Clean Seed Production In Otago

New Zealand Journal of Agriculture, Volume 63, Issue 3, 15 September 1941, Page 199

Clean Seed Production In Otago

By

S. H. SAXBY,

Instructor in Agriculture, Dunedin.

The Link

Between The

Farmer And The Merchant

E)R many years a number of mercantile firms in New Zealand have specialised in the cleaning of farm seeds, and improvements in both machinery and methods have been made continuously, with the result that at the present time the standard of seed-cleaning is very high. The New Zealand seed trade has to supply two . .markets. . Firstly, there is the New Zealand or local market, and, secondly, '.there is the export or overseas market, which is worth some quarter of a million pounds each year to New Zealand. Overseas buyers demand that the standard of purity of all seed must be of the highest. Consequently, New Zealand merchants are able to export only seed of the very highest purity, and it should therefore be the aim of every seed producer and dresser to produce not merely “seed” but “the purest seed.”

In the seed trade, in which both farmers - and merchants are ; participants, good quality, clean seed is marketed at a premium, and it should be the aim of every seed-producing farmer to assist both himself and the seed cleaner by harvesting seed with a minimum of undesirable impurities. By doing so, not only is the firm handling the ? seed ; able to make a more satisfactory job from the point of view of the subsequent sale of the seed, but also the farmer himself is -assured of correspondingly low dressing losses, thus ensuring a better net return to himself.

Purity Standards

With the use of certified seeds, where the standard of purity required is comparatively high, the production of clean seed becomes more necessary, especially as the value of this seed is,

as a rule, higher than that ruling for ordinary commercial lines. The following purity standards which seed must reach before they may be finally sealed and bagged certified seed should serve as a guide to growers:— Browntop (Agrostis tenuis') .—Purity 97 per cent. Cocksfoot (Dactylis glomerata).— Purity 70 per cent with maximum of 5 per cent of ryegrass.

Perennial Ryegrass (Lolium perenne) . —Purity 96 per cent. Italian Ryegrass (Lolium multiflorum). — Purity 98 per cent. Red Clover (.Trifolium perenne).— Purity 96 per cent, with maximum of 2 per cent of weed seeds. White Clover (Trifolium repens).— Purity 85 per cent, with maximum of 3 per cent, of weed,seeds. Good as the seed cleaners’ machines are, there are certain groups of seeds that are very difficult to separate, or, if separation can be effected, it is often accompanied by high and costly dressing losses, which are disliked both by the farmer and the merchant. The production of clean seed undoubtedly begins on the farm. Farmers intending to go in for seed production should, among other things, always procure, and sow seed that is as far as possible free from objectionable impurities and sow 'it on ground that is equally free from these impurities. Nevertheless, although these precautions may be taken, objectionable impurities frequently reach and worry the seed cleaner. . It/ is all very well

for a farmer with a dirty sample of seed to consider that it is for the seed cleaner to do the worrying, but he is apt to forget that this worrying of the seed cleaner is likely to become a costly item, and that it is reflected

in the net return to the farmer. It is not uncommon for a farmer with a dirty, line of seed, to haunt the dressing plants while his seed is going through and to express his disgust at what appears to be an unnecessarily

large amount of good seed being removed in the “seconds.” The seed cleaner knows that he is obliged to produce a high quality line of seed and that in order to do so it is essential for him to sacrifice some of the good seed, much as he dislikes the necessity for doing so. < That this sacrifice of good seed in dirty lines is necessary is not always recognised by farmers. Seeds Discussed It is quite impossible to make a complete ■ list of impurities which are difficult to separate, as the difficulty of separation varies ; with the species of seed being dressed. For example, suckling clover (.Trifolium dubium) causes little or no trouble when being dressed out of ryegrass, but 100 per cent, separation of suckling clover and white . clover is practically impossible.

