Weeds are the bane of a gardener's existence. Whether you are planting vegetables, ornamental plants, fruit trees or even a lawn, weeds rear their ugly heads, so please excuse me if I continue weeding while we talk. It is a labour-intensive and back-breaking endeavour, but there's no safer way to get rid of these unwanted plants.
GET DIRTY: weeding by hand is labour-intensive, but it is the safest way of eradicating weeds from the garden.
Unfortunately for Eric Hales, whose house in Pattaya is surrounded by lawns, weeds are growing faster than he could remove them by hand.
''I asked my friends in the UK if they knew of any product that I could use which would not kill the grass but would kill the weeds,'' he wrote. ''I was told that yes, there are a number of products, one of which was called 'Weed and Feed'.
''I have looked for this or similar products in Pattaya with no success,'' he wrote. ''I also looked on the internet for Thai companies producing weed killers but their information was in Thai. I eventually found a weed killer that is used in the growing of rice. I tried it on a small portion of grass, with no success.''
All is not lost, however. Mr Hales has asked his son, who is coming to Thailand for a holiday next month, to bring him some lawn weed killers that are manufactured and used in the UK. As an agricultural country, Thailand is not lacking in herbicides, or chemicals used to control weeds.
Mr Hales cannot read Thai and speaks very little of the language, but I am sure that if he looks in the right place, he will be able to find a herbicide for his lawn.
However, whether imported or locally made, the use of herbicides is controversial. Even those which are touted to be safe are toxic, not only to the weeds but also to the soil and the user, and must be handled with care. Inorganic herbicides have great residual effects on the soil and underground water, and are not recommended for use around the house, especially when there are pets or children who play on the lawn.
Herbicides can be selective or non-selective. Selective herbicides kill certain plants without harming others. Some are designed to kill weeds with broad leaves, while others kill only weeds with narrow leaves. Non-selective herbicides kill all plants exposed to them, weeds and grass or crops alike.
DON’T POISON POOCH: it is not safe to use herbicides on lawns, especially when there are pets or children who play on it.
Herbicides kill either by direct contact or by absorption. Contact herbicides must be applied to all plant parts completely, while systemic herbicides are applied to the soil and absorbed by the roots, so complete coverage of the plant is not necessary.
I guess the herbicide that Mr Hales tried is effective if used on the right weeds and at the right time. To be effective, the weeds to be controlled must be correctly identified so that the appropriate herbicide can be used. Contact herbicides are effective against annual weeds, while systemic herbicides are more suitable for controlling perennial weeds.
When controlling weeds, the recommended rate of application should be followed. If the chemical is overdiluted, the weeds will not be killed, so herbicide use is just a waste of time and money. On the other hand, too high a concentration is not necessary and also just a waste of money.
The time of application is also important. Herbicides may be applied when weeds are in their most vulnerable seedling stage, before they emerge, or right after they have emerged from the soil. Some weeds are difficult to eradicate, but their spread can be slowed if the weeds are controlled before flowers appear so that they do not bear seed.
Herbicides are more effective on younger plants than older ones. Weed-control measures should be carried out before weeds mature.
If the ground is not completely covered during herbicide application, weeds may germinate and survive at untreated spots. Some herbicides are less effective on soils that are high in organic matter or on clay soils; in such cases, a higher rate of application may be necessary for better results.
We have used herbicides on our farm, but after a while the weeds come back. To sum up, the effectiveness of herbicide application depends on the type of herbicide (selective or non-selective), mode of action (either contact or systemic), timing of application and such factors as plant species, age of weeds and type of soil.
If the area to be weeded is not so big, it is more effective, not to mention safer, to pay someone to do the weeding than spend your money on a weed killer.
About the author
- Writer: Normita Thongtham