PRODUCTION OF DISEASE-FREE SWEDE SEED

Stratford Evening Post, Volume II, Issue 240, 11 May 1933, Page 2

PRODUCTION OF DISEASE-FREE SWEDE SEED

The Man or* the Laud

Preliminary Trials Under the Small-Farm Plan

(J. C. Neill. Field Mycologist, Plant Research Station. Palmevston North)

Tho swede provides the most valuable fodder crop in New Zealand. Tt well almost everywhere, from the light pumice soils of Auckland' Province to the heavy clays of Southland. On mixed farms it is an essential crop in a balanced ration, and on nloughable hill country it is unrivalled as a provider of winter feed. The full utilisation and maintenance of pasture deoends on an adequate supply of stock to cope with tinspring growth, and swedes provide one of the best and cheapest fodders to carry that stork over the lean winter months*.

with strong branching systems both of The root and head. Such a plant will pod heavily to produce the maximum weight of plump evenlv ripening seed. Harvesting is done by hand with a sickle, the plants being immediately tied in small bundles. These are laid in windrows and carefully (turned from, time to time. At Palmerston North it has been found that the drying process takes about three weeks to allow time for the greener pods to ripen off. It would probably be advantageous to then slack for two or three months bo?"'" 3 threshing but unite a.

The swede is thus of j:rent national importance in maintaining the average stock-carrying capacity of the Dominion. Of recent vears, however, the area sown to swedes has steadily declined, and this for one reason only —the fear of disease. The two diseases of swedes—dry rot and club root — become so widespread in incidence and so destructive in effect. that the swede has become a risky and often unprofitable crop, to be replaced where possible by other less satisfactory but more certain fodders. Owing to disease it is no longer safe to grow more than one crop of swedes in several years on nuv piece of land, and the continual breakig up of established pasture, even where sufficient nloughable land is available, makes the cost and inconvoicono of the crop more than it. is worth. Investigations into tho problem of theso two diseases. extending over years, have now brought certain facts to light : (1) Dry rot infection is carried in +he. seed. If seed free from the disease Is sown on land that has not carried a diseased crop for the nest two seasons, nor is in the neighbourhood of swedes or t'lrnips grown from infected seed, then the resultant crop will remain free from dry rot. (2) Club root can be practically controlled by the use of certain varieties or strains of swede which are hitbh resistant +f - tho disease, if certain precautions are taken in the sowing.

satisfactory .sampli has boo;, obtained by threshing in the paddock. The thre«l;ing is done by hand fla'-s or a l.iige canvas sheet, cleaning being effected by riddles and a final wind winnowing. Not more than 1001 b to 1501 b of seed should be placed in each sack, and tho sacks stacked to allow for the maximum ventilation. If the cleaning is carefully performed this seed is ouite fit for sowing, but, to produce the best looking sample, it may be machine dressed in a properly, equipped mill. This oneration will separate out any remaining rubbish and also the "seconds" or smaller seed, which, though r.'sually showing nuite as good germination as the "firsts." detracts from the even appearance of the sample. A danger that must be guarded against at all costs in mill cleaning is the admixture of seed left over in crannies in the machinery from previously dressed lines that may have been infected with dry rot.

It is therefore of great importance that adcouate supplies of guaranteed dry rot.free seed of club root resistant strains should he available to the farmers of New Zealand. The following pages detail Hie method* nnd outline a plan by which it is proposed to attain this end. Methods of Production Experimental work has boon in progress for the last fohr years at the plant research station on the best methods for the production of hisrh qualify disease free swede seed. Much of this work has beer, based on information secured bv the mycologist in the course of a thorough personal investigation of the methods in use in Great Britain and on the Continent of Europe. The swede is a biennial plant which, whether sown in the spring or in autumn, will flower and seed in the following summer. If spring sown it will produce a largo bulb with no lateral roots, that, if not attacked by

