A young transplant can be cut off at the soil line overnight by a cutworm
A young transplant can be cut off at the soil line overnight by a cutworm, a caterpillar that curls around the tender stem and severs it just above the ground. A collar around the stem blocks it.
Promising A person has checked it against its sources. If you skip this, it still grows, just less well. The planner suggests it.
How it works
Cutworms are the soil-dwelling caterpillars of several night-flying moths. They feed after dark, curling the body around a seedling's stem and chewing through it at or just above the soil surface, which topples the whole plant. A young transplant is vulnerable because its stem is small and tender; as the plant grows the stem thickens past what a cutworm can encircle and cut, so the risk is an early-season one. A collar of cardboard, stiff paper, or foil, set around the stem and pushed into the soil, is a physical barrier the cutworm can neither climb over nor tunnel under to reach the stem.
What to do about it
Around each new transplant, set a collar of cardboard, folded paper, or foil a few centimeters tall, with one edge pushed a few centimeters into the soil and the rest standing above it, so the cutworm cannot get over the top or under the bottom to reach the stem. Once the stem thickens the collar can come off.
How much it matters: No incidence figure is stated or estimated. Cutworm pressure is local and episodic, and the collar is a cheap preventive for the early-transplant window, which is why the rule only advises.
The evidence
Evidence: checked against 2 sources in the research-based literature.
The 2 sources
Cutworms curl their bodies around the stem and feed on it. This feeding causes the plant to be cut off just above the soil surface
Collars of cardboard, aluminum foil, or metal can be placed around transplants at planting to prevent feeding
Where this rule stops
The risk is to young transplants with soft stems; once a stem has thickened, cutworms leave it alone.
Read next
How this rule has changed
Every change is dated, newest first. The full record, with each reason, is in the data download.
- Details updated
- Wording made clearer
- Added to the rules
Cite this page
Milpa Gardens. "A young transplant can be cut off at the soil line overnight by a cutworm, a caterpillar that curls around the tender stem and severs it just above the ground. A collar around the stem blocks it." Evidence grade: Promising. https://milpa.garden/rules/young-transplant-can-be-cut-off-soil/
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- Plausible by its mechanism, but field studies are thin, so treat it as a lean.
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