Tactical agronomy of safflower and linseed: place in the rotation, yield potential, time of sowing, plant growth and marketing

Take home message

• Safflower and linseed are winter oilseed crops best suited to be grown in rotation with cereal crops. Agronomic attributes include roles in integrated disease, weed and pest management programs.
• Limited market development of linseed and safflower restricts their current contribution to farming systems.
• The development of safflower crop technology for the biodiesel industry presents the potential of a significant addition to crop options in northern farming systems.
• Safflower is heat and drought resistant, adaptable to arid and semi-arid climates as well as irrigation.
• Linseed is best suited to medium to high rainfall environments in the NGR.
• Linseed can play a key role in managing of root lesion nematodes. It is resistant to Pratylenchus thornei and P neglectus.

Introduction

Safflower and linseed are winter-spring growing oilseed crops offering key benefits to diverse summer and winter crop systems as well as components of mixed production systems.

As oilseed crops, benefits include improved productivity of subsequent crops, lifting farm income, reducing the impact of disease and weeds; and producing edible and industrial quality oil and meal. Their integration offers the opportunity to enhance overall environmental, production and economic sustainability.

These crops are grown largely for the food industry in Australia. Safflower has received focused attention as an industrial oilseed and potentially represents a significant new crop industry for the Northern Grains Region (NGR). Research to establish baseline data to develop agronomic management is crucial for future industry development of safflower and linseed.

Safflower

Safflower comprises cultivars that are of two oil types, high in linoleic or oleic fatty acids. Safflower historically has remained a secondary crop. Linoleic cultivars were principally marketed as a component of feed mixes for birds and small animals; and oleic cultivars used in manufacturing industries producing paints, resins, pharmaceuticals and cosmetics.

Areas sown to safflower vary widely, ranging between 6100 and 45 000 ha in the decade from 2003 (FAO 2015). Reasons for this include few available cultivars, susceptibility to alternaria (Alternaria carthami) and phytophthora (Phytophthora cryptogea), limited agronomic research, disappointing farmer experiences and adverse seasons. A history of inconsistent prices and market opportunities because of competition from both alternative oilseed crops and the continuing development of petroleum substitutes have further hampered adoption.

Commencing in June 2004, a strategic partnership by CSIRO and GRDC established the Crop Biofactories Initiative (CBI), a 12 year program to examine the potential of plants to make alternative compounds for specific industrial uses, including biofuels, bioplastics and biolubricants derived from high oleic oils.

CBI scientists developed a GM process to produce super high oleic oil (SHO) safflower. Conventional oleic genotypes currently comprise approximately oleic acid levels of 75% of total oil content. SHO lines contain up to 95% oleic acid. In 2015, CSIRO issued a licence to GO Resources to commercialise GM safflower technology.

Rotation fit

Rotation benefits include:

• Late winter crop option if there is a late break or failed establishment of the winter crop
• Potential to double crop out of sorghum
• Heat and drought tolerant oilseed crop suited to lower rainfall areas where canola and sunflower are not adapted.
• Broadleaf crop option – break crop for cereal diseases including Crown rot (Fusarium pseudograminearum), Common root rot (Bipolaris sorokiniana), Yellow leaf spot (Pyrenophora tritici-repentis) and Spot form of net blotch (Pyrenophora teres f maculata). 
• Resistant to both P thornei and P neglectus root lesion nematodes.
• Safflower is regarded as a good host to arbuscular mycorrhizae fungi (AMF), promoting the increase of AMF in the soil.
• Safflower is subjected to a different weed spectrum to most other crops. It offers the opportunity to control late germinating weeds and/or herbicide resistant winter weeds and to incorporate additional IWM strategies.    
• Greater crop enterprise diversity to spread economic and production risk.
• Used in a soil ameliorant role to improve soil structure. Used strategically as a first crop in the rotation after cotton to break up subsoil to remove compacted layers, improve aeration and water infiltration; and root development to subsequent crops (anecdotal reports of rooting depths of 2.2 m)

Other advantages include:

