How is canola grown

In these trials, better establishment was obtained by using large seed and the hybrid varieties established better than open pollinated varieties in difficult conditions. In the situation where crop establishment is compromised, consideration should be given to the relative merits of reseeding versus not reseeding.

The plasticity of canola has meant that yields above 1. Failure to optimise fertiliser rates can diminish the gross margin of a canola crop through excessive input costs too much fertiliser or reduced yields not enough fertiliser. Canola has slightly different nutritional requirements to other crops and a tailored fertiliser program can be developed using some of the many tools available for this purpose.

These include software packages, mobile and online apps, information products and professional services. Develop the nitrogen strategy by considering the crops potential yield, soil test results and other rotational, soil type and rainfall information.

Nitrogen is generally applied in split applications, allowing post emergence rates to be determined once yield potential can be more accurately estimated.

Check soil phosphorus status, as maintenance rates at seeding may be all that is required. Canola has a higher requirement for sulfur than wheat. Canola is no more susceptible to micronutrient deficiencies than wheat.

Monitor the crop within the season and tissue test to identify deficiencies to micronutrients. Regular soil and tissue testing is fundamental to tailoring fertiliser programs to crop demand. The Critical nutrient levels for canola in Western Australia can help canola growers interpret their soil and tissue test results. There are several herbicide tolerance systems available in WA canola varieties see below. Considerations for choosing a system include the weed spectrum and resistance status of weeds, crop sequence, rainfall zone as well as cost.

Numerous insect species can infest canola crops but the application of a chemical insecticide is not always necessary. It is important to monitor crops through the season to allow time to respond to potentially damaging infestations.

Canola - insect threshold levels lists the insects commonly found in canola crops, as well as information to help determine the threshold population level, above which spraying of insecticide may be worthwhile.

Infestations of turnip aphids, cabbage aphids and green peach aphids can all reach damaging levels in canola crops in WA.

Aphid management in canola crops and Diagnosing canola aphids has detailed information about aphid management. It is important to actively monitor canola crops for disease through the growing season to allow time to consider and implement management options.

Fungicides can be used to complement other management strategies but can not be relied on alone. Options include dressing of seed, treatment of fertiliser and foliar fungicides. All commercially sold seed comes with a fungicide seed dressing, however if retained seed is being sown it is important to ensure a fungicide seed dressing is applied.

Canola Flower Midge. Diamondback Moth. Lygus Bugs. Painted Lady. Red Turnip Beetle. Herbicide Residue and Drift Injury. Herbicide Rotation and Residues. Weed Management. Fusarium Wilt. Powdery Mildew. White Leaf Spot and Grey Stem. Harvest Management. In order to make effective crop management decisions, it is helpful to understand the different canola growth stages throughout the growing season, from planting to harvest.

The impact of climatic factors such as soil moisture, rainfall, air and soil temperature, seed germination and emergence, and the efficiency of crop inputs such as fertilizers, herbicides, insecticides and fungicides drive the rate speed of plant growth and development. The proper application timing of crop protection products Pesticides herbicides, insecticides or fungicides used to protect against or reduce the amount of damage caused by weeds, pest insects or plant diseases.

For these reasons it is important to be able to properly identify canola growth stages and understand what influences application timing has on them. Canola plants grow nearly every day of the growing season, from when they are planted until harvested. Growth begins with the seed, then leaves, stems, flowers, pods and seeds, in a cycle. The length of each phase or stage of growth is influenced by cultivar A cultivar is a variant in a species developed through the intervention of humans despite the term 'variety' often being incorrectly used to describe this.

A cultivar can be open-pollinated type, hybrid, synthetic, composite, etc. Growth and development of a canola plant is continuous but can be divided into easily recognizable growth stages. Air temperature is one of the most important environmental factors regulating growth and development of canola. A standardized growth stage scale developed by industry research scientists, called the BBCH decimal system, provides an accurate and simplified approach to describing canola growth stages.

The BBCH decimal system is comprised of different growth stages GS which are each further sub-divided into specific developmental increments 1. Canola will move faster or slower through plant growth, cell division and the accumulation of biomass, or plant development, cell specialization and differentiation or the onset and development of reproductive organs, depending on the current environmental conditions the plant is growing in.

This includes air and soil temperature, soil moisture that is available to the plant, photoperiod, solar radiation, fertility, and the presence or absence of crop pests. Furthermore, depending on what stage the plant is in determines how sensitive it is to the current environmental conditions. For example, canola that is flowering is much more sensitive to extreme temperatures, like those exceeding 30 degrees Celsius, than it is during vegetative growth. Oil and protein in the seed provide the energy required for germination, but the seedbed must have sufficient available water, oxygen and adequate temperature for germination to occur.

Water absorption is the first step in germination. Water is the medium and reactant for many biochemical processes. For canola, there is an initial period of rapid water uptake, followed by a lag period, then rapid absorption associated with embryo growth. Since water comes from the soil, the seed must be in close contact with moist soil particles to absorb water.

