Embodiments of the present disclosure pertain to modified plants or seeds that contain a mutated gene. The mutated gene includes, without limitation, a pic30 mutant, a mutant homolog of pic30, and combinations thereof. The modified plant or seed is resistant to at least one herbicide, such as picloram. The modified plant or seed may also be resistant to one or more sources of environmental stress, such as drought, plant pathogenesis, biotic stress, and abiotic stress. Additional embodiments of the present disclosure pertain to methods of controlling the growth of weeds in a field by applying at least one herbicide to the field that includes the aforementioned modified plants or seeds. Additional embodiments of the present disclosure pertain to methods of developing the aforementioned modified plants or seeds by introducing one or more of the aforementioned mutated genes to a plant or seed.