• Alternative crop suited to both dryland and irrigation.
• Low input, low maintenance and easy to grow.
• Crop inputs and machinery requirements similar to wheat production.
• Sowing and harvest windows effectively spread peak workloads and machinery use over a longer period, increasing efficiencies and harvest timeliness of different crops.
• Widely adapted to various soil types, but best suited soils with high water holding capacities.
• Safflower is a competitive crop against weeds after the mid to late spring period.
• With deep roots, and providing sufficient water is available, safflower is tolerant of hot summer conditions during crop maturation.
• Utilises soil water deep in the soil profile. Lowers the water table with dissolved salts, reduces water logging in following crops and improves N efficiency by utilising leached N at depth.
• Increasing climate variability presents opportunities for safflower as an oilseed as it can grow on less rainfall than other major oilseed crops such as canola, sunflower and soybeans.  Potential to be grown across a wide geographic area.

Sowing time

• Main sowing window is June to August.
• Flowering can commence in 85 – 140 days ie at the end of October and during November (depending on genotype, sowing date and environment).

Harvest

• Safflower matures in 110 – 170 days. Harvest period in northern NSW is normally from mid-December through to the end of January, varying with location, seasonal conditions and sowing date. 
• The rate of dry down of seeds and stems can vary. Harvest delays can occur when drying down to 8% moisture content in the seed(delivery standard) where stems have not dried down sufficiently. Stem dry down can be slowed when periods of rain and high humidity occur and when low crop populations produce plants with thick stems.
• Where food and birdseed markets demand clean bright white seed, timely harvest is imperative.

Yield potential

• In most seasons, average dryland yields are 1 – 1.2 t/ha.
• Anecdotally, the highest known commercial yield is reported to be 3.3 t/ha under irrigation in northern NSW.

Marketing safflower

Safflower is currently mainly grown as an oilseed crop comprising two main oil types: 

Linoleic acid is a polyunsaturated (omega-6) fatty acid. The most widely grown linoleic oil cultivar is Sironaria, released by CSIRO in 1987. Linoleic genotypes contain >75% linoleic acid. Linoleic cultivars are grown for seed and oil.

Seed

Safflower seed is used in birdseed and small animal feed mixes. Visual seed appearance is an important market criterion, preference given to a bright white appearance. Sironaria is the preferred variety. Other varieties like S317 (an oleic oil variety) are not desirable for this market because of inherent varietal characteristics like a creamy coloured seed coat and grey stripe on the seed.

Large price variations between seasons are common due to the speculative nature of production. The small market for birdseed and small animal feed mixes is easily over supplied.

Linoleic oil

Linoleic oil is an edible oil, used in products such as salad oils and soft margarines. It is also used in the manufacture of pharmaceuticals, cosmetics and paint in some other countries.

Similarly, overseas in the USA as an example, a by-product after oil extraction is the high fibre meal.  The fibre is important in stock with low fibre diets eg- feedlots and dairy.  The meal containing around 24% protein is used as a livestock protein supplement. Meal from de-hulled seed has about 40% protein with reduced fibre content.

Oleic acid is a monounsaturated fatty acid. Oleic varieties include S317 and S517 which are grown their oil, for use the food industry for frying and in the manufacture of pharmaceuticals, cosmetics, soap, paint additives, adhesive and sealant compounds, plastics and lubricants.

Current oleic safflower production, comprising principally S317, targets the food industry, supplying manufacturers, wholesalers and food service operators. Export in the form of oil or as seed varies with the costs of crushing and oil extraction. Recent increases in crushing costs from $150 / t to $300 /t mean that seed imports have replaced oil imports (Bill Slattery, pers comm).

Presently, India is the main market for oleic safflower oil for the food industry, looking to import around 30 000 t seed. Australia currently falls well short to meet this, struggling to supply 4000 t seed.

