"Weedkiller" Mexican Marigold
Answered by: Inge Poot
Question from: Sharon Bahringer
Posted on: March 2, 2000

We found your email address in your catalog, but nowhere on your website.

Our email addresses are listed in several places on our website, including the "Q&A" section (in the experts’ profiles) and the "Ordering & Shipping" section.

We are looking for the marigold – Tagetes – that you call a "weed-eating plant" in your hard copy catalog. What we’d like to know is: WHAT it eats – which "weeds"? HOW it works? And any other helpful information.

Actually this information is in our printed catalogue on page 35 in the year 2000 version. Marigolds all produce toxic root secretions which help them to overcome competition from plants trying to grow in the same area. The most effective species is Tagetes minuta, with the common name of Mexican marigold. It grows very tall and in this way also adds shading out of its competitors to its arsenal of self defense. It has tiny flowers -hence the latin name "minuta" but these are only produced in very long season regions.

Most marigolds also have an unpleasant odour that also seems to be unpleasant to insect noses. They are therefore used to repel insects like mosquitoes.

The underground secretions are also toxic to nematodes and the plant is therefore used to reduce the populations of this pest in garden plots.

Weeds that have a hard time growing near Mexican marigold because of the root secretions and the shading, are such hard to eradicate weeds as ground elder, bindweed, couch grass and ground ivy. This effect spreads about 90 centimeters (3 feet) from the base of the plant.

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