||Reduce crop yield , Reduce crop quality
||Serve as an alternative hosts of pests: insects, diseases, birds and rodents.
||Provide habitat and food for predatory and parasitic insects.
||Interfere with crop management and harvest.
||Sources of genes for crop breeding.
||Impair human and livestock health.
||Sources of medicines and other useful substances, human foods and animal fodders.
||Depreciate land value.
||Add organic matter to the soil.
||Compete with crops for insect Pollinators.
||Provide aesthetic pleasure and useful for landscape.