SciDev.Net: Farmers may one day be able to target pesticides to only those parts of their fields that are at risk of disease simply by noting which ones are glowing, according to researchers. Scientists have genetically engineered the natural immune system of the tobacco plant to make it change colour or glow in the presence of viruses, bacteria and other pathogens known to reduce crop yields, which normally force farmers to apply costly pesticides. In laboratory tests, these …