Root knot nematodes are plant parasitic nematode diseases. Root knot nematodes mainly occur in underground roots and stems, causing the formation of nodules of different sizes on the roots. In the later stages, the roots will rot in severe cases, affecting the water and nutrient absorption of the plant roots. Tumors of varying sizes were clearly formed on the roots of beets sown in the autumn of 2022 during harvest , affecting quality and yield. Root knot nematodes prefer sandy loam and gravel soil. There are many ways of transmission, including irrigation water, field weeds and seedlings. Root knot nematodes remain in the soil as eggs or larvae for one to two cropping periods.
Beet planting in autumn 2022
Planting marigold, french marigold and other plants of the Asteraceae family Tagetes as green manure crops can achieve effective biological control. Marigold and french marigold are "antagonist plants" with remarkable effects. The special substances secreted in their plants can effectively reduce the hatching rate of root-knot nematode eggs in the soil and kill their second-instar larvae. After planting, mixing the plants into the soil can effectively reduce the population of root knot nematodes in the soil.
Marigold planting in the same area as a green manure rotation in summer 2023
Autumn beet planting in the same area in 2023
Round and smooth root harvested in the early of 2024
If you find that there are nodules or tumors of different sizes on the roots of crops, you can then plant marigolds, french marigold and other Asteraceae marigolds as green manure crops in the crop rotation, which can effectively reduce the population of root knot nematodes in the soil.