Howard Ferris

Nov 30, 2001

Key Points:

1. For any starting nematode population level, e.g., 5, 15, 50, 150 (panels A,B,C,D), the population will increase at a predictable rate on a given host crop, and then decline at a predictable rate under non-host crops.
2. At some time in the future, the population will decline to, or below, the level of the starting population. If a host crop is planted at that time, the population should undergo the same increase and decline pattern as before unless conditions in the field have changed in some dramatic way. Consequently, a length of non-host rotation can be determined that will always bring the population back to its starting level.
3. So, if we calculate the length of non-host rotation necessary to achieve this steady-state cycle for different starting population levels, we can determine the returns from that number of years of non-host production. We can also calculate the returns from the host crop at that starting population level.
4. That allows determination of the population level and years of non-host rotation for which average annual returns are maximized. The result will vary with crop values of host and non-host crop, damage effect of the nematode on the host crop, multiplication rate of the nematode on the host, and survival rate of the nematode on the non-host.

Reference: