Green Vegetable Pests
ANTHRACNOSE
Crops affected: Dwarf beans, and, occasionally, runner beans.
Symptoms: Black-brown, sunken areas on the pods; brown spots on the leaves and stems. Leaves may fall prematurely.
Danger period: Throughout the growing season — especially in cool, wet summers.
Treatment: Destroy diseased plants. Sow seeds from a good supplier and in a fresh site.
BEAN SEED FLY
Crops affected: Beans, especially runner and french, and peas; certain other crops like sweetcorn.
Symptoms: Small white maggots tunnel into seeds which then often fail to germinate. Emerging seedlings wilt and become distorted.
Danger period: Immediately after sowing.
Treatment: Dust the seed drills with pirimiphos-methyl prior to sowing. Pull up and destroy affected seedlings.
BLACK BEAN APHID
Crops affected: Broad beans.
Symptoms: Small black aphids infest young shoots and suck sap.
Danger period: Late spring to mid summer.
Treatment: Spray with pirimicarb, pirimiphos-methyl, dimethoate or heptenophos. Pinch out growth tips once four trusses have set.
CABBAGE CATERPILLARS
Crops affected: Cabbages, cauliflowers and other brassicas.
Symptoms: Large, ragged holes eaten in leaves by the caterpillars of the large and small white butterflies and the cabbage moth. The last two usually burrow into cabbage hearts; the large white prefers the outer leaves. Plants may be totally destroyed, leaving just a skeleton of the tougher leaf veins.
Danger period: Early summer to early autumn.
Treatment: Inspect the undersides of leaves after white butterflies have been seen hovering — rub off and destroy any eggs. Remove and destroy caterpillars by hand if practicable. Spray with permethrin or pyrethrum or use biological control.
CABBAGE ROOT FLY
Crops affected: Brassicas.
Symptoms: Fly maggots in the soil feed on the roots, causing collapse of young plants.
Danger period: Immediately after transplanting.
Treatment: Mix diazinon + chlorpyrifos in the soil when planting, or water in pirimiphos-methyl. Use proprietary brassica collars.
CELERY FLY
Crops affected: Celery.
Symptoms: Maggots burrow into the leaves causing brown blotches. Growth is checked; severe attacks cause complete plant death.
Danger period: Early summer to autumn.
Treatment: Spray plants with dimethoate when damage is seen, or cut off and burn affected leaflets.
CABBAGE WHITEFLY
Crops affected: Brassicas.
Symptoms: Small white moth-like insects take off from the undersides of leaves. These may become soiled with honeydew and sooty mould.
Danger period: Late spring to early autumn.
Treatment: Spray with malathion, permethrin, pyrethrum or pirimiphosmethyl.
CLUB ROOT
Crops affected: Brassicas.
Symptoms: Swollen, distorted roots; yellowing, sickly, wilting foliage.
Danger period: Throughout the growing season.
Treatment: Improve drainage if necessary. Apply a generous dressing of hydrated lime to the soil; put calomel dust in the planting holes or dip roots in a solution of thiophanate-methyl. Burn infected plants.
CUTWORM
Crops affected: Lettuces.
Symptoms: Shoots eaten through at soil level; fat caterpillars in the soil.
Danger period: Early spring and late summer.
Treatment: Control weeds, which encourage cutworms, by hand or by shallow hoeing. Protect lettuces by working diazinon+ chlorpyrifos into the soil.
FLEA BEETLE
Crops affected: All brassicas, swede and turnip tops; also wallflowers.
Symptoms: Youngest leaves pitted with very small holes; growth of seedlings stunted.
Danger period: During dry, sunny spells in late spring.
Treatment: Dust seedlings with HCH, derris or pirimiphos-methyl. Good garden hygiene will often reduce the risk of attack.
GREY MOULD/BOTRYTIS
Crops affected: Peas and beans; lettuces under glass.
Symptoms: Grey mould on pea and bean pods or base of lettuces.
Danger period: Growing season.
Treatment: Prick off and destroy diseased pods by burning. Spray with benomyl, carbendazim or thiophanate-methyl.
LEATHERJACKETS
Crops affected: Brassicas.
Symptoms: Roots eaten by tough-skinned, fat, grey-brown, legless grubs. Plants wilt and may die.
Danger period: Mid spring to early summer.
Treatment: Before planting, dig deeply to expose grubs to birds. Work diazinon+chlorpyrifos or HCH into the soil.
HALO BLIGHT
Crops affected: French and runner beans.
Symptoms: Brown spots surrounded by a halo on pods, leaves or stems. Infected seeds show raised blisters.
Danger period: Growing season, especially in wet weather.
Treatment: Don’t plant infected seeds. Destroy diseased plants. Buy seeds from a good source.
