Favorable spring conditions in many southern areas may necessitate disease considerations, such as planning to manage loose smut in barley in WA. Wet conditions in some parts may also require storage and handling contingencies for weather damaged crops/grain.
Seed retained for sowing is a highly valuable asset and the way it is treated at harvest and in on-farm storage during summer is key to ensuring optimum quality and germination potential at sowing next year.
GRDC has a comprehensive Fact Sheet with tips and tools for ‘Retaining Seed’
Best results from retained seed typically come from:
- pure variety crops;
- paddocks that have not suffered weather damage;
- minimal weed seed contamination
- storage at cool temperatures, using aeration, and at low grain moisture content;
- monthly monitoring for insect pests;
- prompt fumigation where pests are detected;
- early testing that indicates good germination and low levels of seed-borne disease (conducted at least two months before planting).
WEATHER DAMAGE AND DELAYED HARVEST
Rain or weather damage at harvest can lead to development of mould and fungi, darkening of grain and/or stimulation of germination (sprouting) in cereal and pulse crops.
If it is necessary to harvest seed for planting from weather affected crops, it is recommended to retain grain that has moisture levels about one per cent below receival standards if aeration drying is not an option.
If aeration drying is available, GRDC Stored Grain initiative and Department of Primary Industries and Regional Development (DPIRD) researchers advise this can be effective to maintain the quality of retained seed. This is especially important for cereals and pulses and when used in conjunction with:
- slower harvest ground speeds to allow harder threshing;
- stripper fronts on harvesters if conditions are consistently damp;
- testing and grading of seed for germination, vigour and seed-borne diseases.
Canola tends to withstand extended wet harvest periods better than other crops in many parts of WA.
Effective separation of varieties is the biggest issue for retaining canola seed on-farm for subsequent planting.
For lupin crops, DPIRD research officer Martin Harries said research carried out in WA in 2016, as part of the GRDC investment in ‘Tactical break crop agronomy’, has shown pre-harvest rain can significantly reduce seed quality and viability.
His DPIRD field and laboratory trials at Geraldton subjected three lupin varieties – Mandelup , PBA Jurien and Gungurru – to different wetting and drying regimes using irrigation treatments.
This simulated the impact of pre-harvest rain on mature plants with four irrigation treatments or harvest dates tested – October 31 (with no irrigation), November 14 (one irrigation), November 28 (two irrigations) and December 15 (three irrigations). Seed from these plants was then germination tested to measure the effect of wetting and drying on seed quality.
Martin said for all varieties, germination rates were lower when the mature plant was irrigated prior to harvest.
He said key findings included that germination rates fell:
- by 4% on average (in a range of 4–10%) with one cycle of pod wetting and drying;
- by a further 15% (in a range of 10–20%) with two cycles of pod wetting and drying;
- by a further 26% with three cycles of pod wetting and drying;
- to a total 45% reduction (in a range of 35-45%) with three irrigations.
Further results from Martin’s project are available by contacting him on: 08 9956 8553, firstname.lastname@example.org
RETAINING SEED FROM FROSTED CROPS
The GRDC’s Tips and Tactics for ‘Managing Frost Risk’ advises that seed retained from crops that were frosted at flowering tends to remain plump and in good condition (especially for cereals).
But when frost occurs during grain fill, there can be adverse effects on seed quality that can lead to poorer germination and establishment of these damaged grains the following year.
Research through the GRDC’s National Frost Initiative (NFI) and WA grower experience indicates that, even after grading, frosted grain can have 20–50% lower establishment rates than unfrosted grain when subsequently used for seed.
The GRDC Tips and Tactics resource recommends that if crops are frost affected at grain fill, it may be worthwhile to retain a higher amount of seed for planting.
Then, at sowing, using this seed in optimum seed bed conditions and potentially at a higher seeding rate to compensate for any potential lower germination and vigour.
Germination percentage can be tested at harvest, during storage and before seeding and low germination seed should not be used.
For more information, see the GRDC Tips and Tactics ‘Managing frost risk’.
Other useful frost risk management resources include:
- DPIRD-GRDC’s publication Frost – Frequently Asked Questions
- GRDC’s suite of GrowNotes™ publications for individual crop types
- GRDC frost storify hub
DISEASE CONSIDERATIONS FOR RETAINED SEED
DPIRD researcher Andrea Hills said some WA barley growers, particularly in medium to high rainfall areas, experienced significant levels of barley loose smut (Ustilago nuda) last year and favourable spring conditions have meant incidence is likely to be high again in 2018.
She said for affected growers, it could be worthwhile testing retained barley seed for smut after harvest – especially in the more susceptible varieties Hindmarsh and La Trobe – and (if necessary) using a ‘premium’ type seed dressing to reduce smut levels next season.
Seed testing is carried out in WA by DPIRD’s Diagnostic Laboratory Services (DDLS). For more information about sampling protocol contact: 08 9368 3351, DDLS@agric.wa.gov.au
Andrea, who conducts DPIRD research as part of the GRDC investment in crop diseases in WA (through project DAW00229) said to keep smut under control, growers are advised to use seed dressings every year and it is critical to apply it carefully – as every seed needs a dose.
“This is because seed dressings can only control smut already present in the grain and cannot prevent seed becoming infected,” she said.
