To protect pulses, there are several registered fungicides available with varying efficacy and use patterns. When selecting products, it is important to consider products within an integrated disease management (IDM) strategy (see below), the potential of the disease-causing pathogen to develop fungicide resistance, and the overall crop profitability. Remember that withholding periods of these products differ and following label directions is essential to remain within the maximum residue limits (MRLs). Extensive testing has been undertaken to develop these limits and use patterns. Table 1 lists some registered fungicides available for use in pulse crops, the harvest and grazing withholding periods, and some important use constraints.

Table 1. A selection of available fungicides to protect pulses from specified diseases. Always read and follow the label directions, current labels can be found on the manufacturers’ websites or at the APVMA (Public Chemical Registration Information System Search).

(A) Note 63 days for export lambs. Do not graze or feed treated forage or fodder to livestock which may be used to produce milk for human consumption.
(B) Permit PER92791, expires 31 October 2025
(C) Permit PER82476, expires 31 May 2027
(D) Permit PER91123, expires 31 October 2024

Fungicide resistance

Resistance to fungicides is becoming an increasing threat to Australian crops. Currently, there are no field-relevant detections of fungicide resistance in pulses within Australia. Testing is ongoing and the threat is always present.

Pulse production in many requires the use of foliar fungicides and many crops only have single active fungicide products applied multiple times throughout the season. Therefore, there is a high probability that fungicide resistance may develop in the future if growers do not take preventative measures.

There are five strategies that growers can adopt to slow the development of fungicide resistance in pathogen populations and therefore, extend the longevity of the limited range of fungicides available:

• Avoid susceptible crop varieties. Where possible select the most resistant varieties suitable and/or avoid sowing susceptible varieties in high-risk paddocks.
• Rotate crops. Avoid planting crops back into their own stubble or adjacent to their own stubble.
• Use non-chemical control methods to reduce disease pressure. Delaying sowing and early grazing are examples of strategies that can reduce disease pressure.
• Spray only if necessary and apply strategically. Avoid prophylactic spraying and spray before the disease gets out of control.
• Rotate and mix fungicide actives/modes of action. Use fungicide mixtures formulated with more than one mode of action. Do not use the same active ingredient more than once within a season, and always adhere to label recommendations.

Integrated Disease Management

Integrated disease management (IDM) is a strategy of using cultural, chemical and biological measures to prevent and manage diseases in crops. IDM also involves good farming practices and monitoring of biotic and abiotic factors. Hence, it is important to remember that fungicides are only one part of an IDM strategy. A good IDM strategy should consider the following.

• Sowing clean seed –  Sourcing seed from healthy crops/paddocks and conducting quality testing to ensure that seed is disease-free prior to sowing.
• Apply seed treatments – Follow the label of fungicide products.
• Crop rotations – Avoiding close rotations of crops affected by the same disease. An important example is Botrytis which affect faba bean (known as Chocolate Spot), lentil and vetch (known as Botrytis Grey Mould). In general, a minimum 3-year crop rotation period is advisable.
• Choose resistant varieties – Choose a resistant variety where possible or a moderately resistant variety at minimum.
• Monitor for disease throughout season – Weekly inspections are important in susceptible crops.
• Understand the seasonal and local risk – Knowing the history of seasonal changes and the related disease prevalence in the regions is important to predict the disease risks early on.
• Optimise the fungicide strategy – Consider the five strategies mentioned previously to slow down fungicide resistance development. Follow the product label.
• Good agronomy and plant nutrition. A healthy plant is less likely to become affected by many of the diseases.

Currently, development of cost-effective IDM strategies to control Ascochyta Blight and Botrytis Grey Mould in lentil and faba bean in Southern and Northern pulse growing regions are being investigated by a national project (DJP2304-004RTX). This Project is through a co-investment with Grains Research and Development Corporation, led by Agriculture Victoria with collaborations with the South Australian Research and Development Institute (SARDI), Trengove consulting, Field Applied Research (FAR) Australia and the New South Wales Department of Primary Industries (NSWDPI).

Adapting IDM strategies will lead to a better control of foliar diseases in pulse crops, altogether reducing yield loss within season, lowering the risk of disease carryover into the next season, and slowing the development of fungicide resistance.

Useful resources

• Pulse disease guide
• Victorian and Tasmanian crop sowing guide data summary
• Crop protection product details, including Minor Use Permits, can be viewed at the Australian Pesticides and Veterinary Medicines Authority (APVMA) website www.apvma.gov.au
• For more information on the management of fungicide resistance, consult the ‘Fungicide Resistance Management Guide’ available from www.afren.com.au
• 2024 GRDC Update paper – An integrated approach to effectively manage pulse diseases

Acknowledgements

Thank you to Sara Blake (PIRSA), Kurt Lindbeck (NSW DPI) and Gordon Cumming (GRDC) for their contributions and expertise.