Spraying of chickpea
Early program spraying with fungicides
Early application of fungicides is critical in restricting the early development and spread of Ascochyta. Check spray strategies for particular varieties. The fungicides currently registered to control Ascochyta blight in chickpea are preventative, not curative.
Southern Queensland
Prophylactic sprays (programmed sprays applied before symptoms are found) are necessary for most varieties. The 2-1-0 rule needs to be applied. Two prophylactic sprays are required for Ascochyta (S) and (VS) varieties, including Jimbour, Kyabra, Amethyst and Macarena. One prophylactic spray is required for the (MR-MS) variety Yorker, while for Ascochyta (MR) and (MR-R) varieties e.g. Flipper and HatTrick respectiviely, no prophylactic sprays are necessary. The recommended timing of these prophylactic sprays is: first prophylactic spray (for MR-MS, S and VS varieties) - prior to the first rain event, three weeks after emergence, or at the three leaf stage, whichever comes first second prophylactic spray (for S and VS varieties) - three weeks after the first spray, but if two weeks have elapsed since the first spray and rain is forecast, apply the second spray before the rain event.
When Ascochyta blight is found in a crop of Flipper, Yorker, Jimbour, Kyabra etc, a foliar application of a registered fungicide should be made immediately prior to the next likely rain event. Further sprays may be required if wet weather persists.
PBA HatTrick: There is no economical advantage in the application of foliar fungicides during the vegetative stage of crop growth.
If Ascochyta is found in the crop then the application of a registered fungicide is recommended immediately prior to the first rainfall event after the commencement of flowering to produce the developing pods. Additional applications are recommended if wet weather persists.
Consult your agronomist for advice on the most appropriate fungicide for you particular situation.
Central and coastal Queensland
The risk from Ascochyta blight in these regions is considered to be lower than in southern Queensland, due to generally less favourable weather conditions, so a different strategy is recommended for the regions. However, extreme care needs to taken, and careful monitoring for Ascochyta blight must be conducted, because under the right weather conditions the disease is capable of causing significant yield losses even in these regions. Chickpea crops irrigated from overhead sprinklers or centre pivot are at greater risk than other crops. The following two risk scenarios, with their respective spray strategies, have been developed:
Low Risk - fungicide-treated seed purchased from a seed supplier, planted into or beside a paddock in which chickpeas have not been grown for the past three seasons. Carefully monitor such crops, particularly 7-10 days after rain events, and if Ascochyta blight is found, apply a registered fungicide immediately prior to the next likely rain event. Closely monitor the crop and repeat as necessary.
Medium Risk - all other situations, including planting seed from any source into or adjacent to a paddock in which chickpeas were grown within the last three seasons, and planting grower-kept seed into any situation. The seed must be treated with a thiram-based dressing prior to planting. A foliar spray of a registered fungicide should be applied before the first rain event post emergence of the crop. Then carefully monitor the crop, and if Ascochyta blight is found, apply a further application of a registered fungicide prior to the next likely rain event. Repeat as necessary.
Be aware of the withholding periods for all fungicides used and follow label directions closely. No more than four sprays of either a mancozeb or chlorothalonil product can be applied to a crop. Consult the product label(s) for the Harvesting Intervals, Grazing/Cutting for Stockfeed Withholding Periods, and Export Slaughter Intervals. A metiram fungicide, and several chlorothalonil fungicides are now registered for use on chickpeas to control Ascochyta blight.
Monitor the crop closely
While a rain event is the major means of spread within a crop, dews alone can allow spread on a plant, or between plants that are touching. Irrespective of the water source, the plant only needs to be wet for three hours for infection to occur.
Spring is a critical time as it is the most rapid period of crop growth. Also, during pod fill all varieties can be considered to be susceptible, so extra care needs to be taken during this period. Monitoring should continue through to 10-14 days prior to harvest as the disease can spread rapidly on senescing crops.
Crop inspections need to be conducted in different parts of a paddock, with emphasis placed on inspection of the lower parts of the canopy.
Use correct fungicide application technique
Fungicides used for the control of Ascochyta blight are protectants only and need thorough coverage over the entire plant to prevent further infection and spread. Growers need to ensure that their application equipment is set up to maximise spray coverage on the plant, that is:a flat fan nozzle at a pressure that will produce a spray quality of fine - medium a minimum water volume for ground application (preferred method) of 80 L/ha, for aerial application a minimum of 30 L/ha.
Harvest as early as practical
Harvest as early as practical to minimise ascochyta infection on pods, and maximise profitability of the crop. Ascochyta can spread rapidly on senescing or mature chickpea plants, and can create marketing problems if the grain receival standard for Ascochyta infection is exceeded (see Pulse Australia for current minimum receival standards). Harvesting chickpeas at 14-15% and either drying or aerating will normally result in higher yields, better quality, fewer harvest difficulties and less problems with late Ascochyta infection. While PH wheat harvest normally receives the priority at harvest time, in order to maximise returns, harvest delays can be just as costly to the chickpea crop that is commonly worth $350-$450/t.
The strategies outlined above are designed to assist growers produce a profitable chickpea crop this coming season. While adoption of the management package does not guarantee complete freedom from Ascochyta blight, adhering to the appropriate strategy should minimise the risk of incurring serious economic losses.