Safflower is grown under contract on a per hectare basis.  Prices paid for oleic safflower in 2014 were $490 /t and in 2015 - $520 /t. Prices are quoted ex-farm, ex-GST. Contracts are written to Australian Oilseed Federation (AOF) Standards. Payments are based on the percentage of oil in the seed and test weight at 8% moisture and 4% impurities. The baseline oil content is 38% with applied 2% discounts and premiums. In 2014, all deliveries exceeded 38% oil.

Potential industry growth

The unique properties of oleic acid also make it of potential use in biodiesel production. GRDC reports that market analysis indicates global demand for high-purity oleic acid oil could require more than 100 000 ha of the new safflower varieties. As an indication of potential, the size of the Australian cotton industry is estimated to be 270 000 ha in 2015/16 by Cotton Australia.

“Cotton soils” could be classified as “safflower soils”.  Depending on water availability with seasonal conditions, pricing comparisons of crop choice and water costs, and field rotations, some level of substitution may be a potential viable option for some growers.

The NGR’s is characterised by a variable climate where agriculture comprises diverse cropping systems. Predominantly comprising soils with high water holding capacity, it is an environment that suits safflower with its heat and drought tolerance. Oleic oil synthesis within the seed is favoured by warmer finishing conditions, promoting high oleic content.

The existing expertise with modern agricultural technology, including GM crop production, and the region’s pre-existing oil crushing facilities, combine to offer opportunities for the development of an industrial safflower oil enterprise in farming systems.

Economics will determine industry growth with competition from profitable crop options. 

Issues / problems that may be encountered when growing safflower

Genetically modified (GM) crop

The incorporation of GM safflower cultivars into a farming system may involve guidelines and strategies under a Stewardship program to ensure appropriate on-farm crop management and throughout the grain supply-chain.

Soil water use characteristics

Safflower uses more water than other winter crops, attributed to its deeper rooting depth and longer growing season. The deep rooting habit dries the soil profile. This has implications for subsequent crops, limiting crop potential where soil water reserves are not replenished by sufficient rainfall in dryland situations.  When conditions remain dry, planned crop sequences may be disrupted.

Adequate stored soil moisture at sowing is crucial. Safflower production is a greater risk crop in low rainfall areas when there is low stored soil water at sowing. Limited starting soil moisture and lack of timely in-crop rainfall will produce poor or variable safflower yields.

CSIRO research conducted in the late 1980’s at Dalby – Queensland, compared soil water use in safflower, wheat and chickpeas. Sown 2 June, safflower extracted 375 mm, compared with wheat - 212 mm and chickpea - 195 mm (Beech & Leach 1989). This equated to WUE of safflower 2.6 kg /ha/ mm, wheat 6.8 kg / ha/ mm and chickpea 4.9 kg / ha/ mm.

More recently, GRDC funded research conducted in western Victoria in 2000 and 2001 (Waschmann et al 2003) reported safflower used 100 mm of additional water compared to wheat in wetter seasons. Whilst all crop species measured similar daily water use, safflower’s longer growing season (34 – 40 days more than wheat) meant it used additional soil water. To achieve similar yields to canola, safflower used an additional 120 mm. Safflower yielded 3.71 t/ha and canola 3.44 t/ha.

Disease

Seasonal conditions largely determine the incidence and severity of disease in safflower. Management includes preventative strategies and variety resistance. The main issues of concern in the NGR are alternaria and Phytophthora.

Alternaria leaf spot (Alternaria carthami) when present at high infection levels can result in significant yield loss of up to 50%. Oil (and protein) content can be reduced. Sironaria is resistant.

Phytophthora root rot (P cryptogea) (and Pythium root rot). Sironaria is resistant to phytophthora.

Rust (Puccinia carthami) may cause significant yield loss where infection occurs early in the season. Inoculum survives in crop residues and alternative host Carthamus species like safflower. 

Disease carryover – Safflower is a potential host to sclerotinia (Sclerotinia sclerotiorum). Other alternate host crops include sunflower, mustard, canola and chickpea.

Pests

Wireworms and false wireworms are intermittent pests.

Heliothis need to be monitored at budding and during flowering. Definitive thresholds are required.

