About three weeks after root penetration, the female becomes swollen, and pear-shaped. The male at the same time reverts to its previous worm-shape and exits the root without feeding. Eggs may hatch immediately and juveniles may reinfect the root, or may overwinter and hatch next spring. The female dies soon after laying eggs. The number of nematodes in a field varies throughout the year.
Populations usually are lowest at planting and greatest at crop maturity.
Root-knot nematodes have limited ability to survive in frozen soil. Populations decline in the winter when soils freeze. As much as 99 percent of the nematodes in a field may die during the winter. However, the population can increase rapidly during the summer. It is not unusual for populations to increase more than 100 times between planting and harvest.