As part of my coursework for the certificate, I had to write a Pest and Disease project. I researched 15 of the most common pests (vertebrates and invertebrates that feed, inhabit or otherwise live off plants, damaging or killing them) and diseases (caused by microorganisms such as fungi, viruses and bacteria), choosing ones that I had the opportunity to see in person at Wisley. As knowledge is for sharing, I am sharing it below..
We were however not required to study disorders, which are the third issue affecting plant health and as such are included in the acronym “PD&D” that you might have read somewhere, so I want to touch on them here. Disorders are physiological conditions in which the plant behaves abnormally in response to environmental conditions (i.e. nutrient deficiencies, drought, heat, physical damage etc.) – they are very difficult to identify, as this excellent guide from Michigan State University explains.
One such disorders I encountered at Wisley was on ‘Conference’ pears. In some years more than others, some pears develop corky lesions on their skin, maybe due to some nutrient deficiency and possibly facilitated by dry weather. These may on occasion be mistaken for fungal disease scab (Venturia pirina) but have been identified as a likely disorder. ‘Conference’ pears are particularly prone to them: not only did I received a good few questions from visitors that spotted it in the Fruit Garden, I had it on my tree at home. Dealing with it means simply removing the worst affected fruitlets, so that they do not take up the plant’s energy, but keeping in mind that most fruits grow out of it to become happy pears.
 |
 |
| Disorder, unspecified (badly affected fruitlets, left; mildly affected, right) | |
 |
| Pear scab (Venturia pirina) damage |
together with the table of contents:
Fruit
Apple (Malus domestica) and pear (Pyrus communis)
Brown rot of apple and pears (Monilinia fructigena, M. laxa)
Apple and pear canker (Neonectria galligena)
Apple powdery mildew (Podosphaera leucotricha)
Rosy apple aphid (Dysaphis plantaginea)
Codling moth (Cydia pomonella)
Apple and pear scab (Venturia inaequalis, V. pirina)
Blackcurrant (Ribes nigrum)
Big bud mite (Cecidophyopsis ribis)
Gooseberries (Ribes uva-crispa)
Gooseberry sawfly (Nematus ribesii)
Grapes (Vitis spp)
Grey mould (Botrytis cinerea)
Raspberry (Rubus idaeus)
Raspberry beetle (Byturus tomentosus)
Cane blight (Leptosphaeria coniothyrium)
Vegetables
Cabbage (Brassica oleracea)
Cabbage root fly (Delia radicum)
Mealy cabbage aphid (Brevicoryne brassicae)
Leek (Allium porrum)
Leek rust (Puccinia allii)
Pea (Pisum sativum)
Wood pigeons (Columba palumbus)
Plum days
I have not written for a while, busy as I was with coursework deadlines, but in the last two days I have spent some time with plum trees, which I think is worth sharing.
Yesterday I helped the Plant Health and Seeds Inspectorate (PHSI) pick leaves from the orchard to be tested for plum pox virus, so that its spread can be monitored and contained. We picked 24 leaves each from 125 of the 127 trees that constitute the new plum orchard (2 of the trees did not have enough leaves on them to provide a full sample). To avoid cross-contamination of the samples, we used a new pair of gloves for every plant. The picked leaves were sealed in plastic bags and kept in a cool box until they were sent for testing. It was an interesting experience to make, as I had not realised the risks from plum pox before, but I must admit I was slightly uncomfortable with the amount of plastic gloves ending up in the waste bin.
Today, instead, I was helping our fruit specialist with chip budding plums, something I had been looking for. The process does not look too difficult, but of course it’s just because it’s done by a skilled person.
First, one has to collect the bud material: ripe new-year wood that has started changing colour. This is often found on the south facing side of a plant.
The stems are trimmed of the leaves, leaving a small part of the petiole (if we were doing T budding, we would leave a longer piece, as it would serve the purpose of a handle).
They are then labelled and kept in a cool place, preferably wrapped in moist towel until use.
Sometimes one cannot find first year wood, so it is possible to try with second year material (hardened wood).
 |
| Toe cut (the “lip” on the left), and buds removed |
The buds are removed, one by one, with some 3-4 cm of stem around them: practicing a “toe cut” at the bottom and then sliding the budding knife from the top of the bud down to the toe cut.
