Chemical control and resistance management of tomato leaf mould

Industry-standard fungicides and biofungicides can be vital tools to help tackle tomato leaf mould (Passalora fulva).

P. fulva infects via the stomata and lives inside the leaf tissue. Fungicides with translaminar or systemic action provide the most effective treatment option as they are able to penetrate the leaf and give better control.

Thorough coverage is essential when using purely contact-acting treatments. Contact fungicides are less effective.

It is essential to keep the top third of the plant as free from disease as possible as a severe attack here is most likely to affect yield.

The use of other products from different fungicide groups should be incorporated into a resistance-management spray programme, as part of an integrated management strategy.

A few biofungicides are now approved for use on tomatoes in the UK, with several more in development for registration.

AHDB project PE 018 found Serenade ASO to be the most effective biofungicide tested, although it was not as effective as conventional products.

The preventative use of a biofungicide as soon as early symptoms are seen can delay the onset of the disease, minimising the number of fungicide sprays or extending spray timing intervals. One grower reported that without the use of Serenade ASO to extend spray intervals, they would have experienced significant disease problems.

Biofungicides need to be used preventatively; when used effectively, they have the capacity to have good effects on controlling several diseases, including tomato leaf mould, powdery mildew and botrytis.

Restricted numbers of fungicide treatment applications, combined with developing resistance and the removal of existing actives, means the use of biofungicides such as Serenade ASO is likely to become an important component of the P. fulva treatment programme.

The combination of its fast life cycle and rapid mutation rate makes the disease’s development of resistance to fungicides a concern.

To combat this, strategies should integrate cultural practices which optimise fungicide use, including the use of different fungicide groups to minimise the risk of selecting for fungicide-resistant strains.

A list of different fungicide groups is available on the Fungicide Resistance Action Committee (FRAC) website. 

AHDB has a dedicated team which works on getting plant protection products through Extensions of Authorisation for Minor Use (EAMUs) and providing different options for crop protection for the industry.

For specific information on crop protection options for protected edible crops, please contact Jo McTigue.

If you would like to order a hard copy of the Tomato leaf mould best practice guide, please contact:

Email: publications@ahdb.org.uk

Telephone: 0247 799 0069

Tomato leaf mould web pages originally authored by Sarah Maybe and Dave Kaye (RSK ADAS).

Please note this information was originally published in 2018, and the biocidal and plant protection products references were correct at time of publication.

Biocidal and plant protection products must only be used in accordance with the authorised conditions of use. Regular changes occur in the authorisation status of biocides and plant protection products. For the most up to date information, please check with your professional supplier, BASIS registered adviser or the Chemical Regulation Division (CRD) of HSE (https://www.hse.gov.uk/crd/) before use.

While the Agriculture and Horticulture Development Board seeks to ensure that the information outlined on this page is accurate at the time of publishing, no warranty is given in respect thereof and, to the maximum extent permitted by law the Agriculture and Horticulture Development Board accepts no liability for loss, damage or injury howsoever caused (including that caused by negligence) or suffered directly or indirectly in relation to information and opinions contained in or omitted from this information.