News and features about paraquat, illustrating its multitude of uses and the benefits it brings to farmers around the world, are regularly posted on the Paraquat Information Center website. Here are the highlights from some popular recent articles.
Paraquat's Evening Performance
Spraying paraquat towards the end of daylight hours can boost the efficacy of weed control. The same factors are at work as when better effects are obtained when paraquat is applied on a cloudy day. These usually result in longer lasting weed control.
Paraquat diffuses through leaf tissue in the water in cell walls, but as cells desiccate this limits how far it can penetrate into weeds. The reason for improved activity under lower light intensity is because paraquat’s fast speed of action is slowed, allowing it to move further through weeds and give a more thorough kill when the sun rises the following day.
However, there are options to improve the control of difficult weeds with paraquat without delaying operations to late in the day or having to rely on cloudy weather. Low rates of PSII inhibitors slow photosynthesis in a way analogous to the low light intensity found in the evening or on cloudy days. This allows paraquat to move further before being limited by its own desiccating action.
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Paraquat supports sustainable tea in Vietnam
Tea is a thriving crop in Vietnam and farmers rely on paraquat for a weed control system that reduces soil erosion. Much of the tea crop is grown on sloping land prone to losing very significant amounts of soil each year.
Results of research conducted by the Northern Mountainous Agriculture and Forestry Science Institute show that using paraquat for weed control instead of hand hoeing can save huge amounts of soil. Paraquat is more effective than glyphosate because it leaves roots intact to anchor the soil.
The traditional weed control system of hand hoeing needed almost twice as much labor as the paraquat-based system. Consequently, it was much more expensive. Using paraquat saved on average the equivalent of nearly $200/ha. Yields of tea leaves improved too. From May through July, nearly 20% more leaves were picked from plots where paraquat had been used.
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Paraquat is glyphosate's bodyguard
A paraquat-based herbicide has become an essential land preparation tool for Brazilian farmers to stem the spread of glyphosate resistant weeds. The extensive adoption of GM soybean varieties tolerant to glyphosate has led to farmers using this non-selective herbicide too much and too often. Although glyphosate is encouraging the continued adoption of no-till, with all the benefits to soil conservation that brings, excessive use is also encouraging glyphosate resistant weeds.
However, an integrated weed control system has been developed to ensure the benefits of glyphosate can be preserved. This involves continuing to spray glyphosate for burndown, but following just before or just after planting the crop with an application of a paraquat-based herbicide. This contains a second active ingredient, diuron. Diuron is a soil residual herbicide, but at the low rates used in this product it has little or no residual effect, but enhances the activity of paraquat.
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