Thrips at budding and flowering can cause significant yield losses. Well grown safflower is reported to be quite tolerant of damage. Regional research to define damage levels, pest thresholds yield losses are required.

Bird damage

Safflower offers an attractive alternative food source to birds. Some degree of crop loss can be expected.  The timing of crop maturity places safflower after the winter crop harvest period and just prior to sunflower seed fill. 

Weed management

Safflower is subjected to a different weed spectrum to most other crops. Its sowing window offers the opportunity to control late germinating weeds and/or herbicide resistant winter weeds and to incorporate additional IWM strategies.

Options may include cultivation, changing timing and application; and herbicide MOA eg- bipyridyl herbicides (Group L) such as paraquat. Safflower is a competitive crop against weeds after the mid to late spring period.

In cotton production systems, inter-row cultivation and shielded sprayers can be a key tactical option in weed management in safflower.

Herbicides and weed management

Herbicide registrations

There are few registered herbicides for use on safflower. Registrations for pre-emergent weeds in Sironaria safflower are trifluralin (TriflurX®), pendimethalin (Stomp®) and tri-allate (Avadex® Xtra). These herbicides control a narrow range of weeds species. Post-emergent registrations are limited to Group A’s such as diclofop-methyl (Rhino®) and propaquizafop (Shogun®). Their effectiveness is dependent on the resistance profile of the post-emergent options.

Broadleaf weed control is limited to metsulfuron-methyl (Ally®) and crop competition.

Weed control prior to planting is necessary.  Safflower is planted in the cooler months and so subsequent growth is slow, making the crop vulnerable to competition from weeds. As the crop canopy rapidly increases in spring, crop competition increases.

Variety sensitivity

Pre-1998 and in 2008 Devexco conducted herbicide tolerance testing with metsulfuron-methyl, pendimethalin and trifluralin. It was reported that there was a narrow safety margin with pendimethalin on S317.

Diclofop-methyl and tri-allate appear safe on Sirothora and Sironaria cultivars.

There has been some limited work conducted on some high oleic genotypes with metsulfuron-methyl (Ally®) using rates up to 7.5 g /ha ai applied at the 4 – 6 leaf stage. Results showed no significant effect on yield, seed size or oil quality.

In 2014, further crop safety work was conducted on Sironaria with metsulfuron-methyl as well as other potential post emergent broadleaf herbicides at 2 – 4 leaf and 4 – 6 leaf growth stages. Results are pending, but significant crop damage was measured with some herbicides. 

Paddock selection

Knowledge of the weed density and spectrum of individual paddocks is essential. Similar to other broadleaf winter crops, avoid situations where there are high populations of broadleaf weeds present.

Safflower’s seasonal time of year and matching growth pattern is different to other crops. The stem elongation growth stage begins in the late spring period. Rapid canopy development increases the crop’s competitive ability, creating greater stress on small weeds. At the same time, the expanding crop canopy can inhibit weed target herbicide coverage. Safflower crops sown mid-June and July commence flowering in late October to early November, preventing herbicide and mechanical control options.

This timing of safflower growth and development has implications for management of specific weed species in the northern grains region.

Black bindweed (Fallopia convolvulus) emerges mid-winter to mid-spring.. There are confirmed reports of herbicide resistance to metsulfuron-methyl, so reliance of pre-emergent herbicide strategies is important.

Species like fleabane (Conyza bonariensis) germinate throughout the year; however wet springs stimulate maximum germination. Similarly common sowthistle (Sonchus oleraceus) germinates year round, with emergence determined largely by rainfall events.

Summer active weeds like awnless barnyard grass (Echinochloa colona) and barnyard grass (Echinochloa crus-galli) can be potential problems, particularly where wider crop spacing reduces crop competition. Barnyard grass germinates throughout late spring and during summer. In contrast, liverseed grass mostly germinates in a single flush in late spring. As you move further north, the spectrum changes to be dominated by feather-top Rhodes (Chloris virgata), particularly on lighter textured soils.

