Growing linseed and linola in Victoria
Linseed and Linola™ are different seed quality types of the flax plant, Linum usitatissimum, which has been grown as an oilseed plant for many years.
Linola ™ is a new crop in the flax group. It was developed in Australia by plant breeders from CSIRO, Canberra. Linola is a registered trademark of CSIRO and the crop is protected by patents.
Linola plants are identical to those of linseed but the seed is golden yellow instead of the usual brown colour of linseed. (There is also some specialty golden seeded linseed grown in Australia). Linola oil is quite different from industrial linseed oil, being an edible polyunsaturated oil very similar to polyunsaturated sunflower oil.
In Victoria, linseed is currently grown mainly in high rainfall districts in the south-west region, where the average yield is about 1.25 tonnes per hectare. Most of it is sold and used as whole seed for bakery and confectionery products such as breads and muesli bars, and also for specialist stock feed.
A growing and important use of linseed is for cold pressed Flaxseed oil, widely sold in Australia and overseas as an Omega 3 health food.
Almost all linseed in Victoria is grown by farmers under contract to seed companies, who clean and grade the seed to supply those specialist markets.
Linseed can be produced as an organic crop, and certified organic linseed finds a ready market and commands good prices, especially from processors whose business is predominately in health foods. Great care is required for successful organic linseed production, particularly in insect pest management.
Linola ™ production has been at a standstill in Victoria until recently, and at present there is no Linola oil being used in Australian food products. The crop has been widely grown in North and South America, and there are markets in Europe for Linola oil for edible oils and margarines.
The Australian industry embraced mono-unsaturated oils for margarine production over Linola's poly-unsaturated oil profile.
All of the information linseed growing can be applied to growing Linola. Only the varieties are different.
Climate and soils
Linseed grows best where rainfall is from 450 to 750mm per year. That makes it suitable for:
- south west Victoria
- southern Wimmera
- Central districts
- some parts of north-east Victoria and Gippsland
It can be grown under irrigation. Linseed is rarely an economic crop to grow in major dryland cropping areas such as the Wimmera or the Mallee.
Linseed grows best in well structured soils, with heavier textured soils preferable to lighter sands. It can tolerate some waterlogging, but should not be sown in the autumn on land that is poorly drained. It can be grown very satisfactorily using the raised bed controlled traffic cropping technology that is employed in south west Victoria and some other districts to improve the soil and prevent waterlogging of crops. It will tolerate acidic soils unless the pH values are very low, in which case crops may benefit from lime application.
Linseed fits well into crop rotations, being particularly useful as a break crop for cereal production. If kept free of grass weeds it will help control or reduce soil borne cereal root diseases such as take-all. Many broad leaf weeds can also be readily controlled in linseed crops.
There are currently 3 linseed and 3 Linola™ varieties available. All current and future Linola varieties are or will be protected by Plant Breeders Rights (PBR) legislation. The current linseed varieties are not protected, but any new ones that become available are likely to be covered by PBR.
Glenelg is a white flowered variety which became the standard in Victoria until problems arose with a soil borne fungal disease called fusarium or flax wilt. This disease builds up in paddocks that are sown consecutively or too frequently to flax type crops. In badly affected paddocks all plants of Glenelg or any other susceptible variety will die before reaching maturity. Glenelg is rarely grown in Victoria now but it is still grown in northern NSW.
Croxton, a blue flowered variety, was released to counteract the wilt problem. It has a good level of wilt resistance and should always be chosen above Glenelg in situations where flax wilt is at all likely. It has a very slightly lower yield than Glenelg, is a little taller and is more prone to lodging.
Both Gelnelg and Croxton can lodge quite severely if sown in autumn, but are not known to lodge when sown in early to late spring.
One or more new wilt resistant linseed varieties, with lodging resistance derived from Argentinian linseed lines, may become commercially available. These varieties will be more suitable for autumn sowing, which will greatly increase the yield potential of linseed crops in Victoria.
Seed of an Argentinian variety, believed to be Areco, is available from some companies that offer contracts to grow linseed. Areco is wilt resistant, blue flowered, may grow slightly taller than Croxton and may be a few days later in flowering. Like the two crossbreds, it has good lodging resistance and should have a higher yield potential than Croxton, particularly if sown in autumn.