If the salt concentration is too high, the seed cannot absorb sufficient water for normal germination. This partially explains why a seed may fail to germinate in the fertilizer band or in severely saline soils.

Water absorption is also critical for the efficiency of some seed treatments. Oxygen must also be present for cell respiration to provide adequate energy for germination.

Normally, oxygen is a limiting factor only under conditions leading to lower oxygen diffusion rates, such as waterlogged or compacted soils. Soil temperature must be five degrees Celsius for successful germination, and the rate of germination increases from this to about 30 degrees Celsius 2. While water absorption by the seed is not sensitive to temperature, new growth is temperature-dependent because of the effect of temperature on biochemical processes.

The root grows downward and develops root hairs that anchor the developing seedling. The new stem, or hypocotyl, begins growing up through the soil, pushing two heart shaped leaf-like organs called cotyledons or seed leaves. The seed coat is usually shed in the process. Canola seeds have two cotyledons, and are described as dicotyledonous or dicots.

When exposed to light, the cotyledons unfold and become green. Other factors that influence germination are seed viability, seed size, soil microorganisms, seed soundness and seed diseases. Viability describes whether the embryo is alive and able to germinate. Soil microorganisms can decay seeds, especially under poor germinating conditions. Seed treatments may help protect the seed and seedling against soil-borne disease infection.

Upon emergence, four to 15 days after seeding, the seedling develops a short 1. The cotyledons at the top of the hypocotyl growing point expand, turn green and provide food to the growing plant.

Unlike barley, where the growing point is protected beneath the soil for five to six weeks, the growing point of canola is above the soil, between the two cotyledons. The exposed growing point of canola renders seedlings more susceptible than cereals to spring frost, soil drifting and wind damage, insect feeding and hail.

Heat canker may occur when the bare soil temperature becomes so high as to burn the hypocotyl at the soil surface. Canola plants have a tap root system.

Rooting depth varies from three to five centimetres 1. The root system continues to develop with secondary roots growing outward and downward from the taproot. Root growth is due to cell division and enlargement at the tip of the root. Root growth is relatively constant, averaging nearly two centimetres 0. Young developing roots quickly become colonized by soil microorganisms — bacteria, fungi, actinomycetes — which provide nutrients, increase plant nutrient uptake, protect against various environmental stressors, and promote positive plant health and growth.

They also can help protect the plant from diseases. However, at times, microorganisms that cause disease outcompete beneficial microorganisms, and plant health and productivity declines. When soil water and nutrients are abundant, the balance of root to stem and leaf growth typically shifts in favour of stem growth at the expense of the roots. When water is limited, the opposite usually occurs. Root and stem growth complement one another by adjusting their relative size to meet the basic requirements of the whole plant in response to climatic and soil conditions.

With moisture stressed canola, roots account for about 25 per cent of plant dry matter at stem elongation compared to about 20 per cent for unstressed plants. At peak flowering and maximum stem length, roots will have reached about 85 per cent of their maximum depth. Root depth, like plant height, will vary from 90 to centimetres 36 to 76 inches and will average about centimetres 56 inches at maturity.

The root system varies with soil type, moisture content, soil temperature, salinity and soil physical structure. Roots absorb water and nutrients from the soil and transport them upward into the stem.

Roots intercept water and nutrients present in the soil pore space that they contact. Factors limiting root penetration through the soil include a high water table, dry soil, soil compaction, weed competition for moisture and nutrients, a salt layer or cool soil temperatures.

As roots grow, they use oxygen and release carbon dioxide. Restricted soil aeration, because of excess water or soil compaction, results in low oxygen, high carbon dioxide, and eventually root death.

Moist topsoil with dry sub-soil during the early stage of plant growth promotes a shallow root system. Roots penetrate dry soil only slightly beyond available moisture supplies. Insect and disease species such as root maggot and brown girdling root rot will damage the root and restrict the uptake of water and nutrients.

Four to eight days after emergence the seedling develops its first true leaves. The first true leaf to develop and fully expand is frilly in appearance. The plant quickly establishes a rosette with older leaves at the base increasing in size and smaller, younger leaves developing in the centre.

There is no definite number of leaves produced by a canola plant. A canola plant under optimal growing conditions normally produces nine to 30 leaves on the main stem depending on the cultivar A cultivar is a variant in a species developed through the intervention of humans despite the term 'variety' often being incorrectly used to describe this.

The maximum area of individual leaves on the plant in the absence of stress is around square centimetres. Count the leaves of a canola plant when it has become visibly separated from the terminal bud. During this rosette growth stage, the stem length remains unchanged although its thickness increases. The growth rate of the crop is closely related to the amount of solar radiation captured by the leaves.

Rapid leaf development also encourages root growth, reduces soil moisture evaporation and competes with unwanted weeds. There is a positive correlation between seed yield and maximum leaf area index LAI. Leaf area index LAI is a measure of the upper surface area of leaves per unit of ground surface. An LAI of four refers to four square metres of leaf surface area per square metre of ground surface.

