210 



THE AGRICULTURAL NEWS. 



Jdly 2, 1904. 



ment of Agriculture this season has all been steeped 

 in a 1:1000 solution of mercuric chloride (corrosive 

 sublimate), a violent poison which has been used with 

 success against ' smut ' of cereals, potato ' scab,' and 

 other diseases. The most common steep, perhaps, is 

 a |-per cent, solution of copper sulphate (blue-stone): 

 the seeds are allowed to soak in this for a night 

 (twelve to si.Kteen hours); they are then taken out, 

 drained and dried. Sometimes after treatment with 

 copper sulphate, the seeds are steeped for a few 

 minutes in milk of lime. 



Another method of treating seeds is to steep them 

 for fifteen minutes in hot water. This mode has been 

 very successfid, but requires careful mani[)ulation. The 

 temperature of the water must be kept between 130 

 and 134" F. ; a lower temperature will not kill the 

 spores, a higher one will injure the seeds. Formalde- 

 hyde is another steep that has been used with success. 



The most important point about the application of 

 all these methods is that they must be carried out 

 throughout a whole district. This is a point which has 

 been ensured this year with cotton seed. 



We ne.Kt come to treatment aimed at killing the 

 fungus, or its reproductive organs, on the diseased host 

 plant. This consists in spraying or dusting the host 

 with some fungicide. 



Powdered sulphur is used against various mildews, 

 such as those found on grape vines and rose leases. 

 The sulphur may be shaken from a tin with a per- 

 forated lid or a powder gun may be used. In either 

 case the sulphur should be applied while the leaves 

 are wet, so that it stands a better chance of remaining 

 attached. 



Among liquid fungicides may be mentioned 

 a solution of potassium sulphide (liver of sulphur) and 

 a number of preparations containing copper. The 

 most important copper preparation is the well-known 

 Bordeaux mi.xture, which is a 2- to -i-per cent, solution 

 of copper sulphate and lime ; the object of the lime is 

 to cause the copper to assume an insohible form so that 

 it cannot injure the foliage. Sometimes molasses or 

 soft soap is mixed with the Bordeaux mixture to 

 make it adhere better. 



Other copper preparations used are an ammoniacal 

 solution of copper carbonate and Eau Celeste. The 

 former is made by mixing copper carbonate with water 

 to a paste and dissolving the paste in just sufficient 

 strong water of ammonia. The mixture is then 

 diluted with sixteen times its volume of water- 



Eau Celeste is made by adding strong water of 

 ammonia to a solution of copper sulphate in water. 



The first use of fungicides is to kill any part of 

 a fungus which is external to its host plant. There 

 are a few parasitic fungi which live entirely outside 

 their host, an<l only absorb nouiishment by little 

 jtegs which grow into the outermost cells of the plant. 

 These fungi can be killed out entirely by the projier 

 fungicidal treatment. 



]\Iost parasitic fungi, however, are endophytic, that 

 is, the mycelium (or vegetative part) is inside the body 

 of the host. Their reproductive branches bearing the 

 spores are often produced on the surface. The object 

 of spraying is to get at and kill these reproductive 

 organs, and thereby prevent their spread to other, still 

 healthy, plants. 



The other main object of fungicides is to kill any 

 spores of the fungus which may light on a leaf that has 

 been sprayed. In both cases the spraying is rather 

 a preventive, than a curative, treatment. 



It is perfectl}' obvious, therefore, that, to be 

 effective, spraying must be done early, while only a few 

 plants are affected. 



Leaf and fruit diseases are the ones which are 

 most usually treated with fungicides ; root diseases, 

 caused by soil fungi, cannot be reached by them, and 

 it is seldom that a stem disease can be effectually dealt 

 with by spraying. Moreover, in the case of fruit 

 diseases, spraying must be stopped some time before 

 the fruits are ripe. 



Other methods of destroying the fungi themselves, 

 such as removing the large toadstools, which are the 

 spore-bearing organs of wood-destroying fungi, the 

 removal and destruction of diseased plants and parts of 

 plants, have often been insisted upon in the A<jvl- 

 ealtaral Xews and in other publications of the Imperial 

 Department of Agriculture and need not be dealt with 

 at length here, though they are of the utmost 

 importance. 



The method of preparation of the fungicides 

 mentioned is given in Pamphlet No. 17, 'The General 

 Treatment of Fungoid Pests' and on p. 214 of this issue. 



Ylang-Ylang Sachet. Powdered orris root, 3 R).; 

 ground cassie flowers, 1 It). ; rose petals, 1 It). ; iiiiueiitos, 

 4 oz. ; ground Tonka beans, 2 oz. ; ground vanilla, 2 oz. ; 

 ground benzoin, 1 oz. ; essence of musk, 1 oz. ; essence of 

 civet, ], oz.; oil of berganiot, 2 drachms; oil of ylang-ylang, 

 2 drachms; oil of pimento, 1 drachm; oil of rose geranium, 

 1 drachm; otto of rose, 20 minims. {Pharmaceutical Joar- 

 nnJ, May 28.) 



