Australian Pulse Bulletin

Field pea fungicide guide: 2021 season

Fungicide sprays will help control some field pea diseases. There are four main fungus diseases in field peas that require monitoring Ascochyta blight (AB), Botrytis grey mould (BGM) and Powdery mildew (PM) and Downy mildew (DM). 

A further disease of field peas, Bacterial Blight (Pseudomonas syringae) cannot be prevented or controlled with fungicides.

The disease risk to the crop needs to be assessed and likelihood of economic returns calculated before undertaking a fungicide program for field pea. Decisions need to be made such as when to start the spray program and how often to spray, depending on the disease risk (including crop rotation, paddock position to last year’s stubble and time of sowing), varietal resistance, the prevailing weather conditions and the potential value of the crop, especially if harvested for high value human consumption grain markets. 

Fungal disease control is based on protection from infection rather than curing. The first fungicide may be applied early to minimise the establishment of the disease. Additional sprays may be required if the weather conditions favour disease.

Disease monitoring should be started after crop emergence as AB can infect crops in the early stages. If the disease takes hold, it can be impossible to recover crops as the fungicides have only limited curative action. Protective sprays may be needed in longer growing seasons until the end of flowering. Fungicides remain effective for approximately 14–21 days. Keep in mind that all new growth after spraying is unprotected and in periods of rapid growth and good rainfall, usually occurring in early spring, the protection period will reduce to around 10–14 days.

Timing of fungicide sprays is critical. These diseases are spread rapidly, so DO NOT DELAY spraying. A spray in advance of a rainy period is most desirable. Delaying until after a rainy period will be ineffective.

The need for repeated fungicide applications depends on the growth stage of the crop, the time since the last fungicide application and the likelihood of further conditions favouring disease development. Unprotected crops may be quickly defoliated and destroyed by the infection. The choice of fungicide is less important than the timing, but when multiple sprays are required during the season it is critical to rotate different products and modes of action to preserve the effectiveness of all the fungicide choices. Follow this link for advice on maintaining fungicide efficacy for the grain industry. 

Seasonal Conditions in 2021

After a bumper season in 2020 that produced record yields in many areas of NSW, Victoria and South Australia, rainfall has been variable over summer in many regions. NSW and southern Queensland have had good rainfall over summer that has given full soil moisture profiles. Victoria and South Australia started with dry conditions for sowing winter crops but have recently received adequate rain to get crops germinated. In Western Australia conditions have been very favourable for sowing crops and regular rain events have followed. This season forecasts show that conditions are likely to be favourable for many diseases as we head into spring. Many of these diseases need only limited moisture to infect crops (heavy dew may provide enough moisture), so monitoring needs to be continued through the different growth stages of the crop. With good access for ground sprayers allowing for high water rates and canopy penetration, timely fungicide application will give the crop the best chance of a high yield. 

For more detailed information on disease management: 

• Field pea best management guide
• CropPro field pea disease manual
• Fungicide resistance in grain crops (including pulses)

Fungicides registered for disease control in field peas

Field pea Foliar Fungicide	Trade Name example	Ascochyta blight	Botrytis grey mould	Powdery mildew	Downy mildew	WHP Harvest
Chlorothalonil 720 (M5)	CC Barrack 720	NR	NR	NR	1.1 to 1.8 L/ha Qld, Tas, WA only	7 days
Mancozeb 750 (M3)	Dithane DF	1.7 to 2.5 kg/ha	NR	NR	NR	14 days
Azoxystrobin (Group 11) + Tebuconazole (Group 3)	Veritas	1.0 L/ha	1.0 L/ha	NR	NR	28 days
Metiram700 (M3)	Polyram DF	1.0 to 2.2 kg/ha	1.0 to 2.2 kg/ha	1.0 to 2.2 kg/ha	1.0 to 2.2 kg/ha	42 days
Triadimefon 125 (Group 3)	Genfarm Triadimefon	NR	NR	500 mL/ha NSW, Vic, Tas only	NR	14 days
Zineb 800 (group Y)	Barmac Zineb	NR	NR	NR	125 g/ha	7 days
Copper Oxychloride (M1)	Champ 500DF	2.5 kg/ha	NR	NR	NR	1 day
Tebuconazole (Group 3)	Folicur SC	NR	NR	145 mL/ha	NR	3 days
Prothioconazole (Group 3) + Bixafen (Group 7)	Aviator XPro	400 to 600 g/ha	NR	NR	NR	35 days

Many of the Minor Use Permits have short term expiry dates (e.g. 30/11/2022) 

NR = Not Registered for this disease

Read the Label As with any chemical application, care should be taken to observe all the label conditions for each product. Some label advice is different for each state or region, so for best results, it is important that this is followed. Many of our pulse crops are exported for human consumption, so market access is dependent on having the product free of chemical residues. Australian has a reputation for providing clean and safe produce so it is vital that this is maintained by using chemicals according to regulations. All permits have label recommendations for use rate and withholding periods (WHP) that must be observed so grain will comply with Maximum Residue Limits (MRL) allowable for market access.

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Last updated: 9 July 2021