The root knot nematode pathogen is a tiny, microscopic round worm that can infect a wide range of host plants, including tobacco. Infested fields typically have irregular patches of stunted, yellowed plants. Notice the various growth sizes of plants in this image. (Photo: Kenneth Seebold, UK)

This tobacco plant is stunted due to root knot nematode. On hot days, infected plants wilt more readily than healthy plants. (Photo: Kenneth Seebold, UK)

Galls and swellings form on roots infected with root knot nematode. Roots become dysfunctional, which results in the above-ground symptoms of stunting, yellowing, and wilting. Severely infected plants die. (Photo: Kenneth Seebold, UK)