Are Weeds Hitchhiking a Ride on Your Car?

PlosOne - Michael Ansong, Catherine Pickering

Type: Research Paper
Knowledge level: Advanced

Farm Table says:

Seed dispersal on cars shows how adaptive and pervasive weeds can be. What was especially surprising was the number and variety of weed species that can, and are, dispersed this way. A good read if you would like to improve your on farm biosecurity.

Are Weeds Hitchhiking a Ride on Your Car? A Systematic Review of Seed Dispersal on Cars

What is this paper reviewing?

This article reviews previous research on seed dispersal and spread via vehicles. This was done in the hopes of identifying what species are transported this way and where they are considered a pest.

From 13 papers, they summarised that:

  1. There are 626 species from 75 families that have seed that can be dispersed by cars. Grasses were the most common group, containing 28% of the species found.
  2. Of these, 599 are listed as weeds in some part of the world. Some of these species such as Chenopodium album (lambs quarters), Poa pratensis (Kentucky bluegrass) and Trifolium repens (white clover) were common among studies
  3. Species that favoured roadside conditions were highly successful in hitching a ride (with traits such as: disliking shade, benefiting from disturbances, high seed output, released seed <1m from the ground).
  4. Per car number of seeds ranged from 1-6, and multiplied by a regions number of cars will give an estimate of the number of seeds being dispersed by cars.  The seeds are predominantly found around front and rear bumpers, as well as wheel wells. These are areas that come into contact with mud frequently but are less exposed than areas such as the actual wheel. Interior floor mats are also common locations.
  5. Climate has a large impact on dispersal. More seeds were found on cars driven under dry conditions either on paved or unpaved roads than driven under wet conditions, irrespective of the location of seed on the car. Despite the greater potential for seed attachment in wet and muddy conditions, the seeds are more commonly washed off in these conditions.

Why should you read it?

An interesting look at how vehicles impact weed dispersal and factors that can control the extent of the spread. It could also help you to establish some cultural controls in Integrated Pest Management strategies, such as wash zones for cars before entering your property.

Final comment

There are 370 naturalized alien weed species in Australia that are frequently dispersed by cars. Care should be taken when driving into new regions, especially cropping zones, to avoid the potential spread of weed grass species.


This paper was summarised by Mia Courtney (Agricultural Sciences Student – La Trobe University) and reviewed by Nickala Best (PhD Student – La Trobe University). Learn more about Mia and Nickala here.

2013 - Australia - PlosOne - Michael Ansong, Catherine Pickering
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