Canola varieties

By BCG Staff and Contributors
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 TAKE HOME MESSAGES

  • Though canola did not fare well in 2014, it still plays a vital role in farming systems; growers should avoid making decisions based on one year’s experience alone.
  • With increasing herbicide resistance in both grass and broadleaf weeds, canola will play an integral role in the future. Canola variety decisions should always be based on the weed spectrum and long-term integrated weed management strategies.
  • In a year with frosts, insects and very dry finish, earlier varieties yielded well, most notably those that were Roundup Ready (IH30 and GT41); Clearfield and Triazine Tolerant varieties performed comparatively poorly.

BACKGROUND

A perfect break to the 2014 season (30-40mm in early April) was ideal for canola. For many growers, based on previous years’ experiences, the decision to sow canola was an easy one. Unfortunately, for many, the early break was the only significant rainfall the crop received for the entire season. Challenges also came in the form of insects, disease and frosts. Below average yields, poor grain prices and high production costs led to low profit margins from canola. Warm moist conditions in April/May promoted rapid crop growth in all early sown crops. These spring-like conditions (especially in the Mallee) brought on the arrival of the green peach aphid (GPA), which transmitted Beet Western Yellows Virus (BWYV) to canola crops in most of southern Australia’s grain growing regions. GPA are a major host of (BWYV). Although damage from the virus itself is not yet properly understood, the feeding pressure of the GPA is thought to have caused sufficient damage in itself. Crops in South Australia were the first to fall victim, with significant yield loss for growers there. BWYV was also confirmed in a number of Victorian crops, although with infection occurring later in the season, yield losses were less pronounced.

Later in the season, the Mallee experienced an outbreak of diamond back moth (DBM), which also has a high level of resistance to commonly applied insecticides. These unforeseen insect and disease infestations, combined with the frosts, lack of rain and low grain prices, significantly affected profitability and influenced growers’ attitudes to canola.

Despite this, the benefits of canola in a rotation still exist; growers are encouraged to choose a canola group that will contribute to the best long term weed control strategy for their system. Once the group has been decided upon, the next task is to select a specific variety most likely to meet yield goals.

Responding to member inquiry, each year BCG continues to examine and compare canola varieties. This work is funded by BCG members through their membership.

AIM

To determine the performance of commercial canola varieties in the Wimmera and Mallee.

TRIAL DETAILS

Table 2. Trial details and inputs for Wimmera and Mallee sites. 

BrowneCraig_1_2014

Weeds were managed according to the herbicide group directives. Insects were controlled to best management practice using the most effective insecticides.

METHOD

Trials were sown at Horsham, Beulah and Kooloonong, each with four replicates. At Horsham, varieties were compared using a split plot design, while at Kooloonong a randomised trial design was used. Varieties at the Horsham site were grouped by their maturity, as the site had multiple harvest dates, and then randomised within (sub-plots). The canola varieties at Beulah main site did not make it to harvest due to lack of rainfall.

To ensure all varieties were ripe at the time of harvest, the plots were desiccated. The timing was based on the standard variety within the trial. At Horsham, the design of the trial allowed for a more timely harvest to occur based on maturity group.

RESULTS AND INTERPRETATION

Wimmera

With below average, (Decile 1) conditions experienced by most Wimmera growers, 2014 turned out to be an unrewarding season for canola at BCG’s Horsham research site. The site was sown into vetch stubble with 48kg/ha of starting soil nitrogen; with an opening break to the season in April, the canola emerged very well across all varieties. From April to July the site received 144mm of rainfall which ensured there was adequate moisture supply during crop establishment to early budding. However, the very low summer rainfall (43mm from November 2013 to February 2014) and the harsh, dry finish to the season, resulted in below average yields. Frost events across the region from July-September caused concern for many growers, though the trial site was not notably affected.

In comparison to the Mallee, BWYV observed around the Wimmera was minor. Slight purpling, yellowing and mottling of the leaves was evident in some varieties. However, while this may have been a symptom of disease, it could also have been a consequence of nutritional deficiencies or simply a ‘trait’ of the variety. Testing for the virus was not undertaken, but precautionary sprays were carried out with the premium product Transform®.

The shorter season varieties (early and early-mid maturing) consistently were amongst the highest yielding (Figure 1). Clearfield (CLF) varieties Hyola® 474CL and 43C80 yielded significantly better than all other CLF varieties. In the conventional varieties, NuSeed Diamond performed well, out-yielding the ever reliable AV Garnet. Despite its maturity group suggesting it is similar to other early varieties, it was the first variety to flower in all BCG trials. The other early varieties IH30, GT-41 and GT-50 were the next to flower, a week after NuSeed Diamond.

