Wheat breeding companies, working closely with Sydney University, lead agency in the National Australian Cereal Rust Control Program, are providing growers with an increasing range of varieties that combine high yield and quality with greatly improved resistance against the three rust diseases.
Many of today’s farmers have only rarely or not at all seen the devastation stem, leaf or stripe rust can individually or collectively do to wheat crops. That is because, despite the periodic occurrence of new lethal mutant rust strains, plant breeders have largely been able to keep ahead of these diseases with the release of resistant varieties.
Recent new releases add significantly to the range of wheat varieties available that combine excellent rust resistance, high yield (relative to competitive varieties), high quality as well as other attributes like tolerance to other important issues.
Reliant is one such new variety. It is consistently yielding high in mid-season maturity trials. Quality is APH (Australian Prime Hard for northern NSW/Qld and AH for southern NSW.
Reliant is resistant to stem rust (R) and leaf rust (R/MR) and has adult plant resistance to stripe rust (rated MR/MS). Varieties with a stripe rust MR/MS rating may require some fungicide support in high-pressure situations, but the rating is improved on several currently available popular varieties.
Reliant has yielded high yield in independent GRDC-funded NVT (National Variety Trials) testing. In main season sowings it has yielding highest among the APH varieties in northern NSW and Qld in 2014 and 2015. It has shown broad adaptation. It is particularly well adapted in low-to-medium yielding situations. Reliant has good grain size and test weight with lower screenings than many other popular competitors.
Also increasingly coming through in many new varieties is Reliant’s improved root lesion nematode tolerance (P. thornei). It also has useful yellow leaf spot tolerance compared with many varieties (MS/S), and compared to many varieties also useful crown rot tolerance (MS/S preliminary).
Coolah is a second improved rust-resistant high yielding, high quality new release. It is similar in many respects to Gregory, suited to the earlier sowing window of late April to mid May for many areas. Its maturity is driven by moderate photoperiod and vernalisation requirements and matches Gregory in most NSW environments.
In early sown NVT trials Coolah has shown a three to eight per cent yield advantage over Gregory. It has performed well across many regions.
Resistance against the three rusts is excellent (stem R/MR, stripe R/MR, leaf MR). Also important for many areas is good tolerance to root lesion nematodes (P. thornei) and useful tolerance to yellow leaf spot (MS/S). Coolah also has tolerance to acid soils performing well across acidic, neutral and alkaline soils.
Coolah has large and consistent grain size across a range of environments, resulting in low screenings loss and high test weight. Coolah is also slightly shorter in stature than Gregory, resulting in a lower likelihood of lodging. As soon as the go-ahead is given, details about a new high yielding, rust resistant, dual purpose winter wheat with APH quality will be featured in this column.
Choosing wheat varieties is a complex issue generally requiring a range of varieties to suit different sowing times, different disease and pest risks (for example nematodes), different qualities, and different soil types. The release of Reliant and Coolah add to the improving options available.
Next week. Effective legume nodulation critical for top pastures field day noted.
- Bob Freebairn is an agricultural consultant based at Coonabarabran. Email robert.freebairn@bigpond.com or contact (0428) 752 149.
