What you should know to inform your decisions?
When are pruning wounds susceptible to Euytpa lata infection?
Does time of the year make a difference? Wounds are susceptible all through winter. SARDI trials* have showed susceptibility consistent from early to late during pruning season
Most susceptible period is first two weeks after pruning.
Does grapevine cultivar make a difference? Wound susceptibility during first two weeks similar for all cultivars evaluated*. SARDI McLaren Vale Trial.
Control of eutypa dieback can be achieved by protecting wounds from infection by the fungus, Eutypa lata or by physically removing infected wood.
Wounds can be protected with fungicides, paints, pastes and biological control agents. It is also important to time pruning in order to avoid rainfall events and to maintain good sanitation. Pruning in wet weather should be avoided and preferably delayed to dry periods.
Controlling established infections is achieved by removing infected wood and retraining of watershoots from below infection. Removal of dead wood from grapevines and alternative hosts in and around the vineyard will reduce the potential inoculum level.
How to limit Eutypa by;
CULTURAL CONTROL
The level of infection may be reduced by double pruning, the practice where mechanically pre-pruning is used to leave long spurs in early winter followed by hand-pruning to short spurs in late winter.
Contamination of pruning tools is NOT a major means of spreading the disease (although viruses can be spread this way). Don’t expect by cleaning snips you will be limiting pruning wound disease.
WOUND PROTECTION
Paints and pastes on the wound
The application of acrylic paints and Greenseal paste (containing tebuconazole) or Gelseal (also tebuconazole) are recommended as wound protectants, especially on large wounds. Other treatments such as and Garrison (cyproconazole + iodocarb) are also effective but are not yet registered for use on grapevines. There use is not recommended without winery permission.
Fungicides sprayed onto wounds
Pruning wound protectant spray after pruning (photo by Dr. Doug Gubler, UCCE.)
Certain formulations of tebuconazole are registered for use on grapevines, and are the most effective fungicides tested as a spray on wound protectant available. Again consult with your winery if you have any concerns about their use. Use these fungicides at label rate. They can be applied efficiently to pruning wounds with commercial spray machines. It is important to direct nozzles to target the pruning wound zone and use high spray volumes (600 L/ha) to maximise coverage on wounds.