Horticulture Newsletter - March 2011

Developments in Biocontrol

The Priory Barn of Bridgewater College was the venue chosen for a meeting of the Professional Horticulture Group South West to hear a presentation on Developments in Biological Control.

Tony Girard, UK Director of Koppert BV, opened the meeting by describing the history of the company. Founded in 1967 to supply Phytoseiulus persimilis to Dutch growers for the control of red spider mite, Tetranychus urticae, the company expanded to supply other biological agents for pest and disease control. They have been exporting these to growers in the UK and other European countries since 1977. In 1988 they joined the developing market to supply bumble bees for the pollination of tomatoes. Over the years the company has expanded its range of products and now has 18 subsidiaries, supplying 80 countries worldwide. (photo: Peter Grimbly: Beehives in a tomato crop)

This expansion has necessitated a high level of logistic and quality control procedures to ensure that the living material is in good condition when it leaves the breeding centres and remains so during transport and on arrival at the growers holding. Added to this is full traceability so that if something does go wrong the cause can be rapidly identified and corrected.

Talks followed by Product Development Manager, Karen Girard, and Technical Consultant, Jasper Hubert, who described some of the now traditional agents for biocontrol as well as the latest developments.

A major issue with natural pest control has always been controlling a pest that could arrive at any time and frequently with a very uneven distribution through the crop. The principle of introducing the pest on a known date evenly through the crop has been known for many years to be a potential solution. Understandably there has always been reluctance on the part of growers to adopt this process. However, with the help of good technical support some pepper growers are now adopting this procedure. There remains the time-consuming process of distributing both pest and predator through the crop. The solution is a system that gently blows a controlled dose of the beneficial insect into the plants enabling the operator to move much more rapidly through the crop. Needless to say considerable care has gone into the design of this system to ensure that the insects are not damaged in the process. (photo: Koppert: A mini-airbug sprayer in use)

Once a good balance of pest and predator or parasite is achieved, all should be well. Unfortunately, as Augustus de Morgan observed ‘Great fleas have little fleas upon their backs to bite 'em, and little fleas have lesser fleas, and so ad infinitum'. In the last few years this has come true with the appearance of significant levels (up to 80%) of hyperparasitism; hyperparasites that attack the beneficial insects introduced to control a pest species. Since, at present there are no controls available for hyperparasites a second species of insect, unaffected by the hyperparasite, is needed to take over control of the pest. Thus if the initial control of aphids was achieved using Aphidius which has subsequently succumbed to hyperparasitism then other beneficials like Aphidioletes, lacewing larvae, hoverflies, and Aphelinus can be introduced.

Much work has been done to assess the benefits of using the fungus, Trichoderma harzianum, to improve the root environment by reducing pathogenic fungi and enhancing nutrient uptake. This has now been taken a step further with the experimental introduction of NatuGro. This system involves the initial introduction to the growing medium of a balanced mixture of soil micro-organisms followed by monitoring of the soil microflora. Based on the proportion of different microflora found in the growing media supplements are added to ‘rebalance' the substrate. Growing media such as rockwool tend to have a predominantly bacterial microflora while others like coco-peat have high levels of soil fungi. The object of the Natugro system is to create a ‘balanced' microflora in all media. Its use is still in its early stages but has been introduced on the understanding that it can do no harm to the crop but may well be of benefit.

Plant of the Month

Colocasia esculenta (taro, Araceae)

Taro (photo: Kahuroa) is one of the most widespread food crops in the world. It is originally native to South East Asia but has become a staple of African, Oceanic and Asian cultures. There are hundreds of local names and many different sub types and cultivars. This article will concentrate on the paddy field type commonly grown on the Hawaiian islands.

On a recent visit to Hawaii (Oahu, Kauai and Maui) I saw first-hand the vast paddy fields of taro growing as well as the traditional terraces (lo'i) in Limahuli garden (part of the National Tropical Botanic Garden). In Hawaii taro is known as kalo and it is believed that the taro plant was the ancestor of all Hawaiian peoples. Kalo root (corm) is cooked and then pounded to create a paste that can either be left with a dough-like consistency or thinned by the addition of water to give a liquid. This processed kalo is known as poi and is an important and sacred part of Hawaiian life. At the Limahuli garden, they grow many different cultivars and each of these would have had its own special use. One type with upturned leaves catches rain water and this water is used in special traditional ceremonies. The better, more exclusive cultivars would have been reserved for eating by the higher echelons of society with the coarser types left to the masses.

