Leading into the 2017 season the risks presented by Ascochyta blight in chickpeas are at an elevated level. The occurrence of a new virulent strain of the Ascochyta blight pathogen has resulted in all resistance ratings being revised to susceptible or moderately susceptible. Throughout the Southern Region there is also an increased inoculum load due to the large crops grown in 2016. This means that planning for proactive management, budgeting and sourcing fungicides is a must for anyone growing chickpeas in South Australia and Victoria in 2017.
Seed treatments are a must
With the high inoculum load and reduced resistance ratings of all chickpea cultivars preparing for the seasons fungicide applications at the start of the season is vital. Applying a thiram based fungicide seed treatment will prevent the transmission of infection from the seed to the seedling, thus limiting the seed based sources of inoculum.
Assess cultivar resistance to determine fungicide strategy
Assessing the cultivar resistance rating for Ascochyta blight (Table 1) will determine the fungicide strategy required. The required amount of fungicide for the season can then be planned and attained to ensure that the fungicide is on-farm prior to any outbreaks of disease. This will aid in keeping the crop clean and disease free.
2017 Chickpea resistance ratings to foliar Ascochyta Blight
|PBA HatTrick||Genesis™ 509|
|PBA Striker||PBA Slasher|
|Genesis™ 079||Genesis™ 090|
*All varieties are rated susceptible to Ascochyta Blight pod infection.
Plan, budget for and source fungicides in advance
Planning for the application of foliar fungicides in season should not only include growers knowing what to spray but also having adequate chemical supplies in their shed on farm. For moderately susceptible varieties 3 to 4 applications prior to rain events throughout the season will be required, with each application offering 2 to 3 weeks protection. Susceptible varieties will require a fungicide spray every 2 to 3 weeks prior to rain events throughout the growing season. For both moderately susceptible and susceptible varieties the foliar fungicide strategy should commence 6 to 8 weeks post sowing prior to the first post emergent rain event, even before the disease is detected.
Other management strategies to protect chickpeas from Ascochyta blight include:
- Avoid planting chickpeas adjacent to last years chickpea crop.
- Observe a three year rotation between chickpea crops in the same paddock.
- Burning cereal stubble in the paddock that chickpeas are being sown into since information from the northern cropping region has shown that ascochyta inoculum can blow into the neighbouring cereal stubble during the harvest of the 2016 chickpea crop.
- Sow later in the sowing window.
- Remove chickpea volunteers as even volunteers killed with herbicide can still carry inoculum. Ensure that the whole plant is removed from the paddock.