Paraquat for vegetables
Paraquat has an important role to play in vegetable cropping because its unique characteristics are particularly suited to the challenges posed by controlling weeds in these diverse crops. Growing vegetables also helps with growing other crops in a sustainable way. Legume vegetables have bacteria associated with their roots which convert nitrogen from the air into forms which can be used by plants as nutrients and these remain in the soil to fertilize following crops. A vegetable break crop, such as peas or potatoes, prevents the build-up of pests and diseases in cereal rotations and provides an opportunity to control weeds by alternative approaches. Using paraquat for weed control helps to address many of the challenges to vegetable production including soil erosionErosion of soil by wind and water can be a common problem on the generally lighter soils used for vegetable production. Paraquat is a contact herbicide which only burns down weed shoots. Roots are left intact and provide an anchoring effect in the soil. Paraquat has no residual activity, being inactivated immediately on contact with soil. Spraying paraquat keeps weeds from competing with the crop, yet allows them to re-establish after a few weeks, anchoring the soil and also providing habitats for beneficial insects and predators of potential crop pests. Light soils are also more prone to leaching of nitrogen and agrochemicals. Paraquat, however, is immediately bound to soil particles on contact. This binding is extremely tight preventing any leaching, regardless of rain or irrigation. Vegetables which are early to market generally fetch higher prices. Growers often aim for early harvests which may mean planting early in unfavourable weather conditions. Unlike glyphosate, paraquat gives reliable weed control when sprayed at low temperatures because it does not rely on weeds being actively growing to kill them. Also, paraquat needs only 15-30 minutes before rain to give maximum levels of weed control, compared to glyphosate’s need for several hours. As many crops may be grown in one season with continuous production schedules, a fast turnaround time between crops is critical. Paraquat gives complete control of weeds within a day or two even in cold weather, and within hours in hot sunny weather. This is a critically important asset in contrast to the one to three weeks needed for the full effects of glyphosate to show. Agrochemical residue levels on vegetables are sometimes controversial. However, paraquat is sprayed to control weeds before vegetable crops are planted or later in between the rows, not over the whole crop. Any paraquat accidentally landing on leaves is tightly bound, just as it is in soil, and finds it very difficult to enter, and even more difficult to move to fruit or tubers. Furthermore, UV radiation in sunlight degrades paraquat on leaf surfaces and soil absorption prevents entry via roots.
DescriptionDisplacement 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 Resourceshttp://soilerosion.net/ 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., leaching
DescriptionThe natural process by which water soluble substances are carried downward through the soil into groundwater. of agrochemicals, early harvests for best prices. Paraquat is used to prepare the land for sowing or transplanting and is safe to use for inter-row weed control in growing crops by careful application with knapsack sprayers or from tractor mounted sprayers with shielded spray nozzles. Unlike systemic herbicides which are too dangerous to use, even if small amounts of paraquat land on crop plants they cannot move within the plant to cause damage.
Vegetables fact file
- 70 million hectares grown worldwide
- 70% grown in Asia
- 5 portions a day recommended for health
- 1893: the year when the US Supreme Court ruled that tomatoes are vegetables for legal purposes