ART Blog

Despite bad weather conditions our contractor has managed to control a fair amount of Japanese Knotweed on the lower Irvine.  There were some very large stands around the Caprington area and it will be interesting to see the outcome of the treatment.

Japanese Knotweed below Caprington Bridge (downstream view)

The picture above shows a very large Japanese Knotweed stand below Caprington Bridge on the left bank looking downstream. The picture below shows the same stand looking upstream.

Japanese Knotweed below Caprington Bridge (upstream view)

I will post pictures of this stand again once it dies away. Stuart had mentioned in an earlier post that another very large stand in the same area had been treated on the right bank. The photo below shows this stand with the path running through the middle.

Japanese Knotweed below Caprington Bridge on the right bank

We have a contractor carrying out stem injection treatment on the River Ayr catchment, I will post an update once I have spoken to him. We will also be controlling Japanese Knotweed on the River Doon for the third year in a row and  a huge reduction is already evident, this treatment will commence ASAP.

Last week we had another two volunteers pass their PA6AW training course. John Muir and Alan Knox from Dalry Angling Club both passed without any problem and will now join a group of 22 other volunteers already trained by ART. Our training budget had now run out for 2012 and as there was only a few places left on the last training course some people may have missed out. ART will however have more training on offer in 2013.

Our contractors have now completed the Giant Hogweed control across Ayrshire and have done a very good job. Our next target was Himalayan Balsam but extreme weather conditions have made it difficult in many areas. On the evening of Thursday 9th August we managed to get a few volunteers together and went to work on the Fenwick Water. We managed to cover a good section from Fenwick downstream. Although there were not all that many plants we pulled around 70 in total so hopefully when we return next year this section of the water will be clear. The best way to deal with this plant is to pull it. It comes up very easily in most cases and the soil should be shaken from the roots and the plant hung up somewhere to dry out and die.

Some Himalayan Balsam Hung in a tree after pulling

On the same day i spoke to Gary Anderson of Galston Angling Club who had been pulling Himalayan Balsam all week. A huge thanks must go out to Gary for all his efforts and indeed to club member Brian Luke for helping. Gary has now cleared the Galston Club waters of Himalayan Balsam and on Thursday alone they pulled over 2000 plants. When this amount of plants are pulled the best thing  to do is put them into large piles. The work that Gary and Brian did this year just goes to show that with a few club members getting involved it doesn’t take long to clear.

Gary sent me this picture of Brian next to one of 6 piles they had pulled on Thursday

It is nearing the time that the Himalayan Balsam will go to seed so although we encourage all club members/riparian owners and members of the public to pull the plant whenever they can, if the seed pods are fully formed it is best not to go near the plant. These pods can pop and shoot seeds up to 7 meters .Seeds can attach themselves to cloting and footwear and can be transferred to other areas very easily.

Himalayan Balsam plant (seed pods starting to form are circled)

If possible I plan to have another go at some more pulling on the Fenwick water this week as none of the plants we pulled on Thursday had seed pods on them.  The weather however is not looking great. If i am going out I will post a blog and email our volunteers to see if they can lend a hand. Anyone wishing to join us can get in touch with me at the ART office on 01292 521223. I know that Dean Castle have been out pulling further down stream so if we can make it down to there this year at least that will be a start. Next year however we will concentrate more on this plant and start a lot earlier. My plan is to get local communities involved as well as the angling clubs/riparian owners and hopefully together we can make a big difference.

The Japanese Knotweed is now starting to flower in some places and it won’t be long before our contractors make a start on it’s control. The best time to spray this plant is when it is in flower. This has the greatest effect on the plant and should kill it off. The plants stems can also be injected however and ART staff have already done this a few times this year. More information on the Japanese Knotweed control will follow soon.

This week I will also be updating the ART website with information on the CIRB project as well as information on identifying and controlling these invasive species. We also have information leaflets and ID sheets to hand out and will get these into circulation as soon as possible.

It’s great having Alba to assist with our Invasive species research. The only trouble is that she keeps producing more and more data!

Seriously, she is fantastic and a real asset.  I’ve summarised some of her latest findings that I thought blog followers may find interesting. This follows on from last weeks post about GHW roots. This is Alba’s work, I’m only summarising it and correcting some minor grammatical errors for her. If the roles were reversed and I was working in Spain, I’d  manage a quick ‘Ola’ and ‘Sangria por favor’ and  that would be me finished. She really puts us to shame with her language skills. Anyway here are some key facts from her research at the Dobbie’s site.

