Cover crops have been shown to both reduce and increase pest problems in cropping systems. Problems can be avoided with a little research and good planning. When planning a rotation, it is important to use the same considerations for cover crops as income-producing crops. For example, avoid planting any two crops from the same plant family on a particular parcel of land in sequence (such as winter annual hairy vetch (Vicia villosa L.) followed by spring green bean (Phaseolus vulgaris L.). This minimizes the likelihood of an increase in soilborne diseases or nematodes.
Most cover crops reproduce by seed and not by vegetative propagules. Cover crops allowed to form mature seed pose a risk of becoming weedy volunteers in subsequent crops. This can easily be avoided by terminating the cover crop when it is in midbloom, or when approximately 50% of the flowers are fully expanded.
Insects are often attracted to cover crops, including those that serve as vectors of viruses and diseases. When cover crops are used as surface mulch, as in reduced tillage systems, the mulch can attract slugs and rodents, in addition to beneficial insects such as carabids beetles and predatory spiders.
Typically, the benefits of including cover crops in the farming system outweigh the risk of detrimental effects; however, producers should consider both advantages and disadvantages of the selection and management of cover crop species.
