Clover pests and disease

From slugs to stem eelworm, read about the common pests and disease of clover.

• Stem eelworm – causes distortion of growing buds and young leaves, and death of the plant. (Note: not the same strains for white and red clover, so white clover can be sown between red clover crops to break the pest cycle)
• Slugs – major pests for both red and white clover. Use molluscicide*
• Sitona weevil – more common in arable areas, leads to removal of small, semi-circular sections of leaf. Treatments for frit fly or leatherjackets can reduce the pest problem, but no specific insecticide is available
• Leatherjackets – more common after ploughing old pastures. Sprays for leatherjacket control are no longer available. Consider killing off the grass in the autumn and leaving the land fallow over the winter, before reseeding in the spring. Improve soil drainage. Potential biocide use, e.g. Bacillus thuringiensis, but no clear scientific support as yet
• Clover yellow vein virus (CYVV) – severe strains can cause intense, severe yellowing of leaves, followed by premature death. Plants are usually stunted and seed pods show some deformation
• Pepper spot – small, blackish-brown lesions of about 1mm in diameter are produced in great abundance. The whole leaf looks as if it has been sprinkled with black pepper. The surrounding areas gradually turn yellow and eventually the leaf withers 

• Stem eelworm – most important pest. Most effective control is rotation, a 5-year break is recommended between red clover crops, extended to 7 years if stem eelworm is present
• Slugs – major pests for both red and white clover. Use molluscicide*
• Powdery mildew – visible in small patches of fine, white-grey, cobweb-like growth on upper leaf surface, which develops into a white dusting. Apply fungicide* at first sign of disease, unless late in season, when application will not be cost-effective. Use resistant varieties
• Red clover vein mosaic virus (RCVMV) – causes plants to be stunted, with yellowing, curling leaves. Plants rapidly wilt and collapse. Several aphid species, including the pea aphid, can transmit the virus. There are no known, resistant, commercial cultivars

*Seek advice from a qualified professional and ensure sprayer operators are fully qualified.

White clover will often rapidly recolonise areas affected by pests or diseases by extending the stolons of the remaining plants into the gaps.

Red clover plants grow from a single crown, so recolonisation of areas affected by pests or diseases is not possible. Grow with companion grasses to help prevent weed ingress into bare patches.

If you would like to order a hard copy of the Establishing and growing clover guide or Recommended Grass and Clover Lists, please contact publications@ahdb.org.uk or call 0247 799 0069.

The information in these web pages was sourced from Germinal, Grassland Development Centre (IBERS, University of Aberystwyth) and Charlie Morgan (GrassMaster Ltd).