PEA AND BEAN WEEVIL
Crops affected: Peas and broad beans.
Symptoms: Leaf edges are eaten in a scalloped or U-shaped pattern by small beetles. Growth of young plants is retarded. Seedlings may die if the attack is severe. Pea and bean weevils can also transmit a virus disease which affects broad beans.
Danger period: Throughout early spring to early summer.
Treatment: Prepare the ground thoroughly before sowing to encourage rapid growth. Hoe between the young plants in mid to late spring. Apply HCH dust or fenitrothion spray to young plants as soon as the symptoms are seen. Older plants are not seriously affected and they generally recover without loss of yield. Clear away plant debris and coarse vegetation which harbour overwintering weevils.
PEA MOTH
Crops affected: Peas.
Symptoms: Peas inside the ripening pods are eaten and a small maggot-like caterpillar — about 6mm (Vain) long with a pale yellow body and a black head — is present, which eventually eats its way out and crawls to the ground.
Danger period: Early summer to late summer.
Treatment: Spray about one week after the flowers first open, and again two weeks later, with fenitrothion or permethrin. Alternatively, grow early or late-maturing pea varieties which are not in flower or pod during the critical egg-laying period. Cultivate the soil thoroughly in winter to expose the caterpillars — which overwinter in the soil in cocoons — to predatory birds and cold weather, which should destroy many of them.
PEA THRIPS
Crops affected: Peas.
Symptoms: Minute, elongated insects feed on the leaves and pods causing silver mottling and distortion of pods. Severe attacks result in stunted growth and few flowers.
Danger period: Hot, dry summers.
Treatment: Spray with dimethoate or fenitrothion as soon as symptoms appear.
ROOT APHIDS
Crops affected: Lettuces, beans.
Symptoms: White, waxy aphids on roots. Leaves wilt and turn yellow.
Danger period: Summer and autumn.
Treatment: Water infested plants with a spray-strength solution of pirimiphos-methyl. Some varieties are immune to root aphids.
WHIPTAIL
Crops affected: Broccoli and cauliflowers, mainly on acid soils.
Symptoms: Leaves ruffled, thin and strap-like. This is caused by deficiency of molybdenum.
Danger period: Throughout the growing period.
Treatment: Lime the soil or apply a fritted trace element product containing molybdenum.
More on Green Vegetable Pests
Other problems affecting green vegetables
More on pests and diseases affecting peas and runner beans
Crops affected: Dwarf beans, and, occasionally, runner beans.
Symptoms: Black-brown, sunken areas on the pods; brown spots on the leaves and stems. Leaves may fall prematurely.
Danger period: Throughout the growing season — especially in cool, wet summers.
Treatment: Destroy diseased plants. Sow seeds from a good supplier and in a fresh site.
BEAN SEED FLY
Crops affected: Beans, especially runner and french, and peas; certain other crops like sweetcorn.
Symptoms: Small white maggots tunnel into seeds which then often fail to germinate. Emerging seedlings wilt and become distorted.
Danger period: Immediately after sowing.
Treatment: Dust the seed drills with pirimiphos-methyl prior to sowing. Pull up and destroy affected seedlings.
BLACK BEAN APHID
Crops affected: Broad beans.
Symptoms: Small black aphids infest young shoots and suck sap.
Danger period: Late spring to mid summer.
Treatment: Spray with pirimicarb, pirimiphos-methyl, dimethoate or heptenophos. Pinch out growth tips once four trusses have set.
CABBAGE CATERPILLARS
Crops affected: Cabbages, cauliflowers and other brassicas.
Symptoms: Large, ragged holes eaten in leaves by the caterpillars of the large and small white butterflies and the cabbage moth. The last two usually burrow into cabbage hearts; the large white prefers the outer leaves. Plants may be totally destroyed, leaving just a skeleton of the tougher leaf veins.
Danger period: Early summer to early autumn.
Treatment: Inspect the undersides of leaves after white butterflies have been seen hovering — rub off and destroy any eggs. Remove and destroy caterpillars by hand if practicable. Spray with permethrin or pyrethrum or use biological control.
CABBAGE ROOT FLY
Crops affected: Brassicas.
Symptoms: Fly maggots in the soil feed on the roots, causing collapse of young plants.
Danger period: Immediately after transplanting.
Treatment: Mix diazinon + chlorpyrifos in the soil when planting, or water in pirimiphos-methyl. Use proprietary brassica collars.
CELERY FLY
Crops affected: Celery.
Symptoms: Maggots burrow into the leaves causing brown blotches. Growth is checked; severe attacks cause complete plant death.
Danger period: Early summer to autumn.
Treatment: Spray plants with dimethoate when damage is seen, or cut off and burn affected leaflets.
