Publications

The Garden
May 2004

What generation gap?

Two head gardeners, supposedly generations apart in the way they controlled pest and diseases, were brought together by Alexandra Baulkwill to compare methods from their respective eras

Neil Porteous, Head Gardener at Clumber Park, Nottinghamshire and Harry Dodson, former Head Gardener at Chilton Foliat, Wiltshire Images: Tim Sandall

Harry Dodson, now 84, Head Gardener at Chilton Foliat in Wiltshire for 54 years, came to the attention of the gardening public in the 1990s BBC television series that began with The Victorian Kitchen Garden. A decidedly different, unashamedly reminiscent style of garden television, it inspired a new generation of gardeners with its potent recollection of horticultural life on a private estate, the management of which had indeed changed little since Victorian times.

Harry managed both pleasure and kitchen gardens for Colonel and Lady Ward, and up to 30 gardening staff, and still won several RHS gold medals in the 1950s and 1960s. Since his so-called retirement, he keeps similar hours to those he worked as a young man, tending the walled garden awarded him in perpetuity. He is one of the longest-serving members of the RHS Fruit and vegetable committee, and judges at RHS shows.

Neil Porteous, aged 41, is Head Gardener at Clumber Park and manages 13ha (32 acres) of the 1,500ha (3,800 acre) National Trust estate near Worksop in Nottinghamshire. Formerly a seat of the Dukes of Newcastle-under-Lyme, the house was demolished in 1938.

Neil has been instrumental in restoring the 1.6ha (4 acre) walled kitchen garden, which now grows a range of Edwardian heirloom vegetables. He manages three full-time staff, a careership student, three seasonal gardeners and a group of about 30 regular volunteers. Neil gardens mainly organically, combining old gardening methods with the latest biological and cultural controls.

‘It’s fair to say that Harry’s television series inspired my interest in learning more about, and experimenting with, historic growing techniques,’ says Neil, who is researching and writing a book for the National Trust on historic methods of growing vegetables.

Neil Porteous (left) hopes to document the time-honoured techniques of gardeners such as Harry Dodson (right) in his book

How many of us learned gardening, and its practical side in particular, from a parent or grandparent? Professional gardeners from Harry’s era absorbed their knowledge ‘on the job’, from observing and working with senior colleagues. Harry and Neil’s discussion showed how ideas and solutions change with time, particularly in the field of biological control, but also how much stays broadly the same. They were asked to focus on the pests RHS members had told the advisory service they found most troublesome today (see Pest Profiles, below, for current advice on these problems).

Red spider mite

During the 1950s, Harry was supplying the ‘big house’ of Colonel and Lady Ward with peaches, nectarines and grapes from early May until July. In the grower’s equivalent of sending coal to Newcastle, he also sent a weekly supply of peaches to the south of France, where Lady Ward spent her summers.

To ensure fruit was fit for the top table meant keeping a close eye on pests and diseases in the glasshouses. Problems with red spider mite could start in early May even before the fruit began ripening. Peaches trained on trellis were affected particularly badly. ‘We used to burn nicotine vapourising cones,’ Harry explains. ‘They made a really good job of it but you didn’t want to use them too much once the fruit began to ripen as it could affect their taste.’
Neil has had similar problems at Clumber: ‘All the humidity in the world does not seem to stop red spider mite on the peaches. We use biological control in the from of Phytoseiulus persimilis, a predatory mite.’ ‘It’s still the same pest, in spite of all the changes,’ Harry remarks dryly. ‘You can bet your bottom dollar on that.’

‘One thing we have done,’ continues Neil, ‘is to prune early with peaches. Leaving two shoots on each side branch for the fruit next year, we cut out the old wood really early, about the end of August, to help prevent spider mite build-up.’ Harry used to prune his glasshouse peaches as soon as the leaves had dropped in autumn.

Plenty of ornamental plants are affected by red spider mite too. ‘If you didn’t look after your fuchsia, gloxinias and winter-flowering begonias and catch spider in the early stages, before the whole leaf started to spot, you could run into trouble,’ says Harry. ‘In times gone by we used nicotine fumigating lamps. A cone used to go in the top, was warmed and worked by evaporation. You had to leave the glasshouse immediately as it was really nasty stuff – 50 percent nicotine compound.’ Its broad toxicity led to restrictions on the concentrations on sale compared to those available in Harry’s day, and nicotine was banned from home use in the 1970s.

