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Green Fingers

Renaturing is risky

Week 39


If I ever have doubt about renaturing, I look from the kitchen window onto my land beyond when it is raining. Fault Lakeland if you wish, but its ability to withstand rainfall is remarkable. It has been raining in the region for centuries. For the past few days, it has once again been bucketing, so that roads have been blocked, cars abandoned, and deliveries postponed. Meanwhile gardeners garden, roofers roof, builders build, postmen deliver, and I am out and about supporting Nature. It takes much to deter Lakelanders - perhaps it is their warrior blood.

Wilting hostas
Wlting hostas as autumn takes hold

My house is towards the bottom of a hill. Outside, at the top of my land are some traditional flower beds that are presently flooded. Down the hill from them is a 30-metre stretch of long renatured grass, declining dandelions[i], struggling lavender[ii], wilting hostas[iii], persisting Japanese anemones[iv], an occasional buttercup[v], and waning bird’s-foot trefoil[vi], as autumn takes true hold. It is the bottom of the 30-metre stretch that impresses me. There is no surface water to find, it is dry as a bone. The long grass in between has absorbed the lot and is the perfect example of how supporting Nature can help mankind. The grass is a remarkable flood control system. My finding is reinforced by another stretch of nearby hillside that I scythed of its lengthy grass barely a week ago. At the bottom of the hill, which now carries grass that is short and stubbly, the water is flooding through. Lawn mowers beware. When in search of beauty, a mower may be harming more than they realise, and is doing nothing for water control.


I have spotted a new, purple addition this week that I was not expecting - vervain. Known to many as Verbena, it has appeared on my land for the first time this year. I have plenty of it and was surprised, as September is when the flower is meant to disappear, not feature on this first occasion. Vervain has a long association with divine and supernatural forces. Some even say that the plant was used to staunch Jesus’ wounds when he was taken from the cross. It is why folk can call vervain the holy herb[vii], or Devil’s bane by the Welsh[viii]. To the Victorians, the flower held the dual meaning of enchantment and sensibility[ix]. Whatever the lore surrounding the flower, it is clearly remarkable and worth protecting. My Devil’s-bit scabious[x] may have disappointed me this year, but vervain is an excellent replacement.

Vervain (Verbena)
Vervain (Verbena)

I have learned plenty with renaturing, but near the top of my list is the realisation that few appreciate why I renature. To most it still seems odd. The frequent passers-by, the intentional visitors, schoolchildren in particular, may be fascinated and ask so many questions. Yet when they return to their homes and cities, they remain within the cosy womb of traditional gardening. Renaturing and rewilding are steps too far. This is a shame, as human health can suffer when it is not exposed to green space, so restoring an original ecosystem is beneficial[xi]. It is not only land that can be renatured, but the human body, too[xii].


Meanwhile, the animals around me believe my land is theirs and I am an unwelcome visitor who should be tolerated. The other early morning, when I opened a bedroom window, I was immediately met by the offended stare of two red-legged partridges. They had decided to set up home with me, since the felling of some nearby trees had destroyed their habitat. My land was their haven. I cannot say who was more surprised, me or them. They did not scuttle away when I opened my window, but looked hard at me, as if to ask, “What are you doing here?” Then they turned and walked slowly away, with an occasional glance over a partridge shoulder to be sure I was behaving.

Conjunctivitis - here caused by allergy
Conjunctivitis - here caused by allergy

The plants are not troubled at all by my existence, although I am bothered by theirs. I worry when some plants fail, and I wonder why others have appeared. Many of them are beneficial, plenty can be eaten, a lot have medicinal value, but several are allergenic. This is a medical word for a substance, an allergen, that causes an allergic reaction. To me, that is not good news. Contact with allergens, or their pollen, can make me sneeze, occasionally wheeze, and sometimes give me red eyes. That is despite wearing a facemask before I scythe or prune, in addition to wearing protective goggles.


