Paraquat for coffee

CoffeeMillions of people around the world wake-up each day with a cup of freshly brewed coffee and later meet their friends or do business in fashionably expensive coffee houses. But for many farmers there has been a coffee crisis. Although consumption is growing in some markets, coffee is a victim of its own success, and recently there has been considerable over-supply. In 1970 the average US consumer drank 36 gallons of coffee and 23 gallons of soft carbonated drinks. In 2000 these figures were 17 gallons and 53 gallons, respectively. The key to success and the way out of the coffee crisis lies in quality through a sustainable approach to production. Best quality speciality coffee growers can get twice the regular price. Paraquat has a key role to play by controlling weeds that would otherwise seriously reduce productivity, in conjunction with other agronomic practices that protect the environment. Although it is termed ‘non-selective


A chemical product used for eliminating all types of weeds (annual and perennial grasses and broadleaved weeds).

Authoritative On-line References and Resources An invaluable source of contemporary information about herbicides and weeds from Iowa State University.
’, 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 which 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.

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
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.  This is because maintaining a particular balance of weeds in the plantation flora is important for sustainability by providing habitats for predators of insect pests and minimising soil erosion


Displacement of solids (soil, mud, rock and other particles) usually by the agents of currents such as, wind, water, or ice by downward or down-slope movement.

Authoritative On-line References and Resources This site brings together reliable information on soil erosion from a wide range of disciplines and sources. It aims to be the definitive internet source for those wishing to find out more about soil loss and soil conservation.
though the anchoring effect of plant roots. Intensive use of glyphosate and residual herbicides has led to changes in plantation weed flora (‘weed shifts


A change in the weed community within a field i.e. relative abundance or type of weeds. This can be the result of a management practice like herbicide use or any other phenomenon that brings about a change in weed species composition. Species or biotypes adapted to current weed management practices increase, whereas weeds susceptible to those practices decrease.

Authoritative On-line References and Resources A classic article on weed population dynamics on the Iowa State University Weed Science website.
’) as species more tolerant to their particular modes of action become more dominant. ‘Soft’ weeds, typically prostrate annual grasses


The leaves are "narrow" as opposed to the "broad" leaves of broadleaved weeds. Also called 'monocots' having one seed leaf opposed to 'dicots' having two seed leaves.

Authoritative On-line References and Resources

The International Weed Science Society represents individual associations around the world. 
which are easily controlled, are replaced by re-invasion of cleared land by more aggressive ‘noxious’ weeds which reduce crop yields. They compete with the coffee crop and make spray operations, fertilizer application and harvesting difficult.
The coffee we drink comes from roasted seeds (‘beans’) found in berries Using paraquat, however, 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 variety of life in all its forms, levels and combinations. Includes ecosystem diversity, species diversity, and genetic diversity (IUCN, UNEP and WWF, 1991).

Authoritative On-line References and Resources EarthTrends is a comprehensive online database, maintained by the World Resources Institute, that focuses on environmental, social, and economic trends. Statistics on biodiversity indicators are available.
. 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.