Neil has had trouble in the past with spider mite on citrus trees brought back under glass at the end of summer, but in general other plants are not badly affected. ‘We tend to keep a very buoyant atmosphere,’ he says. ‘Shutting the vents of the glass for only half an hour during the day and letting everything fug up seems to help keep most of our ornamental plants mite-free.’

Aphids

As Head Gardener a major part of Harry’s job was to provide arrangements of fresh flowers and potted plants for the house. He usually put together more than a dozen large displays every Friday. For celebrations such as Easter there were even more containers. Cinerarias (Pericallis x hybrida) were in season for Easter, but a constant headache for Harry. ‘We used to do so many tubs; some stood by the drawing-room window, in the dining room and the picture gallery. They went into the house perfectly clean, but in a few days the Lady would tell me how nice the cinerarias were but “they have that wretched fly on them, Dodson. Please can you see to it”.’

‘We used to blame the close conditions. It was so stifling, I don’t know why her Ladyship always had to have the temperature over that of anyone else,’ he recalls with affection. Cymbidium orchids were also aphid magnets. ‘Right as ninepence down here, with beautiful spikes, but take one to the house and within 10 days the flowers were smothered.’

Depending on the species, aphid attacks were often dealt with using soft brushes. Harry says, ‘it worked as long as the infestation did not get too bad. If there were too many, you had to brush a bit harder and it bruised the leaves, which soon showed up.’

At Clumber Park Neil grows fuchsias and bedding plants for glasshouse display. He tends to spray with a soft soap (‘fatty acids’ in contemporary parlance) once a week in the propagation house but he says there are drawbacks. ‘With certain plants like fuchsias the soap can make the foliage quite “hard”, and you have to watch it in bright sunlight as it can scorch the foliage. It’s best to spray on a day that is slightly overcast.’

Neil’s other solution to aphids is biological: lacewing (Chrysoperla rufilabris) larvae. In summer, batches of 250 larvae are delivered to his doorstep. Voracious predators, ‘they can take a lump out of the finger of unsuspecting gardeners if not treated with respect’.

One of Neil’s gardeners came up with an ingenious update on Harry’s aphid brushes. Last summer, he could be found walking up and down the lines of Brussels sprouts with a battery-powered car vacuum cleaner.

Both men agree keeping your eyes open when carrying out everyday tasks such as watering is the best way to spot potential problems, as at this stage they are much easier to deal with than a large-scale infestation.

Vine weevil

A journeyman gardener in Harry’s day could get into deep trouble if he missed the characteristic leaf notching that marked the start of a vine-weevil infestation on fruit crops, particularly the peaches, nectarines and gages grown under glass for early crops.

Harry says it is worth searching for the nocturnal adults by torchlight from spring until autumn. Neil agrees. ‘I put down a sheet under the grapes in our glasshouses, shine a bright light on the vine and tap it firmly. The weevils seem so surprised they fall out onto the cloth.’ He also fills the trays in which the containers of fuchsias and phygelius stand with Hydroleca (expanded clay granules). ‘When you lift the pots up you often find weevils underneath. We just squeeze them between thumb and forefinger,’ he says.

Grubs are targeted with another biological control: Steinernema kraussei, a nematode that is watered onto the compost surface or soil, and which infects weevil larvae with a fatal bacterium. In addition, most of the indoor display collections are repotted annually, allowing larvae to be spotted and removed.

Nicotine vapourising lamps (left) were common in Harry’s time, when nicotine was a favourite pesticide. One manufacturer claimed in 1939 a 6.6 percent formula was ‘a penetrating and powerful yet perfectly safe liquid wash. Fatal to mealybug, scale, thrip and all forms of filth’

Indoor vines

One old technique which Neil has revived to great effect is bark stripping the indoor vines. ‘When I arrived at Clumber, we didn’t get a single grape from the four vineries, not one. It was a combination of two types of mealybug and powdery mildew,’ he says. ‘We stripped the bark off in the autumn to get rid of overwintering insects and their eggs, and lightly brushed the spurs with methylated spirits. Harry approves: ‘You can take all of the outer bark layers off and get back to a good skin beneath.’

