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Paddock Practices – Tips for retaining seed this harvest

Guest Author, November 2, 2016

Seed for planting 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 for sowing next year.

Best results from retained seed will 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 in storage for insect pests
    Prompt fumigation when pests are detected in storage
    Early testing that indicates good germination and vigour and low levels of seed-borne disease (at least two months before planting).

Weather damage and delayed harvest

Parts of the Western Australian grainbelt are likely to experience harvest delays this season due to moist and cool early spring conditions.

This can expose crops to potential seed quality issues and grain yield losses.

Any rain/weather damage at harvest can lead to development of mould and fungi, darkening of grain and stimulation of germination (sprouting) in cereal and pulse crops.

Symptoms of deterioration in seed quality resulting from these issues range from a loose and wrinkled seed coat to staining and full germination.

If it is necessary to harvest seed for planting from weather affected crops, it is recommended to retain grain that has moisture levels about 1 per cent below receival standards if aeration drying is not an option.

If aeration drying is available, GRDC Stored Grain initiative and Department of Agriculture and Food WA (DAFWA) 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.

DAFWA advises that retained seed from open-pollinated varieties should be tested by a commercial laboratory for presence of approved genetically modified (GM) varieties before the next sowing. This increases confidence in meeting the CAN (non-GM canola) segregation.

It is also advises that, when harvesting canola seed for next year’s crop, it is important to have a 400 metre buffer between seed crops and crops of glyphosate-tolerant varieties – including on neighboring properties.

Hybrid canola seed should not be retained for subsequent planting, as the crop will not be true to the original first generation (F1) seed.

The GRDC Fact Sheet ‘Retaining seed’ contains more information about weather damaged seed and storage and can be found via this link.

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 it outlines that 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 and experience shows that, even after grading, frosted grain can have 20-50 per cent lower establishment 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 next year, using this seed in optimum seed bed conditions and potentially at a higher seeding rate to compensate for any potential lower germination and vigour.

For more information, see the Tips and Tactics ‘Managing frost risk’ via this link.

There is also a useful AWB ‘Wheat quality fact sheet’ for dealing with frosted grain found via this link.

Late season herbicide use and retained seed

Strategic application of a registered herbicide close to the final maturity of a crop before harvest can be used for desiccation (with or without windrowing/swathing) or crop-topping in a lupin/pulse, canola or cereal phase.

It is generally recommended by researchers from DAFWA and the industry-led WeedSmart initiative not to use seed from desiccated or crop-topped paddocks for planting the following year, as there is a risk of lower vigour.

As with all herbicide applications, the GRDC advises strict adherence to product label registrations, rates and withholding periods for harvest and livestock grazing when undertaking desiccation and/or crop-topping in any crop.

GRDC’s Fact Sheet ‘Pre-harvest herbicide use’ contains a comprehensive list of herbicide options and management advice for these tactics and can be found via this link.

Choosing paddocks for retaining seed

When choosing crop areas to harvest for retained seed, it is advised to firstly select varieties that meet rotation requirements.

This will be based on sequence planning and knowledge of constraints that include: the maturity of varieties required to cover a range of sowing windows; paddock status; and diseases, such as crown rot, nematodes and yellow spot.

It is advisable to harvest planting seed from paddocks where there is a high degree of confidence of varietal purity.

To ensure no unwanted surprises at sowing, it can also be valuable to choose paddocks that have:

  • Low weed and disease burdens
    No nutritional constraints
    Relatively even areas of crop
    Low levels of ‘off-types’ that are taller or shorter than the surrounding crop
    Grain with low moisture and good protein levels (cereals).

 

Preparing on-farm storage for retained seed

 

philip-burril-grdc

GRDC’s Stored Grain Extension Project development agronomist Philip Burrill says retained seed is a valuable asset and needs good management at harvest and during storage in summer. PHOTO: GRDC

In the lead-up to harvest, it is advisable to prepare on-farm storage facilities for retained seed by ensuring good hygiene and checking equipment.

GRDC’s Stored Grain Extension Project development agronomist Philip Burrill says during storage over summer, it is important to conduct monthly checks of seed to ensure cool temperatures are being achieved from silo aeration systems and that there is effective insect pest control.

He says this will help to achieve good germination and vigour of retained seed the following year.

Ideal on-farm storage temperature for cereal and canola seed during the summer months is 20-23°C and, for lupins, seed is best maintained at less than 20°C. This can be achieved with effective aeration cooling.

Philip says it is ideal to use cone-based silos that can be both aerated and sealed. This is an advantage if stored grain pests are detected, as the silo can then be sealed to a gas-tight standard (meeting Australian Standard AS2628) to allow an effective fumigation.