disease, will keep through the winter to send up a flowering stalk in the J spring. If autumn sown it produces i little or no bulb but well developed lateral roots, and in the spring bolts strongly to seed. The seed head produced by tlie large.bulb from spring sown draws its nourishment from the stored food material in the bulb, little or no fresh root development taking place. As a consequence the, flowering head ,though developing strongly at first while food ami moisture aro plentiful, becomes weaker as development proceeds, until, while the seed is forming, most ot T the stored food material is used up and many of the later seed pods fail to develop. The result is a light crop of undersized seed. Moreover, the bulbs are very liable to attack by various rot forming fungi and bacteria before the seed has filled. It is thus not practicable to produco seed commercially by this method, which is used only for j the growing of mother <eed—that is, J seed to be sown i:i the-autumn for the production of tho next year's commercial crop. This is necessary since selection for type and quality can only be done when the plants are grown to full maturity under the best, conditions for bulb development. The main seed crop, then, is produced from plants grown from mother seed sown in the autumn. This may be sown in place and the resultant plants thinned to about 18 idles, but experiments have shown that a better result is obtained by raising the seedlings in special nurse beds and transplanting to tlie final position'for seeding. In the mild winter climate of Palmerston North swedes if left undisturbed continue to grow, and will produce quite fair sized bulbs even when late autumn sown. These bulb | forming plants do not make such strong feeder root development in the spring as do plants which lwe been checked by transplantation. It is commonly supposed that ?vm\ produced in this manner will tend to produce "boilers" when sowi for an ! ordinary crop. There is no evidence to support, this supposition, but much to tlio'contrary. Most, if not all, th< swede seed of commerce is sn produced. Good well drained soil is essential for this crop, tt broken out. of the lea the turf should Ik skim ploughed in January or February, disced and harrowed a* intervals till May or June, then deeply ploughed and thoroughly worked down ready for planting out in late June and July. The plants should have _ plenty of room to develop, a very suitable spacing being 18 inches in four-feet rows. Cultivation should be thorough and i continuous a- long as it is possible t<> 1 work between 'he rows. The primary llower stalk is topped at about 18 inches in order to promot. strong lateral brnnchiug. Experience has shown (hat the whole object jhnuld too to produce a vigorous plant'

The whole of the harvesting operations must bo done with the utmost: ear" since the seed pods are very brittle nnd careless handline entails a substantial loss of seed. From flic time the first nods are nearing maturity, in December, until the seed is in the ba.srs. which may not be until March, constant guard must bo kept against the ravages of small birds. Further, close and continuous watch must T ;o kent for the possible accidental introduction of the drv rot fungus, so that, by drastic rogueine of all plants in fV >o vicinitv of an observed initial infection, tho disease may be prevented from spreading i" th n crop. Returns i«d Coi;tr Judging bv experience at Palmerston North the yield Of seed grown in the foregoing manor should exceed 10 cwt of dressed seed per aero: in one experiment nearly 12cwt was hnrvested from nbou! three-quarters or an ncre. The average value : ? the country of origin of imported swede and turnip seed is given in the import statistics for 1031 at very dose to Is per pound. Since turnip seed is generally cheaper than swede seed it would seem reasonable to estimate Is per pound as a basis for the wholesale price of swede seed grown in Ih ; s country, even at the lower price levels now ruling. A yield of lOcwt at Is per pound represents a gross return of £56 per acre. On the cost side mu'st he debited rent of land, equipment and labour. With this system of production rent and equipment costs are comparatively low, the main expenditure being in labour. For this reason the industry is particularly adapted to small holdings where family labour can be fully utilised. It is estimated tlfat an averago family should be able, where the crop is the main source of revenue, to handle efficiently three acres of seeding swedes, providing a cash return of about £l5O. This compares very favourably with the returns possible from any other source on this class of holding. The main difficulties to be foreseen are, firstly, the doubt of producing high grade disease free seed by this system; secondly*;, the ability to sell it at a reasonable price when produced. Only experience can demonstrate how real are these difficulties or what methods are best to overcome them, but, under the present circumstances of the country, a limited trial <>C "he possibilities appears to be thoroughly justified.

Preliminary Trials For the coming season it is proposed to utilise three 10-acre holding's under the smuli farm plan. These hold ings have been specially chosen as j representing different classes of laud, isolated from other crops, and within | easy reach of the plant research sta- • tion. Three acres of each holding will which is to he grown and harvested under the direct supervision of myco bo devoted to. the swede seed crop, logical officers of the station. The seedling plants will he grown at the plant research station from dry ret. free mother seed selected an 1 br. d at the station. These seedlings will b distributed to the growers for planting out in June and July, and fhe seed crop he harvested in the following January or February. Judging by results obtained at lb ; station over the last three seasons, the result should make available a supply of about five tons of seed. This seed will be taken over by the department for disposal to the trade, the proceeds, less expenses, going to the grower. Should ibis initial experiment prove satisfactory, and the resultant seed j find favour with merchants and I'arI mors, the foundation will have been j laid of a new rural industry of great j potential values. Such an industry bej cause of its high per acre value, large I requirement of family labour, and low cc.-<t in equipment, is eminently suitable for the typo of close settlement ; contemplated by the small farm plan. I Once successfully established its I scope, should widen to cover many other classes of seed, especially those I in which freedom from seed borne I disease is of prime important. If the j infant industry is carefully controlled J from its inception, under expert official supervision, there seems every I likelihood that it will n"t only save I New Zealand the £60,000 now spent nbroad for these seeds, but that it)

may grow into a flourishing source of export. But of greater significance is the opportunity it offers to reduce the enormous annual economic lows caused by seed-borne plant, diseases in this country.