It is then the turn of the rootstock, which has to be previously cleared of any side branches at the base for 20-30 cm.
Then, standing astride over the plant,
- on the north side of the main stem (so that the bud
straightens up by growing towards the sun), - at a height
of 10-15 cm from the ground to avoid rain splashes (with possible fungal spores) and - possibly above a node (which will stop the knife from sliding
accidentally)
one makes another toe cut, then measures the length of the bud and cut a similarly sized superficial slice out of the stem. The bud is
then slid into the toe cut, ready for binding with grafting tape (a
clear plastic strip).
 |
 |
| Chip bud with first year bud | Chip bud with second year bud |
Binding needs to be tight: the fruit expert reckons that a good bud with
bad binding has less likelihood to succeed than a so-so bud with good
binding. The buds need to be covered with the tape too, unless it’s too
big to fit (i.e. on second year wood). The best way to bind is with
clear stretchy grafting tape. Starting from the bottom, this is tucked in, then wrapped upwards, and closed with a knot, pulling any hanging bits to finish.
 |
 |
| Binding over new-wood bud | Binding around two year old bud |
I was in charge of the binding, and we went through some 90 rootstocks!
The tape will be on for 4-6 weeks until callusing of the wound is well underway. The fronds of the rootstock will be left on the whole season; cutting back will only take place next year in February (late February for apples), just when the sap start to rise, but before the pull is too strong, which may “flood” the bud and kill it.
Chelsea Flower Show 2015
It’s press day at Chelsea Flower Show and the RHS trainees flocked into London to lend a hand while getting some insider’s knowledge of the UK’s most famous display of plants and garden design.
I was assigned to assist one of the judging committees for the exhibits in the Great Pavilion: on a tight schedule for two and a half hours, we had to help the judges navigate their way through 17 exhibits, which they were to judge from the perspective of their specific expertise.
The displays are judged based on the brief submitted by the designers, and according to horticultural and design criteria such as:
- plants,
- overall impact;
- endeavour.
The best displays receive a medal: bronze, silver, silver-gilt and gold, but during the show garden and exhibits are also assigned special awards.
The judging process is very confidential as the stakes are high for the participants to such a high-profile show, and the results will not be announced until tomorrow. That is why trainees are asked to make room for the judges around the exhibition so that they can observe thoroughly and are allowed the privacy to and discuss their votes without prying eyes. In the process, we got first hand experience of what it means to judge an exhibit. Once the medals were assigned, a group of us also helped the judges on a further round of judging for the awards. The judges were then going to spend the rest of the day finalising the distribution of medals and awards, while we got time to spend visiting the Show.
While Chelsea is mainly a flower show, there were some fruit, vegetables and herbs exhibits and I was on the committee in charge of evaluating them, which was fascinating!
 |
| Potatoes at Chelsea! |
My favourite edible exhibit was an educational potato display with some 140 varieties grouped by species: the colours and shapes really stood out, highlighted by the black background. Morrice and Ann Innes designed the display, which was sponsored by seed and plant company Thompson & Morgan.
For some people, the enormous variety of potatoes must be a novelty indeed… it was for me when I was first invited to join a Facebook group of potato breeders and growers called “Kenosha Potato Project” where I’ve seen the strangest, more colourful and interesting shaped tubers from across the world and learned that “papas” is the original name of these favourite of tubers. They come in such coloured and varied shapes as exemplified below!
