Nematodes are microscopic, non-segmented roundworms that occur naturally in soil worldwide. They are beneficial nematodes because they can be used as a biological control agent against various soil-dwelling pests, including grubs. The best time to apply nematodes to control grubs is in the spring or fall when soil temperatures are within a specific range.
Key Facts
- Timing: Nematodes can be applied in two periods: in the spring when soil temperatures are above 10°C (often early May to early June) and in the fall before the soil gets too cold (mid-late September to mid-October).
- Soil temperature: Beneficial nematodes should be applied when soil temperatures range from 42°F to 95°F (5.5°C to 35°C). They remain effective up to 95°F, but no longer parasitize prey above that temperature.
- Application rate: The application rate of nematodes depends on the size of the area to be treated. For example, 5 million nematodes treat 1,600 sq. ft., 10 million treat 3,600 sq. ft., 50 million treat 1 acre, 250 million treat 5 acres, and 500 million treat 10 acres.
- Multiple applications: It is recommended to make at least two applications of nematodes, separated by 7-10 days, to stagger the life cycles of the nematodes and ensure complete coverage. In cases of severe infestations, applications should be made every 7-10 days or until the infestation subsides.
Spring Application
In the spring, nematodes can be applied when soil temperatures reach above 10°C (often early May to early June). This timing is crucial because it coincides with the active period of grubs in the soil. As the grubs feed on plant roots, they become susceptible to nematode infection. The nematodes enter the grubs’ bodies through natural openings and release bacteria that kill the grubs within 24 to 48 hours.
Fall Application
Nematodes can also be applied in the fall before the soil gets too cold (mid-late September to mid-October). This application targets grubs that have hatched from eggs laid by adult beetles in the summer. The nematodes infect and kill the grubs before they can cause significant damage to plant roots.
Application Rate and Frequency
The application rate of nematodes depends on the size of the area to be treated. For example, 5 million nematodes treat 1,600 sq. ft., 10 million treat 3,600 sq. ft., 50 million treat 1 acre, 250 million treat 5 acres, and 500 million treat 10 acres.
To ensure effective control, it is recommended to make at least two applications of nematodes, separated by 7-10 days. This staggered application helps to target grubs at different stages of their life cycle and ensures complete coverage of the treated area. In cases of severe infestations, more frequent applications may be necessary.
Soil Temperature and Nematode Efficacy
Nematodes are most effective when applied at soil temperatures ranging from 42°F to 95°F (5.5°C to 35°C). They remain effective up to 95°F, but they no longer parasitize prey above that temperature. Therefore, it is important to apply nematodes when soil temperatures are within the recommended range to ensure their optimal performance.
Conclusion
Timing is a crucial factor in the successful application of nematodes for grub control. Applying nematodes in the spring or fall when soil temperatures are suitable allows for effective targeting of grubs and minimizes the risk of pest damage to plants. By following the recommended application rates and frequency, homeowners and gardeners can effectively manage grub populations using beneficial nematodes.
FAQs
When is the best time to apply nematodes for grub control?
The best time to apply nematodes for grub control is in the spring (early May to early June) and fall (mid-late September to mid-October) when soil temperatures are within the optimal range for nematode activity (42°F to 95°F).
Why is timing important for nematode application?
Timing is important because nematodes are most effective in controlling grubs when applied during their active periods in the soil. Spring and fall applications target grubs at different stages of their life cycle, ensuring effective control.
How often should nematodes be applied?
It is recommended to make at least two applications of nematodes, separated by 7-10 days. This staggered application helps to target grubs at different stages of their life cycle and ensures complete coverage of the treated area.
What soil temperature is ideal for nematode application?
Nematodes are most effective when applied at soil temperatures ranging from 42°F to 95°F (5.5°C to 35°C). They remain effective up to 95°F, but they no longer parasitize prey above that temperature.
How long does it take for nematodes to kill grubs?
Nematodes typically kill grubs within 24 to 48 hours after infection. However, it may take up to two weeks to see a noticeable reduction in grub populations.
Can nematodes be applied in the summer?
Nematodes can be applied in the summer if soil temperatures are within the optimal range (42°F to 95°F). However, it is important to note that nematodes may be less effective in hot and dry conditions.
Can nematodes be applied in the winter?
Nematodes can be applied in the winter in mild climates where soil temperatures remain above 42°F. However, in colder climates, nematodes may not survive the winter and may not be effective in controlling grubs.
Are nematodes safe to use around plants and pets?
Yes, nematodes are safe to use around plants and pets. They are naturally occurring organisms that do not harm beneficial insects, wildlife, or humans.