Pepper

Blossom end rot

What you will see

A dark sunken rot forms at the end of the fruit (the side opposite the stalk); it is caused by a lack of calcium in the fruit when water is uneven.

The source says: large-fruited vegetables like this one are particularly susceptible.

How to protect

1. Prevention

   • Never let the plant dry out; in hot weather water even 2× a day, preferably twice a little rather than once a lot.
   • For a grow bag or pot, consider a larger container, automatic watering or mulch.
   • Extra calcium in the soil helps only a little: calcium reaches the fruit only when water flows evenly.

Aphids

What you will see

Colonies of tiny insects on young shoots and under leaves, stunted and distorted growth, sticky honeydew and black sooty mould on it.

The source says: peppers are especially prone to aphids.

How to protect

1. Prevention

   • Tolerate a small number: aphids are food for beneficial insects.
   • Check plants often so you can act in time.
   • Encourage ladybirds, hoverflies, lacewings and parasitic wasps.
2. By hand as soon as you spot themSquash colonies with your fingers or remove affected shoot tips.
3. Biological before a heavy infestationIn a greenhouse you can buy in hoverfly larvae, lacewings and parasitic wasps.
4. Chemical — only when nothing else helps according to the product labelLast resort only: a product authorised in your country against aphids. Try non-chemical methods first.

Grey mould

What you will see

Soft, rotting parts covered in a fuzzy grey coating.

The source says: it is among the vegetables susceptible to grey mould.

How to protect

1. Prevention

   • Keep things clean: remove dead and diseased parts.
   • Ventilate polytunnels and greenhouses.
2. By hand as soon as it appearsCarefully remove affected parts into a bag (spores spread easily) and dispose of them.

Two-spotted spider mite

What you will see

Speckled leaves and early leaf drop.

How to protect

1. Prevention

   • Plants in a hot, dry, overcrowded greenhouse suffer more: increase humidity and airflow.
   • In autumn, remove heavily infested plants and clear away debris, canes and ties; disinfect the greenhouse thoroughly.
   • Weed around the greenhouse; weeds are hosts.
2. Biological March to OctoberPredatory mites (from a biological control supplier) are the most common biological control against spider mites.
3. Chemical — only when nothing else helps according to the product labelLast resort only: a product authorised in your country against mites. Try non-chemical methods first.

Glasshouse whitefly

What you will see

Sticky honeydew on leaves, black sooty mould and tiny white winged insects.

How to protect

1. Prevention

   • Inspect new plants and, if possible, quarantine them.
   • Get rid of unneeded plants from the greenhouse so the whitefly has fewer hosts.
2. By hand throughout the growing seasonYellow sticky traps are for monitoring, not a major control measure.
3. Biological early, before a heavy infestationParasitic wasps (from a biological control supplier) attack whitefly larvae; release them early, before plants are heavily infested. Parasitised larvae turn black.