Beau White of Campbells Fertilisers outlined the benefits of biostimulants for onion production

In collaboration with Muirs, AUSVEG presented at an informative event in Murray Bridge, bringing together onion growers from across South Australia to hear the latest results on onion research and chemistries that are available to aid in onion production.

The Muirs Annual Onion Grower Night is held every year by Muirs in South Australia. The event on the 11th of July 2024 attracted a record number of growers, drawn in by a number of expert speakers.

Michael Rettke, researcher with the South Australian Research and Development Institute (SARDI), presented his recent findings on fusarium basal rot in onions through the onion-levy funded project Epidemiology and management of fusarium basal rot in onions (VN20006).

Michael’s project concludes at the end of this year, and aims to develop integrated pest and disease management strategies (IPDM) to reduce the impact of fusarium basal rot in onions.

Michael commented on the ability of fusarium to suppress yield if practices such as irrigation and nitrogen application aren’t adequately managed.

“The trend between the incidence of rotted bulb nitrogen levels is hard to ignore,” said Michael. “It is a part of the story and something that needs to be managed.”

“The research showed that it is important to manage irrigation– both under and over-irrigated crops can create an optimal environment for fusarium basal rot. The trials found high levels of fusarium basal rot in both high moisture soils and dry soil zones.”

Dr Belinda (Brandy) Rawnsley from Syngenta presented on the company’s new Group 30 insecticide, SIMODIS. In bulb vegetables SIMODIS acts to suppress onion thrips and plague thrips.

Onion thrips feed on the leaves of onion plants causing the leaves to turn white or silver. The presence of onion thrips in-crop can lead to several problems, including reduced marketable yield, crop stunting, and decreased bulb weight due to extensive feeding.

Thrips are known to carry various diseases which can result in the introduction of new pathogens into the crop. It is important to monitor for onion thrips in onion storage facilities as they often enter the bulb post-­harvest and breed.

SIMODIS is a foliar insecticide that affects insect pests either through direct contact or ingestion whilst feeding. The chemical targets the nervous system of insect pest species, inducing involuntary muscle contractions and cramping, inhibiting the insect’s ability to move and feed, causing the insect pest species to die.

Syngenta demonstrated that the insecticide has excellent sunlight stability and rainfall resistance properties, ensuring extended residual activity. Dr Rawnsley highlighted the effective nature of the insecticide to manage onion and plague thrips in bulb vegetables, supporting productivity and quality.

Beau White from Campbells Fertilisers presented on both existing and new plant biostimulants, as well as fertilisers in onions, including CoRoN, Talete, MC Extra.

L-R. Ryegrass herbicide resistance is an issue for South Australian onion growers, Dr Peter Boutsalis of Plant Science Consulting demonstrated a ‘quick’ ryegrass test for growers. Dr Michael Rettke presented the latest findings on research into fusarium basal rot under project VN21000 at the onion grower event in Murray Bridge.

Timing the release of nitrogen in onion crops is essential, Beau told attendees at the event, as proper timing ensures nitrogen is available when the plant needs it most.

In onion crops nitrogen is particularly important during the bulbing phase, and having a controlled-release nitrogen source readily available during this growth stage can enhance bulb size and yield. Timing nitrogen release can also reduce the risk of nitrogen leaching into the groundwater or running off into nearby water bodies.

Beau introduced CoRoN, a controlled release nitrogen source in the form of urea. This foliar fertiliser gives plants a consistent stable source of nitrogen which is released according to the plant’s nutritional needs. This can lower costs by preventing over-application of nitrogen, leading to better economic returns.

CoRoN has a low burn potential, wash-off tolerance, reduced drift and low surface tension. In onions, CoRoN should be applied at mid set development.

Beau White spoke on Campbells Fertiliser product Talete. Talete aids in improving plant water-use efficiency in conditions of water availability, and in conditions of permanent and temporary water shortages.

Beau commented on how Talete can aid in onion production.

“By improving the ability of the plant to be more efficient with its water use, we can even out the lags in growth production when we have shortages in available water.”

Plant biostimulants are a rapidly growing sector in sustainable agriculture due to the large amount of crop benefits they provide, including enhanced nutrient uptake, improved stress resilience, and improved root development, among other features.

Beau presented on a biostimulant from Campbells Fertilisers called MC Extra.

MC Extra is derived from the algae Ascophyllum nodosum. MC Extra supports balanced plant growth, improving vegetative to productive balance, in order to maximise high quality crop yields.

This is beneficial in onions as vegetative growth is essential for photosynthesis and nutrient uptake, however if the vegetative growth is too strong compared to bulb growth, the plant may not produce the desired bulb size and quality. Conversely, if the plant only focuses on productive growth, it may not develop enough foliage leading to reduced yields. Healthy foliage can act as a barrier and can contribute to the plant’s overall disease resistance. Additionally, plants that are overly focused on either vegetative or bulb growth may struggle under stress conditions.

Zarmeen Hassan, National Manager for Biosecurity and Extension at AUSVEG, provided an update on the onion extension project, Accelerating the adoption of best management practices for the Australian onion industry (VN21000). Zarmeen explained how the project is working to address the key focus areas identified by South Australian onion growers. The focus areas for the state include herbicide resistance, pest and disease management, and mechanisation.

South Australian onion growers attending the Murray Bridge event were also asked to bring along ryegrass samples for complementary herbicide resistance testing.

Ryegrass resistance testing was completed by Dr Peter Boutsalis, Director of Plant Science Consulting. Dr Boutsalis has dedicated his career to managing herbicide resistance in Australia and overseas, extending messages on best practice weed management throughout the industry.

Dr Boutsalis conducted a ‘quick test’ for the South Australian onion growers present at the event to establish resistance status in the ryegrass samples they had brought along.

Ryegrass resistance testing equips growers with the knowledge needed to make informed decisions on-farm, improving yield and reducing input costs associated with ineffective chemical spraying. Decreasing competition from resistant weeds can further lower on-farm input costs.

The Muirs Annual Onion Grower Night was a well-structured event with delicious food catered by the Murray Bridge Hotel. The event was a great opportunity to engage with industry bodies and growers, fostering a supportive environment for learning and sharing of ideas.