Narcissus: Investigation into the benefits of using water disinfection options during HWT


Summary: Hot water treatment (HWT) is used to control pests and diseases, notably stem nemtaodes, bulb scale mites and fusarium. This has been the standard approach for at least 70 years. For most of that time, formalin was added to HWT tanks as a general biocide, however approval for formalin was withdrawn in 2008 which meant that an alternative was required. Work in BOF 61 identified FAM 30 as a viable alternative and this has since become standard practice in the UK. However, FAM 30 is expensive in comparison to formalin and the result has been that growers do not always use it at the required rate. This issue is exasperated since FAM 30 rapidly depletes in tanks under a high bioload. Alternatives have been considered in other studies. Chastagner and Riley (2002) concluded that chlorine dioxide was effective against spread of Fusarium and chlorine dioxide is currently used by American narcissus growers. However, AHDB Horticulture projects BOF 61 and 61a examined a number of alternatives, including chlorine dioxide and did not recommend its use. The use of chlorine dioxide was reviewed in BOF 70 which recommended that further investigations were required before it could be recommended to growers.  Other biocides have been examined, e.g. peroxyacetic acid (Hanks and Linfield, 1999), hydrogen peroxide and UV (Stewart-Wade, 2011) but require further commercial scale testing before they can be recommended. UV has much to recommend it since it is relatively cheap and non-corrosive but its efficacy is very dependant of water clarity which is a problem with high bioload HWT.

Project code:
BOF 077
01 January 2016 - 31 December 2019
AHDB Horticulture
AHDB sector cost:
Project leader:


BOF 077_Report_Annual_2016 BOF 077_GS_Annual_2016 BOF 077_Report_Annual_2017 BOF 077_Report_GS_Annual_2017 BOF 077_Report_Annual_2018 BOF 077 Grower Summary 2018 BOF 077_Report_Final_2020 BOF 077_GS_Report_Final_2020

About this project

Aims and Objective: 

The aim is to identify commercially viable alternatives to current practice, which is FAM 30 (based on iodine).

1. Review of the literature
2. In vitro laboratory tests
3. Assess the feasibility and cost of retrofitting biocide delivery systems to existing HWT tanks
4. Assess impact of different treatments on infrastructure
5. Small-scale tank tests
6. Commercial scale testing
7. Field trials
8. Health and safety considerations