Grass pollen allergy, especially to rye grass[xiii] and Timothy[xiv], is one of the most common causes of allergy symptoms, and certainly the most common factor leading to hay fever, although there is a long list of problematic plants[xv]. If you read the list, it is surprising any of us plant anything. Pollen seasons vary between countries, but from January to May trees are a concern, especially oak[xvi], ash[xvii], birch[xviii], and pine[xix]. Grasses are troublesome from April to June. So-called weeds, notably ragweed[xx], nettles[xxi], and dock[xxii], can be problematic from July to November[xxiii], and moulds[xxiv] from July to September.


Moulds release spores, which are allergenic. There are several well-known conditions, such as Farmer’s lung[xxv], or Sauna-taker’s disease[xxvi], that can be caused by mould allergy. The most common moulds to cause allergy are Penicillium notatum and Cladosporium herbarum. The former is widely distributed in soils and can be isolated from decaying vegetables and leaves. It is present throughout the year, although it reaches highest concentrations in spring and winter. The latter is the most frequently encountered in the air and one of the most common colonisers of dead plants in soil. It is also the mould that can be found on uncleaned refrigerators, in houses with poor ventilation, and in damp areas.

Mould spores are allergenic (Image by Pete Linforth from Pixabay)
Mould spores are allergenic (Image by Pete Linforth from Pixabay)

Other common moulds include Aspergillus fumigatus, Alternaria alternata, Trichophyton rubrum, and Pityrosporum orbicculare. Aspergillus fumigatus is found in soils, leaf, and plant litter, and even in stored sweet potatoes. Alternaria alternata is again found in soils, but also in food and textiles. Black spots on a tomato? It is likely to be Alternaria alternata. Meanwhile Trichophyton rubrum and Pityrosporum orbicculare are yeasts that live within the skin and are associated with certain types of eczema[xxvii].


Allergies to plants and moulds in a garden is something of which the world is fully aware. Because of this, some gardeners try to create allergen-free zones[xxviii]. Also, if grass is cut slightly wet and kept low, this can inhibit its seeding and reduce the chances of allergy. Natural compost can also produce allergenic moulds, as can decomposing mulch, so manmade materials may be less of a problem. If female plants can be used, their lack of pollen can significantly reduce any allergen load[xxix]. In these respects, the Stripy Lawner has a head start. For the renaturer, it is different, as the technique depends on allowing Nature to have her head. Consequently, if she decides to allow Lily of the Valley[xxx] to pop up in one location - the plant can be very toxic[xxxi] - or an oak seedling, a sycamore sapling, a clump of daisies[xxxii], a beech, some chamomile, or a chrysanthemum, allergy to each of these has been reported. The best I can achieve is to wear protective clothing and glasses, have antihistamine medication nearby, and hope I am lucky. I sometimes succeed, while on other occasions I fail. As a renaturer, I am doing everything wrong, as my land will be buzzing with allergens. I leave my grass long, I have my own compost heap, and my mulch comes from within. If there is an allergen to be had, I will have it. It is one of the unspoken perils of supporting Nature. I am unsure if she is supporting me back.

Pellitory on a Lakeland wall
Pellitory on a Lakeland wall

Fostering biodiversity, as a renatured garden can do, may thus inadvertently host an array of plants that produce significant amounts of potentially allergenic pollen. A good example is one of my Lakeland walls, where a few days ago I found some pellitory-of-the-wall[xxxiii]. It is known to be extremely allergenic and is sometimes even called the asthma weed[xxxiv]. It is a particular problem in the Mediterranean[xxxv] and the south of my country. I was not expecting to see it in Lakeland, as I am so far north, but I sense climate change and warmer weather has brought pellitory northward.


Allergy is not always a problem that people acknowledge. To some there is a stigma attached. Yet the statistics are frightening, as allergy is an increasing[xxxvi] and costly problem with up to 80% of people with one identified allergy being allergic to multiple allergens[xxxvii]. The common grass allergy is known to affect up to 20% of Europeans[xxxviii]. Common ragweed also exemplifies the increasing problem well, as it increases its growth in response to raised carbon dioxide levels[xxxix]. In our era of climate change, such a finding is significant as common ragweed is extremely allergenic and already affects nearly 20% of people in the UK. Work from Canada, which looked at 3371 allergic people, found that 44.9% were sensitised to ragweed[xl]. No wonder allergy is increasing as the climate deteriorates.