All Linola varieties are named after Australian lakes.
Eyre (white flowered, wilt susceptible) and Wallaga (blue flowered, wilt resistant) were the two earliest Linola varieties, but they have been largely replaced by Argyle.
Argyle is the most recently released wilt resistant Linola variety and it incorporates some beneficial characteristics from its Argentinian linseed parentage. It has excellent lodging resistance, which together with its longer flowering period gives it a yield advantage over Wallaga and makes it a suitable variety for autumn sowing. In spring sown crops its yield is usually close to that of Eyre and Wallaga.
Paddock preparation and sowing
Linseed has small seed and requires a weed free seedbed, with some tilth for good seed soil contact. For rapid and even seedling emergence, the seed should be sown shallow, between 10 and 30mm depth. On raised beds in particular, the use of press wheels behind the sowing tynes will help seedling emergence.
In Victoria linseed is usually sown between June and September, (although Argyle Linola can be sown in May). October or even November sowing is sometimes successful, although crops sown in those months are very dependent on good rains in late spring and summer.
Linseed can be sown using any machine that will sow cereals, at a seed rate of 35 to 45kg per hectare. Linseed can be affected by frost, both as a seedling and at flowering, but serious losses are not common.
It is best to use local knowledge, paddock history and local wheat rates as a guide. Any trace elements required locally for cereals or other oilseeds should also be applied to linseed crops.
The phosphorus (P) requirement of linseed is a little less than wheat. In southern Victoria 15 to 20 kg per hectare of phosphorous is generally applied, banded with the seed.
If linseed is grown in short rotations, with good clover pasture breaks, nitrogen (N) fertiliser applications will generally not be required. Linseed crops grown as part of more intensive crop rotations are more likely to require nitrogen fertiliser applications to achieve optimum seed yield. For spring sown crops 20kg per hectare of N drilled with the seed may be sufficient, but for earlier sowing in reliable rainfall districts a further topdressing of N in late winter or early spring may improve yield.
Oilseeds require more sulphur than cereals and sulphur should be applied in paddocks which have a long history of low sulphur fertiliser use. Gypsum at about 300kg per hectare will correct any shortage of sulphur for several years. Alternatively, most companies supply high analysis cropping fertilisers that contain added sulphur.
Young seedlings of linseed emerge with 2 cotyledons, after which they run up initially as single stems with small leaves carried at close intervals up their full length. In favourable conditions, and depending on plant density, 1 or 2 (occasionally more) pairs of branches then form near the base and these grow up parallel to the main stem, usually not quite reaching the same height. Before flowering, clusters of branchlets form at the tops of main stems and branches, each bearing one flower bud.
Flowering is spread over several weeks depending on conditions. Each bud opens its petals early in the morning, fertilises itself, and the petals fall off before evening. In warm weather they will all be gone by midday. Fertilised flowers then develop into a five celled capsule or boll containing up to ten seeds, arranged radially within it. The seeds ripen in these bolls as the plants mature and die.
Effective weed control is essential for linseed because its upright, open growth habit makes it a very poor competitor. Yield will be severely reduced if grass and broadleaf weeds are not controlled in the early growth stages of the crop.
Some weeds, if not controlled, may also cause harvesting difficulties or seriously contaminate the harvested sample.
A weed control plan for the crop should be made in advance of sowing, based on the likely weeds in the paddock. There are selective pre and post-emergence herbicides registered for the control of a wide range of grass and broadleaf weeds. Seek sound advice and carefully read and follow the entire label of all chemicals.
All linseed crops should be carefully and regularly monitored for insect pests, which can do very serious damage if not detected early and controlled. There is an adequate range of registered insecticides to control pests of linseed and Linola. Always read the label and follow all directions, safety precautions and withholding periods.
Brown cutworms (Agrotis munda) can be a problem in spring sown crops. These cutworm grubs live just below the soil surface and emerge at night to chew through the plants at ground level, lopping them down like felled trees. Effective control can be obtained by ground boom applied insecticides.
The 2 most serious insect pests of linseed are redlegged earth mites and other mites including blue oat mite in the seedling stage, and Native Budworm caterpillars during flowering and grain fill.
