Pepper fruit rots: control

Read about options for prevention and control of pepper fruit rots.

This information was last updated in 2015.

Variety

Varietal differences have been observed for numerous fruit rots, including Botrytis, Phytophthora and Fusarium.

This may relate to sugar content or other substances in peppers, or how fruit are held on the plant. It may also be due to the persistence of flower petals after fruit set.

Breeder catalogues do not generally give the genetic resistances of varieties to common fruit rots, but some varieties are listed as resistant to X. campestris pv. vesicatoria.

Glasshouse climate control and post-harvest storage

In general terms, fruit rots are encouraged by warm, wet, humid conditions.

To minimise their occurrence, steps should be taken to manage glasshouse conditions to avoid excessive humidity and condensation events.

This can be achieved with appropriate glasshouse heating and venting and the use of fans.

Points to remember

• Damage to plants due to blossom end rot or sunscald should be avoided, as this may allow entry to fruit rot pathogens.
• Leaks in irrigation systems, or pooling of irrigation water around the glasshouse, should be rectified.
• During picking and packing, fruit should be handled carefully to avoid causing damage that might allow a rot entry.
• When harvesting, peppers should be taken with some stalk remaining.
• Fruit should not be packed wet and conditions should be managed during transport and storage to inhibit the growth of pathogens (typically below 10°C).

Hygiene

There is evidence that some fruit rot diseases, such as Fusarium internal fruit rot, may be seed-borne.

A clean growing environment is key to reducing the risk of fruit rots. All staff should be educated on the importance of observing good hygiene practices in the crop and packhouse.

Good hygiene is especially important for bacterial rots for which there are no conventional chemical control methods. Additionally, end of season clean-up should be thorough.

Removal of plant material:

Any fruit that becomes mechanically damaged, insect-damaged or affected by sunscald or blossom end rot should be removed. This will reduce the tisk of them becoming infected by air-borne spores and acting as a reservoir for fruit rot pathogens.

Infected fruit, or entire plants in the case of diseases such as P. capsici, should be removed from the glasshouse.

However, evidence of the effect of regularly removing fallen aborted fruit and flowers on the incidence of Fusarium internal fruit rot is conflicting.

Some fruit rots, such as Botrytis, may survive in plant debris. It is important to remove all infected plant material and any pruned material from the glasshouse.

Fruit trapped in the crop canopy, and rotten fruit left attached to plants, can lead to foci of Fusarium internal fruit rot.

Disinfection

A variety of effective disinfectants are available for use in commercial horticulture.

A thorough clean-down and disinfection should be carried out at the end of each season, before new plants are brought in from the propagator.

All visible debris which could carry infection over into the new crop should be removed.

Walkways

A disinfectant should be applied to concrete walkways and plastic floor covering. Rows and especially stanchions and glasshouse walls where dust and debris could be hidden should also be thoroughly cleaned.

If fruit is washed at any point, it is imperative that clean water is used.

Properly chlorinating the water should prevent spread of pathogens onto the fruit.

Packing and grading lines should be regularly cleaned and disinfected.

Notes for staff

Fungal and bacterial fruit rots can be easily spread by staff and by tools used to harvest fruit and prune plants. As such, it is necessary to disinfect pruning tools regularly, especially between work on plants suspected to be diseased and then healthy plants.

Staff should wash their hands with soap in warm running water before entering the glasshouse, and after handling any infected material. Alcohol-based hand-wash may also be used on entering the glasshouse.

Plant protection products 

In work conducted in the UK, Fusarium internal fruit rot was reduced by sprays of Amistar, Switch and Serenade ASO.

Recent work in the Netherlands also reported a reduction with Serenade ASO.

However, it should be noted that Fusarium spores germinate and grow down the style within three hours of landing on the flower.

Therefore, effective control of Fusarium internal fruit rot by spray application of conventional chemical plant protection products to flowers may be difficult.

Further work

Further work is needed to determine if a reduction in Fusarium inoculum in the environment through use of chemical and/or biological fungicides (such as sprays to debris on pathways and rockwool slab surfaces) results in a reliable reduction in Fusarium internal fruit rot.

In the case of seed-borne diseases, seed treatments such as hot water treatments may be effective in removing or reducing the chances of infection.

No chemical seed treatments are currently approved for use on pepper in the UK.

This information was last updated in 2015. Ensure you check with your plant health advisor and the latest regulations before using any products on your crop and they may no longer be approved for use.

Authors

This information was originally authored by Tim O'Neill and Sarah Mayne (ADAS).

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.