Beans and Herbs
       
  Peas and Beans are robust plants and generally there is no difficulty at all with growing and an excellent yield of crops can be expected. Well-grown seedlings will throw off any problems as the season progresses. The single most important practice is to rotate your crops so that they grow on different ground over a 4-year cycle. See Crop Rotation. The following table may only be of interest to larger scale market growers requiring organic solutions.    
 
PESTS AND DISEASES in Peas and Beans
ANTHRACNOSE Rare. Brown sunken spots on beans. Also dark specks or patches on foliage of French and Runner beans enlarge to become dark brown cankers. Later these are covered in white or pink fungal spores. Can kill plants. Worst in very wet, cool summers. Rarely serious. Control-burn infected plants.
Prevention-rotate crops.
Do not save seed from affected plants.
CHOCOLATE SPOT Not common. Red/brown patches show on foliage of broad beans. Similarly coloured streaks show on the stems, and these may merge. Markings change to black and plants die. Can occur in wet season especially if drainage is poor and plants are growing soft due to either insufficient or excessive nitrogen, are growing in shade, or are too crowded. Overwintered crops are most vulnerable in a wet spring. Burn affected plants after harvest to prevent overwintering the fungus. Autumn potash.
Maintain pH 7- optimum for favas. Spring thinly-sown crops often escape infection.Ensure soil is well drained.
HALO BLIGHT Not common. Semi-transparent, angular watery spots surrounded by a yellow ‘halo’ show on foliage of French and Runner beans. The patches often join together and become brown and dry. Pods and leaves shrivel if the outbreak of this bacterial disease is severe, but attacks on runner plants are never severe. Can be spread by infected seeds. It is a bad practice among gardeners to soak bean seeds before sowing them Do not soak seeds before sowing.
After cropping burn plants. Do not save seed from affected plants.
Control – none.
Black Fly Very common on Broad beans.
They congregate near the growing tip from May onwards. Leaves also covered with black sooty mould. They increase rapidly if unchecked leading to weakened plants and a lower yield. Newly planted French and Runner beans also attacked from June on. Colonies suck sap from the plants. Plants sicken and can die.
A few can appear on the underside of French and Runner bean leaves if the plants are short of water at the roots.
Numbers decline from July on.
They overwinter on native euonymous.
Pinch off any young shoots that appear at ground level and at the base of broad bean plants. As soon as first pods are setting, pinch out growing point of each plant once 5 flower trusses have developed. This removes the most attractive feeding site. Keep weed-free.
Ensure that all bean plants are well watered in dry weather as a preventative measure.
Ladybirds and other insects may eventually control, but not until after damage done.
Prevention – none.
Millipedes Common. Seeds do not germinate. When dug up they are found to be rotten and infested with tiny, light brown, thread-like creatures. Rarely occurs with Broad beans. Female millipedes lay eggs in rotting vegetation. The seeds have rotted because they were sown in cold soil. Sow seed when the soil is warming.
Pea and Bean Weevil Common. Leaves notched. They feed by eating notches from the leaf margins of pea and broad bean plants. Leaf-edges of Broad bean and Pea seedlings have U-shaped holes. The larvae feed on the roots in late spring. The weevils are grey/brown, ½ cm long and emerge from the soil in June or July. They feed until the autumn. Not serious. Few gardeners worry about this pest. Damage is rarely severe and strongly growing plants quickly grow out of trouble.
Pea Aphid Large pale green or pink aphids start to colonise pea plants during May or early June. Large numbers cause damage and need to be controlled. Organic soap-based spray before the colony has had time to build up.
Slugs Common. Bean seedlings are eaten and pods which touch the ground are also frequently damaged. Practise clean cultivation. Do not leave large stones, bricks or debris around the garden. Grow away from hedges and walls.
Wireworms Common where wasteland or lawn has been prepared for vegetable growing. Seeds do not germinate or young plants die. Small hard-skinned, shiny yellow grubs are found on rotting seeds or roots. Kill all wireworms found when digging and hoeing. Hoeing also exposes the pests to birds which eat them. Baiting can be helpful – bury pieces of carrot. Inspect every few days and pick off the wireworms.
Bean Seed Fly Seeds fail to emerge. Soil-living grubs up to 8mm long feed on the seeds and emerging seedlings of peas and beans, especially early in the season. Maggots can prevent germination of French and Runner bean seed. Damage usually occurs in cold, wet seasons when germination is slow. Prevention – do not sow too early, but when soil is warming, or sow in small pots and plant out when soil has really warmed up.
