Pests & Diseases - Peas

DISEASES

11. Pea Fusarium wilt PGROPea wilt (Fusarium oxysporum f. sp. pisi)

  • Plants appear stunted and may become discoloured before shrivelling and dying.
  • Wilt is a soil-borne disease which can occur in any pea growing area.
  • It is generally confined to fields with a very long history of peas and may occur in patches or individual plants.
  • It can cause substantial reductions in yield, but is effectively controlled by genetic resistance.
  • See PGRO Pulse Agronomy Guide.

12. Pea downy mildew PGRODowny mildew (Peronospora viciae)

  • Individual or small groups of plants appear stunted or pale.
  • Gray velvety fungal growth develops on the underside of leaves.
  • This disease produces resting spores, which persist in the soil and initiate primary infections in young pea plants.
  • Secondary infections develop in cool, damp conditions.
  • Pods develop yellow patches on the surface and a cottony growth on the inner pod wall.
  • See Technical Update TU33 and the PGRO Pulse Agronomy Guide and Vining Pea Growers Guide for varietal resistance.

13. Pea leaf and pod spot PGROLeaf and pod spots (Ascochyta pisi, Mycosphaerella pinodes and Phoma medicaginis)

  • A. pisi produces brown to grey rounded lesions with pin-prick sized fruiting bodies (pycnidia).
  • M. pinodes produces numerous purple-black small lesions on stems and foliage. Lower stem may become black.
  • P. medicaginis produces smaller dark lesions and black stem girdling.
  • Leaf and pod spots are spread by seed infection, soil or plant debris.
  • The most frequent is M. pinodes, which can cause losses in both yield and quality in wet conditions.
  • The use of disease-free seed will help to reduce the incidence of disease.
  • See Technical Updates TU33 and TU12.

14. Botrytis in peas PGROBotrytis, or grey mould (Botrytis cinerea)

  • Botrytis produces brown, watery rot with a grey furry mould.
  • This can affect stems and pods during wet weather.
  • It is initiated when petals stick to plant parts after pod set.
  • See Technical Update TU12.

Powdery mildew (Erysiphe pisi)

15. Pea powdery mildew PGRO

  • Powdery mildew is characterised by irregular areas of powdery white fungal growth on the upper leaf surface and pods.
  • The disease can delay maturity.
  • The disease can adversely affect the flavour of processed peas.
  • See Technical Update TU12 and the PGRO Vining Pea Growers Guide.

Foot and root rots (Fusarium solani f. sp. pisi, Phoma medicaginis var. pinodella)

  • 16. Pea foot rot in field PGROThe diseases produce areas of pale discolouration, stunted plants and yield reduction.
  • Plants can be brown or black at soil level.
  • Roots are often brown.
  • The effects of these diseases are particularly common on heavy land with a history of frequent pea cropping.
  • A predictive soil test is available from PGRO.

Sclerotinia, or white mould (Sclerotinia sclerotiorum)

  • 17. Sclerotinia in peas PGROS. sclerotiorum causes a stem rot rather than a foot rot.
  • Dense, white mycelium cover stems and pods.
  • Stems collapse in a watery soft rot.
  • Infected stems and pods may contain black, elongated resting bodies.
  • The disease affects peas, spring beans, oilseed rape, linseed, and sometimes potatoes and certain field vegetables.
  • See Technical Update TU12.

18. Pea Bacterial blight PGROBacterial blight (Pseudomonas syringae pv. pisi)

  • This is a potentially serious seed-borne disease, which can occur on all types of peas.
  • Symptoms consist of water-soaked brown lesions on the lower leaves, stems and stipules.
  • The lesions may coalesce and show a fan shape on the leaf, between the lines of the veins.
  • Some pod spotting may occur.
  • Severe infections have not occurred in spring-sown peas and effect on yield has been negligible.
  • See Technical Update TU32.