CABBAGE WHITEFLY
Crops affected: Brassicas.
Symptoms: Small white moth-like insects take off from the undersides of leaves. These may become soiled with honeydew and sooty mould.
Danger period: Late spring to early autumn.
Treatment: Spray with malathion, permethrin, pyrethrum or pirimiphosmethyl.
CLUB ROOT
Crops affected: Brassicas.
Symptoms: Swollen, distorted roots; yellowing, sickly, wilting foliage.
Danger period: Throughout the growing season.
Treatment: Improve drainage if necessary. Apply a generous dressing of hydrated lime to the soil; put calomel dust in the planting holes or dip roots in a solution of thiophanate-methyl. Burn infected plants.
CUTWORM
Crops affected: Lettuces.
Symptoms: Shoots eaten through at soil level; fat caterpillars in the soil.
Danger period: Early spring and late summer.
Treatment: Control weeds, which encourage cutworms, by hand or by shallow hoeing. Protect lettuces by working diazinon+ chlorpyrifos into the soil.
FLEA BEETLE
Crops affected: All brassicas, swede and turnip tops; also wallflowers.
Symptoms: Youngest leaves pitted with very small holes; growth of seedlings stunted.
Danger period: During dry, sunny spells in late spring.
Treatment: Dust seedlings with HCH, derris or pirimiphos-methyl. Good garden hygiene will often reduce the risk of attack.
GREY MOULD/BOTRYTIS
Crops affected: Peas and beans; lettuces under glass.
Symptoms: Grey mould on pea and bean pods or base of lettuces.
Danger period: Growing season.
Treatment: Prick off and destroy diseased pods by burning. Spray with benomyl, carbendazim or thiophanate-methyl.
LEATHERJACKETS
Crops affected: Brassicas.
Symptoms: Roots eaten by tough-skinned, fat, grey-brown, legless grubs. Plants wilt and may die.
Danger period: Mid spring to early summer.
Treatment: Before planting, dig deeply to expose grubs to birds. Work diazinon+chlorpyrifos or HCH into the soil.
HALO BLIGHT
Crops affected: French and runner beans.
Symptoms: Brown spots surrounded by a halo on pods, leaves or stems. Infected seeds show raised blisters.
Danger period: Growing season, especially in wet weather.
Treatment: Don’t plant infected seeds. Destroy diseased plants. Buy seeds from a good source.
PEA AND BEAN WEEVIL
Crops affected: Peas and broad beans.
Symptoms: Leaf edges are eaten in a scalloped or U-shaped pattern by small beetles. Growth of young plants is retarded. Seedlings may die if the attack is severe. Pea and bean weevils can also transmit a virus disease which affects broad beans.
Danger period: Throughout early spring to early summer.
Treatment: Prepare the ground thoroughly before sowing to encourage rapid growth. Hoe between the young plants in mid to late spring. Apply HCH dust or fenitrothion spray to young plants as soon as the symptoms are seen. Older plants are not seriously affected and they generally recover without loss of yield. Clear away plant debris and coarse vegetation which harbour overwintering weevils.
PEA MOTH
Crops affected: Peas.
Symptoms: Peas inside the ripening pods are eaten and a small maggot-like caterpillar — about 6mm (Vain) long with a pale yellow body and a black head — is present, which eventually eats its way out and crawls to the ground.
Danger period: Early summer to late summer.
Treatment: Spray about one week after the flowers first open, and again two weeks later, with fenitrothion or permethrin. Alternatively, grow early or late-maturing pea varieties which are not in flower or pod during the critical egg-laying period. Cultivate the soil thoroughly in winter to expose the caterpillars — which overwinter in the soil in cocoons — to predatory birds and cold weather, which should destroy many of them.
PEA THRIPS
Crops affected: Peas.
Symptoms: Minute, elongated insects feed on the leaves and pods causing silver mottling and distortion of pods. Severe attacks result in stunted growth and few flowers.
Danger period: Hot, dry summers.
Treatment: Spray with dimethoate or fenitrothion as soon as symptoms appear.
ROOT APHIDS
Crops affected: Lettuces, beans.
Symptoms: White, waxy aphids on roots. Leaves wilt and turn yellow.
Danger period: Summer and autumn.
Treatment: Water infested plants with a spray-strength solution of pirimiphos-methyl. Some varieties are immune to root aphids.
WHIPTAIL
Crops affected: Broccoli and cauliflowers, mainly on acid soils.
Symptoms: Leaves ruffled, thin and strap-like. This is caused by deficiency of molybdenum.
Danger period: Throughout the growing period.
Treatment: Lime the soil or apply a fritted trace element product containing molybdenum.
More on Green Vegetable Pests
Other problems affecting green vegetables
More on pests and diseases affecting peas and runner beans
