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Efficacy tests for Bemisia tabaci on poinsettia cuttings - PH0405

The poinsettia strain of the tobacco whitefly Bemisia tabaci remains a serious threat to the UK horticultural industry. The damaging B-biotype is of specific economic concern because it is an effective vector of over 111 viruses from several groups, particularly geminiviruses. In addition, this biotype is more polyphagous, develops faster and is more fecund than other strains. The feeding activities of B. tabaci can also induce the development of physiological symptoms in the foliage and fruits of some plants and nymphal stages of the pest produce a sticky honeydew which often becomes colonised by sooty moulds, both sources of damage affecting marketability of the crop. Within the European Community the UK has “Protected Zone” status to prevent the spread of B. tabaci.

A recent desk study (Cannon & Matthews 2004 Unpublished CSL report) investigated the potential for developing control protocols for B. tabaci which would give an equivalent level of security to that of ‘three weeks pest freedom’ in the place of production. Recommendations for R&D work in support of such a protocol were included. They comprised a list of products as candidates for efficacy testing aimed at establishing their use for eliminating B. tabaci on poinsettia cuttings, together with supporting phytotoxicity studies.

This project will undertake the efficacy testing component of the recommended work. Parallel phytotoxicity tests of the selected pesticides as dip treatments to young poinsettia plants will be undertaken by ADAS under separate HDC funding. The efficacy testing work will investigate a range of low toxicity, IPM-compatible insecticide products against all relevant Bemisia tabaci life-stages that infest cuttings of selected poinsettia varieties. Pesticides will be applied as dip treatments (or in the case of entomopathogenic fungi, as spray drenches), using techniques developed under previous Defra funded work (project PH0172; Cuthbertson et al 2005 Mycopath 159, 23-29). Tests will be repeated on both un-rooted and rooted cuttings. The products tested will include Majestik (natural plant extract), Agri-50 (alginate/polysaccaride), Spraying oil (petroleum oil), Savona (fatty acids), Mycotal (described on the label as Verticillium lecanni but now reclassified as Lecanicillium muscarium), and Oberon (spiromesifen). In addition work on identifying the compatibility of each candidate product with the use of fungal control agents, and the maximum dose rate of a selected product that can be used in combination with an entomopathogenic fungus will be investigated.
To test the potential of a range of low toxicity, IPM-compatible insecticidal products for use in control/eradication programmes for Bemisia tabaci infesting un-rooted and rooted cuttings of selected poinsettia varieties to give an equivalent level of security to that of ‘three weeks pest freedom’ at place of production by:
1. Determining the efficacy of a pre-selected range of conventional insecticide, soap, spray oil and fungal products, against the main B. tabaci life stages
2. Determining the compatibility of selected conventional insecticide, soap and spray oil products with an entomopathogenic fungus
3. Determining the effect of dose rate of products on their compatibility with an entomopathogenic fungus
4. Developing field-use protocols and conducting glasshouse testing/validation of the recommended equivalence protocols for rooted and unrooted cuttings.

Project Documents
• Final Report : Efficacy tests for Bemisia tabaci on poinsettia cuttings   (219k)
Time-Scale and Cost
From: 2005

To: 2006

Cost: £29,433
Contractor / Funded Organisations
Central Science Laboratory
Plant health              
Plant Pests and Diseases              
Plants and Animals              
Fields of Study
Plant Health