root knot nematode of watermelon
Figure 1. Roots of watermelon many galls due to root knot nematode. 
Figure 2. Galls of root knot nematode on watermelon roots. 
Figure 3. Root nematode galls on a watermelon root system that has been washed to reveal symptoms of root knot. 
Figure 4. A watermelon seedling that has been recently transplanted in the field has root knot galls visible. Note that symptoms of decline of the plant foliage are visible. 
Figure 5. Close up of watermelon roots of transplant with galls. 
Figure 6. Severe root knot nematode galls on watermelon roots.