Browse By
 Join us on Face Book!
Order a 2012 Catalogue
Fruit Hill Farm is Certified
by the Organic Trust
Links
|
You are now in:>>thermal weeding
THERMAL WEED CONTROL
1.) Why use thermal weed control ?
Up to the year 1987 herbicides were used indiscriminately in agriculture, municipal areas and in railway network maintenance. Only the alarming increase of ground water contamination by herbicides led to the prohibition of certain herbicides in municipal use, and reductions in their use for network maintenance.
This restriction led to a search for alternative methods of weed control. An optimal solution seems to be the flame weeding technique, which has been used for twenty years, mainly in organic growing and agriculture.
As with mechanical weed control, thermal weed control only destroys the above ground parts of the weeds. Compared to the application of herbicides or mechanical weed control, flame weeding has several important advantages:
* it is environment-friendly, there is no air pollution, and no chemical residues remain in the soil
its use is independent of wind and rain
* there is no preparation of poisonous chemicals, no decontamination of man nor machine, and no need
for record-keeping of used chemicals.
* it is easy to operate and much faster and cheaper than weeding by hand.
2.) How does thermal weed control work ?
It is sufficient to heat parts of the plant, especially the leaves, up to 70 °C to damage the protein. To check whether a leaf has been heated up enough, and in order to find optimum working speed, a finger pressure test can be applied. If you lightly squeeze a leaf that has been exposed to heat between your thumb and index finger, a dark green mark should become visible.
The time required for the flame weeding to be effective depends on several factors. The leaves of a young shoot can be heated up to 70°C in a fraction of a second. Fleshy and hairy leaves need a longer exposure because of the larger mass of the leaves or the insulating effect of the hairs. The same applies to creeping weeds, that need more heat than free standing plants, because of the cooling effect of the soil. Plants that have undergone heat treatment have a darker colour and appear limp. If thermal-weeding is carried out in the morning of a hot summer's day the heated plants should be wilting by midday.
3.) When is flame weeding most effective ?
The optimal time for thermal weed control is in early spring. Weeds in their early stage of growth (2-4 leaves) are still small and don't have any reserves stored in their root system. The bulk of the foliage is still small and allows fast economic and effective treatment. If fIame weeding is carried out when the weeds are already flowering, the treatment will take considerably more time and energy. In addition to that, seeding of the weeds might occur.
It is advantageous for the next season if there is one last flame treatment in autumn. This will destroy or severely damage weed seeds that have been carried in by wind, birds or insects. They won't germinate and therefore reduce the amount of weeds in the next growing season.
Work with an open flame is efficient. The plants are surrounded on all sides by hot combustion gas or are directly touched by the flame. The effect of the heat is much more intense, and it requires less time to heat a leaf up to 70-80°C. The working speed can be influenced by the size of the burner as well as the gas pressure. Depending on the burner type used, a working speed up to 6 km/h can be reached.
The special regulator which is supplied with the flameweeder requires a PROPANE gas bottle (usually red bottles) with a SCREW TYPE connection. Most gas dealers will be able to order those if they do not stock them.
4.) Risk of fire
To work safely use the flameweeder:
* in the morning, when it's cool and there is dew on the ground
* after watering or spraying
* not at the hottest part of the day
* during or after some rain
* not when it's very windy
|
|
