Apple scab, biostimulants and a new garden at the Newt in Somerset
It’s been an odd week weatherwise as we’ve plenty of mizzle, that combination of drizzle and mist that leaves everything damp. Round here I’ve heard some of the older locals call it ‘letty’ because it makes working outside unpleasant which is the perfect description. It’s not great for seed harvesting either, and now I wish I had harvested the last of the French beans last week when the pods were dry.
This week I have collected the last of the apples. Harvest-wise, it’s been a great year, much better than I had anticipated back in summer. But some of the trees have had a lot of apple scab so I have dug bit deeper into the biology of this fungal disease and investigated the emerging world of biostimulants. I finish with my visit to a new garden at the Newt in Somerset.
Today’s news is all about the results of the US election. I am not going to comment on that, but just say that from a climate change point of view, how different the world would be today if Al Gore had been elected to the White House in 2000. He won the popular vote but lost the electoral vote 266 to George Bush’s 271 and they fought in the courts for a month over the results in Florida. And in case you have forgotten, in 2007, he was awarded the Nobel Peace Prize, along with the IPCC for “Informing the world of the dangers posed by climate change”. How I wish …………
Apple scab
Have you been harvesting apples that have been damaged by apple scab? Apple scab is caused by the fungus Venturia inaequalis and it leaves unsightly marks on leaves, fruits and twigs. The apples are still edible, but it detracts from their appearance and quality. There’s high levels of disease when the weather is wet and we have had plenty of that this year!
Commercially, scab devalues apples quite a lot. In fact, UK apple growers lose as much as 12% of their crop to the disease. Traditionally, the disease is controlled by copper and sulphur-based products, but growers have a problem now as many of these products are being withdrawn so they need to look to other control methods. Research has highlighted one alternative approach using plant health products known as biostimulants.
What are biostimulants?
Biostimulants don’t affect pests and pathogens directly, but work by boosting the plant’s own defences. Some are simply a mix of nutrients, others comprise a diverse mix of microorganisms, rather like compost teas. Research shows that they work best for a plant that has been stressed, for example if it had had too little or too much water, insufficient nutrients, experienced frost or wind damage or put under pressure from pests and disease. We still don’t know enough about the way these products interact with the plants, but applications of the right biostimulants in minute quantities at the right time can boost shoot and root growth.
There are lots of different biostimulants on the market, including combinations of beneficial bacteria and fungi that mimic the action of soil life in protecting plant roots against chewing insect pests. There’s a seaweed extract rich in macro- and micro-nutrients that boosts rooting and cell growth, and mixes of humic and fulvic acids that bind with nutrients in the soil to make them more available to plant roots. There are a few products that are available to gardeners as opposed to commercial growers. One is called Amvista Phyter which contains seaweed, phosphite, and humic acid. The description says: ”A combination of three biostimulants to improve rooting, resistance to fungal attacks, and increase defence against drought and other stress factors". For fruit trees, the spray rate is 50mls per 12 litres.
There are a couple of biostimulants that have been found to be very effective in controlling apple scab, one is based on Saccharomyces cerevisiae (the active ingredient in yeast) and another which uses an extract from the fermentation of Lactobacillus and a dry yucca extract.
Since biostimulants are preventative they need to be applied before any disease symptoms emerge so timing it critical. And in the case of apple scab, the critical infection phase is invisible to the naked eye. So, research has focused on developing a hyperspectral camera that can detect and analyse a wide range of light frequencies. There are unique spectral fingerprints for diseases like scab, so by developing an affordable camera that can detect the infection stage and act like an early warning system, it can help growers know when to apply the biostimulants.
How can gardener control apple scab?
The fungal spores are spread on the wind, and they overwinter on fallen leaves. You can remove these leaves or let the grass under the trees grow long in spring to make it more difficult for rainwater splash to distribute the spores onto the new foliage. It’s wise to clear up infected leaves from paths and compost them.
Another option is willow. Willow is rich in salicylic acid and there is research to suggest that a thick mulch of willow around an apple tree reduces the incidence of scab through induced resistance. This is when the plant’s own defences are stimulated by the treatment of biological or chemical agents, in this case the salicyclic acid, and it may act by restricting the growth of the pathogen and suppressing disease symptoms.
