Herbicide Damage

I am very concerned about the number of gardeners that have asked me why their tomatoes/beans/potatoes are growing funny this season. When we say funny we are referring to distorted or rolled leaves, new growth that is mishapped, beans that come up and die off and feather like foliage. These aspects are related to mainly tomatoes, potatoes, beans, grapes and roses.

The pictures that I have asked to be sent to me have all indicated herbicide damage.
Usually other plants in the same area appear to be unaffected which indicates that the amount of herbicide is very small at parts per million. Stronger amounts would kill the herbicide sensitive plants (tomatoes etc) and likely have shown as die back in other plants including weeds.
Where did the herbicide come from? The first thought is from the spraying of weedkillers somewhere in the neighbourhood. If someone nearby has sprayed on a day when spray drift can be carried by the wind then that is a possibility.

If someone has sprayed on a calm day within a few miles of your property then that could be the cause. What can happen on a calm day is the minute droplets of spray are lifted on conventional air currents up into the air, from there; they are carried by air currents for any distance before dumping, maybe on your tomatoes.
The worst time for anyone to be spraying herbicides is on a windy or calm day. The best time is on a day when there is a light breeze and the person spraying can direct the spray to target plants only.

Placing a shield over the nozzle of the sprayer is recommended to prevent any drift or uplift of the chemicals into the air. You can make a shield very simply by taking the nozzle off the end of your spray wand, then making a hole in the middle of a plastic 2 litre ice cream container to fit nicely over the end of your sprayer’s nozzle, after which you screw the nozzle surround back on.
Most effective and all you need to do is place the ice cream container over the target weeds and pull the trigger. All the chemical spray stays inside the container.
Then move to the next weeds making sure you don’t drip herbicide on preferred plants.

If you are not using a shield then make sure your nozzle on your sprayer is not producing a mist, instead make sure it is producing heavy droplets by adjusting it. You can also use a food dye in the mix to determine where your sprays are going.

Unfortunately you have very little control as to what other people are doing around you and your gardens are always at risk from air borne sprays.

If you know that a neighbor is spraying weed killers then the best thing to do is to apply good amounts of water to the foliage of your herbicide sensitive plants with the hose and water other plants as well.
By diluting any air borne chemical that may land on your plants will reduce the potential problem.
Likely you have read about the commercial grapes that were hit recently with a herbicide, causing possible losses of millions of dollars.

Every now and then I hear about gardeners who have sprayed their roses or gardens with a sprayer that has either a herbicide in the sprayer or has been used in the past for weed killing.

Herbicides are fairly good keepers and if you don’t use all the made up product there is a great temptation to leave it in the sprayer for next time. This is ok if you mark in bold letters on the sprayer, ‘Weed Killers Only’

Have a separate sprayer for other sprays that are not weed killers.
If you wash out a plastic sprayer that has had a weed killer in it, there is a very good chance that you will damage roses, grapes, tomatoes, potatoes and beans if you use that sprayer for insecticide. The plastic is porous and it can retain some of the herbicide which is very difficult to wash out completely, but can release out with other spray mixes.

Be safe, not sorry, as it costs a lot more to replace plants than buy a second sprayer.
So we have looked at the possibility of air borne sprays from our surrounds and our own sprayers yet there is a more devious way of harming your sensitive plants.

The first time I came across another herbicide problem was many years ago when a fertiliser drive to raise funds sold sheep manure to local gardeners.
The gardeners placed the manure around their roses and other plants and then over the next few weeks the roses and other sensitive plants curled up their toes and died.
What happened was this, a farmer had sprayed his paddocks with a herbicide to kill gorse/thistles etc and one which does not harm grass. The sheep came along a little later and ate the grass prior to going the shearing shed. The manure collect from the shed was full of herbicide.

A more common way is any herbicide used on the lawn to kill various weeds, the lawn is mowed and the clippings are taken to the dump at a cost or to a green waste recycling centre.
At the recycling plant they have no idea if there is a herbicide in the lawn clippings or not.
The herbicides available both to the home garden market and commercially can have a residue for very long periods, not just a few mowing’s.
From what I can gather it can be as long as  18months with the composting material been turned several times during that time, before it is safe to use.
Thus if you are making your own compost don’t place any lawn clippings in it that have been sprayed with a herbicide. The best solution for those clippings is to place them under well established trees and shrubs where no other plants are growing.