Pea Moth Caterpillars badly damage peas, eating the green peas and spoiling the crop, particularly mid-season varieties. Pea moths active May/early June and lay eggs on flower stalks.
Grubs move inside developing peas until August and then overwinter in the soil as cocoons.
Sow early-maturing (round) peas. Sow middle of March - these usually escape damage because they flower before the pea moth lays its eggs. Or sow peas after mid-May. Can also sow hardy varieties in autumn to overwinter (winter cultivation will destroy some caterpillars).
BEAN MOSAIC VIRUS Leaves mottled yellow or dark green and crinkled. Plants may also be stunted and pods may be discoloured and distorted. If stems of pea plants are affected, the whole plants may collapse. The virus is spread by aphids. French and Runner beans may be affected. Remove and destroy affected plants. Control aphids.
DOWNY MILDEW Yellow patches on leaves. Lower surfaces are covered in mauve or white fungus. A problem on peas in cool, wet seasons. Affected leaves eventually turn brown and die, and the yield is reduced. Control – destroy affected plants.
Prevention – none.
Mexican Bean Beetle Turns bean leaves to lace. Handpick beetles and their tiny yellow, spiny larvae. Clusters of orange eggs can be crushed in the process.
POWDERY MILDEW Leaves covered with white powdery mould. Occurs in hot dry summers. Keep plants well watered if a very warm season.
FUSARIUM WILT Plants wilt, starting with the oldest leaves. French and Runner beans are affected. If the stem is cut, a brown stain running through the internal tissues confirms the presence of the fusarium fungus. Control – destroy infected plants as soon as possible.
Prevention – practise crop rotation. Improve soil structure and drainage.
FOOT AND ROOT ROT Leaves turn yellow and die, stems become blackened at soil level and roots rot. Both peas and beans may be attacked by this soil-borne disease. Yield will be affected and plants may be stunted. Control- destroy affected plants.
Prevention-practise crop rotation.
DAMPING OFF Seedlings fail to appear or collapse at soil level. Spray with chamomile infusion.
Mice Seedlings fail to appear. Look for signs of burrowing or seedlings nipped off at soil level. Mice are the most likely culprits and they often move systematically along the rows. Control – trapping is effective.
Prevention –none, but laying spiky leaves on top of the seed can act as a deterrent.
POD SPOT Brown sunken spots on pea pods. Peas inside may be discoloured. Leaves and stem may be spotted too. Early crops are most vulnerable and this disease is worst in wet seasons. Control-lift and destroy diseased plants.
Prevention-rotate crops.
Do not save seed of affected crops.
Pea thrips Silvery patches on pea pods. Pods may also be distorted and yield reduced. Silvery patches may occur on leaves. Attacks are worse in hot, dry seasons when the small (2mm) yellow or black thrips are more numerous. Prevention-practise crop rotation.
MARSH SPOT Brown cavity inside peas. Look also for yellowing of the leaf veins. The cause is lack of manganese in the soil. It is most common on alkaline soils. Control-none.
Prevention-incorporate organic matter into the soil before sowing. Use a fertiliser containing trace elements, such as one based on seaweed, or fritted trace elements.
GREY MOULD Pods, stems and leaves covered in grey/brown fluffy mould. This is worst in wet seasons. Prevention-avoid overcrowded or damp conditions.
RUST Brown, red or orange powdery spots or streaks on leaves. Different species of rust fungus attack a whole range of plants. Control and Prevention-remove badly affected plants to limit spread. Practise crop rotation. Do not wet the leaves when watering.
Bean root aphid Infests the roots of runner, French and sometimes broad beans during the summer. This aphid is a creamy brown colour and can be difficult to detect among the soil and roots, but its presence is indicated by the white waxy powder that the aphids secrete. This white dusting of the insects and roots can be mistaken for a mould. The aphids suck sap from the roots, and this can lead to poor growth, wilting and reduced cropping. Do not grow beans in the same soil in consecutive years if root aphid is known to have been present.
     

Companion planting
Mix of aromatic herbs – Savory, Garlic, Nasturtium, Hyssop, Sage, Calendula and Borage are bug-baffling.
Plant beans next to potatoes to deter bean beetles and potato bugs.
Root exudates from peas increase the availability of N, K, P and Ca. Tomatoes will help minimise the damage to beans caused by leaf hoppers.

     

Notes
The following are carried by seed from one season to the next - Pod spot; Anthracnose; Halo blight.

Varieties resistant to Downy mildew and Fusarium wilt :
PEA Hurst Greenshaft
PEA Markana
Resistant to Fusarium wilt :
MGT Sugar Ann
MGT Sugar Snap