With some key conventional herbicides under threat, vegetable growers are urged to gain experience of biorational alternatives by integrating them into weed control programmes.
With conventional and long-standing herbicides, such as glyphosate and diquat, on increasingly shaky ground and new molecules increasingly difficult and expensive to bring to market, interest in biorationals is growing rapidly.
One such example is Finalsan, a botanical contact herbicide based on ammoniated soap of fatty acids, which penetrates a target weed’s leaf wax layer and destroys cell membranes, providing rapid knockdown of green material.
Approved in pome and stone fruit orchards, ornamentals, vineyards, soft fruit production and amenity, the product has recently been issued an Extension of Authorisation for Minor Use (EAMU) in several vegetable crops.
These include beetroot, bulb onion, salad onion, shallot, garlic, carrot, parsnip, swede and turnip, where it can be applied with a hooded band sprayer or robotic precision guidance spot applicator, such as Garford’s Robocrop.
Certis’ technical specialist, Alan Horgan, explains that with questions over glyphosate’s longevity, and diquat under scrutiny by the European commission, it’s increasingly important to look at alternatives.
“Growers should certainly be considering biorational products, as they offer another effective tool in the ICM armoury,” he explains.
Where growers are using inter-row applications of glyphosate or diquat, where permitted in accordance with product labels, Finalsan could provide a viable alternative.
“It’s effective against young stages of grass and broad-leaved weeds with quick knockdown, taking between three to seven days to kill the weed, but has been known to take as little as a day if applied in optimal conditions,” he says.
“The product should be applied in a minimum of 1,000 litres/ha of water for best results and during bright and sunny weather conditions, with temperatures of 15°C or above, which will help to improve efficacy.
“Weeds should also be treated before they reach the four-leaf stage and the crop reaches 10cm in height.”
Mr Horgan adds that if Finalsan contacts the crop, it may cause some leaf spotting, but importantly it will not get into the growing point and kill the plants, which is an advantage over the highly-systemic glyphosate.
“It‘s also biodegradable and will quickly break down in the environment, therefore crop safety is improved, especially in the case of short season crops, such as spring onions.
“Consider best practice use and familiarise yourself with guidelines on sunlight, temperature and rainfall to get the most out of the product,” adds Mr Horgan.