CERTIFICATION OF POTATOES.

Press, Volume LXVI, Issue 20026, 6 September 1930, Page 19

CERTIFICATION OF POTATOES.

DEPARTMENTAL ADVICE. For many years past farmers occupying the best potato-growing land, and using the latest cultural methods, have often boeu much disappointed with tho crops they have obtained, even when every endeavour has been made to secure tho best seed on the market. Growers in some cases came to the conclusion that their soil was exhausted for potato growing, and did not seriously consider the position from the point of view of the deterioration of tho seed that had given such poor results. The position bocamo so unsatisfactory yiat in 1927 the Fields Division of tho Department of Agriculture took steps to bring about an improvement in the general position, and thus certification of potatoes camo into operation. In this connexion Mr R. McGillivray, Fields Superintendent, has provided some interesting particulars:—

In the 1927-28 season, 137 crops wore entered—an area of 894 acres. Of these 54 crops passed—an area of 471 acres. •In the 1928-29 season, 167 crops were entered—an area of 835 acres. Of these 66 crops passed—an area of 569 acres. In tho 1929*30 season, 323 crops wore entered —an acreago of 1281$ acres. Of these, S7 crops were passed—an area of 427-J acres.

No grower should accept any seed as certified, unless it has tho Department's certification label attached to tho sacks. The label is only attached to sacks that havo passed three inspections, including the tuber inspection, which is of a very searching nature. Tho aim and object of certification is to eliminate weak, low producing lines of potatoes. The difference in cropping power of different lines of the samo variety, when all are grown under similar soil conditions, and with the same manurial treatment, is quite arresting. At the trials at Ashburton, of the Dakota variety, the yields ranged from 11 tons per acre down to two tons table potatoes per acre. The Epicure variety ranged ' from Of tons table potatoes, down to as low as $ ton per acre.

The cropping power is ascertained in the Department's trial areas at the Ashburton Experimental Farm, and at the Plant Besearch Station, Palmcrston North, and ono can say to-day that it is not so much a question of what variety a farmer should grow, but rather he should grow his favourite variety, and obtain his seed from a line of high oropping power, as ascertained by the Department's trials. The cause of low production is almost entirely due to attacks of virus disease. The degeneration of tho potato crop is not to any extent due to fungus attacks. Virus diseases are in the sap and are spread by aphis, which transmit such diseases from unhealthy plants to healthy ones. Plants that are attacked by virus disease run out rapidly, and tend to produce potatoes that aro practically unsaleable for household purposes. Planting of this seed would result in an. unhealthy, unprofitable crop. Under tho certification scheme, poor yielding lines are rojected. AH crops entered are subject to inspection in the field, and tho final inspection ia of the tubers, after they are bagged, ready for sale. Provisional certificates havo been issued with tho object (it affording growers some indication of the general trend of their crops, and to assist them in the disposal of their seed. Tags to affix to certified potato sacks are issued later, provided an officer of the Department of Agriculture inspects tho graded potatoos, and is. satisfied that they are of the same standard in regard to purity and freedom from disease as was indicated by the field inspections. The cropping power is arrived at by means of the trial plots undertaken by the Department of Agriculture, and is calculated by adding together the yield of the table potatoes plus half the yield of seed size tubers. Pig-size tubers are discarded altogether in the estimation of cropping power. In the 1928-29 season 51 crops were rejected for low cropping power, due to virus infection; 89 for too high a percentage of rogues; 12 for powdery scab; nine for eelworm; five for late blight, and two for wilt disease. These ■figures give' some idea why so many crops fail to reach our standards. Growers are invited to submit their crops for inspection. Those who havo not previously entered* and are growI ing uncertified seed, are invited to got I in touch with the Dopartment, with a I view to submitting 80 representative tubers from the variety they are growing. Theso 50 tubers will be grown at the .Ashburton Farmland a report promptly furnished to the grower when the oropping power returns are available. If the .report is favourable, his crop will be received for trial for certification in tho following season. Any grower who has had his crop certified previously; or who has purchased certified seed for sowing, is eligible for certification this season, and from such growers 150 tubers will be collected by an officer Of the Department of Agriculture, on application being received from such growers. Circulars are being issued to all known growers of certified seed, in order to ascertain if thoiy J" 8 ~, 0 enter their crops for certification tms season. . , . . The closing date for receiving entries for this season's certification scheme "will be Tuesday, September 16th, 1930.