An LAI of about four is required for the crop canopy to intercept about 90 per cent of the incoming solar radiation. The larger the leaf area the crop can expose to the sun, the more dry matter the crop can accumulate per day. The more dry matter, the greater the potential yield.

Plants in low population density crops ex. Plants compete with each other for light, soil moisture and nutrients. In uneven germinating crops the leaf area of early emerging plants can become large enough to cause weak, spindly growth or stunting and death of later emerging plants.

This growth stage GS refers to the development of side shoots tillering and occurs in many plant species but it is not applicable to the spring canola cultivars grown in Canada. Reproductive development begins before flowers are visible to the human eye and can be observed at the microscopic level just prior to bolting. Stems orient leaves to sunlight and air, which are also important photosynthetic structures throughout reproductive development.

Stem elongation GS 30 overlaps leaf development and normally occurs before the vegetative rosette has stopped growing GS At or just prior to stem elongation, flower and branch initiation begins. Maximum stem length GS 39 overlaps flower development and is reached at peak flowering GS As stems elongate, roots continue to grow deeper.

The amount of time spent in the vegetative stage, or days from seeding to first flower, can range from 40 to 60 days, depending on the date of seeding, cultivar A cultivar is a variant in a species developed through the intervention of humans despite the term 'variety' often being incorrectly used to describe this. Canola plants vary in height, but average between 75 to centimetres 30 to 70 inches.

Stem diameter and height are influenced by seeding date, moisture, cultivar A cultivar is a variant in a species developed through the intervention of humans despite the term 'variety' often being incorrectly used to describe this.

Plants in low-density stands will have thicker stems and are more tolerant to lodging. Plants in high-density stands are thinner and more prone to lodging. A lodged stand leads to uneven pod maturity, creates an optimal microenvironment for disease development such as sclerotinia and alternaria , and can be challenging to swath or harvest.

This growth stage GS is not important for canola management but applies in the development of harvestable vegetative plant parts such as broccoli or cauliflower. Lengthening days and rising temperatures trigger flower bud formation. The rule of thumb is that canola needs about 80kg per hectare of nitrogen for every tonne of grain expected to be produced.

Some special varieties of canola have tolerance to herbicides that will kill conventional varieties, and can survive being sprayed with that herbicide while many weed species are controlled or suppressed. These include triazine tolerant, Clearfield, Roundup Ready R and TruFlex R types, as well as varieties with more than one type of herbicide tolerance.

They also allow growers to sow canola earlier into dry soil rather than wait for the autumn break and emergence of weeds. Canola crops that emerge earlier tend to produce higher yields and higher oil content. Canola can be affected by a number of insect pests, which may require chemical control if they start to cause significant crop damage. Adoption of an integrated pest management IPM system reduces, but does not eliminate, the use of insecticides by allowing the build up of beneficial insects that may keep populations of pest insects in check.

At the seedling stage, canola crops are vulnerable to redlegged earth mite and a number of similar or related pests such as blue oat mite and lucerne flea. Chemical mite control is often necessary and one option is to apply an insecticide seed dressing.

In areas such as south west Victoria, skylarks and slugs can also cause damage to emerging canola crops. Other possible pests during the growing period include aphids and a range of insect species as well as mice. Two major differences exist between canola and most other crops which affect crop management. The first is seed size. Canola is a tiny seed, which means that sowing depth must be well controlled. Alternate wetting and drying of the seed at the soil surface can cause patchy germination.

The seed is best sown shallow, but still covered by a thin layer of soil to protect it from drying out before or after germination. Many farmers use devices called press wheels, which follow the sowing tyne and press the soil over the seed to give it better contact with the soil so it does not dry out quickly. Press wheels are very beneficial in improving the establishment of canola crops. The second difference is the need to windrow the crop to minimise seed loss.

A ripe standing crop of canola is vulnerable to wind damage. Swaying stems bring the brittle pods in contact with each other, which causes shattering and seed loss. Windrowing or swathing involves cutting the crop 8 to 10 days before the seed is fully mature.

The window of opportunity for ideal timing of windrowing that avoids shattering losses or reduced grain yield and oil content is only 3 to 4 days. The windrow lies in horizontal bundles 10cm to 20cm off the ground supported on the cut stems. Ripening of the pods and seeds continues with less risk of movement caused by strong winds. Windrowing is a specialised operation that adds to the cost of production.

There are many contractors who specialise in windrowing, but more and more growers with large areas of canola crops are opting to purchase their own machines in order to exercise better control over the timing of windrowing.

Picking up the windrow may involve fitting a special front to the harvester. Again, many farmers are prepared to invest in this, while others prefer to use contractors to windrow and harvest. While most canola crops in Victoria are windrowed, many crops are now harvested without windrowing direct headed. This can reduce costs associated with harvesting canola. There are numerous advantages and disadvantages associated with direct heading.