The stewardship of crop protection products involves managing them responsibly throughout their lifecycle. This covers all stages from research and development, including obtaining and maintaining registrations, through manufacturing and distribution, to use and finally disposal of containers and any unused product. The overall aim is to maximise the benefits from using a product and to minimise the risks to human health and the environment.
Australian farmers attending a paraquat stewardship workshop
The leading manufacturer of paraquat in Australia has produced a series of online stewardship videos, describing best practices in the storage, handling and use of a new paraquat product. The practices and points made in the videos apply generally to paraquat herbicides.
A product with a higher concentration of paraquat active ingredient is now available to Australian farmers. This contains 360 g/L paraquat as opposed to the more common 240 g/L products (2 pounds/US gallon).
Transport, storage and handling are easier because of 30% less weight and volume, and thanks to a number of innovative pack design features. The improved packaging technology also safeguards against exposure to the greater risks associated with more concentrated products.
A new 20 litre container has an anti-tamper cap to deter unwanted access; a wide mouth for fast, smooth and consistent flow, avoiding glugging and splashing; and two handles for safer and easier pouring. The shape of the pack also makes stacking on palettes more efficient.
Storage, manual handling and mixing
Before starting work the label and safety datasheet must be read carefully. Personal protective clothing must be worn when handling and mixing. This involves wearing full-length overalls and long PVC gloves, fully enclosed footwear and a face shield.
Fill the spray tank three-quarters full with clean water, then add the herbicide and, in this case, an adjuvant.
The pack should never be transported with the cap off and take care to avoid splashing when putting down a container with liquid still inside. Empty drums should be triple rinsed and stored in a locked room to await proper disposal.
Remaining product should be placed in a storage area, which should then be locked. Never, ever, decant paraquat products into other containers for storage. Always leave partially used products in the original labelled container.
A video describing correct and safe storage, handling and mixing can be found here.
Application
When applying paraquat it must be borne in mind that it is a contact herbicide and the sprayer should be set-up and used to ensure that as much spray as possible reaches and sticks to the leaves of target weeds. The addition of an adjuvant is recommended for some products. Usually, a non-ionic surfactant is the best choice to ensure good contact with weed leaves, but others may be recommended depending on the purpose. For example, emulsified vegetable oils (including esterified oils) are recommended to reduce the evaporation of water diluent in warm, low humidity environments, such as often found in Australia, and others may be added to reduce spray drift.
The volume of water used should be that recommended on the product label. In Australia, the volumes used are typically low compared with much of the rest of the world. In the video, a water volume of 80 L/ha or more is mentioned. Usually, 200 L/ha of water is recommended, so specific product labels should be consulted.
An appropriate type of nozzle must be selected. Flat fan nozzles producing medium sized droplets are usually recommended, but a specially adapted air induction nozzle to reduce spray drift is noted in the video.
The speed of the tractor or sprayer should be kept to 18 km/h or less. Faster speeds mean that air moving over the spray boom causes a reduction in pressure behind the nozzles encouraging smaller droplets to drift off-target. Droplets need to travel vertically down to make best contact on weeds.
A video describing best-practice application of paraquat under Australian conditions can be found here
Notes
The brand name of the leading paraquat product is GRAMOXONE®. The high concentration product available in Australia is GRAMOXONE® 360 PRO.
GRAMOXONE® is a Registered Trademark of a Syngenta Group Company.