| - Not present. | 1 Of little importance. |
| 2 Occasionally important. | 3 Liable to cause damage if present. |
| Pest | Effect on winter rape | Effect on spring rape | Stage of crop attacked | Description of pest | Damage |
|---|---|---|---|---|---|
| Brassica pod midge | 3 | 3 | Late flowering and pod set | Adult:small delicate fly. Larva:tiny, white, legless. Usually about 10 per pod. | Adults are not damaging. Larvae feed on pod wall leading to premature shattering. |
| Cabbage seed/pod weevil | 2 | 2 | Flowering and pod set | Adult:small, grey weevil with long snout. Larva:cream, fleshy, with shiny brown head, legless. Usually only one per pod. | Adults cause no obvious damage but can be found on plants. Feeding and egg laying punctures in pods provide entry sites for pod midge. Larvae feed on seed within developing pod. |
| Cabbage stem flea beetle | 3 | - | Establishment and during winter | Adult:metallic greenish-black or brown beetle, long antennae, large hind legs, can jump like fleas. Larva:white with black head and black plate at hind end. Six legs. | Adults make holes in leaves. Usually unimportant unless crop is backward or slow growing. Larvae mine in stem and leaf petioles. Can be serious, killing young plants. |
| Cabbage leaf miner | 1 | 1 | Establishment and during winter | Adult:medium sized yellow and grey fly Larva:white with black head and black plate at hind end. Six legs. | Adults are not damaging. Larvae mine in shoots and stems. Leaves turn yellow and die. Usually unimportant. |
| Rape winter stem weevil | 3 | - | Establishment and during winter | Adult:black, similar to seed weevil in shape tips of legs reddish-brown. Larva:similar to seed weevil. | Adults are not damaging. Larvae tunnel in leaf stalks and stems. November to May. Terminal bud killed. |
| Cabbage root fly | 1 | 1 | All stages | Adult:grey/black fly with black bands on thorax Larva:white, legless. | Adults are not damaging. Larvae mines in roots. Plants wilt in autumn during dry weather. |
| Cabbage stem weevil | - | 1 | Establishment and later | Adult:very similar to seed weevil. Larva:similar to seed weevil. | Adults are not damaging. Larvae tunnel into leaf stalks and stems during May and June. |
| Cabbage aphid | 1 | 1 | - | Dense colonies of blue-grey aphids | Looks bad but seldom is. Usually only isolated plants affected. |
| Pollen (blossom) beetles | 1 | 2 | Flowering | Adult:small, metallic greenish-black beetle. Larva:pale with shiny brown head, six legs. | Adults feed in buds. Usually leads to blind bud. Larvae feed within bud, mainly on pollen. May lead to blind bud. |
| Flea beetles | - | 1 | Establishment | Adult:smaller than cabbage stem flea beetle but also have large hind legs. | Feed on newly emerged plants, pitting the seed leaves. Rarely damaging. |
| - Not seen. | 1 Uncommon. |
| 2 Common in some years. | 3 Common in most years. |
| Disease | Leaves | Pods | Colour on upper leaf surface | Description |
|---|---|---|---|---|
| Alternia (dark leaf/pod spot) | 3 | 3 | Black to dark brown | Often in groups, circular, black/brown spots up to 5mm diameter. |
| Downy mildew | 3 | 2 | Yellow or white | Yellow: Variable size, irregular black speckling. White fungus on underside of spots. White: Yellow margin and irregular brown/black speckling. Little/no fungus on underside, speckling can occur pods. |
| Phoma leaf spot | 3 | 2 | Light green/fawn/white | Spots up to 10mm diameter, bearing small black fruit bodies (pycindia). Brown spots bearing pycindia occasionally on pods. |
| Powdery mildew | 2 | 2 | Faint yellowing | Radiating fluffy white fungus, Most on underside of leaves, occasionally on pods. |
| Light leaf spot | 3 | 2 | Light green/fawn | Irregular mealy blotches with bleached centres. Tiny white spots around blotch edges. Occasionally on pods. |
| Botrytis (grey mould) | 3 | 3 | Grey | From flowering onwards, associated with deposition of petals and pollen on leaves. Fluffy grey fungus, often on previously damaged pods. |
| White leaf spot | 1 | 1 | White with grey/black centre | Small , circular white spots on leaves, 1-5mm diameter, similar on pods. |
Key - Symptoms:
| - Not seen. | 1 Uncommon. |
| 2 Common in some years. | 3 Common in most years. |
| Disease | Roots | Stems | Colour on stem | Description |
|---|---|---|---|---|
| Phoma canker | 3 | 3 | Fawn/white | At stem base, variable size with small black fruiting bodies (pale centre), dark outer margin. |
| Sclerotina stem rot | - | 2 | Bleached white | White or black resting bodies within stem cavity. |
| Botrytis (grey mould) | - | 3 | Bleached white with grey fungus | Associated with previous damage. |
| Light leaf spot | - | 3 | Pinkish-brown | Streaking with black speckling at edge of pink tissue, develops from leaf base. |
| Powdery mildew | - | 2 | White/grey | White fungus. |
| Downy mildew | - | 3 | White | Sparse weft of fungus. |
| Alternaria | - | 3 | Black | Small black spots, 1-3mm diameter. |
| Clubroot | 1 | - | . | Roots abnormally swollen and contorted, flesh has marbled appearance. |
| Phytophthora root rot | 1 | - | . | Roots rot and outer layers slough off. |