422 Journal of AgricvUitre. Victoria. [10 July, 1918. 



experience. Possibly it serves to give more " body " to the swab, which, 

 as it dries, leaves a pasty mass of highly acid crystals in cracks and 

 scars where the sclerotia lurk. 



As regards the application of the swab, there is little to add, except 

 that the spraying outfit largely used in Mildura last season appears to 

 have given very general satisfaction; it certainly saves labour, and 

 enables a considerably larger area to be treated in the same time; in 

 this, in fact, lies its chief danger. There is a tendency to go too fast, 

 and to sacrifice efficiency to speed. For this reason, several careful 

 growers still prefer the old-fashioned swab. 



The Double Swab. 



French authorities are very generally agreed as to the greater 

 efficacy of a double swab ; in other words, a repetition of the application 

 after a lapse of a fortnight or so. The reason for this greater efficiency 

 is not very clear; possibly the first application may have a preparatory 

 action, rendering the sclerotium more vulnerable. 



On vines which suffered severely last season, the double application 

 is strongly recommended. The two swabbings should he so timed that 

 the second, which follows a fortnight or three weeks after the first, shall 

 be executed just before the buds break in spring.* 



A Supplementary Copper Sulphate Spray. 



In cases where the vines have suffered most severe damage, such as 

 would justify extra drastic treatment, this supplementary spray is worth 

 trying. It should be made with a 5 per cent, copper sulphate solution, 

 just as the buds are bursting. Even though a certain amount of burn- 

 ing of the first leaves may occur, fungicide action of considerable value 

 would probably result, and. this at a critical period for the fungus. 

 Though copper sulphate has no effect on the wintering stage, such an 

 application would catch, just as they are sprouting, the tender processes 

 which will bear the conidia or summer spores, and which arise in 

 spring from such sclerotia as may have been missed by the swab. This 

 supplementary spray must not be looked upon as a regular treatment to 

 be applied to all vineyards ; it is only suggested as an emergency precau- 

 tion, of a somewhat experimental nature, for vines which have suffered 

 unusual damage. Being entirely soluble, it would soon be washed off 

 by rain, and would need to be quickly followed by spraying with 

 Bordeaux Mixture, which is about to be described. 



Spring and Summer Spraying. 



Were it possible to completely destroy all wintering forms, no further 

 treatment would be necessary; unfortunately, such cannot be hoped for. 

 Some sclerotia will inevitably survive, but it must be remembered the 

 more thorough the swabbing, the fewer the survivors. f Given weather 

 conditions suitable for fungus development, fresh infection will thus be 

 caused, which must be combated by spring and summer treatment. 



* A preliminary swabbing has recently been suggested in late autumn or early winter (about May), 

 such as would catch the recently formed sclerotia, which are then less resistant than in mid-winter. Very 

 early pruning of vines to be thus treated is, of course, necessary. 



t Investigations now being conducted by one of us show "thit on thoroughly swabbed vines a very 

 limited number of sclerotia are capable of germinating when placed in a moist chamber at suitable tem- 

 I'urature. 