Plant-back periods

Metsulfuron-methyl is registered for early post-emergent weed control in safflower.  Its use in safflower has implications for some subsequent crops. The re-plant interval is 14 months before sorghum, maize or millet can be planted. This would prevent a possible double-crop sequence if soil water availability was suitable. Planting a successive broadleaf crop is not recommended.

Conclusions

The suitability of safflower to the NGR environment combined with industrial crop technology creates a potential new industry - the ability to produce renewable high purity oleic acid oil suited to a range of compounds that can replace non-renewable petroleum-based industrial chemicals. However, further agronomic research and development is required.

More safflower cultivars are needed to increase adaptation and marketability. The release of quicker maturing cultivars may increase the reliability and yield through improved harvest index (HI) and WUE. Disease resistance to Alternaria and Phytophthora would be important desirable features.

Better understanding of plant growth and development of safflower coupled with water use patterns are needed to develop and adapt agronomic recommendations like sowing time, crop population and row spacing to environments across the NGR and interactions with crop yield and oil quality.

As part of a rotation, safflower’s long growing season and high water requirement will impact on subsequent crop choices and performance. The economics of safflower need to offer at least similar benefits and profitability to growers as alternate crop choices.  The development of stable market opportunities is integral to future industry development. Wider weed and pest control options and registrations are needed.

Linseed

Linseed is a winter growing oilseed crop grown for its seed and oil. Linseed contains alpha-linolenic acid, polyunsaturated oil. Alpha-linolenic acid is classed as an omega-3 fatty acid, considered to be an essential fatty acid in human health diet.

End uses have changed in recent decades as advances in technology have resulted in synthetic substitutes where linseed oil was used. Greater focus on human health and natural products has resulted in most of the Australian linseed crop grown for seed, and a lesser extent oil, in the food industry.

Linseed contains 35 – 40% oil, with alpha-linolenic acid levels of between 45 and 60%. Linoleic (omega-6) fatty acid levels, desirable for its human health attributes, are generally between 17 and 22%.

Rotation fit

• Linseed is a winter oilseed crop alternative.
• Linseed grown after cereal crops is effective in reducing soil borne root diseases including Crown rot (Fusarium pseudograminearum) Common root rot (Bipolaris sorokiniana), Yellow leaf spot (Pyrenophora tritici-repentis) and Spot form of net blotch (Pyrenophora teres f maculata). 
• Linseed is resistant to both main species of root lesion nematodes – Pratylenchus thornei and P neglectus.
• Linseed has a high arbuscular mycorrhizae fungi (AMF) host dependency. Significant yield losses can result if grown in low AMF situations. Linseed is best grown after AMF host crops like wheat.
• As well as grass selective herbicides, a number of broadleaf herbicide options are registered, covering a wide spectrum of broadleaf weed species and including Group C and Group I herbicides.

Sowing time

Linseed is generally planted in mid-May to mid-June in northern NSW.

Soils

Linseed is adaptable to soils ranging from vertosols to loam-textured soils. Linseed will grow on acid soils where pH_(Ca) levels are as low as 4.5, if exchangeable aluminium levels are also low. Linseed performs best on well-structured heavier-textured soils. It is not suited to sandy soils. Linseed is classified as having a low to moderate tolerance to salinity.

Varieties

There is presently no active breeding program in Australia since the closure of the CSIRO breeding program several decades ago.

Glenelg is an early to midseason maturing variety that was released in 1970. A white-flowered public variety, it is the most widely grown variety in northern NSW, accounting for more than 95% of the crop area.

Croxton is a long season public variety. Blue-flowered, Croxton has been grown since 1985 in mostly southern Australia, but with small production areas in the cooler higher rainfall slopes area east of Moree.

LM14 and LM17 are two cultivars licenced to Austgrains Pty Ltd at Moree. Both blue flowering types, their maturity lies between Glenelg and Croxton.

Row spacing

Linseed is generally grown on row spacing varying between 18 cm (7”) and 38 cm (15”).

Plant growth

Linseed has a very small seed. Seed placement, particularly depth and soil contact with moist soil is critical for even crop emergence. Early plant growth is slow during cooler seasonal temperatures after planting. After emergence, a single main stem elongates. This is usually followed by the growth of one or two pairs of basal branches that extend almost to the height of the main stem.