Within the RoundUp Ready varieties, IH30RR, GT50 and GT41 were the highest yielding. The triazine tolerant (TT) group had a much smaller spread between varieties, with little separating the top yielding ATR Stingray, ATR Bonito, ATR Gem, Hyola® 450TT and Hyola® 559TT.

Most varieties achieved the minimum test weight specification for canola (>62 kg/hL). The varieties that fell under the minimum requirement for test weight were Victory® V5002RR, Victory® V5004RR, Hyola® 577CL, Hyola® 575CL, and Hyola® 474CL. The oil content of varieties ranged from 39-42% (average 41%) and there was a trend towards higher yielding varieties having higher oil content.

BrowneCraig_2_2014

Figure 1. Yield (t/ha) of all canola varieties at Horsham site (P<0.001, LSD 0.1t/ha, CV 8.8%).

Mallee

The Kooloonong site had a full soil water profile prior to sowing from earlier summer rainfall events. Parts of the Mallee also received this rainfall, but it is important to note that these were isolated and certainly were not repeated in the southern Mallee and parts of the central Mallee in 2014. The full profile of moisture enabled the trial to cope more effectively with the infrequent and variable rainfall events of the remainder of the season.

The finish to the season was similar to the Horsham experience: the site was dry and encountered severe frost events throughout July-September. The most severe frost occurred on September 3, when temperatures fell to minus 3.6°C. Many crops in the area suffered damage (stem frost) as a consequence. However, due to the location of the trial (on a sand dune), the plots were not severely affected. The presence of GPA and DBM in the trial raised concerns. In both instances, the premium products (Transform® and Affirm®) were applied to ensure adequate control. Yields are assumed to have not been affected. Some varieties displayed purpling symptoms typical of BWYV, sulphur deficiency and environmental stress. It was later revealed that some canola varieties have purpling traits and this need not be a reflection of greater susceptibility to BWYV or sulphur inefficiency. DBM numbers exceeded the commercial threshold of 100 larvae for every 10 sweeps, justifying the decision to spray.

During the season, variability in crop height throughout the plots became evident. The variation was not apparent at plant establishment, and was possibly caused by compaction, BWYV or root disease. Assessments of plots were made prior to harvest to account for these differences and badly affected plots were removed from analysis.

The early and early-mid maturing varieties performed better in the dry, shorter finish to the season. In the CLF varieties, 44Y84 achieved the highest yield, but was not significantly different from 44Y87 (Figure 2). Throughout the year, 44Y84 looked notably better and had greater vigour. Commercially, growers reported significant yield differences between these two varieties, with 44Y84 being superior. In the case of this trial, both varieties performed poorly in comparison with varieties from other herbicide groups. This was possibly due to their tendency to produce greater biomass, thereby using valuable water reserves before grain filling. Alternatively, the late frost may have affected those varieties more.

As was the case in Horsham, RoundUp Ready varieties yielded very well: GT-41, Hyola® 404RR and IH30 all yielding the highest. ATR Stingray stood out from its TT counterparts, but there was no significant difference in yield. The new Hyola® 525RT variety which offers dual-herbicide tolerance as well as excellent standability and shatter tolerance, yielded no differently from the TT varieties.

All varieties achieved the minimum test weight specification for canola (>62 kg/hL) besides Victory® V5002RR. The oil content of varieties ranged from 39 to 45% (average 42%). Higher oil content was most commonly found in the higher yielding varieties.

BrowneCraig_3_2014
Figure 2. Yield (t/ha) for the different canola varieties at Kooloonong (P<0.001, LSD 0.3t/ha, 20%).

COMMERCIAL PRACTICE

The role canola plays within rotations is sometimes misrepresented in variety trials such as these.

Unfortunately, this year, the season did not suit canola and poor economic returns were exacerbated by the higher input cost and low grain prices in 2014.

Nevertheless, canola delivers invaluable benefits to the cropping system, thanks to its capacity to help reduce weed numbers and break down stubble and root-borne disease cycles, delivering greater profitability and production to subsequent crops.

Herbicide plant backs (particularly CLF, Atrazine and Lontrel) need to be considered in 2015, especially if there has been a history of CLF herbicides over the past three seasons and growing RR or TT canola is being considered. CLF has particularly long plant-back implications, especially following dry years such as 2014. The effect of herbicide residues can significantly reduce yields and aggravate disease effects on the following crop.

