ABOUT 60 growers and advisers gained practical experience in identifying and managing soil-borne root diseases through a series of workshops held in Adelaide, Maitland and Blyth recently.
Cereal root diseases cost growers in excess of $200 million annually in lost production, but with the right management these losses can be reduced.
Principal Scientist and Leader of Soil Biology and Molecular Diagnostics for Primary Industries and Regions SA’s (PIRSA) research division the South Australian Research and Development Institute (SARDI), Dr Alan McKay , said the workshops were designed to be informative and interactive and raise awareness of crop root health in cereals and pulses, especially in early sown crops where strong early growth can mask a root health issue later in the season.
The workshops, funded by the South Australian Grain Industry Trust (SAGIT), demonstrated the importance of assessing root health to growers and advisers, as well as how they can identify the symptoms of main root diseases, whilst highlighting the importance of soil testing prior to sowing.
“Pre-sowing management decisions such as variety selection, use of fungicides and crop rotations are the best line of defence for many soil-borne diseases, so it is important to understand the risks to make the best decisions,” Dr McKay said.
“When root diseases affect crops during establishment, areas of poor growth often develop and these are a good indication that there is a problem.
“When crops are sown early and seedlings establish in warm moist soil, root diseases may not impact root growth until later in the season.
“In these crops, canopy growth can be a poor indicator of root health, and if the crop is stressed in spring, yield can be reduced. This can cause growers to observe that the crop looked good, but it didn’t finish well.”
While options to reduce the impact of soil-borne diseases in-crop are limited, knowing that there is a problem is useful for making late season decisions such as further nitrogen application and whether to cut the crop for hay.
It is also important for planning future crops and identifying which paddocks need to be tested using the PREDICTA® B soil pathogen testing service to confirm the diagnosis.
Growers brought along their own samples to the workshops and were shown how to assess the roots. To back up the observations, the root samples were tested using PREDICTA® B to identify specific pathogens involved in symptoms.
Dr McKay said the workshop samples show root diseases are still prevalent in current farming systems which are characterised by earlier sowing times.
They also highlighted that traditional methods of visual diagnosis based on symptoms, while useful for identifying crops with poor root systems, are not necessarily reliable to diagnose the cause.
Feedback from attendees was positive, with an appreciation that Dr McKay brought the ‘lab to the land’ to assist them with on-farm decision making and to help practice change.
Post-workshop survey results found all participants were more likely to complete soil testing once they understood that root disease can occur despite the crop looking healthy.
“To support growers to monitor root health, we are now investigating developing new versions of PREDICTA® B to test cereal, pulse and oilseed root samples,” Dr McKay said.
A national survey is currently underway, coordinated through SARDI and funded in collaboration with SAGIT and the Grains Research and Development Corporation (GRDC), aiming to assist in better diagnosis and management of pulse root diseases.
The survey uses a combination of visual assessment and PREDICTA® B testing to identify which of the known pathogens are most commonly associated with poor performing pulse crops and help develop new DNA sequencing methods to check for new or emerging pathogens.