A seed head consisting of clusters of buds forms. Each flower bud opens, eventually forming a capsule (boll) potentially producing up to 10 seeds.

Linseed is an indeterminate crop. Flowering can continue for several weeks extended period until seasonal conditions and /or plant resources cause flowering to cease. Seeds ripen within the capsules, crop senescence indicated by yellowing, then browning of leaves, stems and capsules. Mature seeds rattle within the capsule.

Yield potential

Linseed is suited to the higher rainfall areas of the NGR, with best performing crops generally grown east of the Newell Highway. Linseed does not tolerate periods moisture or temperature stress during the flowering period. Spring rainfall patterns have a large influence on crop yields. Reported average yields range between 1.0 and 1.5 t/ha.

Pests

Heliothis is the most significant pest in linseed in the NGR. One, sometimes two pesticide applications are required. Heliothis can damage the crop before budding, but are most prevalent during budding-flowering.

Disease

Few diseases have been reported to be of concern in linseed in the NGR. The relatively small production area and annual variations of the crop contribute to low inoculum levels and long paddock rotations between crops. Potential disease issues of linseed include:

Fusarium wilt (Fusarium lini) has been reported to a major disease in southern Australia, but with few recent reports in northern NSW. Glenelg is very susceptible to fusarium wilt, the main reason why it is no longer grown in southern Australia. It has been replaced by Croxton, the only resistant variety. The reaction of LM14 and LM17 are not known.

Pasmo (Mycosphaerella linorum) Pasmo is a fungal disease that may cause yield and seed quality. The last known reports of Pasmo in NSW linseed were in the 1970’s and 1980’s during moist conditions in spring. It has not been considered to be a major disease risk in linseed production. Neither Glenelg or Croxton are resistant to Pasmo. The status of LM14 and LM17 is unknown.

Marketing

The market for linseed is small, anecdotally between 12 000 and 20 000 t per annum for the domestic human consumption market. The limited market demand and sometime plentiful supply cause large variations in prices season-to-season.

Most of the northern Australian linseed crop is grown under contract on a per hectare basis.  The licenced cultivars LM14 and LM17 are grown under contract for delivery to Austgrains Pty Ltd at Moree.

Payment is based on 7.5% moisture receival standards.

Linseed permits

Permit ID	Description	Expiry date
PER81763	Indoxacarb / Linseed / Helicoverpa spp.	31-Aug-16
PER81877	Steward / Linseed / Flax / Heliothis	31-Dec-16

(Source: APVMA)

References

Beech GJ & Leach DF (1989) Comparative growth, water use of chickpea, safflower and wheat in south-eastern Queensland. Australian Journal of Experimental Agriculture 29 (5) 655-662

Waschmann N, Norton R, Jochinke D & Knight S (2003) Proceedings of the 11^th Australian Agronomy Conference, Geelong, Victoria (Australian Society of Agronomy).

Acknowledgements

The research undertaken as part of this project is made possible by the significant contributions of growers through both trial cooperation and the support of the GRDC, the author would like to thank them for their continued support.

Trial co-operators gratefully acknowledged: Jack Gooderham “Myling” Tullloona, Alan Riordan “Nullabean” Nea (via Breeza) and IA Watson Plant Breeding Institute – Sydney University – Narrabri

Technical support: Stephen Beale, Joe Morphew, Mitch Whitten, Tim Grant, Rosie Holcombe, Stacey Cunningham, David Cain, Stephen Morphett, Pete Formann and Jim Perfrement – all NSW DPI

Valued comments: Jim Simpson – Austgrains (Moree) and Bill Slattery – Fabi Foods Pty Ltd, Tony Cook - NSW DPI

Contact details

Kathi Hertel (R&D Agronomist)
NSW DPI
Locked Bag 1000, NARRABRI   NSW   2390
Mb: 0427 104 344
Email: kathi.hertel@dpi.nsw.gov.au