PESTS


19. Pea weevil damage PGROPea and bean weevil (Sitona lineatus)

  • The adult is 4-5 mm long with a narrow body, short snout and angled antennae.
  • The larva is white and legless with a brown head.
  • The pest causes damage to spring sown crops if large numbers appear when plants are small.
  • Leaves of attacked plants show characteristic ā€˜Uā€™ shaped notches around the edges.
  • The main damage occurs as a result of the larvae feeding on the root nodules.
  • See Technical Update TU08.

20. Field thrips in peas PGROField thrips (Thrips angusticeps)

  • Field thrips are black, 1-1.5mm in length and are found in enfolded leaflets.
  • They feed on the leaf surface of emerging seedlings.
  • Foliage becomes thickened and puckered.
  • Seedlings may appear pale in colour.
  • In the majority of cases the peas will outgrow the effects of thrips.
  • See Technical Update TU07.

21. Pea aphid PGROPea aphid (Acyrthosiphon pisum)

  • Pea aphid adults are 1-2 mm long, bright green, pear shaped with slightly dark legs and have distinctive red eyes.
  • Aphids can cause severe yield loss when feeding in large colonies.
  • Aphid feeding causes growth distortion of foliage and pods, and abortion of flowers.
  • Early infestations can result in crops becoming infected with pea enation mosaic virus.
  • See Technical Update TU05.

22. Pea moth caterpillar PGROPea moth (Cydia nigricana)

  • The pea moth has a wing span of 12-15mm, is silvery-brown in colour with indistinct black and white markings on the wing tips.
  • The larva is creamy white, with a brown to black head and is up to 6mm in length.
  • The larvae feed upon the developing seeds within the pod.
  • Yield loss is minimal, but the effect on quality can be dramatic.
  • Damage to the seed reduces the value of the produce.
  • An automatic telephone forecasting service is provided by PGRO on 01780 783099.
  • See Technical Update TU03.

23. Pea cyst nematode PGROPea cyst nematode (Heterodera gottingiana)

  • Affected plants are stunted and pale, and the root systems do not develop nitrogen-fixing nodules, but become studded with white, lemon-shaped cysts.
  • Infestations occur in distinct patches that vary in size.
  • Pea cyst nematode is a very persistent soil-borne pest, often causing severe yield loss.
  • Frequent cropping of peas and Vicia faba beans favours the build-up of infestations.
  • See PGRO Pulse Agronomy Guide.

Silver Y moth

25. Autographa gamma 5894127. Autographa gamma26. Autographa gamma 91338

  • The main damage occurs due to produce contamination in vining peas by the caterpillar
  • Adult moths are about 10 - 15 mm in length, have a brownish grey hairy body and greyish coloured wings, with a distinctive silver coloured y marking on each forewing
  • Most moths migrate to the UK during June, from Mediterranean countries or North Africa
  • The moths feed on nectar and lay eggs singly or in pairs on the foliage
  • After 10 ā€“ 14 days, the eggs hatch and caterpillars begin feeding on the leaves
  • Caterpillars are bright green in colour varying in size up to 20 - 25 mm in length
  • Silver Y moth migration is sporadic and because of this, populations vary between years and it is difficult to predict numbers in any one season. However, moths can be monitored using a pheromone trap available from Agralan Ltd., The Old Brickyard, Ashton Keynes, Swindon
  • In peas, the trap is placed at crop height in the field in late May and moths, caught in the base, are counted on three occasions during each week of monitoring. A threshold is reached when a cumulative total of 50 moths has been reached by the time that the peas have reached the first pod stage (gs 204)
  • When the threshold has been reached, a single spray of a pyrethroid insecticide, approved for pea moth control, should be applied 10 - 14 days later. This application will control both large and small caterpillars, which fall off the plants before the crop is harvested
  • See Technical Update TU04

DISORDERS


24. Marsh spot in peas PGROMarsh spot

  • Marsh spot is a disorder of peas, which is due to deficiency or unavailability of manganese.
  • The deficiency causes the formation of a brown spot in the centre of many of the peas produced, and the produce is spoilt for human consumption and for use as seed.
  • It is particularly associated with organic and alkaline soils.
  • See Technical Update TU01.

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