The next line of Neil’s attack was to introduce Cryptolaemus montrouzieri, a species of ladybird and a predator of mealybug, to mop up any survivors. For the mildew, sulphur sprays were tried. ‘You have to spray every fortnight, which is a bit tedious,’ Neil says. ‘We also took out all the nearby gooseberries, as they harbour mildew, and in autumn we put a 10cm (4in) layer of manure on the beds topped with straw, sealing in the overwintering spores. We whitewashed the walls and cleaned the glass, and haven’t had a mildew problem again.’

There will never be another generation of Head Gardeners like Harry. ‘Only three of us were in charge here in the last hundred-odd years, and I have done the longest,’ he says. Neil began at Clumber Park in 1999, and is applying some of the best pest and disease controls from Harry’s era alongside biological controls. He has some way to go to match Harry’s 54 years continuity of service, but nevertheless hopes to pass on horticultural knowledge and skills from bygone ages in his book, due for publication next year. Tried-and-tested pest-control methods from Harry’s day and earlier may be set for a renaissance.

Harry Dodson demonstrates the hand-held sprayer he used for many years at Chilton Foliat, where nicotine was the pesticide of choice

Alexandra Baulkwill is Features Development Manager for The Garden

Pest profiles

Andrew Halstead, Principal Entomologist at RHS Garden Wisley, gives the background to Harry’s and Neil’s choices of control methods, and suggests other options including pesticides still available for garden use

Red spider mite

Glasshouse red spider mite attacks a wide range of indoor and garden plants. Individual mites are tiny, but heavy infestations can be extremely damaging, particularly in hot, dry conditions.

Symptoms include a fine pale mottled discoloration developing on upper leaf surfaces. In heavy attacks, leaves can dry up and fall prematurely, and a fine silk webbing is often produced between the leaves.

Biological control with the predatory mite, Phytoseiulus persimilis, is now widely used in preference to pesticides, as red spider mite has become resistant to many chemical controls.

Pesticides approved for use by home gardeners against red spider mite on peaches are limited to organic pesticides such as rotenone (derris), fatty acids (soft soaps) and vegetable oils. The last two work by blocking the mites’ breathing tubes, preventing respiration. Nicotine, one of the pesticides Harry used most, is highly toxic in its concentrated form to virtually all animal life, including humans. The permitted concentrations sold were lowered until its complete withdrawal from domestic-garden use in the 1970s.

Aphids

There are many different species of aphids and few plants are never attacked. They infest shoot tips and flower buds in particular.

Symptoms include distorted shoot and leaf growth, sticky foliage from the honeydew the aphids excrete, which encourages the growth of unsightly sooty moulds. Not all aphids are green: blackfly are also aphids. Some species attack a wide range of plants, others are extremely host specific.

Most plants get aphids at some time. Minor infestations can be squashed or rubbed from shoots and buds with the fingers.

Gardeners can choose between spraying with synthetic insecticides, such as contact-action bifenthrin or the systemic-action imidacloprid, or using sprays derived from natural substances such as pyrethrum, rotenone, fatty acids
and vegetable oils.

There are also natural enemies, mainly for use in glasshouses during spring to late summer. These include parasitic wasps and predators, such as midge larvae, ladybirds and lacewings. There are now no glasshouse fumigants licensed for use by home gardeners during the growing season.

Vine weevil

This destructive pest attacks a wide range of plants, especially those grown in containers. Its larvae devour roots and often kill plants. The nocturnal adults feed on the leaves forming characteristic, irregular notching in leaf margins.
Plants attacked by vine weevil larvae show poor growth and a tendency to wilt. The plump, creamy white larvae are up to 10mm long. Plant deaths usually occur from autumn to spring. Adult weevils are dull black with small, yellowish-brown flecks on the wing cases.

Vine weevil has become a more frequent pest with the switch to containerised plant production. It was difficult for home gardeners to tackle for years, but there are now two effective options. Biological control is by a nematode, Steinernema kraussei, watered into the potting compost. This remains active at soil temperatures down to 5°c (41°f); the first nematode previously used needed temperatures of 12–20°c (54–68°f). Ornamentals in pots can be treated with the systemic insecticides imidacloprid or thiacloprid. Searching for and killing adult weevils is worthwhile as all are female and each can lay 1,000 eggs.

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