Posted by Edilberto Soto Tenorio on Sunday, 22 March 2015
The Grenada’s ‘Pure Grenada’s Rainforest’exhibit was also rather gorgeous, displaying lush green, bright colours, spices and fruits that are native to the island: one had to recognise that some places on earth are blessed with particularly show-worthy flora, such a Solanum mammosum or titty fruit, which is said to resemble a human nipple on one side and a cow’s udder on the other, and pink banana Musa velutina.
 |
 |
| Solanum mammosum | Musa velutina |
Delicious fruits, such as the colourful fruit of Theobroma cacao that gives us chocolate, or the versatile Zingiber zerumbet, with its edible tubers, juice, leaves that can be used as flavouring, and flower heads that are turned into shampoo!
 |
 |
| Pouteria sapota and Theobroma cacao | Zingiber zerumbet |
I also found a delightful herb garden
 |
| Herbs exhibit |
where I was particularly attracted by 3 herbs: Galium odoratum with edible dainty leaves and white flowers, which I first saw in a garden I worked in last year and two non edibles: Polemonium caeruleum with dark leaves and blue flowers and Prostanthera rotundifolia a shrub with pink flowers.
 |
| Pennard Plants stand |
 |
| Detail of vegetables at Pennard’s |
To conclude I will mention the rather glorious exhibit by Pennard Plants, inspired by a R. Kipling’s poem “The Glory of the Garden” in its 150th anniversary, with stunning vegetables.
P.S.: Glad to say the potatoes I helped being judged got a gold medal, the first of its kind! Grenada and Pennard Plants were also gold medallists.
In the veg garden
Sowing sowing everywhere, then thinning out, planting out, covering, watering… it’s a busy time in the veg garden where the spring rush is on to get the beds filled and looking lush! That is what I have been doing over the last two months in the veg garden particularly, and below is more information by technique and crop.
Sowing
To get the perfect sowing, the beds need raking to a fine tilth.
Then, with the help of a row maker, you can draw straight lines at even, well calculated distances, and of course perfect grids (for planting out).
 |
 |
| Rows to sow | Grids to plant out |
Summer radishes are sown 1-1.5 cm deep, at 1 cm spacing (thinned to 5 cm), with and 20 between rows (15 in a greenhouse); one shouldn’t water seedbed until germination. In summer, if the soil is dry, water the drill before sowing the seeds to create a microclimate for them to germinate but not the surrounding soils.
There are two type of summer radishes: rosette leaves (ideal for early sowing, require
lower light levels) for example ‘Rudi’, ‘Scarlet Globe’ and tuft leaves (ie ‘French Breakfast’) which are best sown towards the end of March. If you sow them too late they go straight to flower; the same happens if you don’t thin them out.
Winter radishes you sow beginning of summer to Aug, they are ready Sep to
Nov, some like mooli, also know as daikon, overwinter but require wider spacing, at least 30 cm and 30 cm between rows.
 |
| 2 March |
 |
| 13 March, thinning out |
 |
| 13 April |
 |
| 30 April |
Spinach
Spinach is sown at 2.5-3 cm, then thinned straight away to 5 cm. Depending how big you want your plants, you can also decide to harvest one in every two plants as baby leaf. Mind you leave 30 cm between rows.
Spinach is very sensitive to day length so pay attention: there are early sowing (flowering on longer days) and late sowing varieties (that can be sown both spring and autumn, as they are flowering on shorter days).
 |
| 2 March |
 |
| 20 April, thinning out |
 |
| 13 April |
Beetroot
Beetroot is for sowing April to June, but a few varieties that do not bolt if they get cold (ie ‘Boltardy’) can be sown earlier.
Spacing: 5 cm (seeds are in a cluster) and 30 cm in between rows. They require
thinning by snipping off any extra seed in the cluster that germinates.
 |
| 2 March |
 |
| 20 April, thinning out, poor germination |
 |
| 13 April |
Carrots
Carrot ‘Marion’ is very good for growing all year round even if its flavour is not perfect, but aside from that variety carrots are either early maincrop or late.
Carrots seeds are very thin, and difficult to handle. Taking only a small pinch at the time helps with getting the right sowing spacing, which is 1 cm by 30 cm.
Because of the risk of carrot fly (Psila rosae) attack, early maincrop carrots are covered at sowing, only uncovered once for thinning out, then covered again until picking, which is done in one go. However, since the carrot fly is not around in autumn,
overwintering carrot can be picked as needed.
 |
| 19 March |
 |
|
|
 |
||
| Fleecing the carrots against carrot fly | ||
 |
| 30 April thinning out, uncovering |
Broad beans
 |
| Sown in the first week of March, took about a month to germinate |
 |
| 25 May |
Thinning out
Once you have done your thinning, it is best practice to firm the remaining seedlings in the row, by earthing them up slightly from the sides, then watering them well.