Natural compost is full of allergens
Natural compost is full of allergens

Meanwhile a study[xli] undertaken in only part of the USA identified 21,200 emergency department visits in one year for asthma associated with oak pollen alone. Financial damages of this at the time (2010) were USA$10.4 million, with nearly 70% of cases being in children under the age of 18 years. Climate change is expected to lengthen the oak pollen production season, so oak allergy can only deteriorate. Birch pollen is also troublesome, with work from Denmark suggesting that 13.7% of the general population are sensitised to it[xlii]. Cypress allergy, too, which is certainly an increasing problem. A survey undertaken of outpatients visiting Israeli allergy clinics established that cypress allergy accounted for up to 32% of patients with hay fever[xliii]. Allergy is a large and deteriorating problem, evidently linked to climate change.


There are tips for those who are allergic types. I am but one of many. The following can help[xliv]:

  • Work outside when pollen counts are low. Peak pollen times depend on the plant, the weather and location. Watch the local forecast.

  • Talk with an allergist, who can identify which plants trigger your symptoms and provide practical tips and treatment options.

  • Take allergy medications before gardening rather than after symptoms start.

  • Wear a mask to limit exposure. An allergist can help find the type of mask that works best.

  • Avoid touching your face and eyes while working outdoors.

  • Wear long trousers and long sleeves. Keep skin exposure to a minimum.

  • Gardening gloves are essential.

  • Watch for rain showers to temporarily clear pollen from the air. Brief thunderstorms, however, can sometimes increase pollen counts and trigger allergies[xlv].

  • Wash hands often and rinse eyes with cool water after coming indoors, to remove clinging pollen. Shower and wash hair at night to prevent pollens from getting into the bedding.

  • Change your clothes once the tasks outside are complete for the day.


As a renaturer, I always keep these tips in mind as I spend so much time outside. Renaturing is risky.


***



Acknowledgement

Take it from me - none of this would be possible without the help of RSG Horticulture. Rufus, who runs it, has far more energy than me and is full of ideas and skills. Do contact him through https://www.rsghorticulture.com.