As in other small seeded plants, red-legged earth mites and similar pests can quickly cause serious damage to emerging seedlings. Bare earth sprays post sowing can work well but the emerging seedlings must still be monitored carefully and frequently for mite damage.
Very few crops escape some damage from budworm caterpillars, and control should be allowed for in the pre-crop budget.
In Victoria, the most common pest in this group is the Native Budworm. The adult moths fly in and, during late afternoon or evening, lay many single pearly white eggs on the foliage, flower buds or seed bolls.
Native Budworm is a particular problem for organic linseed producers.
New products are becoming available for linseed, under the agricultural pesticides permit system, that were developed for the cotton industry, and which may be permitted under certified organic linseed production standards. Some of these are biological control agents based on viruses or other pathogens of the caterpillars themselves. Organic linseed growers should always seek advice from their certification group before using any products on their crops.
As a rule, linseed crops in Victoria do not suffer serious yield losses from disease, but there are a few to watch for.
Fusarium wilt in Victoria is the most serious disease of flax, linseed or Linola. It is caused by the soil living fungus Fusarium oxysporum lini. This fungal strain invades through the roots and causes severe wilting followed by rapid death of the plant.
Always use resistant varieties if possible. All new varieties will have been rated high for resistance before release. The fungus lives for a long time in the soil, and it is most important never to grow successive linseed or flax based crops in a paddock. This will result in a build up of the fungus, putting pressure on the resistance of the cultivars. A rotation between flax type crops of two or three years is safest.
Flax rust is a potentially serious disease caused by the fungus Melampsora lini. Its symptoms are bright orange powdery pustules on leaves (particularly the undersides), stems and bolls. Flax rust has not been seen in Australia for many years, but an increased area of production might change this situation. Growers who see any signs of rust, or a rust like disease, on linseed or Linola crops should report it to an agronomist for diagnosis and action.
Pasmo is a fungal disease attacks the above ground plant parts, causing brown patches on the stems and leaves. Pasmo can cause defoliation, premature ripening and occasionally boll drop. Linseed is most susceptible to pasmo at the ripening stage and in Australia significant yield loss rarely occurs. There are no resistant varieties available. The seed can be treated with a fungicide, but the best control is rotation with several years between linseed crops.
Linseed and Linola are ready to harvest when the bolls, their branchlets, the leaves and at least the top parts of the plant are mature and dry, and the seed is at no more that 9% moisture. In some circumstances the lower parts of the main stems and major branches may still be green. The crop is direct headed with no windrowing required and, unless left standing for a very long time after it is ripe, rarely loses grain through shattering.
Set the harvester carefully to thrash the seed out of the bolls without cracking it, as this reduces quality. A lower drum speed but closer concave setting than for wheat is a good starting point. Cut the wind back to avoid blowing good seeds out of the machine. Linseed straw can wrap around harvester shafts, particularly if bad weather has delayed harvest, and it is a good idea to watch for this happening.
The relatively small amounts of linseed and linola currently grown in Victoria are usually bought by seed and grain trading companies who have developed specialist or niche markets for the seed. Price paid is by arrangement between growers and buyer. Generally, it is considered advisable for linseed growers to arrange a contract in advance with such a company, as this guarantees a market for the produce, provided it meets contracted standards.
CSIRO own Linola ™ by virtue of their patent rights and trademark protection, and they license the production and marketing rights while retaining their plant breeding program. To grow linola, it is essential to arrange a contract with the company that holds the production and marketing rights at the time.
Seed of both crops is generally received by buyers on the basis of national quality standards set by the Australian Oilseeds Federation (AOF), or the buying company's own standards based on AOF ones. If the seed is to be used for crushing for oil, then the AOF or other oil content standards may apply. The AOF standards are currently 40% oil content with price bonuses for over and reductions for under, maximum 4% impurities with associated weight adjustments and maximum 9% moisture.
Now that linola is again able to be commercially grown in Australia it is sound practice to avoid growing both linseed and linola on one farm or with one set of cropping and grain handling equipment. There would be a high risk of quality problems, because the difference in oil type, end use and (usually) seed colour means each is potentially a major contaminant of the other.