We often get a lot of people asking us how we control giant hogweed. It's no secret that we use chemical - but we want to give the explanations to why we control giant hogweed the way that we do.
If you don't know what giant hogweed is - check out our blog post about it here - but essentially it is a not very nice plant that was brought over here and now causes both harm to human health as well as the environment which is why we want to remove it.
What are giant hogweed control methods?
There are many different ways in which people control plants. Unfortunately, there is not a one size fits all, and most of the time, we need to use different methods, and not rely on just one. Below you will find various methods for controlling giant hogweed.
Biological control: biological control also known as biocontrol, is a method of controlling pest/invasive non native species by using other organisms. Prior to being released, the methods of biocontrol are extensively tested in lab conditions to ensure that they won't negatively impact our native species. This has been successful in some species (check out our blog on Japanese knotweed and Himalayan balsam biocontrol project here). One of the biological controls for giant hogweed is a small insect, a weevil, however, it can't be used in the UK as it likes our native carrot family too much (parsnips in particular), therefore it is not able to be released. However, this has been successful in other areas of the world such as Russia and Georgia.
Digging out: This method would be perfect to do, if for example, we found one plant around. Such as a one off somewhere on road verge or a garden. Essentially this involves using a spade to cut deep into the root of the giant hogweed plant and removing it from the ground. However, with the shear volume we have in the Tees catchment this would not be practical. Its also worth mentioning that giant hogweed tends to grow on our riverbanks, which makes access quite difficult! Not only would this be very time consuming but the biggest reason is that its dangerous and we don't want our staff/volunteers being put at risk.
Salt: Did someone order salt with that? You may have seen recently that we took a trip to Estonia (if you missed the post, you can read about it here). One method that they have been trialling on a small scale is cutting the giant hogweed plants and then filling the stem with salt. Interestingly this has worked at killing the plants off! However some of their sites such as ones they have along the coast haven't been affected (perhaps because these sites are already tolerant to some levels of salty water). However, this is not something that we can use in the UK due to the fact it affects soil pH - interesting method nonetheless!
Geo-textile: Another method which we have seen from our friends in Estonia is the use of geo-textile to manage giant hogweed. This is a method we will be looking into the future but will depend on funding. This is a very site dependent method as the textile can be affected by flooding, animal tracks and wind (you can see photos of the geo-textile on our Estonia blog post linked above).
Chemical: as mentioned above, the amount of giant hogweed that we have in the catchment is crazy! We are in a constant battle with removing it as it is present from Ovington, through Darlington, Stockton and all the way down to Middlesbrough. Due to the volume of giant hogweed and continually getting reports from people in the area about new plants, the safest and most efficient way for us to control it, is through spraying. With each plant producing 20,000-50,000 seeds and a 95% viability rate, it can feel like a losing battle! However, with the help and support from our funders (National Lottery Heritage Fund), volunteers and community groups such as angling clubs, we are able to make a difference year on year.
Annually we get permission for a pesticide licence to spray which we submit to the Environment Agency. This is due to the fact we are so close to a water course. The chemical which we use is Round Up Provantage which has aquatic approval. Of course chemical use is not the perfect solution, but at present this is the best way we can reduce the volume of giant hogweed in the catchment.
Once we have treated an area to a more manageable level of giant hogweed, we then go in boosting biodiversity. This is done through wildflower planting, bulb planting, plug planting, tree planting! Anything that can support biodiversity in areas that were previously a monoculture are a huge bonus.
Wildflower meadow planted at Round Hill, Ingleby Barwick
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