Plant Health at the RHS: a very brief history

Plant health has been a key part of the RHS for well over a century. While there has been a plethora of research, new disease reports and new species discovered during that time, the core values of the Plant Health department have remained a constant.

In 1868, the RHS decided to appoint a scientific advisory board, in response to the number of scientific questions around horticulture discussed at the Fruit and Floral Committees. During the 20^th century, the purpose of this advisory board broadened to include ‘diseases, pests and newly imported plants’.  

It all started with a fungal canker

In 1784, botanist William Forsyth was working as the superintendent for the Kensington Royal Gardens. He had noticed the fruit trees in Kensington Palace were “in a very cankery and unfruitful state”. To treat the cankers, he concocted a plaster made of lime, dung, ashes and urine, which he claimed cured the tree defects.

This plaster received a mix of praise and criticism. Horticulturalist Thomas Andrew Knight heavily criticised the plaster, rebuffing Forsyth’s extreme claims – Forsyth was adamant that the plaster could be used to revive tree stumps. Knight’s criticisms and the subsequent controversy led to Forsyth not inviting Knight to the founding meeting of the RHS. 

Engraved portrait of William Forsyth (1737-1804)

William Forsyth went on to write Treatise on the Culture and Management of Fruit Trees, which included treatments for other concerns such as mildew. For this, he recommended a mixture of tobacco, sulphur and lime. This is effectively the first recipe for lime-sulphur, the main fungicide used in the 19^th century.

Forsyth became one of the founding members of the RHS in 1804.

The succession of RHS work on plant health (referred to then as plant pathology) over time fell into four main categories: environmental and physical methods of pest control, causes of plant disease, chemical pest control and biological pest control.

The ‘old’ laboratory and early scientific endeavours

As you approach the entrance to RHS Wisley, the first building you’ll notice is one we refer to now as the Old Laboratory. Established in 1907, this was the original home for horticultural science, with the aims of delivering research into ornamental horticulture as well as training for students. The construction of the laboratory enabled research to take place that was widely renowned.

First RHS entomologist: Harold Maxwell-Lefroy

After being appointed the first Professor of Entomology at Imperial College London in 1912, Maxwell-Lefroy was also given the position as the RHS’ first entomologist (insect specialist) in 1913. He taught at RHS Wisley, and one of his lectures was converted into a leaflet titled On Keeping Fruit Trees Clean, published by the RHS in 1916. This was reprinted six times up until 1942, and is still part of our library’s collection.

Harold Maxwell-Lefroy (far right) at RHS Chelsea Flower Show in 1913

The daffodil saviour: James Kirkham Ramsbottom

As a research student at RHS Wisley in 1916, James Kirkham Ramsbottom was asked to examine a puzzling disease that was seriously damaging the

These are fleshy, rounded, underground storage organs, usually sold and planted while dormant. Examples include daffodils, tulips, hyacinths, lilies, onions and garlic. The term is often used to cover other underground storage organs, including corms, tubers and rhizomes.

The groundings of the first RHS Plant Health team

Under the directorship of Frederick Chittenden in 1919, a new wave of scientists joined the RHS. This included entomologist George Fox Wilson and mycologist (fungal specialist) Walter John Dowson, alongside Norman Gould as assistant botanist.

 W.J. Dowson and G. Fox Wilson holding grapes in the Laboratory at RHS Garden Wisley, taken from the RHS Lindley Collections

Ahead of his time: George Fox Wilson

George Fox Wilson worked as an assistant to the first RHS entomologist, Maxwell-Lefroy, before taking this position himself, where he served until his death in 1951.

Fox Wilson was the first to trial biological controls for glasshouse pests, studying Encarsia formosa – a parasitoid wasp – for the control of glasshouse whitefly. Encarsia is still used for this purpose today, in a horticultural landscape where biological controls are becoming ever more crucial in place of indiscriminate and ecologically disruptive pesticides.

Fox Wilson researched a diverse range of horticultural entomology, including

The transfer of pollen grains from a male anther to a female stigma, either within the same flower or between two different flowers. It’s usually followed by fertilisation and seed production. Some flowers are pollinated by insects or other small creatures, others are wind pollinated. It’s also possible to pollinate flowers by hand, if you want to breed new plants or ensure successful pollination when there are few natural pollinators.

Plant Health team support Britain’s Dig for Victory

The RHS was involved quite heavily with the famous Dig for Victory campaign, and the Plant Health team at the time were a key part of that involvement. Courses were offered to members of the armed forces, as well as the Women’s Land Army, which included lectures on controlling vegetable diseases and George Fox Wilson teaching on vegetable pests.

Special courses were also arranged for the Royal Air Force, which focussed on food production, pests and diseases, and demonstrations of spraying machines.

Evolution of Plant Health in the last few decades

By the 1960s, the role of RHS scientific staff was advisory, and any research stemmed from problems arising out of the advisory work.

It was not until the 1970s that the RHS became more active around conservation issues, developing conservation policies and leaflets and becoming involved in issues such as pollution, the exploitation of peatlands, the use of endangered hardwoods, and the planting of invasive plants, as well as promoting water-saving practices, energy conservation in greenhouses, recycling and wildlife gardening.

The early 2000s saw the beginnings of larger, ongoing research programmes such as the research into honey fungus, which has been our most enquired-about disease for at least the last 28 years.

Since its arrival in the UK in 2007 and subsequent spread, box tree caterpillar has also become a focus for the team, topping the annual charts as most enquired-about insect several times since 2015.

Box tree caterpillar (Cydalima perspectalis) on box (Buxus)

 

• RHS Plant Health team’s top 10 garden diseases of 2023

In 2018, the first RHS biosecurity team was established to provide advice to RHS staff and the public on best practice for gardening safely.

The RHS Science teams now reside at RHS Hilltop: the Home of Gardening Science

A Plant Health lab at RHS Hilltop

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