11 March. 1918.] 



Vinei/a rd Sp raying. 



u; 



years back, tliat spraying as usually carried out, especially with the 

 larger power sprays, could not afford the maximum of protection ; they 

 recommended knapsack spraying with bent nozzles, so used as to apply 

 the bulk of the spray to the lower side. Obviously under-side spraying 

 can best be carried out Avith machines of knapsack type, or, at least, with 

 hand-directed nozzles. Fortunately for growers, the superiority of 

 under-side spraying has not been borne out by experience during the 

 last few years; practically equal protection was obtained by 

 spraying in the usual way.* This phase of the question will 

 be dealt with at greater length in a subsequent article. For 

 the present it will suffice to state that ordinary spraying, if 

 timely and thorough, can afford complete protection. 



Xotwithstanding these advantages, the knapsack spray has several 

 serious drawbacks, the chief of which is its limited capacity. It is 



Fig. Irl. — Rousset's Pack horse Spraying Outfit. The pump for charging and 

 air compressing is not shown in the illustration. 



scarcely possible to treat more than an acre and a half per day with 

 one of these machines. As has been already pointed out (Journal, 

 Xovember, 1917, p. 694), the time within Avhich spraying should be 

 executed is largely governed by the incubation period of the Mildew 

 Fungus, w'hich usually occupies seven days. It is thus within this period 

 that the whole vineyard must generally be treated. The small grower, 

 with 20 acres or so of vines, can achieve this result with one, or at most 

 a couple, of knapsack sprays — not so the owner of larger areas, who will 

 find this means of application far less satisfactory. 



With this machine, the cost of spraying per acre in labour alone is 

 very considerable, since each man only directs one nozzle. It is by 



* Under-side sprayinfr may prove advantageous for the earliest application The first infect ion results 

 from the germination of the oospores, or winter spores, in the soil, and the zoospores, which they emit, 

 leing splashed by heavy raia on to the lower leaves. Subsequent infection is by air-borne spores. 