Overall, we estimate more than 530 seeds, 630 surface seedlings and 440 buried seedlings in just one square meter (1600 in total). We know that mostly of these seeds or seedlings, will not germinate nor survive next year, but the size of these taproots, 1 cm diameter and about 5 cm long, raised new questions about the timescale of seedling development and seed viability. We must take into account that no plants survived and produced seed in 2011; hence we are finding viable seeds and seedlings that arise from plants that grew on the site no later than 2010.

These results help to understand the enormous reproductive capacity of the weed, but actually, these numbers are relatively small compared to its seed potential. How many seeds can a big Giant Hogweed plant produce? What are we risking if we allow just one flowering plant to disperse its seeds?

Counting the main flower's seeds

To answer this question, we decided not to spray a big plant (around 3 meters tall) and allow it to produce seeds, and thus be able to count them. We counted the number of flower heads, the florets per flower head, and finally the number of seeds per floret. We did the maths, and we counted about 4000 seeds in the main flower head, 28000 in the 12 flower heads from the sides, and 21000 seeds in smaller flower heads, resulting in a total of 53000 seeds in just one plant. The average plant reputedly produces 10 – 20,ooo seeds but what is average? The plant we looked at was certainly not uncommon or unusual in any way.

Each floret produced a mass of seeds

Around 15% of the seeds could be viable next year, which show us the high dispersal capacity of this plant. Furthermore, seeds produced by self-pollination are viable, meaning that even a single isolated plant is capable of founding a new population.Understanding the incredible reproductive  capacity of this species and its biology will help us to improve our control methods and management strategies.

Alba

While we have spent the last 4 years controlling Giant Hogweed on the River Ayr, it is only now that we are starting to look closer at the plant itself.

Last year we controlled a plot of land opposite Dobbies Garden Centre near Holmston. This land was very badly contaminated and has been for years. Google Earth images from 1999 confirm this although the Hogweed had spread across the entire site by 2011. This was possibly the greatest density site we have come across. The picture below is from Google Earth taken in 1999.

Vacant plot used for unlicensed tipping. GHW is in flower and can clearly be seen - taken in 1999, from Google Earth

We started controlling this site towards the end of May last year and finished spraying at the start of July. It took several visits to safely progress through the site due to the height and density of the plants, some of which were nearly 5m tall. The first image below is from July last year before the plants had died off. The second image was taken this week and shows flowering plants dying after having been sprayed. No plants survived and produced seed in 2011 yet plants flowered this year. This raised a few questions.

Plants flowering in 2011. All were sprayed and died before producing seed

The same view in 2012 after spraying. Notice the flowering GHW

This plant reputedly takes 4 years to mature and flower but clearly this can’t be the case; or can it? Little is published about the plant’s development so I asked Alba, our Spanish Intern to have a look at this site to see what she could find. The main question we needed to answer is, Can this plant reach maturity and flower within a year? We knew that juvenile plants if mowed will suddenly throw a flower as a stress response but nothing that we have read indicates that the plant can flower within a year under normal circumstances. Why then were plants flowering this year on the site?

We knew that plants germinate throughout the year and also, following treatment last season there were young plants developing on the site after the flowering plants died off. These plants could easily have reached around 0.5m tall by the end of last year but without a central flower stalk. It had to be these plants that produced flowers this year; in their second growing season but still only one year old. Alba and I decided to dig up a few plants and seedlings that had germinated this year since the first spraying. Comparing the seedlings that had just emerged above the ground with a plant that had emerged earlier this season threw up more questions.

The tallest plant that we dug up was around 50cm tall and consisted of two leaves. It had been sprayed recently but must have emerged following the initial treatment this year. The smaller plants we looked at were seedlings, just recently emerged. The contrast between these plants couldn’t have been greater. The root of the taller plant was well developed and certainly not just a few weeks old. Perhaps this plant germinated last year? The seedlings were very small but their roots was extremely well developed for their size. Could these have germinated several months ago and only recently have pushed seed leaves through the surface? Have a look at the photos below. The number of plants within close proximity is very worrying. In one square foot (30cm x 30cm) we counted 57 seedling showing above the ground. Many more were well developed below the surface and only just developing seed leaves. We also removed seeds from the surface to count later. Most of these seedlings are out competed as only one or two plants per square meter reach flowering but it does demonstrate the plants incredible ability to dominate an area quickly.

Seedlings that had just recently emerged or were about to emerge. The size of their roots indicate that they may have germinated some time ago.

The larger plant that we would have considered as in its first year until now had an extremely well developed root. The visible root is only a fraction of what was still buried in the soil. Could this really be a plant in its first year? I suspect this plant is in its second season.

Seed leaves had only just emerged but the root must have been developing for some months