SEED POTATOES

Timaru Herald, Volume CXXXIX, Issue 20065, 23 March 1935, Page 15

SEED POTATOES

LOCALITY IN RELATION TO PRODUCTION The importance of renewing periodically stocks of seed potatoes from selected localities such as Scotland or the North of Ireland has long been recognised by progressive potatogrowers in Great Britain. Recent experiments conducted in Wales have indicated that localities in North Wales can lay claim to the, same advantages as the above-mentioned regions in the production of healthy seed and that the vigour of the seed from such suitable districts is bound up with relative freedom from virus diseases which in turn is largely dependent on the degree or the time of attacks of green aphis (Myzus per-

In order to investigate the suitability for the production of seed relatively free from virus of certain localities in the South Island of New Zealand two series of experiments have been conducted over the past few seasons and a third series of experiments is at present being carried out. The results of three series of experiments to investigate the effect of locality in relation to seed-potato production are given in this month’s Journal of Agriculture. The following is a summary of the results:—

Part of a ine of Arran Chief potatoes was grown in Southland and part grown at the Ashburton Experimental Farm. In each of the four seasons 1927-28 to 1930-31 the seed grown in each locality was compared in a yield trial. In the last two seasons seed

“once grown” from Southland—i.e., grown at Ashburton for one season after having been grown in Southland —was included, while in the 1930-31 season’s trial seed ‘‘twice grown” from Southland was also included in the yield trial.

In three seasons Southland-grown seed was significantly higher in yield than seed continuously grown at Ashburton. In both seasons where seed “once grown” from Southland was compared with seed continuously grown at Ashburton the former was significantly higher in yield. In the 1930-31 season’s trial Southland-grown seed was significantly lower in yield than seed “once grown” from Southland, and was not significantly different from “twice grown” seed.

In a second series of trials a line of Arran Chief potatoes was divided up and portions grown in the following districts: Willowbridge, Rangiora, Cheviot, Highbanks, and Fairlie (in Canterbury); Alma and Balfour (in Otago); and Winton (in Southland). In each of three seasons (1930-31 to 1932-33) seed from each crop was included in a central yield trial. The disease counts (virus infection) taken on these trials indicated progressive increases in percentage of virus infection from seed continuously grown at Willowbridge, Rangiora, Alma and Cheviot respectively. Potatoes grown from seed raised at Highbank, Fairlie, Balfour, Annat, and Winton respectively showed no increase in the amount of virus during the period of trial. Such differences in virus infection were reflected in the yields, although unfavourable seasons combined with the poor cropping-power of the line of potatoes used precluded any large increases. Even then the differences between the best line and the worst line in total potatoes were—l93o-31, s ton; 1931-32. 1.9 tons; 1932-33, 2.4 tons. The districts producing seed giving rise to crops relatively low in virus infection and relatively high in yield were those which by reason of latitude or altitude were possessed of cooler climates than the district supplying the remaining lines under trial. A third series of trials (uncompleted) in which the Dakota variety is being used are described. The first year’s results substantiate those secured in the second series of trials and differences both in virus and yield are far more markedly in favour of seed from cooler districts, such as Sheffield and Highbank (Canterbury), Tahakopa (Otago), and Waipounamu, Tuatapere, and Winton (Southland).