This topic was the subject of a field lab by Innovative Farmers https://innovativefarmers.org/field-labs/investigating-the-efficacy-of-willow-woodchip-mulch-as-a-control-for-apple-scab/ which found that there was a trend towards lower leaf and fruit scab severity and higher leaf nutrient content following the application of a willow mulch around the base of the trees, although the differences were not significant.
Generally, scab not a problem as the fruits are still edible, but the damage to the twigs can provide entry points for bacterial canker. There are a number of resistant varieties amongst the traditional apples, such as Ashmead’s Kernel, Beauty of Bath, Court Pendu Plat, Discovery, Egremont Russet and Sunset.
A new garden at the Newt
Living just a few miles from the Newt in Somerset, I pop in regularly and there is always something to see. Earlier this year, a whole new garden opened its gates. Called the Four Seasons Garden, its located on the opposite side of the road, near The Farmyard and I popped along a few weeks ago to have a look.
The new area is quite extensive and includes four individual gardens, each with a focus on a different season, linked together by walkways, arches and pergolas. This means that there is always going to be a garden ‘in season’.
The largest is the Spring Garden which features a lily pond, a lawned area and lots of Japanese cherry trees. There are wildflower areas and beehives too.
Summer Garden features lots of roses. I liked the spatial interest created by the pergola and the thick wires that link the uprights which in time, I’m sure, will be festooned with roses. Here, the beds are edged in lavender. The focal point of the garden is a full-size cast of the Peter Pan statue that can be found in Kensington Gardens in London.
The Autumn Garden is formed by an extensive arboretum and the colours were already looking good.
The Winter Garden is quite a contrast to the other areas, with its limited colour palette of dark green (yew) and snow white (gravel). There’s no softness here, lots of straight lines and topiary shapes. It’s not my favourite area, but I liked the way water has been used. There’s a central fountain with pond and several rills that create vistas through the garden. There was a lot of topiary, some quite impressive, but others were quite shaggy, especially at the top. I noticed that the lower areas had been trimmed, so may be it’s a question of access. But if you are going to create a topiary garden, the plants need to be trimmed regularly to maintain that sharpness.
I had two favourite areas. One, the wonderful walkway from the southern entrance with its perennial planting, the laburnum tunnel, pergolas and archways planted with wisteria and jasmine. When this matures, it’s going to be delightful and a ‘goto’ garden to visit in spring. One of my all time favourite garden vistas is along the laburnum tunnel underplanted with alliums, designed by Rosemary Verey at Barnsley House, and hopefully this one will be just as good.
My other favourite area is the koi pond, dug out in the shape of a crested newt. You don’t notice the shape at first, but when you get above it, all becomes clear. And to one side amongst the rockery is another pool and this one is guarded by a reptilian rather than an amphibian - a rather large crocodile! Love it!
Having wandered over from the main garden, you will be in need of refreshment and, fortunately, there is a small café. It’s located in a small, quite secret area, surrounded by clipped hornbeam hedges, and it will be used as an exhibition space.
I’ve been watching how the main garden has matured since The Newt opened its gates in 2019, and I’ll be following the development of the Four Season Garden with interest. It’s a bit of a trek to walk from the main garden, via the tunnel under the road and through the orchards, but I’m really looking forward to visiting on a sunny May day to enjoy the apple blossom, laburnum tunnel, magnolia walk and the spring bulbs. Can’t wait.
Don’t forget, if you are a member of the RHS you can get in for free on Tuesdays.
Happy Gardening
Sally
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Talks
I am talking at a number of venues in the coming weeks. Most of these clubs allow non members to attend for a fee.
19 November Mayfield Horticultural Society by zoom
21 November University of Bristol Botanic Gardens
23 November I am talking at the inaugural LandAlive conference at the Bath and West showground on Sat 23 November. The topic is on creating a climate resilient allotment.
4 December Castle Cary Gardening Club
Sally, to your comment about the 2000 U.S. election (Bush v. Gore) and the loss to the climate change movement, I'll add: In 1980, Jimmy Carter was defeated by Ronald Reagan. Carter was convinced of the need for renewable energy and had 32 solar panels installed on the White House roof. They were taken down during the Reagan administration--in 1986, 2 years before James Hansen testified to Congress.
Yes, think of the years lost . . . and the cost to the planet.