lo Sept., 1910] " Scab '' and Eel-ivorm in Potatoes. 577 



As will be seen from a study of the figures in the above table, there 

 was an average increase of cleanness due to the use of one or other of the 

 manures varying between 8.3 per cent, and 17.6 per cent. Nitro-super- 

 phosphate again came out on top though potato manure A is practically 

 on the same level with it. In this case, strong potash manure fell con- 

 siderably below the manure of normal strength, but it must be remembered 

 that although this decline took place with the strong manure still it shows 

 a consideraljle increase in clean potatoes over those rows which received no 

 manure. 



When a strong manure like the above is applied in as heavy a dressing 

 as 4 cwts. to the acre, and produces a cleaner crop than where no manure 

 is used, it can scarcely be contended that its presence in the soil is highly 

 beneficial to the increase of Eel-worm. However, as the table shows, a 

 moderate strength manure is to be preferred to a strong application in the 

 case of this pest, both from the point of view of cleanness as well as cost. 

 The same may be said in the case of the extra acid superphosphate. Here, 

 the difference is not very great in favour of the normal manure, but still 

 as the normal manure is more efficient it needs no further recommendation. 



The results from the use of iron sulphate have nothing to recommend 

 it for future use. It cannot be classed as a true manure and gave no 

 increase in yield or cleanness. 



Formalin Treatment and Spraying. — The treatment of the seed with 

 formalin, used at the same strength as in the case of Scab, was not attended 

 with any remarkable results. This pest, not being of a fungoid nature, 

 would scarcely respond readily to a fungicide, and even if the seed were 

 rendered free from the living parasite by immersion in a formalin solution, 

 it could hardly be expected that the action would continue over several 

 months in a soil which was at once the home and breeding ground of the 

 parasite. 



Taking the above into consideration, it is not a remarkable fact that 

 the formalin-treated seed turned out, taking an average, practically the 

 same percentage of clean potatoes as the plots which were sown with 

 untreated seed. 



What has already been said respecting spraying in the plots for Scab 

 applies equally in the case of Eel-worm. The spray used was the same, 

 namely, Bordeaux mixture with Paris green. As before, in most cases 

 the yield was slightly increased, but the average percentage of clean 

 potatoes was about the same as where no spraying was given. 



Summary. 



Taking a general review of the plots, I think that it has been demon- 

 strated that the treatment of seed with formalin was efficacious in prevent- 

 ing Scab in that form at least in which it occurs in the Ballarat district, 

 while clean seed and artificial manures were also factors worthy of notice 

 as aids in the production of a clean sample. 



As regards Eel-worm, green manuring and the use of artificial manures 

 and especially the latter, are worthy of consideration for future experi- 

 ments. Formalin treatment did not prove as efficacious as in the case of 

 Scab, but as in the case of Scab the use of clean seed is to be recommended. 



The following is a full tabulated return of the results obtained from 

 the five experimental plots. 