Planting out
Several crops are grown in the propagation facilities and then planted out, ie all the brassicas and the lettuces. Planting them out has its own requirements.
One of the most interesting things I learnt while here is that some crops like to be planted at the same level they were in the pot, even if they flop when planted (for example brassicas and lettuces). Others instead need firming in, for example celery, which is also planted close together to provide a minimum blanching effect, even though modern varieties are self-blanching and do not need to be earthed up or otherwise be covered.
Brassicas
Brassicas like firm soil around them, and the taller the brassica, the firmer the soil needs to be. Brassicas need cabbage collars to keep the cabbage root fly (Delia radicum) at bay (if kept soil free, they form a dry environment that desiccates any eggs laid on them, while in the process helping to slow down slugs).
Covering is also required from the cabbage white caterpillar (Pieris spp). However, brassicas requires a lot of light and netting shades them, so we used netting with large holes, pulled taut so that butterflies cannot squeeze in!
 |
| 14 April, cauliflowers |
 |
 |
| 13 Apr, cabbages | 28 April, covered |
Lettuces
I did plant quite a lot of lettuce, so I now feel rather confident. It is generally grown in jiffy’s here, planted out when the seedlings are about 10 cm tall. You need to water them well to start with, peel off the ridge of the pot, then plan them at soil level, having loosened the soil well (for example with a bulb planter) before firming gently. As usual, then you finish with watering.
 |
 |
| 13 April | 20 April |
 |
| 28 Apr |
Potato day(s)
With April I have started spending more time in the veg garden, up to 2 days a week, which is something I have worked to achieve, as I expect that veg growing will be a relevant part of my future involvement in horticulture.
One of the first crops that I’ve been involved with has been potatoes.
I staked some early potatoes ‘Jazzy’, which had been grown in bags after being started indoors in week
13, which we then displayed in the glasshouse in the veg garden.
 |
 |
| Potato ‘Jazzy’ being staked | Potato ‘Jazzy’ in the glasshouse |
 |
| Potato fertiliser |
I fertilised the soil where potatoes would go in in week 14 (end of
March) by top dressing it before the rain came. We used general
fertiliser at 10 g per sqm.
Today (week 18) I planted some second earlies. At 40 cm between them in rows 60 cm apart, we planted them at 10 cm depth, by using a marked stick and adding 50 g potato fertiliser per hole, well forked in (it will need another 50 gr as topdressing at emergence, in 2 weeks).
 |
 |
| Marking the spacing of potato | Planting at the right depth |
As we were expecting one of the last frosts, I was also asked to earth
up the other potatoes that had emerged. With soil from either side of
the row, we covered every single leaf to avoid it getting damaged.
 |
 |
| Potato ‘Catriona’ earthed up | Week 20 and ‘Catriona’ has emerged again, safe from frosts now |
We had some sweet potato (Ipomoea batatas) slips too so I was shown how to root them in propagation, by laying them in a tray.
 |
 |
| Rooting Ipomoea batatas | |
The mint collection
It was the end of February when I helped in the herb garden to remove the mint from its bed for propagation purposes. I was struck at the time that you could count be so many different scents of mint, but there was not much left in the pots that we removed from the ground to sample them well (some mints had completely died back and there were only some rhizomes well hidden in the compost to be found) .
Today, however, I had the opportunity to help pot up the mint that had been propagated and to take it back to the display area in its new pots, so I could try and small a few of the cultivars, albeit by no means all of them.
There are no less than 25 species of Mentha* (22 are listed in PFAF database).
Mint, however, is quick to hybridize so identification is often difficult. To complicate matters further, in common language the word “mint” does not refer only to the genus Mentha, but often to other plants either within the family Lamiaceae (for example, Korean mint, Agastache rugosa, or mint bush, Prosthantera spp) or even in other families. In the latter case, it is the resemblance in the fragrance that promted to use the name (i.e. Vietnamese mint, Persicaria odorata is in the Polygonaceae family).
