Coffee fact file
- 2 types: Arabica and Robusta
- 60 countries grow coffee
- 2.1 million hectares grown in Brazil
- 2nd most traded commodity after oil
- 70% is grown on small farms
- 10% or less of value reaches growers
Although it is termed ‘non-selective’, paraquat is safe to coffee crops for several reasons. Firstly, it is immobilised on contact with the soil meaning that it cannot move to roots and be taken up into plants. Secondly, it is sprayed around the coffee plants, which are protected by their bark that paraquat cannot penetrate. Thirdly, even if small amounts of paraquat land on coffee leaves there is little or no damage because paraquat does not move through plants systemically like the alternative non-selective herbicide glyphosate.
Paraquat is very fast acting and rainfast, unlike glyphosate. Weeds sprayed in the morning will often show symptoms by the afternoon, making it easy for spray operators and plantation managers to see which areas have already been sprayed. This holds even if rain falls within 15-30 minutes, making it possible to spray for longer before rain is expected. In perennial plantation crops such as coffee, emphasis is on the management of weeds rather than their permanent removal.
Using paraquat can help to maintain a balanced flora which precludes the dominance of aggressive species. Paraquat only removes the top growth of well established weeds, and does not affect the germination of new seedlings allowing vegetation to re-establish after 1-2 months. A controlled presence of soft weeds maintains the balance of the weed flora and prevents weed shifts to noxious species simply because bare ground for them to colonise is less available.
The presence of non-competitive vegetative cover also provides habitats to encourage biodiversity. The wildlife encouraged will include predators of insect pests which would otherwise have to be controlled chemically. Using paraquat also avoids the extended periods of bare soil left by using glyphosate and residual herbicides which leads to problems with soil erosion, which can be severe where coffee is grown on steeply sloping land.