594 Journal of Agriculture. [lo Sept.. 1909. 



disease. Hence, we mav undertake the work uf stamping out the Irisli 

 Blight with great confidence. The area affected is small ; only four farms 

 are know'n to have produced diseased potatoes. By taking the precautions 

 set out below the risk of the re-appearance of the disease is lessened to a 

 very great extent, and if the hearty co-operation of growers can be secured 

 in reporting all cases suspicious of the disease it is quite practicable to free 

 Victoria from this j:)est. As our average crop of potatoes is about 160,000 

 tons and its value on the farm averages £^2i Pf' ton or a total of nearlv half- 

 a-million sterling the magnitude of the interests involved is apparent. New 

 South Wales alone imports over 60,000 tons a vear, (Queensland and ^^'estern 

 Australia about 15,000 tons each. Tasmania is the chief exporting State, 

 with Victoria a good second. No effort shouhJ therefore be spared to secure 

 our position, and no sacrifice for one season can be too great if it leads to 

 the permanent prosperity of one of the most important sources of our agri- 

 cultural wealth. On the other hand, if we lose our export trade the potato 

 industrv is ruined, because the local demand is not nearly sufficient to 

 maintain the present acreage under cultivation. 



Not only is if recognised that soil and climate exercise a great influence 

 upon the potato crop, but conditions which are suitable for the production of 

 the best varieties are not necessarily the best for the production of " seed " 

 or sets. It is the universal experience that " seed " potatoes grown in a com- 

 parati\-ely cool climate give better results when planted in a warmer or 

 drier climate than are obtained from locally-grown " seed." It is the 

 knowledge of this fact which has made Tasmania the great centre for the 

 supply of seed to South Australia, New South Wales, and Queensland. 

 Similarly, it has been found that in several potato-growing districts in Vic- 

 toria a much more profitable crop is harvested if the " seed " is obtained 

 from one of our districts wath a heavier rainfall. The length of the dav 

 in districts further from the Equator and the correspondingly increased 

 number of hours during which sunshine is available is probably the chief 

 cause accounting for the very high returns of tubers per acre which are 

 frequently obtained in potato-growing countries in comparatively high 

 latitudes. In this zone, however, potato culture is often to a considerable 

 extent a matter of luck owing to the liability to early and late frosts. The 

 increased profit derived from getting the new season's crop at the earliest 

 possible moment on the large markets has led farmers to push the cultivation 

 of the potato in many districts into areas w-hich otherwise w'ould ,be deemed 

 unsuitable for this crop. In our own State, the Warrnambool and Ballarat 

 potato-growing districts enjoy a considerably heavier rainfall than Lance- 

 field, Kilmore, or the metropolitan area. It is the accidental combination 

 of good volcanic soil with a rainfall of 30 inches or over which has led to 

 the development of the potato industry in the three first-named centres. 



So far as the distribution of Irish Blight in Australasia has been ascer- 

 tained, the rainfall is in all cases over 40 inches. The progress of the 

 disease in Queensland, to the north of Brisbane, will be watched with 

 interest, for it has been usually assumed up to the pre.sent that temperatures 

 above 75 degrees were unfavorable for the de\elopment of the fungus. It 

 must be remembered, however, that in the northern States the potato 

 season is the coolest part of the year, and as the winter temperature at 

 Svdney averages 57 degrees, and at Brisbane 60 degrees, it is evident 

 that the temperature of the soil, as well as the atmospheric temperatures, 

 all through the affected districts of Queensland and New South Wales 

 must be verv favorable to the propagation of the fungus during the 

 period when the potato crop is occup\ ing the ground. 



