March 2011. A member from Australia wrote to say that two trees have been lost to glyphosate coming from a next door neighbours garden. Is there anything that can be put in the soil to stop the spread of the herbicide? The barrier much still allow the movement of water.

It was thought very unlikely that glyphosate would move through the soil, unless the soil was extremely low in organic matter; the glyphosate should be immobilized in the soil. Very small amounts of glyphosate drifting in the air can be very damaging to susceptible plants, especially papaya trees and tomato plants. The neighbour could try spraying at lower pressure, at a different time of day, and use a sticker to reduce drift. It would be surprised if Australian law does not protect residents from careless spraying by neighbours.

Planting Wedelia trilobata (syn. Sphagneticola trilobata, Thelechitonia trilobata). This ground cover is very tolerant. (Editor: it is also very invasive, and can become a terrible weed!).

There are absorbent socks, pillows and tubes available for soaking up chemical spills; however, they are expensive and usually used around chemical storage and filling areas where they are stored dry ready for use in an emergency. They can made using pet litter or vermiculite. Once wetted they will not absorb chemicals and they decay in sunlight. A better approach may be to use straw or grass clippings to prevent chemical movement associated with soil particles in runoff water. Glyphosate binds strongly to clay particles in the soil and organic matter, so movement in water might only be an issue if the soil is very sandy.

The loss of trees suggests that foliar application has occurred and the neighbour is applying the chemical in an inappropriate manner. The neighbour needs to be made aware that it is probably glyphosate that is killing your trees and informed that more care needs to be taken when spraying adjacent to your property.

However, it is necessary to be sure that only glyphosate is being used as trees are usually tolerant of the ‘overspray’ whne they suffer drift at weed control rates. Are there photos of hte damage that can be shared?

A subsidary question was asked by a person in Fiji, and that was whether herbicides in general affect the fertility of the soil. There was no answer to the question, but an article on the environmental impact of glysphosate on glyphosate-tolerant crops was provided see, message 7910). This was less than the impact of other herbicides on non-glyphosate tolerant crops when the breakdown products of glyphosate, which are said to be more toxic than glyphosate, are taken into account.