I have recently heard of several instances where purchased composted, vegetable compost and organic compost have been used in gardens and the sensitive plants such as tomatoes and beans have displayed damage. Some of these purchased composts have been brand names which is really bad news.
I have used three makes of compost in recent times which come from Daltons, Oderings and Colin MacPhersons all of which have been ok.
There is a problem because of  the large amount of composts been made and sold, is that you could get a bag that has herbicide residue in it where another is 100% ok.
The test if you are going to place around or plant sensitive plants into purchased compost is to place a few bean seeds into the compost. If they come up ok you know there is not a problem.

If they don’t then take the bag back to where you got it from and complain. Placing any herbicide residue compost around non-sensitive plants is not usually a problem.

9 comments on “Herbicide Damage

  1. I read this with great interest having recently lost approximately 50 seedlings after potting up (from seed raising mix) into a purchased potting mix – a brand I hadn’t used previously.
    The sympotms would indicate a burn and although I repotted into my own mix as soon as I was able, I saved only about 10% of the seedlings.
    Broadly speaking, my production is organic. This episode has been a lesson to work even nearer to that principle 🙂

  2. Having moved into a new house in late Autumn, we waited until Spring to plant out the already established vegetable garden. After applying compost, lime, etc, we started planting out. However almost every seedling we planted seemed to shrivel up and die. Only a few seeds directly sown germinated and they quickly succumbed too. Our casualty list includes lettuces, silverbeet, broccoli, peas, radishes, spring onions, and carrots. 2 of 12 silverbeet plants have survived and have very small, deformed leaves. Yet the rhubarb in the back corner has flourished and the potatoes are coming through albeit inconsistently. Three broccoli in another corner have survived – interestingly that’s the only part of the garden with weeds! The weeds are non-existent elsewhere in the garden. After lots of head-scratching, we’re guessing that the previous owner used some heavy-duty weedkiller just before he left (as evidenced by dead strips around the edges of the lawn). We’ve been unsuccessful in trying to contact him. What would you advise we do? Should we leave it to lie fallow? Wait a while longer and plant a cover crop in late Summer then plant with vegetables next Spring? Get the soil tested (who would do this?) Or should we remove the soil and replace it with a new lot? Do we dig up the potatoes to replant in tubs? Would the rhubarb and broccoli be safe for human consumption? (Lots of questions I know!)

  3. Wally Richards on said:

    Removing soil is a lot of work and cost and it still may not be successful.
    I would drench the soil with Magic Botanic Liquid (MBL) and then a few weeks later soak deeply with water.
    A few weeks later MBL again then later water.
    In between each time plant a few bean seeds and if they continue growing ok it means you have cleared the area.
    Wally Richards

  4. this is unrelated to the above topic but i cant seem to fine what i want on the site. What can you tell me about digging out the lawn and building retaining walls? How much can we do ourselves? What do we need concent for?

  5. Hi Kate, The best advice I can give is to contact a local designer or contractor and have a one – two hour consultation with them. It might cost a couple of hundred to get your answers but better in the long run. They will be able to give you technical advice etc on construction and possibly work with you so you can do the grunt work if needed.



  6. Hazel Lucy on said:

    Please please tells us if the vegetables from these herbicide damaged plants are safe to eat

  7. J.Hall on said:

    I would like to know if herbicide damaged plants are safe to eat – e.g. rhubarb stalks. There was a two month period from herbicide spraying to consumption of the rhubarb.

    Thank you.

  8. J.Hall on said:

    Sorry, I need to clarify that the damaged plants were damaged by herbicide drift.

    Thank you.

  9. Hi J,

    It depends on how much weight you put on herbicide in the food chain. A few days and washing the plants should be fine in the short term and you wont get sick. You can read about roundup here It has information about testing on rats and mice both orally and in their eyes. Nice.



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