Andrea has also undertaken seed dressing product efficacy trials that have shown all registered seed dressings investigated reduced smut levels.
DPIRD plant pathologist Geoff Thomas said there are seed treatments registered that can help to manage stem, leaf and stripe rusts in cereal crops for this year.
He said for barley, fluxapyroxad (e.g. Systiva®) is registered to provide protection from foliar diseases, including leaf rust, until flag leaf emergence (growth state BBCH37).
For leaf and/or stripe rust in WA wheat crops, seed treatments registered to provide disease protection or suppression (particularly in seedlings), include some products with the active ingredients fluquinconazole, flutriafol, triadimenol or triticonazole. It is advised to always check the label for specific registration of individual products.
More information about these and other registered seed treatments for a range of crop diseases for WA can be found on the DPIRD website HERE or the Australian Pesticides and Veterinary Medicines Authority HERE.
Information about developing a rust management strategy can be found on the Rust Bust website.
Other diseases and variety choice for 2018
Geoff said planning variety selection for 2018 is a key tactic for managing a range of crop diseases and other agronomic traits.
He said understanding each variety’s disease resistance profile included looking at the risks of various diseases in the context of potential yields.
“In years or environments with significant disease risk, growing susceptible varieties contributes to ongoing disease pressure, exposes crops to risk of significant yield loss and potentially requires significant and expensive disease management input,” he said.
“Choosing the most resistant variety available will reduce disease management requirements.
“But if this variety is lower yielding, this may not always be the most profitable approach.”
Geoff said using a variety with better disease tolerance (eg. moderately susceptible – MS – or moderately resistant/moderately susceptible – MRMS), integrated with disease management that is appropriate to the disease ranking, may be more profitable and sustainable
He said DPIRD had released 2018 Crop Variety Sowing Guides for wheat, barley and canola that outline latest disease resistance and susceptibility information for varieties commonly grown in the western region as part of the GRDC investment in Tactical agronomy. These can be found HERE.
In these guides, DPIRD has included a table of minimum disease ratings for five major wheat diseases in WA to help growers know what to look for when viewing a new variety disease resistance package.
There is more information about the phenological traits that affect wheat variety management, including explanations about frost management, the importance of coleoptile length, seed depth and the effect that temperature and day length have on maturity (and therefore sowing time).
New information about research into pre-harvest sprouting and falling number rating is also included.
ON-FARM STORAGE CONSIDERATIONS
GRDC’s Stored Grain Extension Project development agronomist Philip Burrill said during storage of retained seed during summer, it was advised to conduct monthly checks to ensure cool grain temperatures are being achieved from silo aeration systems and that there is effective insect pest control.
He said taking readings with a grain temperature probe, along with sieving grain from the silo base and checking insect probe traps left in grain at the top of the silo, were simple methods to monitor seed in storage.
“This will help to retain germination and vigour of the seed,” he said.
“Optimal seed storage temperatures to aim for are 20°C or less.
“While this can be difficult, it can be achieved with a well-designed and managed aeration cooling system.”
Philip said an aeration controller would automate the timing of aeration fans, providing the best chance of achieving these temperatures.
He said it was ideal to use cone-based silos that could be both aerated and then sealed if a fumigation is required for insect pest control.
“To ensure an effective fumigation, silos need to be sealed to a gas-tight standard,” he said.
“When buying new silos, check they will meet the Australian Standard AS2628. “When selecting silos for seed storage, zincalaume and white painted silos are highly reflective and will keep grain cooler than older, dark-coloured galvanised silos.”
The GRDC Stored Grain information hub has a useful video outlining how to best store planting seed. It can be found HERE
and there is a checklist for on-farm seed storage – just type ‘checklist’ into the search box.
The GRDC Grains Industry Guide ‘Aerating stored grain – cooling or drying for quality control’ also has a checklist of best practices for storing and aerating grain and is available at: storedgrain.com.au
More information about effective grain storage is available by contacting Ben White in WA on: 1800 933 845, or email@example.com
TESTING RETAINED SEED
Retained seed can be tested for vigour, germination, purity/weed seeds and disease pathogens.
It is advisable to undertake testing at least two months before sowing.
Vigour and germination tests provide an indication of the proportion of seeds that will produce normal seedlings and this helps to determine seeding rates.
For soil-borne diseases, the most sensitive test should be used to determine the level of seed infection.
It is recommended diagnostic tests for viruses are conducted on germinated seed (seedlings), especially in lupin, as disease may sometimes infect the seed testa without infecting the embryo or seedling.
Seed testing services for grain growers are available at:
- DPIRD’s DDLS-Plant Pathology Services
- Primary Industries and Regions SA (PIRSA)/South Australian Research and Development Institute (SARDI) Seed and Plant Pathology testing Service
- Plant Science Consulting
- Tasmanian Government TASAG ELISA Testing Services
- SGS Australia
GRDC Project Codes:
DAW00227, DAW00229, DAW00224, PRB00001, UA00149, ARN0001, ICN00009, PAD00001
Geoff Thomas, DPIRD
08 9368 3262
Georgia Trainor, DPIRD
08 9690 2083
Philip Burrill, GRDC Stored
Grain and DAFF Qld
0427 696 500