Philip also recommends:

  • Cleaning out any old grain residues from empty silos/storage areas
    Applying a diatomaceous earth (DE) treatment (such as Dryacide®) to internal surfaces
    Cleaning out grain from harvesting equipment, including augers and headers
    Inspecting insect probe traps, identifying any pests and recording any treatments
    Checking grain quality testing equipment (such as moisture metres, protein testing, test weight, screening sieve, weighbridge and recording spreadsheets)
    Checking supplies of registered grain protectants and nozzles/calibration of spray equipment.

Practical tips and advice about storing grain on-farm will be outlined at pre and post-harvest grain storage workshops to be held across the WA grainbelt by the GRDC Stored Grain initiative team this year.

Topics include pressure-testing silos in preparation for fumigation, insect identification, planning for optimal storage and effective fumigation practices.

Workshops in WA can be convened on request by contacting Ben White on:1800 933 845, or via his email.

The GRDC Stored Grain information hub has a useful video outlining how to best store planting seed. It can be found via this link and there is a checklist for on-farm seed storage – just type ‘checklist’ into the search box found here.

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 via this link.

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.

Below is a summary of key points for testing retained seed and links to industry resources and information.

Germination and vigour tests

Harvest machinery (predominantly augers), weather and chemicals can damage seed and potentially reduce its viability and germination the following year.

Vigour and germination tests provide an indication of the proportion of seeds that will produce normal seedlings and this helps to determine seeding rates. Typically, these tests require a one kilogram sample for every 25 tonnes of seed and are carried out over a 10-day period. Seed samples will be classified into normal seedlings, abnormal seedlings, dead seed, fresh seed and hard seed.

DAFWA says it is best to focus on results for normal seedlings (which are fully viable) and abnormal seedlings (which show significant defects that will prevent the plant from growing into a typical productive plant – even under ideal conditions).

Disease tests

Testing seed from a range of crops through an accredited laboratory before sowing will identify potential soil-borne disease problems and help with risk management planning.

Tests typically require 1kg of seed and results show the amount of disease inoculum in terms of: proportion of infected seeds; degree or severity of infection (inoculum per individual seed); and viability of the inoculum (effectiveness of the pathogen in seed).

Low levels of seed-borne inoculum can lead to considerable disease incidence, so 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 lupins, as disease may sometimes infect the seed testa without infecting the embryo or seedling.

Seed testing services

Seed testing services for WA grain growers are available at:
DAFWA’s Diagnostic Laboratory Services (DDLS)-Plant Pathology services
(formerly AGWEST Plant Laboratories) via this link
Primary Industries and Regions SA (PIRSA)/South Australian Research
and Development Institute (SARDI) Seed and Plant Pathology testing
Service via this link
Plant Science Consulting via this link
FeedTest via this link
Tasmanian Government TASAG ELISA Testing Services via this link
SGS Australia via this link
Herbicide resistance testing

Harvest is also a good time to test weed seed samples for herbicide resistance to assess which actives are still effective on a property. This facilitates effective and economic weed control for the next season.

For annual ryegrass (Lolium rigidum), it is recommended to collect at least 25 seed heads from 25 plants (one seed head per plant) and provide the location of the sample to the testing laboratory.

For wild oats (Avena fatua) and wild radish (Raphanus raphanistrum), it is advised to collect a full A4 envelope of seed heads or pods.

  • Testing houses for herbicide resistance are:
    Charles Sturt University, School of Agricultural and Wine Sciences found
    via this link
  • Plant Science Consulting found via this link
    Tips for testing for herbicide resistance are outlined in the GRDC Fact Sheet ‘Take the test for herbicide resistance’ at found via this link.

A YouTube video focusing on herbicide resistance testing is available via this link.

Cleaning seed

seed-cleaning-grdc

Seed cleaning surveys have been conducted using GRDC funding to assess the value of this tactic at harvest. PHOTO: AHRI

Australian Herbicide Resistance Initiative (AHRI) researcher Mechelle Owen has conducted two seed cleaning surveys using GRDC funding. She recorded significant improvements in 2015 when retained seed was professionally cleaned to remove weed seeds compared to 2008 seed cleaning results.

From more than 80 grain samples collected in 2015 from 29 growers in Dalwallinu and Corrigin who undertook seed cleaning using contract services, 41 per cent were completely free of weed seeds. This was well up from 27 per cent of samples being weed-free from the same growers who either undertook their own seed cleaning or used contractors in the first survey in 2008.

AHRI’s Peter Newman says the seed cleaning contractors in 2015 were 10 times better than the growers/contractors at cleaning seed in 2008 and 95 per cent of growers who had paddocks sampled that year were now using professional cleaning services.

He says growers surveyed in 2015 had also typically changed the way they sourced crop seed by selecting paddocks with low weed seedbanks and weed burdens and adopting hygiene practices, such as cleaning on-farm seed storage sheds and silos.

Source: GRDC. Full results from this project are available via this link.

 

 

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