GRAIN growers across New South Wales and Queensland can access a more comprehensive assessment of their soil and stubble-borne disease risks this year following an expansion of the Predicta B testing service.
Predicta B represents an important research investment for the Grains Research and Development Corporation (GRDC) and is a DNA-based soil test available through the South Australian Research and Development Institute (SARDI).
New tests for Ascochyta blight and Phytophthora root rot of chickpea, yellow leaf spot and white grain disorder of wheat, Fusarium stalk rot of sorghum and charcoal rot of soybean, sorghum, maize, mungbean and sunflowers will be reported in the `tests under evaluation’ section on 2018 Predicta B reports along with combined levels of two beneficial arbuscular mycorrhizal fungi (AMF).
This will enable growers to assess potential disease risks to cereals, pulse and oilseed crops, which provides a valuable guide to paddock selection, crop and variety choice and required agronomic management.
Cereal root diseases are estimated to cost Australian grain growers more than $370 million annually in yield loss by limiting water and nutrient uptake within crops.
NSW Department of Primary Industries (DPI) senior plant pathologist, Steven Simpfendorfer, said strategies to minimise yield losses caused by soil-borne diseases had to be implemented prior to sowing.
“Growers need to know which soil borne diseases pose the greatest risk to their planned crop and Predicta B can provide this crucial information,” Dr Simpfendorfer said.
“Predicta B is under continual development and significant work has been undertaken over the past four and a half years to improve the value of the tests in identifying regional risks from different soil-borne diseases.
“This has led to improved management options for growers and helped further industry’s understanding of soil-borne disease distribution and incidence. Consequently, there has been an expansion in the number of tests available to growers.
“Results are reported with categories based on population density so growers and consultants can benchmark levels of pathogen DNA detected in paddocks against the rest of industry.
“When the relationship between the initial pathogen level and disease has been defined, the level detected in the sample is reported with a disease risk rating.”
For results to be accurate, Predicta B requires a dedicated sampling strategy and is not a simple add on to a soil test.
Sampling recommendations for northern-based growers are:
- Collect two cores of one-centimetre diameter and 15cm deep from each of 15 different locations within the target paddock or production zone.
- Samples may be taken to a depth of 30cm if growers are concerned about Pratylenchus thornei (root lesion nematode) detection.
- If using a larger diameter core or coring to 30cm, take fewer cores per location.
- Take soil cores from along/in the rows of the previous cereal crop if still visible and retain any stubble collected by the core. Most soil-borne pathogens are concentrated under the rows of the last cereal crop.
- If the rows cannot be seen, take the cores at random.
- Add two pieces of cereal stubble, if present, to the sample bag at each of the 15 sampling locations to improve the detection of crown rot.
- Each piece should be a single dominant tiller from the base of different plants and include the crown to the first node. Discard material from above the first node.
- Maximum sample weight should not exceed 500 grams.
Crown Analytical Services (CAS) is the service co-ordinator for the northern region Predicta B test and can provide northern growers and advisers with bags, soil corers, protocols and procedures for sampling as well as an interpretation of results once tests are completed.