Farm Economics Popular Literature

The Benefits of Using Certified, Virus-tested, True-to-type Plant Material

Apple and pear trees are prone to infection with a range of viruses, of which the most important in South Africa are Apple mosaic virus (ApMV) and Apple chlorotic leaf spot virus (ACLSV). Both viruses can exist in trees for long periods without showing visible symptoms, i.e. they are latent (especially ACLSV). Visible symptoms of ApMV occur with virulent strains of the virus, or in sensitive cultivars, such as Golden Delicious and Granny Smith, and in old orchards. Rapid emergence of visible impacts can be triggered by conditions leading to stress in the orchard, such as drought and disease. Where trees are affected, fruit tend to be smaller leading to yield reductions and price reductions. Both viruses are spread by grafting with infected plant material. The virus incidence can be managed by planting only certified virus-tested trees, removing infected material from orchards, strict sanitary practices, and using only certified material for re-planting and top-working.Download the full article here