Economic impact of Turnip mosaic virus, Cauliflower mosaic virus and Beet mosaic virus in three Kenyan vegetables

• Published in: Plant pathology 2007-04, Vol.56 (2), p.317-323
• Main Authors: Spence, N.J, Phiri, N.A, Hughes, S.L, Mwaniki, A, Simons, S, Oduor, G, Chacha, D, Kuria, A, Ndirangu, S, Kibata, G.N, Marris, G.C
• Format: Article
• Language: English
• Subjects: Beet mosaic virus; Biological and medical sciences; Brassica; cabbage; Cauliflower mosaic virus; Caulimovirus; chard; Fundamental and applied biological sciences. Psychology; kale; Kenya; Phytopathology. Animal pests. Plant and forest protection; Plant viruses and viroids; Potyvirus; Swiss chard; Turnip mosaic virus
• ISSN: 0032-0862; 1365-3059
• DOI: 10.1111/j.1365-3059.2006.01498.x

Screenhouse experiments conducted in Kenya showed that inoculation of cabbage seedlings with Turnip mosaic virus (TuMV), either alone, or in combination with Cauliflower mosaic virus (CaMV), reduced the number and weight of marketable harvested heads. When viruses were inoculated simultaneously, 25% of cabbage heads were non-marketable, representing 20-fold loss compared with control. By contrast, inoculation with CaMV alone had insignificant effects on cabbage yield. This suggests that TuMV is the more detrimental of these pathogens, and its management should be a priority. Early exposure to TuMV produced cabbages that were 50% lighter than non-infected plants, but later infection was less damaging suggesting that controlling virus infection at the seedling stage is more important. TuMV was far less damaging to kale than it was to cabbage; although high proportions of TuMV-inoculated kale plants showed symptoms (>90%), the marketability and quality of leaves were not significantly reduced, and no clear relationship existed between timing of infection and subsequent crop losses. Early inoculation of Swiss chard with Beet mosaic virus (BtMV) significantly impaired leaf quality (~50% reduction in marketable leaf production), but the impact of disease was greatest in plants that had been inoculated at maturity, where average leaf losses were two and a half times those recorded in virus-free plants. Disease-management of BtMV in Swiss chard is important, therefore, not only at the seedling stage, but particularly when plants are transplanted from nursery to field.