The identification of strobilurin-resistant powdery mildew in Australia has led to a new resistance management strategy for Group 11 fungicides from the CropLife Australia Fungicide Resistance Management Review Group. Growers who have applied strobilurins routinely over many seasons should be particularly aware of the new guidelines.
The latest resistance management strategy outlines:
- Apply Group 11 and other systemic fungicides preventatively.
- DO NOT apply more than two sprays per season of Group 11 fungicides.
- Where Group 11 products have been routinely used for many seasons, field research indicates there is an increased risk of powdery mildew resistance to Group 111 fungicides occurring. To ensure continued protection against powdery mildew in these circumstances, mix Group 11 fungicides with a registered rate of a compound from an alternative chemical group for the control of powdery mildew in grapes.
- Alternatively, if applied alone, Group 11 fungicides should be used in strict alternation with fungicides from an alternative chemical group for the control of powdery mildew in grapes.
The active constituents registered for use in viticulture in the Group 11 category are azoxystrobin, trifloxystrobin and pyraclostrobin.
DOG BOOK: Agrochemicals registered for use in Australian Viticulture 2012/13.
The details below list the significant changes to the published booklet.
New restriction on use:
Cyprodinil + fludioxonil
APVMA 51797, registered for control of botrytis.
The recommended restriction on use is: Use no later than E-L 29, berries pepper-corn size (4 mm in diameter). Do not use within 60 days of harvest.
No longer registered by the APVMA and not permitted for use in powdery mildew control.
New targets and active combinations:
Spinetoram (Delegate) is listed for Grapevine Moth. The recommended restriction on use is: Use no later than E-L 31, berries pea-size (7 mm in diameter).
Captan + Metalaxyl (Duplex WG) is listed for Black spot, Botrytis bunch rot, Downy mildew and Phomopsis cane and leaf spot. The recommended restriction on use is: Use no later than 30 days before harvest.
Recommended control options for Mealybug and Snail are now listed in the Recommendations section of the booklet.
Resistance management strategies:
The resistance management strategy issued by CropLife Australia for Downy mildew has changed. Sprays can now commence from E-L 12 (Shoots 10 cm). Start disease control sprays using a protectant or non-phenylamide fungicide and continue spraying at 7 – 21 days depending on disease pressure and rate of grapevine growth, typically when shoots are 10 cm (E-L 12 stage) or longer.
The resistance management strategy for Powdery mildew now includes Group 7 (carboxamide) fungicides. DO NOT apply consecutive sprays of Group 7 fungicides, including from the end of one season to the start of the following season. DO NOT apply more than 4 Group 7 sprays per season.
The 2012/2013 edition of the AWRI publication, Agrochemicals Registered for use in Australian Viticulture 2012/2013 is available on-line. To access, visit the following link: https://www.awri.com.au/industry_support/viticulture/agrochemicals/agrochemical_booklet/.
This information is provided to inform the Australian grape and wine sector of agrochemical information, and should not be interpreted as an endorsement.