Taro is propagated via small non-saleable corms or from leaf cuttings with a small portion of corm still attached at the base. The plants will take 9 to 18 months to reach maturity.

The leaves and petioles can also be eaten as a leaf vegetable but care must be taken when handling them. They contain crystals of calcium oxalate, known as raphides and have traditionally been thought to be the cause of the skin irritation experienced when handled. Long standing advice is that they are safe to eat and handle once cooked, but chemically does this make sense? Will the normal cooking process break down or alter the form of these inorganic crystals? Recent research suggests that the adverse reaction is due to a protein in the leaves. We all learn at school that cooking or heating denatures proteins and so this explanation does at least seem to tie in with the observations that cooking renders the leaves harmless. It will take a long time before the perceived wisdom is overcome! (photos: Alison Foster: Top, taro paddy fields, bottom, terraces)

Alison Foster, Oxford Botanic Garden

Medicinal Plant of the Month

Curcuma longa (turmeric, Zingiberaceae)

Reports that turmeric may be able to help repair the damage caused after a patient suffers a stroke have been widespread in the media recently. This potential use is just one of many reported for turmeric. Turmeric is a member of the ginger family (photo: Ramesh Raju) and it is the ground up dried rhizome of the plant that we use as an ingredient in curries and other cooking. The magic component of turmeric is curcumin. It has a characteristic yellow colour and is actually used as a food additive. It has an E number (no, they are not all synthetic nasties…..) – E100.

The medicinal properties of curcumin are many and various including neuroprotective, cardioprotective and chemopreventive. There is not enough space here to summarise the vast tracts of work carried out on this molecule so here is just a taster of what's out there!

A pyrazole derivative of curcumin, known as CNB-001 has been synthesised and found to be both neuroprotective and memory enhancing. This molecule activates an enzyme known as CaMKII (Calcium/Calmodulin dependent protein kinase II) which plays an important role in the proper functioning of neurons. This could have huge benefits in treating diseases such as Alzheimer's and Parkinson's as well as stroke.

Curcumin has also been found to have potential in modulating levels of cytosolic calcium in the lysostomal storage disease Niemann Pick disease type C. This disease causes a build-up of toxic materials in the body's cells. It affects the brain and other organs and leads to progressive intellectual decline, loss of motor skills, seizures and dementia. Pharmacologists investigating this disease have found that curcumin elevates the level of calcium in the cytosol. Studies in mice have shown curcumin to prolong the lifespan and slow the rate of disease progression. It certainly seems that curcumin or related substances may prove beneficial in the treatment of this poorly understood disease.

And lastly, I recently met an ethnobotanist who absolutely swears by adding fresh turmeric juice as ear drops whenever he gets an ear infection. I have also been offered hot milk with turmeric added as a cold cure in India. It seems turmeric is good for everything! (photos: left by Badagnani: Turmeric root: right by Sanjay Acharya: Turmeric powder)

Allison Foster, Oxford Botanic Garden

News from our Associates

Commercial Horticultural Association
The Commercial Horticultural Association organised UK Groups at two trade events in February. The first was Fruit Logistica held in Berlin. With just under 2,500 exhibitors from 84 countries this event is vast and attracted 54,000 visitors. It was CHA's first time at this event and they led the small group of eight UK companies. However, they found over twice as many UK companies scattered through the exhibition halls. CHA's Administrative Officer, Stuart Booker, reports that there is great scope for a large UK Pavilion next year. Furthermore there were many UK visitors at the show a number of which were potential exhibitors, daunted by the prospects of exhibiting independently, but very interested in joining a UK Pavilion.

The second event was Salon du Vegetal, an event CHA has attended for over ten years. It is a key French trade show for the nursery stock and fruit sectors and an important potential market for UK companies. 'I think French horticulture hides it light under a bushel' commented Mark Taylor of Kernock Plants after a successful first day at the event.

International Society of Horticultural Science
The Society has started planning for the II International Symposium on Horticulture in Europe - SHE2012, to be held on 1-5 July 2012, in Angers, France. Prof Geoff Dixon will be acting as the UK representative on behalf of the SCI Horticulture Group.

