Radish

Cabbage root fly

What you will see

Plants grow slowly and wilt because the larvae eat the roots; they make tunnels in the radish root.

How to protect

1. Prevention

   • Cover plants with fine mesh or fleece and rotate crops (otherwise flies can emerge from pupae in the soil under the mesh).
2. By hand ongoingEncourage ground beetles and rove beetles, which eat the larvae.
3. Biological when eggs are laid and larvae hatchA mixture of pathogenic nematodes watered into the soil against the larvae (it also works on other insects in the soil).

Flea beetles (Phyllotreta, Psylliodes)

What you will see

Small round holes in leaves, mainly on seedlings; tiny beetles jump away when you touch the plant.

How to protect

1. By hand from sowingCover seedlings with fine mesh.
2. Chemical — only when nothing else helps according to the product labelLast resort only: a product authorized in your country against flea beetles. Try non-chemical methods first.

Club root

What you will see

Thickened and distorted roots; plants lag behind and wilt.

How to protect

1. Prevention

   • Do not carry soil on tools, wheelbarrows and footwear.
   • On acid soil, lime (1.64 oz/sq ft, then 0.88 oz/sq ft in following years) and improve drainage; this reduces the disease but does not rule it out.
2. By hand as soon as it appearsDig up affected plants, roots included, and dispose of them (do not compost). There is no chemical product for gardeners against clubroot.

Brassica downy mildew

What you will see

Whitish downy patches on the underside of leaves.

How to protect

1. Prevention

   • Sow radishes thinly or thin them early so that air can flow between the plants.
   • Remove weed and wild host plants.
   • Remove affected debris straight away and dispose of it.
2. By hand as soon as it appearsRemove affected debris and dispose of it so the soil is not contaminated with resting spores.

Slugs and snails

What you will see

Irregular holes in soft leaves and young shoots and slime trails; they feed at night.

How to protect

1. Prevention

   • Water in the morning, not the evening (evening watering helps them move around).
   • Encourage their natural enemies: birds, hedgehogs, toads, ground beetles.
2. By hand evening, after rainPick them off by hand on damp evenings and take them far away. Traps: hollowed-out citrus halves placed cut side down, or sunken containers of beer; check in the morning.
3. Biological when the soil is warm and moistSlug-specific nematodes (from a biological control supplier) are watered into the soil.
4. Chemical — only when nothing else helps according to the product labelLast resort only: a product authorized in your country against slugs and snails. Try non-chemical methods first.