Weed Identification
Weed Science Society of America: http://wssa.net/wssa/weed/weed-identification/
Weed Science Organization: http://www.weedscience.org/
Resistance Fighter: Herbicide Resistance Management http://www.syngenta-us.com/herbicides/resistance-fighter
University of Minnesota Extension: https://extension.umn.edu/weed-management/weed-identification
University of Nebraska Lincoln Extension grasses: http://extensionpublications.unl.edu/assets/pdf/ec3020.pdf
University of Nebraska Lincoln Extension winter annuals: http://extensionpublications.unl.edu/assets/pdf/ec304.pdf
Insect Identification
Iowa State university Extension field crop insects: https://www.ent.iastate.edu/soybeanresearch/files/page/files/FieldCropInsects final 2012.pdf
Disease Identification
Iowa State university Extension plant diseases: https://cropwatch.unl.edu/plantdisease
