906 



The Production of Seed Potatoes. 



[Jan., 



practically the same, viz., in September, Cumberland 53. 9° F. 

 and Scottish 53.7° F.; in October, Cumberland 47. 3° F., and 

 Scottish 47.2° F. Newton Kigg shows the lowest temperature 

 of all the stations for these two months, viz., 53.2° F. and 

 46.7° F. Lancashire and Lincolnshire are again several 

 degrees higher. 



(S) Honrs of Sunshine. — Long hours of sunshine are very im- 

 portant during the months of growth, both for the formation of 

 starch and the general health of the plant. Damp, sunless days 

 favour the spread of blight and other fungus diseases. Too much 

 sun at the end of the growing period and during the ripening 

 period, if accompanied by a low rainfall, will produce over- 

 ripened " seed." Scottish areas compare unfavourably with 

 the Cumberland stations in hours of sunshine during May, 

 June, July and September, but are nearly equal in August and 

 October. Lancashire shows a distinct shortage of sun. Newton 

 Eigg records more hours of sunshine in June than any other 

 station, including Kew. This is the most important period for 

 the formation of starch. The following is the average number 

 •of hours of bright sunshine each day for the two Cumberland 

 and two Scottish stations 



May June July Auqust Sept. Oct. 

 Cumberland ... 6'18 6-60 5-«2 4-98 4-50 3-01 

 Scotland ... 5'67 6-18 5-43 4-84 3-98 3-04 



(4) Rainfall. — It may be generally stated that 35 in. to 40 in. 

 per annum is an ideal rainfall for potato growing on loams and 

 light loams. The rain which falls during the growing months 

 should be sufficient to produce regular and vigorous growth and 

 should be evenly distributed, without any periods of drought: 

 the latter produces either premature ripening, or if followed by 

 heavy rain, second growth. The driest period should be at the 

 time of lifting. A sufficient rainfall is essential in April and 

 May in order to start growth, and in June, July and August to 

 stimulate it. A large number of rainy days indicates a constant 

 and regular rainfall without periods of drought. Tn all these 

 respects Cumberland compares very favourably with other 

 potato growing districts, the rainfall being as high as in the chief 

 potato growing districts of Scotland, while the number of rainy 

 days is greater. 



(5) Altitude. — Seed potatoes grown at high altitudes are less 

 likely to become baked by the sun or to ripen prematurely. As 

 a rule they are harvested later than in low-lying districts, when 

 the sun has less strength, so that the final ripening is a gradual 

 process and is not over-hastened by hot weather. There is also 