Thus, seed cleaners have for practically every kind of, seed' that they dress one or more impurities which they regard as their pet aversions. The following information has been prepared with the object of pointing out to farmers the undesirable impurities in- various kinds of seed as well as measures which should assist in their control from the farmer’s end. As the treatment of seed at harvest time is also very important, - some notes on this aspect are included where considered necessary. Perennial Ryegrass. Undoubtedly one of the most difficult impurities to remove from perennial ryegrass seed is the damaged seed of goosegrass, (Bromus mollis). Whole and undamaged ■ goosegrass is seldom troublesome, as it is larger than ryegrass seed, and can be riddled out with comparative ease. Damaged goose-

grass seedthat is, seed which has had the awns and wings broken off — is, however, very difficult to remove, as it then becomes almost identical in size, shape, and weight to ryegrass seed. Farmers (harvesting ryegrass for seed should, therefore, endeavour to sow only clean seed on clean land. In the event of goosegrass becoming aggressive, as it often does after several harvests, the paddock should be grazed or at least cut for an early crop of hay or. ensilage. Being an annual plants goosegrass may be -? controlled by , preventing it from seeding. Building up the sward by grazing throughout the summer and topping with the mower is doubtless the best way of controlling goosegrass. Most farmers recognise that goosegrass increases with each harvest, which is, of .course, due to the opening up of the ryegrass sward and the rapid establishment of the somewhat earlier ripening goosegrass. At threshing time, care should be taken that the goosegrass seed is not damaged. • This damage may be obviated to a considerable extent by removing the pegs on the concave or in a beater . type of thresher by opening up the concave- as far as is compatible with efficient threshing. Nevertheless, some damage is unavoidable, especially if the seed is very dry. In this case, steady feeding rather than “bumping’' the. sheaves through will assist. During the last few years methods in harvesting have changed considerably, the latest development being the header harvester. With its advent have come " troubles as well as very great. advantages. , The header does its best work when crops are thoroughly dried out and are consequently very brittle. As the result of this brittleness the straw is frequently broken up into small pieces about jinch long. In some dressing plants these are very difficult to separate from the ryegrass seed. This unfortunate position is brought about not because the header harvester is an inefficient machine— is actually a very valuable addition to our list of modern farm implementsbut because of two sets of circumstances. Firstly, the crop' must be dry to be thrashed efficiently, and secondly, headers can be worked economically only in districts where continuous dry weather can be expected. These two factors have a cumulative effect on the dryness of the ryegrass straw. '' ' ■ . .... / ■<> < Another impurity which sometimes causes concern in perennial ryegrass is unshelled and , partly ripe black medick (Medicago lupulina). Fortunately, black medick is localised, and

is of serious consequence in only a few districts. Comparatively little can be done to counteract this plant when it has become thoroughly established. It increases fairly rapidly, but, being a short-lived perennial, it cannot be controlled as effectively as annuals, such as burr clover or goosegrass. On country where black medick is liable to be a serious competitor seed production might well be confined solely to young pastures, in order that the seed may be harvested before the black medick has a chance to become thoroughly aggressive. It should be emphasised that in sowing down pastures for perennial ryegrass seed production it is essential that Italian ryegrass should , not be included in the seeds mixture. If a mixture of these two were sown and the paddock and its progeny harvested over several generations the product would be a mixture of the two species, together with a large amount of hybrid seeds possessing few desirable qualities. Another point to be watched in the production of perennial ryegrass seed is that hay containing ripe Italian ryegrass is not fed out on proposed seed-producing areas. This practice has on several occasions been responsible for the rejection of seed-pro-ducing areas for seed certification.

Italian Ryegrass.

Although Italian, ryegrass seed is superficially very similar to that of perennial ryegrass— main differ-

ence being the presence of an awn on the former—the more serious impuri- - ties are somewhat different. Firstly, Italian ryegrass does not, as a rule, contain many impurities, as it is by force of circumstances harvested from young pastures only. Secondly, most farmers realise that in order to obtain a good price for

the seed very light threshing is necessary so that the awn is not broken off. On this account, goosegrass is seldom damaged badly, and may be separated fairly easily. Damaged goosegrass is just as difficult to remove from Italian ryegrass as it is from perennial ryegrass, but its presence is not common. • Probably , the most disconcerting impurity in Italian ryegrass seed is unshelled white clover. This is of no moment in' perennial ryegrass seed, as the seed cleaner merely runs the line of seed through the brushes, thus effectively shelling the clover and enabling a separation by blast and riddle to be made. With Italian ryegrass this brushing is not possible, as by doingsb the —which indicates that -it is Italian ryegrass— broken off. It is, however, only on the heaviest country that white clover is liable to grow to such an extent that it is harvested in any quantity in first-year Italian ryegrass.- In the event of white clover being present in large quantities in an Italian'ryegrass seed crop, the binder should be raised sufficiently high to miss as much of the clover as possible.

