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SARDI Diagnostic Services

Seed test to fight disease in your paddock

Yield loss due to pulse and oilseed diseases can be devastating. As many of these diseases are seed borne, taking the simple precaution of testing seed before sowing is a vital link in the chain of integrated disease management.
Seed testing should be carried out soon after harvest to identify the best seed for cleaning and seed treating.

As a risk management tool, laboratory seed testing offers seed buyers and sellers three key benefits:
• Establishes the true disease risk associated with a seed-lot
• Provides solid data for acceptance or rejection of a seed-lot
• Highlights the need for specific disease management
All of these benefits can result in more profitable crop production

PREVENTION IS BETTER THAN CURE

Options for controlling diseases after sowing are limited.
Implementing pre-sowing prevention minimises the risk of a disease outbreak.

PREVENTION
Presowing
1. Identify threats
2. Select resistant varieties
3. Test and treat seed
4. Select paddocks and use crop rotations
5. Adjust sowing date, seed depth and weed control

CURE
Post sowing
1. Use fungicides - provide partial protection and from fungal diseases only
2. Harvest early

Seed testing provides a quality benchmark on the disease status of a seed-lot which allows seed to be traded with confidence.

5 Key Times to Test Seed

1. Buying in seed

Check the disease level of seed before purchase or bringing it into an uncontaminated area where the crop has not been grown previously.
Seed is the most likely source of a new disease pathogen. Once established, other hosts, volunteers or residues may harbour the pathogen helping the disease to flourish.

2. Highly susceptible hosts

Seed testing allows growers to minimise the risk of disease from aggressive pathogens in susceptible varieties . Even when initial
inoculum levels are low, diseases such as bacterial blight in peas, anthracnose in lupins and Ascochyta blight in chickpeas can decimate
production under the right seasonal conditions.

3. High disease environments

Identifying seed with low inoculum level minimises the risk of a disease outbreak - even if the weather conditions are favourable. Some
environments encourage regular outbreaks of certain diseases. We cannot accurately predict growing season conditions, however, seed tests
provide a useful buffer against disease outbreaks in favourable seasons.

4. Saved seed following disease outbreaks

When saving your own seed, then testing is particularly important following disease outbreaks in the previous season. Early testing is recommended in case you need to source alternative seed.

5. Interstate and international quarantine

Seed for export to interstate or international markets may require a disease certification. Specific details are available from State Departments of Agriculture and Australian Quarantine and Inspection Service.

Seed tests from SARDI

Frequently asked questions about seed testing

SARDI Diagnostic services provide accredited laboratory seed tests for a range of crops and diseases. These tests all meet international standards and a range of testing methods, including DNA based tests, are used. The use of a range of testing methods ensures that results are appropriate to the field situation and cost effective.

Crops and the seed-borne diseases which can be tested by SARDI Diagnostic Services

Disease	Crops
Ascochyta rabiei	Chickpeas
Ascochyta/Botrytis	Faba beas, lentils, peas
Bacterial Wilt	Lucerne
Blackleg	Canola
Stem nematode	Various

The sensitivity of each testing method is determined by the number of seeds tested.
The DNA based tests allow a greater number of seeds to be tested quickly
and accurately. Generally 400 - 1000 seeds are tested from a sample to achieve the correct sensitivity.
The number of seeds tested and method used is based on achieving a level of sensitivity relevant to the field situation at minimum cost to the consumer.

More information on seed tests available from SARDI please telephone 08 8303 9358.

Seed tests and sampling

It is essential that the seed sample is collected correctly as this determines how well the test results relates back to the whole seed-lot . Seed samples can be taken from bulk or bags but must represent the total seed lot.
Step 1:
From the seed-lot take several sub samples.
These should be taken from different horizontal and vertical positions in the lot at random. The sub samples should weigh approximately four times the weight of the final required sample size.
Step 2:
Combine the sub samples thoroughly and spread on a smooth, clean surface.
Step 3:
Mound the seed and then divide into two equal portions. Continue to halve each portion until eight equal portions are formed. These should be arranged in two parallel rows of four samples per row.
Step 4:
Retain the first and third sample in one row and the second and fourth sample in the other row.
Discard the remaining four samples.
Step 5:
Combine the four remaining samples.
Step 6:
Repeat steps 3 and 4 until the required sample weight is obtained

Crop	Sample size	Seed-lot size (tonnes)
Chickpea	1kg	20
Pea	1kg	25
Faba beans	1kg	25
Lucerne	100g	10
Canola	200g	10
Lentils	1kg	10