Top five chickpea challenges
A damaging line-up of five crop pathogens can slash northern region chickpea yields when seasonal conditions are right but new prevention guidelines mean growers are better prepared.
Dr Rohan Rainbow, Grains Research and Development Corporation (GRDC) manager crop protection says an effective integrated disease management plan for chickpeas should include paddock selection, variety choice, seed dressing, strategic fungicide use and hygiene.
He says fungal diseases ascochyta blight, botrytis seedling disease (BSD), botrytis grey mould (BGM), phytophthora root rot (PRR) and sclerotinia rot can reduce yields.
GRDC has developed a fact sheet, Chickpea Disease Management – Northern Region, which covers the key tactics.
“We advocate paddock selection to minimise phytophthora root rot as the
first priority; then implementation of an appropriate ascochyta blight strategy based on rain forecasts and the level of varietal resistance,” Dr Rainbow says.
“The GRDC-supported chickpea breeding program is also yielding dividends in the way of resistance.
“The new varieties PBA HatTrick and and PBA Boundary have improved resistance to ascochyta and require fewer or no fungicide sprays.”
Dr Rainbow warns a single disease management strategy rarely provides complete disease control.
“Using integrated disease management techniques means a grower is more
likely to control the disease but regular crop monitoring to detect early disease outbreaks is important.”
He says integrated management has three aims, to:
- reduce inoculum (the disease-causing structures);
- exclude pathogens through the use of clean seed and farm hygiene; and
- protect the crop through the use of resistant varieties, seed treatments and foliar fungicides.
Growers can use paddock selection to reduce inoculum by considering crop sequence, previous occurrence of diseases, proximity to crop residues, and herbicide history, he says.
“Growers should aim for a break of at least three to four years between chickpea crops and know the risk of PRR prior to planting.
“Avoid paddocks with a history of medics, lucerne or PRR in chickpeas; and poorly drained paddocks.
“As well as direct effects from PRR and waterlogging, poorly drained paddocks
compromise a plant’s natural resistance to pathogens and this reduces the ability to manage foliar diseases with fungicides.”
Other tips include:
- Plant chickpeas at least 500 metres (further is better) from the previous year’s chickpea paddocks.• Observe the maximum plant-back period for residual herbicides.
- Control the green bridge of volunteer chickpeas and weeds.
- Bury stubble to stop pathogens releasing spores.
- Use high quality seed and treated with a registered thiram-based fungicide prior to sowing.
- Remember pathogens and root lesion nematodes can be transmitted in stubble and soil, and on machinery and boots.
- Soil and stubble can be moved by machinery, during windy and/or wet weather, and in floodwater.
- If possible, clean headers and sowing equipment to remove grain, soil and stubble before moving from property to property. Spray rigs should also be cleaned to reduce the risk of disease transmission.
- Consider wider rows (50 centimetres to one metre) to increase air movement through the crop and lower humidity in the canopy. This reduces the number and duration of infection events for AB, botrytis and sclerotinia.
- Aim for plant populations of 20 to 30 plants/square metre. Lower densities reduce yield and increase the risk of viruses.
- There are no in-crop fungicides registered on chickpeas for PRR or sclerotinia, but several are registered for BGM and ascochyta management.
- Sprays need to be applied immediately prior to rain. Of the fungicides currently registered for ascochyta, chlorothalonil is better than mancozeb under high disease pressure.
- None of the fungicides currently registered for chickpea ascochyta or BGM will stop established infections. They are protectants and have no curative activity so it is critical that applications are timely and provide thorough coverage.
To download the factsheet, visit www.grdc.com.au/GRDC-FS-ChickpeaDiseaseManagement.
Dr Rohan Rainbow
GRDC Program Manager Crop Protection
02 6166 4500
Rachel Bowman, Senior Consultant, Cox Inall Communications
07 3846 4380 0412 290 673
GRDC Project Code DAN00143, DAN00151, DAQ00154, ICA00008