Original Agriculture Victoria Note Number: AG1443
Published: October 2011. Reviewed: May 2013.
It is important to inspect damage of avocado trees as soon as possible after a hail event as the level of damage can be obscured by subsequent growth. Hail can impact on the foliage, flowers, stems, branches and fruit in various ways:
- Trees can be completely stripped of leaves and fruit.
- Leaves can be bruised, torn, tattered, have holes in them or be completely knocked off the plant.
- Stems and branches can be broken or bruised and scarred.
- Flowers can be damaged but it is difficult to assess unless flowers have been knocked off the plant.
- Fruit can be bruised or be knocked to the ground.
- Pests and diseases can enter fruit and bark through wounds caused by hail.
- Fallen fruit can harbour pests and diseases.
Those with hail damage insurance should contact their insurer and arrange for damage assessment.
Management of hail-damaged trees
- Hail wounds on the fruit and bark may need fungicides to prevent disease entry. Be careful using fungicides if bee pollination is occurring. Read labels on chemicals and follow instructions carefully.
- Wounds are a key infection site for disease, and particularly bacterial diseases.
- Severely damaged stems and branches should be pruned off as soon as possible to prevent infections.
- To reduce the risk of pests and disease remove fruit that has fallen to the ground.
- Fertilizers and irrigation applied at optimum levels will help the trees overcome the stress caused by the hail damage.
- Inspect damaged plants more frequently for pests and diseases.
- Where practicable, wounds on trunks and branches should be covered with a water-based paint to avoid desiccation and disease infection.
- Anthracnose might enter wounded branches and fruit so it may be useful to apply a fungicide to protect wounded branches although damaged fruit are likely to be unmarketable. Contact your local reseller for advice on a suitable fungicide.
- There is now the potential for sunburn where foliage has been stripped, exposing fruit. Consider harvesting exposed fruit earlier to avoid sunburn damage.
Correct diagnosis is essential for effective pest and disease control. A commercial diagnostic service is available at the Agribio, Bundoora.
For further information, contact:
Crop Health Services
Phone: (03) 9032 7515
Fax: (03) 9032 7604
Harold Adem, Senior Horticultural Agronomist, Agriculture Victoria, Tatura. Antony Allen, CEO, Avocados Australia. Simon Newett, Principle Extension Horticulturalist, Agri-Science Queensland. Note number: AG1443. Published: October 2011. Reviewed: May 2013.