The Society of Biology
On the 21 February, the Society of Biology moved a few blocks north to its new offices at Charles Darwin House in Roger Street, London. There it joins the Biochemical Society, The British Ecological Society and the Society for Experimental Biology in the building, which is becoming a major centre for the biosciences.

Horticulture Industry News

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Alan Barber OBE
Sadly Alan Barber, the greatest advocate for public parks and green spaces, has passed away. His death follows a long illness which he bore with characteristic strength, tenacity and remarkable good cheer, still writing and advising and working for the cause right up to within a few days of his eventual passing. Alan Barber fought for many years to reverse the late 20th century decline in public parks. He spent his life in parks: working in them, campaigning for them, and latterly playing in them with his grandchildren. With a combination of practical expertise and reforming zeal, he fought unceasingly for better public understanding of the value of parks, together with dedicated funds for their upkeep. His work has helped to secure the millions of pounds spent on restoring public parks in the past decade.

Weed tree kills superbugs
A University of Missouri researcher has found an antibiotic in the Eastern Red Cedar tree, Juniperus virginiana, that is effective against methicillin-resistant Staphylococcus aureus (MRSA), a 'superbug' that is resistant to most medications. 'I wanted to find a use for a tree species that is considered a nuisance,' said Chung-Ho Lin, research assistant professor in the MU Center for Agroforestry at the College of Agriculture, Food and Natural Resources. 'This discovery could help people fight the bacteria as well as give farmers another cash crop.' (Juniperus virginiana is a source of the anti-cancer drug podophyllotoxin, Alison Foster adds). More

Caterpillars shouldn't take sweets from strangers
Tasty little hairs growing on wild tobacco plants amount to 'evil lollipops' that make caterpillars who eat them more likely to be eaten themselves. Hawkmoth caterpillars (Manduca sexta) readily eat the hairs, reports Ian Baldwin of the Max Planck Institute for Chemical Ecology in Jena, Germany. But consuming them changes the odour of the caterpillars' bodies and excretions making the caterpillars more likely to become lollipops themselves for ants and other predators.

New Centre of Excellence
A Centre of Excellence for UK Farming (CEUKF) aimed at helping the industry meet the increasing challenges in food production and sustainability, is to be established in Cambridge. It will provide a network of expertise to help ensure that the best information and advice on developments in science, innovation and practical know-how are accessible in order to provide real benefits across the supply chain. The two founding institutes are the Institute of Biological, Environmental and Rural Sciences (IBERS) at Aberystwyth University and the National Institute of Agricultural Botany (NIAB), in Cambridge. Supermarket chain Waitrose has agreed to fund the establishment of the centre as part of its commitment to finding long-term solutions to food security, climate change and other issues affecting future agricultural production.

The Biology of Monetary Policy
Biology and the natural world are helping economists build new models to understand the dynamics of the financial sector and why the US sub prime loan crisis caused so much global damage. It sounds unlikely, but a group of scientists working with the Bank of England believe banking has lessons to learn from biological science. More (photo: Bank of England by Adrian Pingstone)

Clones from seed
The production of exact genetic replicas of important food crops has come a step closer. By combining mutations that abolish the shuffling of genes during sexual reproduction, researchers have found a way to force sexually reproducing plants to clone themselves through seeds. The method, published in Science1, has so far only been tested in the model plant Arabidopsis thaliana, but lead author Raphaël Mercier of the French National Institute for Agricultural Research in Versailles says his lab is working to extend the findings to crops. Such an advance would speed up the time it takes for companies to generate new plant breeds. More

A rose by any other name would smell … like celery?
North Carolina State University researchers have inserted a gene from celery into rose plants to help fight off botrytis, or petal blight, one of the rose's major post-harvest diseases. Some fungal pathogens produce a sugar alcohol called mannitol that interferes with the plant's ability to block disease like petal blight. In an effort to make roses live longer, NC State horticultural scientists Dr John Dole and Dr John Williamson lead an effort to insert a gene called mannitol dehydrogenase from celery into roses to 'chew up' mannitol and allow the plant to defend itself from one of its greatest threats. 'This gene is naturally found in many plants, but it's uncertain whether the rose already has it,' Williamson says. 'If it does, it doesn't produce enough enzyme to help the plant fight against petal blight.' More