Weed control Weeds 9 Biological Control 7 Biological control 7 Natural enemies 7 Weed science 7 Weeds and Noxious Plants 7 Cultural control 5 Plant Ecology 5 Chemical control 4 Environmental Pest Management 4 Insect pests 4 Pest control 4 Plant Pests, (New March 2000) 4 Plant ecology 4 Plant pests 4 Taxonomy and Evolution 4 herbicides 4 Arthropod pests 3 Biological control agents 3 Pesticides and Drugs; Control, (New March 2000) 3 Physical control 3 Plant Breeding and Genetics 3 Plant disease control 3 Plant diseases 3 Taxonomy 3 Viral, Bacterial and Fungal Diseases of Plants, (New March 2000) 3 Adaptation 2 Agriculture 2 Conservation 2