The use of defoliants in cotton harvesting
In conventional cotton cultivation, the fields are sprayed with a herbicide just before harvesting that makes the leaves wilt and eventually kills the plants.
Why is this?
One reason is that harvesting machines are not very precise. They harvest cotton bolls and leaves and squash everything together. Cotton harvested mechanically from green bushes would be mixed with snippets of leaves and would therefore turn green – and we all know how difficult it can be to remove grass stains from cotton.
However, there is a more central reason: Not all bolls ripen at the same time. However, a machine cannot differentiate between ripe and unripe bolls. So this biological trick is used in order to force the ripening of all the bolls. All plants will react to severe damage with so-called ‘premature ripening’; a means of ensuring their continued existence by activating an accelerated maturation programme that allows all unripe fruit to ripen at least to germinability. This does not result in the best quality, but it’s better for the plant than not reproducing at all.
Causing this severe damage to an entire field of plants is most efficient with a defoliant.
The side effects
- As the defoliant is applied right before harvesting, the cotton bolls that are already open at this point absorb the poison. The defoliant is then present in high concentrations in the raw cotton and is very harmful to the health of the workers in the initial processing step.
- A large amount of the poison seeps into the ground and thus into the groundwater.
- Part of the defoliant remains in the earth for a long time and prevents other plants from growing, making the soil susceptible to erosion.
- Even when the herbicide has decomposed enough to allow new seeds to be sown, traces still remain that can weaken the plants. These weaknesses then have to be addressed by using more pesticides and fertilisers.
- The prematurely ripened cotton bolls contain low-quality fibres. These are then mixed with high-quality fibres making the material worse than it should be.
The cotton for DIDYMOS is therefore picked by hand .