand 

 arm was normal. In both cases, however, the condition of 

 the wood was normal. It is probable that the condition of 

 the bark in this rcsjject has less significance than the condition 

 of the wood.' 