They main compounds that make of Mentha the economic plant it is are:
- menthol, an antiseptic, decongestant and analgesic, that is present in high concentrations in M. x piperita, peppermint but also in spearmint (M. spicata)
- pulegone, a neurotoxic, abortifacient substance, present mainly in M. pulegium: pennyroyal
- diosphenol, a diuretic, M. longifolia
- carvone, the substance that links M. spicata and Carum carvi (caraway)
Mints are used for culinary (sauces and drinks) and medicinal purposes, that range from antiseptic, antibacterial, antiinflammatory, antispaspodic and antiparasitic, to being a stimulant**. Oils are used in fragrances and for aromatherapy to increase concetration, and reduce headaches.
 |
| Some of the mints in February |
Mint, especially in pots, is prone to root aphids*** (possibly overwintering Ovatus crataegarius, the mint aphid) attack, so propagating plants and using fresh compost every year helps managing infestations.
 |
| Root aphid on mint |
While digging the pots out, we also found a carnivorous slug, new to me, rubbery and engorged on something, likely Testacella scutulum, with a string of eggs. That was rather fascinating.
 |
 |
| Testacella sp slug | |
But, back to today, from 9 cm pots I planted the mint into the 7.5 l pots where it will spend all the season, limiting the risk that its roots will become invasive. We
used 2/3 plants per pot to get enough plant material for display (some people will pull the leaves to smell them), but one would be
enough if you are not in a hurry.
 |
 |
| Some of the mints, before and after propagation | |
 |
| Some of the mints ready to go out in April |
The scent I preferred, from all the mints I sampled, was “basil mint”, which smells of basil and, depending who you ask, is either M. x gracilis or M. piperita x citrata ‘Basil’.
My time in the herb garden after bringing the mints out, however, tells me the most popular, especially among the kids is the “chocolate peppermint”, it must be because of the name! It does really have chocolate undertones, but it’s very much menthol-scented, which I have always found gives me headache. Except in one case: a few years ago I loved a cosmetic product made with a very strong menthol mint, M. aquatica – which is incidentally quite pretty, with its globose flowerheads, but unfortunately is not in the collection, as it requires wet conditions to grow.
References:
*Bown, D (1995) The RHS Encyclopedia of Herbs and Their Uses, London, Dorling Kindersley, pp. 158-159 and 311-312
**McVicar, J (2007 revised ed) Jekka’s Complete Herb Book, London, Kyle Cathie LTD and The Royal Horticultural Society, pp. 154-157
*** Buczacki, S and Harris, K (2005 3rd ed) Pests, Diseases & Disordrs of Garden Plants, London, Harper Collins Publishers, p. 176
See also the website of the National Mentha Collection in Wales, at mentha.info/NationalMenthaCollection/ and the electronic version of Maud Grieve’s A Modern Herbal (1931) at www.botanical.com/botanical/mgmh/m/mints-39.html
Grafting
Back in January, I was asked one morning to join a colleague, who was going to collect scion material in the orchard.
Under the aegis of the fruit specialist at RHS garden Wisley, the collection gets regularly propagated to renew old plants and to replace sickly and dead ones (I helped before with the gooseberries). But material is also sent to other gardens and collections, and it is possible to request propagation material from the RHS on payment of a small fee.
So, armed with a list of required cultivars and their locations, a bucket, sticky tape, a Sharpie and sharpened secateurs, we trawled the orchard.
Scion needs to be pencil-thick, one year old well ripened wood (brown, not green), with relatively short internodes. Sometimes you can try and use two year old material if nothing else is available, but it’s usually better to plan in advance: cut back hard the plant you want to propagate in winter so than it will produce new shoots that you can then propagate a year after.
Checking that it was not affected by mildew, we took two-three cuttings from each cultivar (if available), we taped them together, marked them with their name, placed in the bucket, and so on.
 |
| Scion material, ready for storage |
Once back in the messroom, we shortened the cuttings to 60-70 cm for easier storage and posting, cutting from either the tip or the bottom to try and get the longest pencil-thick part. Then we wrapped the bottoms with 4 layers of wet but not soggy paper towel (wet then wrung) and sealed them into plastic bags, writing indications for retrieval. They were then stored in the fridge, awating their destiny.
