Growers can wash plants and remove visible contamination but small amounts of algae can remain and multiply.
This situation has deteriorated because of the loss of herbicides, products marketed for amateur use only and a lack of information on the efficacy of products that are available.
HNS 176 was launched to determine the efficacy of UK-marketed microbial and natural-aquatic algae control products, to test the concept that ultrasound devices could control algae in plant production tanks and to check for phytotoxicity of some algal control treatments on aquatic plants.Tests were carried out in 2009 and the final report is available to download from the HDC website.
The project recommendations are:
- Ensure tanks are treated for blanketweed early in the production cycle, including the mother-plant tanks.
- Treat blanketweed as soon as any becomes visible.
- Consider adding Cloverleaf Blanket Answer to tanks.
- Before application, check phytotoxicity of Cloverleaf Blanket Answer, using a sample range of a different plant species.
- If testing ultrasound treatment for the control of blanketweed, use it before increasing plant pot density in tanks, and remove any obvious blanketweed before commencing.
Poinsettia meeting, Woodlands Nursery, 28 November; "Keeping it Clean" road show, Belfast, 19 November; HNS panel meeting, London, 1 December.
Next report: FV 348 - an independent assessment of onion varieties.
Horticultural Development Company
For details on all HDC activities, visit www.hdc.org.uk.