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References [i] See week 18 entry. [ii] See weeks 31, 32, 35, & 36. [iii] Wikipedia. Hosta. Widely cultivated, being particularly useful in the garden as shade-tolerant plants whose striking foliage provides a focal point. Although Hosta plantaginea originated in China, most of the species that provide the modern plants were introduced from Japan to Europe in the mid-19th century originating from shady locations with more moisture than they are generally cultivated. While usually grown for ornamental purposes, all species of hosta are edible, and are grown as vegetables in some Asian cultures. However, hostas may be toxic to dogs, cats, and horses if consumed in large quantities because some contain saponins. Symptoms include vomiting and diarrhoea. Hosta leaves and stems are eaten by deer, rabbits, slugs and snails, and the roots and rhizomes are eaten by voles, all of these can cause extensive damage to collections in gardens. Some varieties seem more resistant to slug damage, which is more prevalent later in the growing season, than others. Insect pests include vine weevils and cutworms. See https://en.wikipedia.org/wiki/Hosta. Accessed 22 September 2023. [iv] See week 36 entry. [v] See weeks 25 & 32 entries. [vi] See weeks 1, 25, & 32 entries. [vii] Watts DC. (2007). Dictionary of Plant Lore. Elsevier. p. 197. ISBN 9780080546025. [viii] Wikipedia. Verbena. See https://en.wikipedia.org/wiki/Verbena#cite_note-20. Accessed 20 September 2023. [ix] Language of Flowers - Flower Meanings, Flower Sentiments. www.languageofflowers.com. [x] See weeks 1 and 35 entries. [xi] Mills JG, Weinstein P, Gellie NJC, Weyrich LS, Lowe AJ, Breed MF (2017), Urban habitat restoration provides a human health benefit through microbiome rewilding: the Microbiome Rewilding Hypothesis. Restor Ecol, 25: 866-872. https://doi.org/10.1111/rec.12610 [xii] Leiper C. “Rewilding” the body in the Anthropocene and our ecological lives’ work. See https://www.societyandspace.org/articles/re-wilding-the-body-in-the-anthropocene-and-our-ecological-lives-work. Accessed 20 September 2023. [xiii] See week 27 entry. [xiv] See week 27 entry. [xv] RHS. Potentially harmful plants. See https://www.rhs.org.uk/prevention-protection/potentially-harmful-garden-plants. Accessed 20 September 2023. [xvi] See weeks 1, 23, 37, & 38 entries. [xvii] See weeks 2 & 23 entries. [xviii] See weeks 6, 31, 34, & 38 entries. [xix] Wikipedia. Pine. See https://en.wikipedia.org/wiki/Pine. Accessed 20 September 2023. [xx] Ragweed allergy: symptoms, causes, and treatment. See https://www.yorktest.com/blog/ragweed-allergy/#:~:text=As%20a%20strong%20allergenic%2C%20ragweed,of%20people%20in%20the%20UK. Accessed 20 September 2023. [xxi] Weeks 17 & 32 entries. [xxii] See weeks 14, 17, & 32 entries. [xxiii] Asthma and Allergy Foundation of America. See https://aafa.org/allergies/types-of-allergies/pollen-allergy/grass-pollen-allergy/#:~:text=Grass%20pollen%20allergy%20is%20one,during%20April%20through%20early%20June. Accessed 20 September 2023. [xxiv] Britannica. Mold. See https://www.britannica.com/science/mold-fungus. Accessed 20 September 2023. [xxv] Zergham AS, Heller D. Farmers Lung. [Updated 2023 Feb 5]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK557580/#. Accessed 20 September 2023. [xxvi] Metzger WJ, Patterson R, Fink J, Semerdjian R, Roberts M. Sauna-takers disease. Hypersensitivity pneumonitis due to contaminated water in a home sauna. JAMA. 1976 Nov 8;236(19):2209-11. doi: 10.1001/jama.236.19.2209. PMID: 989816. [xxvii] Allergyuk.org. See https://www.leedsth.nhs.uk/assets/fa698f54dd/Mould_Allergy_Advice_original.pdf. Accessed 20 September 2023. [xxviii] Patterson S. Gardener M. Allergy friendly plants: tips for making gardens allergy friendly. See https://www.gardeningknowhow.com/special/accessible/allergy-friendly-gardens.htm#:~:text=If%20your%20garden%20is%20surrounded,affect%20those%20suffering%20from%20allergies. Accessed 20 September 2023. [xxix] Ditzler D. How plant gender impacts your allergies. See https://allergyasthmanetwork.org/news/how-plant-gender-impacts-your-allergies/. Accessed 