… because grafting is best done in March (and into April), with dormant scion but awaking rootstock. Budding is however done in the summer, July to September (depending on the type of fruit, with a window that more or less follows the succession of flowering: Prunus, Pyrus, Malus) with dormant buds from plants that have started to slow down.
So fast forward to today, and I’ve finally had the opportunity to make use of that scion material I gathered almost 3 months ago (gee, time flies).
For the third time this year I had the fruit specialist all to myself, teaching me whip & tongue grafting. We performed it on M26 stock that was planted in the nursery, which was cut to anything between 15 and 30 cm. Too low, and the splashing from rain may contaminate the graft, besides, it might start to root.
The tools required today were: sharp secateurs, a *very* sharp knife (it
must be able to shave, and some steels are better at that than others, I’m told German brand Tina is good), white labels, Sharpie, grafting tape, hot wax.
After a brief demonstration, I was given some spare cuttings to practice on. I felt so hawkward!
 |
| Demonstration of cutting a whip |
Starting from the bottom of the scion, but having made sure to remove any wood that is too hard with tiny buds, one has to make a smooth, sloping 3-4 cm cut the other side of a bud (the stock bud). One has to pull the knife from the top to the bottom, towards oneself. I found that wearing a plaster on my thumb made me feel safer while I got used to the maneuvre, which starts with the bottom and uses the whole blade lenght to the tip.
Then, starting in the top third of the slice (above the stock bud) and rocking the knife upwards at an angle, one has to carve the whip that will lock the graft together. It is very easy to split a whole lenght of wood if one is not careful when doing that.
Last but not least, the scion is cut to 3 buds (4 if they are very close).
 |
| The scion is ready |
Usually, the top one (or any one) will start to grow, but if they all go, then one chooses 2 and shortens them to 3 leaves: they will photosynthesise and feed the new tree! They are then removed in August, if the main shoot has grown strong and sturdy.
Then one moves onto the stock. During the whole procedure, one has to be careful not to contaminate the tools or the material with soil, which may carry pathogens.
Measuring the scion cut onto the clear side of the stock (no buds, as they are hard), previoulsy cut to a slight slant, one then proceeds with the opposite maneuvre to the scion’s.
 |
| Demonstration of cutting the stock |
Starting from the the bottom and slicing upwards (astride to the stock), one makes another smooth,
slanting cut, rather superficial, that is making sure one does not goes too deep into the wood. Then, just after the top, at an angle, one rocks the knife to cut a whip here too. I found it particularly difficult to find the right angle for this whip, as it came out too thin a couple of times.
 |
| “Church window” |
The scion and stock’s whips are then joined together, so that a “church window” remains visible: that is because if the bark of the stock were to touch the bark of the scion, they would not join together (as the bark has no cambium) and cause a weakness in the graft.
To complete the procedure, the graft is bound really tight with grafting tape (clear plastic, sometimes biodegradable) by wrapping it around, from the bottom of the graft towards the top, with a slight overlap to keep it in place and only making a fastening loop at the top. One has to make sure not to cover the cuts, because those will be treated with hot wax, so as to conserve moisture.
 |
| My first decent graft! |
I started with 3 grafts of ‘Barnack Beauty’, feeling rather frustrated by the results, but fourth time lucky and my graft of ‘Barchard’s Seedling’ was satisfactory, and the next one made me proud: it was firm even before wrapping with the tape!
Of course the closer the size of the scion and the stock, the better the cambiums will align, but sometimes the scion is smaller, like in the picture.
It was rather interesting to have a go at waxing the cuts, and to try hot water melting pot kit.
 |
| Wax |
 |
| Melting pot |
Oh, I had so looked forward to this day! And, as some scion wood went spare, I will have some more practice in the evenings.
About Me
M.Paola Andreoni
I got the first allotment in 2007 (in the UK) and started growing my own food for the first time. Learning as I went along was not enough, so I studied some horticulture. I am striving to abide by organic principles. Brexit gave me a new life in the Netherlands, and two new plots by a nature reserve.
Some Rights Reserved
This work is licenced under a Creative Commons Licence.