Cocksfoot.

. The cleaning of cocksfoot seed gives, on the whole, more headaches to the seed cleaners than any other seed. The seed of cocksfoot varies very much in weight, inert matter, double heads,

and various weeds. Consequently, every line presents a separate problem. This problem also occurs with other species, but it is accentuated with cocksfoot. Inert matter consists mainly of husks, which do not contain a viable seed. Much of this can be removed satisfactorily, but because of the light weight of' the good cocksfoot seed" some of this 'latter is usually removed as well. ' As the amount of seedless husk is governed largely by the weather, ,the farmer is able to do little except to expect a possible high dressing loss. Small ryegrass seed is a serious stumbling block in some lines of cocksfoot. Cocksfoot is a tussocky and shade-loving .grass, whereas ryegrass is much closer growing and will not tolerate shade. These factors are turned to advantage in the best cocksfoot seed production areas, where the cocksfoot is seldom if ever grazed and is usually cut at a height of about 8 to 12 inches. Under this treatment the growth of : the cocksfoot is “ satisfactory, while the ryegrass is ' gradually smothered out. z : .. Any farmer anticipating cocksfoot seed production should make every endeavour to purchase seed free' from ryegrass seed. Even 2 per cent, or 3 per cent, of ryegrass in a line of cocksfoot seed may. result in . trouble with ryegrass, as an impurity for several years. In some cocksfoot paddocks there is present a certain amount of Yorkshire fog ' (Holcus . lanatus), the seed of which may be harvested as >an impurity. Under normal conditions this causes no trouble, as the line is run through the brushes and the fog shelled, making separation simple. If, however, the seed reaches the cleaners in a damp condition, as it sometimes does, brushing is ineffective on the damp un-

shelled Yorkshire fog seed, with the result that the line has to be tipped out and dried on the floor or this part of the separation abandoned. The remedy for this is obvious—send only dry cocksfoot seed to be dressed.

Timothy.

Although only a comparatively small quantity of timothy seed (Phleum pratense) is harvested and dressed in New Zealand, there is no doubt that the southern districts could. produce considerably more than they do. As is the case with other species, the cleaning of timothy seed sometimes presents considerable difficulty. The main bugbear in dressing timothy seed is the presence of white clover and alsyke (Trifolium hybridum). These seeds are very similar in size and

weight, and defy 100 per cent, separation. Consequently, farmers producing timothy seed for sale should try to ensure that the paddock contains little or no white clover or alsyke. If the production of timothy seed is regarded as a long-term project, this objective may be achieved. Timothy, like cocksfoot, is a tallgrowing, shade-enduring plant, and will dominate in a pasture after several consecutive seed crops have been taken. These seed crops will also have the effect of reducing to a small quantity the amount of white clover. Grazing should at all times be ■ light in order that the “bottom” will not be opened up enough for the establishment of young clover plants.

Chewing’s Fescue.

The dressing of Che wings fescue (Festuca rubra, var. j allax) presents certain difficulties regarding impurities. As most of this seed is used for the sowing down of lawns and playing areas, very high purity is desirable. Unfortunately, two of the most difficult impurities to remove are also' regarded as being undesirable in lawns. These are catsear (Hy-pochoeris radicata) and perennial ryegrass. In an undamaged condition, catsear seed has a long, slender beak, and can be easily separated from fescue seed, provided this beak is not broken off. It is very difficult to prevent this from breaking during . harvesting, with the result that control methods should aim at preventing the catsear from seeding. This may be accomplished with considerable success by running a few sheep in the fescue paddocks almost up to harvest time. \ The sheep will pick out a large amount of the catsear without doing much harm to the fescue. So effective is this treatment that merchants are able to tell by the quality of the field dressed seed whether or not sheep have been running in the paddock. ' . Small ryegrass seed is another most undesirable impurity in Chewings fescue, and is very difficult to separate. Because of the fact that ryegrass seed is readily distributed in the' wool of sheep and the fact that fescue areas are periodically renovated, little can be accomplished in the control of ryegrass in fescue paddocks other than by ensuring that clean seed is sown on clean land. -'>!