21 September 2023. [xxx] See weeks 16, 21, & 35 entries. [xxxi] Grant B. Is Lily of the Valley poisonous: understanding Lily of the Valley toxicity. See https://www.gardeningknowhow.com/ornamental/bulbs/lily-of-the-valley/lily-of-the-valley-toxicity.htm. Accessed 21 September 2023. [xxxii] WebMD. Best and worst flowers for people with allergies. See https://www.webmd.com/allergies/best-worst-plants. Accessed 21 September 2023. [xxxiii] Pellitory-of-the-wall (Parietaria judaica). Pellitory-of-the-wall is frequently found growing out of cracks in old walls and pavements, on cliffs and banks, and in hedges. It can often be found around old ruins and castles, as well as on damp church walls. Clusters of tiny flowers appear from June to October. It is a foodplant for the caterpillars of the Red Admiral butterfly. See https://www.wildlifetrusts.org/wildlife-explorer/wildflowers/pellitory-wall. Accessed 20 September 2023. [xxxiv] AllergyInsider. Wall pellitory Allergen Facts, Symptoms, and Treatment. See https://www.thermofisher.com/allergy/gb/en/allergen-fact-sheets.html?allergen=wall-pellitory#:~:text=Wall%20pellitory%20has%20two%20long,and%20summer%20and%20into%20fall.&text=The%20pollen%20from%20this%20severely,allergic%20rhinitis%20(hay%20fever). Accessed 20 September 2023. [xxxv] D'Amato G, Cecchi L, Bonini S, Nunes C, Annesi-Maesano I, Behrendt H, Liccardi G, Popov T, van Cauwenberge P.Allergenic pollen and pollen allergy in Europe. Allergy. 2007 Sep;62(9):976-90. doi: 10.1111/j.1398-9995.2007.01393.x. Epub 2007 May 22. PMID: 17521313. [xxxvi] García-Mozo H. Poaceae pollen as the leading aeroallergen worldwide: A review. Allergy. 2017; 72: 1849–1858. https://doi.org/10.1111/all.13210 [xxxvii] Allergyinsider. Multiple Allergies and the Symptom Threshold. See https://www.thermofisher.com/allergy/gb/en/living-with-allergies/symptom-management/symptom-threshold.html#:~:text=Most%20people%20with%20allergies—up,are%20allergic%20to%20multiple%20allergens.&text=And%20for%20some%20of%20these,lessen%20or%20eliminate%20your%20symptoms. Accessed 22 September 2023. [xxxviii] Larsson O, Hellkvist L, Peterson-Westin U, Cardell LO. Novel strategies for the treatment of grass pollen-induced allergic rhinitis. Expert Opin Biol Ther. 2016 Sep;16(9):1143-50. doi: 10.1080/14712598.2016.1190829. Epub 2016 Jun 9. PMID: 27269991. [xxxix] Ziska LH. Caulfield FA. (2000) Rising CO2 and pollen production of common ragweed (Ambrosia artemisiifolia L.), a known allergy-inducing species: implications for public health. Functional Plant Biology 27, 893-898. https://doi.org/10.1071/PP00032 [xl] Oswalt ML, Marshall GD. Ragweed as an example of worldwide allergen expansion. Allergy Asthma Clin Immunol. 2008 Sep 15;4(3):130-5. doi: 10.1186/1710-1492-4-3-130. Epub 2008 Sep 15. PMID: 20525135; PMCID: PMC2868868. [xli] Anenberg SC, Weinberger KR, Roman H, Neumann JE, Crimmins A, Fann N, Martinich J, Kinney PL. Impacts of oak pollen on allergic asthma in the United States and potential influence of future climate change. Geohealth. 2017 May 3;1(3):80-92. doi: 10.1002/2017GH000055. PMID: 32158983; PMCID: PMC7007169. [xlii] Linneberg A, Nielsen NH, Madsen F, Frølund L, Dirksen A, Jørgensen T. Increasing prevalence of specific IgE to aeroallergens in an adult population: two cross-sectional surveys 8 years apart: the Copenhagen Allergy Study. J Allergy Clin Immunol. 2000 Aug;106(2):247-52. doi: 10.1067/mai.2000.108312. PMID: 10932066. [xliii] Geller-Berstein C, Waisel Y, Lahoz C. Environment and sensitization to cypress in Israel. All Immunol 2000; 31: 92–93. [xliv] Gardening with allergies. See https://acaai.org/allergies/management-treatment/living-with-allergies/gardening-with-allergies/. Accessed 22 September 2023. [xlv] D'Amato G, Annesi-Maesano I, Urrutia-Pereira M, Del Giacco S, Rosario Filho NA, Chong-Neto HJ, Solé D, Ansotegui I, Cecchi L, Sanduzzi Zamparelli A, Tedeschini E, Biagioni B, Murrieta-Aguttes M, D'Amato M. Thunderstorm allergy and asthma: state of the art. Multidiscip Respir Med. 2021 Dec 2;16(1):806. doi: 10.4081/mrm.2021.806.

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