This year the value of the hybrids really came into focus, particularly within the CLF and RR groups. While there are still consistently good yielding OP varieties within the Conventional (AV Garnet and AV Zircon), CLF (43C80 – Horsham only) and the TT (Crusher, ATR Stingray and ATR Bonito) groups, over the last couple of years, the hybrids have performed consistently well. Growers should be aware of the significant up-front cost if they decide to grow a hybrid, which makes it difficult to commit to growing large areas of canola, particularly when there is some doubt about the season. OPs will still have a role to play, particularly in the Mallee, where rotations need to be flexible according to the season to reduce production risk.

Articles in previous BCG Season Research Results publications have discussed the important role canola plays in the long-term integrated weed management strategy. It is the only crop in which growers have the choice of either conventional or four other herbicide tolerance options allowing better management for both grass and broadleaf weeds. The decision about which canola variety to grow should be based on the best ‘agronomic’ practice, tailoring individual paddocks to weed spectrum and crop sequence.

In 2014, conventional varieties proved they still have a place in the rotation with their competitive yields in the Wimmera being as good as the RoundUp Ready® varieties. With limited weed control options in conventional varieties, paddock selection is vital. CLF and TT varieties yielded similarly in the Mallee and Wimmera. This confirms that it is best to pick the herbicide tolerance group most suited to your system, and then to select the highest yielding variety in that group.

While the new variety Hyola®525RT® failed to yield exceptionally well compared with other varieties, its weed control package will excite many growers. This is because one of the biggest concerns with growing RoundUp Ready is the lack of residual control, subsequent late germinations, and the risk of weeds becoming resistant through its overuse. This technology will also allow growers to take the reliance off Group A herbicides such as Select® and Verdict® which are vital for grass control in other crops such as pulses. As this technology develops and higher yielding varieties are found, it’s unlikely that varieties from those other groups (TT, CL and RR) will be widely grown in the future.

When growing canola, there can be issues at harvest if emergence is patchy/staggered. New technology such as Bayer’s IH51 variety, with increased pod shatter resistance due to its ‘PodGuardTM’ technology, will be well received by growers (particularly those who direct head). Similar to the Hyola® 525RT® technology, both varieties will need to improve in yield if their adoption is to be widespread. However, these are the first of their kind in the market; no doubt we will soon see newer, better yielding varieties emerge.

ON-FARM PROFITABILITY

Although 2014 did not break any profitability records for canola, it is important to understand why canola failed this year. If growers were quick to act, using the recommended insecticides (Transform and Affirm) would have added an extra $30-35/ha to the cost of growing. Due to the complexities of the season, it will be difficult to quantify precisely the return on investment for controlling these pests.

Canola, for most growers, has been very profitable in recent years. For those with detailed records, it is a good exercise to compare gross margins over the various seasons to identify the key differences in 2014. While we know the higher cost and lower price played a role, yields were also lower in some areas. For those regions with stored soil moisture, yields should have been close to average, while those without soil moisture would have had yields that were well below average. Finding the right place for canola, and identifying the drivers behind its inclusion in the rotation, are the keys to its success. Even so, it needs to be acknowledged that there will be times when canola just doesn’t perform.

A gross margin based on the previous five years of BCG Mallee trials shows that canola (whilst yielding only a negative return in 2014) has produced a valuable income for growers over that time. Using the estimated cost of growing canola in 2014 and applying it over each of the five years shows an average profit of $444/ha (Table 3). Generally, costs aren’t going to change as much as yield and price. However, should we have to continue to spray for insects, the average would be $390/ha (adding an extra $35/ha costs for 2014). The average (Mallee) canola yield over the last five years was 1.57t/ha. This could be compared with the profitability of other crops to determine from longer term data if it has a fit in the system.

Table 3. Average gross margin ($/ha) for canola grown in the Mallee over the last five years (based on average input costs of $354/ha).

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Arrows denote whether the value was above average or below. For values not represented by an arrow, then the value is close to average.

It’s very easy to be very sceptical about growing canola based on last season. Growers need to compare longer term profitability of canola for their farming systems before they discard it in the rotation.

REFERENCES

GRDC Victorian Winter Crop Summary 2014

ACKNOWLEDGEMENTS

This trial was funded by BCG members through their membership. The report was a collaborative BCG team effort with contributions from Linda Walters, Cameron Taylor and Alli Elliott.

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