Red Clover.

The most serious impurity with which the seed cleaners have to contend in dressing red clover is rib grass (Plantago lanceolata). The com-

plete separation of ribgrass and red clover is possible with specialised machinery, but the cost in relation to the quantity of seed with which it would have to deal is too high to warrant its installation. Ribgrass is common as an impurity in red clover seed harvested in areas which dry out to a considerable extent in the summer and on which the cover of red clover is relatively thin. Almost the only remedy for a paddock which is .badly infested with ribgrass is the plough. Prevention is better than cure, and every effort should be made by suitable management to ensure that a dense cover of clover' is obtained.

White Clover.

The production of clean white clover seed also presents its difficulties in the nature of impurities, of which the most common is undoubtedly suckling clover. Although' the seed-cleaning machinery is extraordinarily efficient in this separation, some lines of white clover which contain large seeded suckling are very difficult to clean thoroughly, with the result that the value of the white clover seed is correspondingly low. In such lines heavy dressing losses are often inevitable in order that a reasonably satisfactory sample of white clover may be produced. Suckling clover is a second-rate annual clover, and is usually present in white clover crops, taken from dry or fairly low fertility country' In addition to this, there is also a large amount of white clover seed saved more by accident than design as an associate seed in a ryegrass crop. In such cases the presence of suckling clover is fairly common. If, however, an area, is sown down with a good strain of white clover on a good seed bed and is well limed and manured, the growth of the white clover is usually sufficient to smother out the suckling clover. Here, again, emphasis should be laid on the necessity for' managing a seed production area for one particular species rather than endeavouring to obtain a crop of two species or, as sometimes happens, shutting up a paddock and harvesting whatever happens to look best at harvest time. Alsyke and ' timothy are also undesirable impurities in . white clover seed, and should be discouraged in any area to be used specifically for the production of white , clover seed. The control of timothy in an area closed for white clover seed production may be secured by topping the

heads of timothy with a mower before they have produced fully-developed seeds. This is roughly a month or so before the clover is ready to cut. Topping later will, of course, be of little use, as the mature heads will merely be picked up and threshed with the clover. ' " ;

Alsyke.

There is comparatively little alsyke harvested in New Zealand, although a certain amount of the larger seed is dressed out of white clover as an impurity. In harvesting alsyke for seed, white clover, suckling clover, and timothy are likely to be most troublesome as impurities when it comes to dressing the crop. It should be understood that in addition to the foregoing species there are several others which are harvested more or less regularly in this country. For example, the annual production of browntop seed is considerable, but pastures are seldom sown down and managed specifically for the production of the seed of this species, and the harvest in many cases is fortuitous. Consequently, it is hardly worth making any recommendations regarding the control of undesirable plants.

Summary.

In the production of “clean . seed” the following points should be borne in mind: — , . (1) Sow seed which is free from impurities that are known to be difficult to separate in the dressing plants. (2) Sow clean seed on . clean land. (3) Try to ensure that the crop desired is the dominant species at harvest. (4) Keep an eye on the seed, not when it is being dressed, but when it is being threshed. (5) For seed production areas sow only mixtures that will not produce undesirable impurities. (6) Remember that the seeds of certain useful pasture plants become almost . “weed seeds” when occurring as impurities in a line of another kind of seed. (7) Don’t send damp seed to be dressed. ' ' The following table shows the most common undesirable impurities encountered in the dressing of pasture seeds:

Acknowledgments

Grateful acknowledgment is made to Messrs. J. E. Macassey and J. Sutherland, of Dunedin, for some of the information embodied in this article. Photographs are by H. Drake. '

Seed being dressed. Impurities that are hard to remove. Perennial ryegrass Italian ryegrass . . Cocksfoot . . Timothy .. ViRed clover Alsyke White clover Chewings fescue Shelled goosegrass, Italian ryegrass, English trefoil in the shell, cocksfoot, broken straw. ' . , Goosegrass (occasionally), White clover in the pod, Hairgrass. Small ryegrass, shelled goosegrass, damp yorkshire fog in the shell. White clover, Alsyke, Suckling clover. Ribgrass, Dock (sometimes). White clover, Timothy, Suckling clover. > Alsyke, Timothy, large Suckling clover. Catsear, small ryegrass, Cocksfoot, Dogstail.