Aromatic species interplanted with brassicas are reported to reduce cabbage-worm damage
Aromatic species interplanted with brassicas are reported to reduce cabbage-worm damage. The mechanism is unresolved and trial results are mixed.
A good hunch 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
Unresolved, and we don't pick one. Two explanations have been proposed. The herbs' volatile oils (their scent) may mask the cues pests use to find the host plant, or they may disrupt the pests' landing. The trials that report an effect measured damage, which can't separate fewer eggs laid from fewer larvae surviving or more predators arriving. So no mechanism here is established; there are only candidates.
How much it matters: Reported reductions vary widely; some trials show none. Do not promise a number.
The evidence
Evidence: checked against 1 source in the research-based literature.
The source
In an Iowa study, thyme, onion and nasturtium helped to reduce cabbage looper and imported cabbageworm damage in broccoli
Plus 4 working notes on how the sources were read. Every note is in the data download.
Plant teams that rest on it
Folklore it answers
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How this rule has changed
Every change is dated, newest first. The full record, with each reason, is in the data download.
- Wording made clearer
- Wording made clearer
- A person read the sources and confirmed it
- Added to the rules
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Cite this page
Milpa Gardens. “Aromatic species interplanted with brassicas are reported to reduce cabbage-worm damage. The mechanism is unresolved and trial results are mixed.” Evidence grade: A good hunch. https://milpa.garden/rules/aromatic-species-interplanted-brassicas-reported-reduce-cabbage/
A garden planner built on graded evidence. Every claim states its evidence grade and links its sources on the page. Cite it with the grade, and add the date you read it.
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How we grade evidence
- Well established
- The rule names its mechanism and is settled, by sources a person has read and checked or by plain arithmetic and geometry.
- Promising
- The mechanism is named and the literature backs it. A few questions are still open.
- A good hunch
- Plausible by its mechanism, but field studies are thin, so treat it as a lean.
- Contested
- The evidence points both ways, or no study has tested it, so the planner does not enforce it.
- Refuted
- The claim did not survive its sources. It is kept so the folklore can be answered.