1922.] 



The Production of Seed Potatoes. 



905 



Factors Influencing Seed Production. — In determining the 

 most ^uiuible county or district for the production of seed pota- 

 toes for planting in more southern and warmer counties, the 

 factors outlined below should be taken into consideration, and 

 while in some districts certain suitable factors may be present 

 to an exceptional degree, yet those districts could not be con- 

 sidered suitable for producing seed potatoes unless all the 

 essential conditions were present. 



d) Soil. — The best soil is a loam or light loam, and for the latter 

 a fairly heavy and regular rainfall is necessary in order that the 

 seed may not become over-ripened. These conditions are found 

 in districts "A,"' " B " and " D." The lightest land is 

 usually found near the coast. In District " B " there is a certain 

 amount of heavy loam running out to loam nearer th'^ coast, and 

 most of the potatoes in this district are gi'own on the loam. 



(2) Temperature. — The mean temperature should be a low one 

 and below that of the county to which the seed* is to be sup- 

 plied. The temperature during the growing months, i.e., 

 April, 2^Iay, June, July and August, should be sufficient to 

 encourage luxuriant and healthy gTowth, and should be regular 

 without being extreme. The temperature during the ripening 

 months, i.e., September and October, should be moderate in 

 order that premature ripening may not take place . There is only a 

 slight difference in temperature between the three Cumberland 

 stations previously mentioned and the five Scottish stations 

 situated at Dundee, Perth, Leith, Kilmarnock and Dumfries, 

 Xewton Bigg with 46.4° F. being the lowest, and Leith with 

 47.9° F. the highest. Taking the mean temperature for the 

 growing m.onths there is little to choose between the three 

 Cumberland and the five Scottish stations. For ]\Iay the Cum- 

 berland and Scottish stations average the same, viz., 50° F., 

 and Xewton Bigg 49.6° F. For June the Scottish stations 

 show 55.7° F., and Newton Bigg 55.7° F. I'or July Scottish 

 stations show 58.3° F., and Xewton Bigg 58.4° F. and for 

 August Scottish stations show 57.4° F., and Xewton Bigg 57° 

 F. In most months Aspatria and Scaleby show a temperature 

 slightly higher than Xewton Bigo-. Other potato gi'owing 

 counties of England have a much higher temperature, e.g.^ 

 Lancashire 59.5° F. in AugTist and Lincolnshire 61.3° F. in 

 July; this is accompanied by a much lower rainfall. 



For the ripening months there is little difference between the 

 Cumberland and Scottish stations, the average for each being 



* Late or main crop varieties are referred to. 



