Science Into Practice - Fighting Botrytis in glasshouse tomato crops

The suppression and control of high humidity in glasshouses is important because it helps prevent fungal disease and promotes crop transpiration and growth. Condensation or relative humidities of more than 90 per cent for prolonged periods increase the risk of stem Botrytis, a devastating disease in glasshouse tomato crops.

Condensation occurs when air is cooled below its dew point, causing water vapour to be released as a liquid and deposited on cool surfaces. Humidity control systems used in glasshouses are mainly based on air-humidity sensing equipment. This does not always avoid condensation on plant foliage because it fails to consider the dew point and the micro environment at the plant/air interface. It also fails to recognise differences in conditions along horizontal and vertical planes.

Growers therefore set humidity controls lower (below 85-90 per cent) than necessary to prevent general condensation. Tomato Botrytis continues to be reported, despite growers employing such strategies.

Tim Pratt of Farm Energy and Tim O'Neill of ADAS set out to investigate whether direct stem temperature measurements could be used to prevent condensation, thereby reducing the risk of Botrytis, in HDC project PC 301. Condensation events at various stem heights were monitored on five commercial nurseries.

No stem condensation was recorded at four sites and only rarely at the fifth, but varying Botrytis levels occurred at three. The researchers concluded that condensation is not a prerequisite for Botrytis. Nevertheless, the study highlighted that stem temperature sensors could be used to fine-tune glasshouse humidity control, cutting energy costs.

Horticultural Development Company

For details on all HDC activity, visit

Have you registered with us yet?

Register now to enjoy more articles and free email bulletins

Sign up now
Already registered?
Sign in

Before commenting please read our rules for commenting on articles.

If you see a comment you find offensive, you can flag it as inappropriate. In the top right-hand corner of an individual comment, you will see 'flag as inappropriate'. Clicking this prompts us to review the comment. For further information see our rules for commenting on articles.

comments powered by Disqus

Read These Next

What does the 25-year plan mean for growers?

What does the 25-year plan mean for growers?

Published on 11 January, the Government's long-awaited 'A Green Future: Our 25 Year Plan to Improve the Environment' brings together a number of policy strands into a single framework that will impact many sectors, not least fresh produce, over the coming decades.

What will 'embracing change' mean for horticulture?

What will 'embracing change' mean for horticulture?

At the Oxford Farming Conference, whose theme was "embracing change", Defra secretary Michael Gove expanded on what a post-Brexit UK agriculture and land-use policy will look like and how it will impact farmers and growers.

Can growers see off the looming labour crisis by boosting efficiency?

Can growers see off the looming labour crisis by boosting efficiency?

Concern over the availability of seasonal labour to the fresh-produce industry has never been greater.