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Calyx Horticultural Services presents

Into Horticulture

Issue 20   June 2016


Lack of time and shrinking garden space are often (rightly) identified as detrimental to home gardening. The weakening of community is less often mentioned.

Not only do plants and knowledge not pass between neighbours like they did, high fences stop us even seeing each other's gardens. Amateur garden clubs, local independent garden centres and specialist retail nurseries also played an important part in both the horticultural and social life of many towns, but now struggle.

However, horticultural connections are still being made, but in different ways. The many ways people can form communities online, as well as purchase actual goods, is an obvious change.

In the offline world, meanwhile, community gardens have been getting a lot of traction in recent years. Special interest initiatives like saving urban trees or providing wildlife habitats can also help bring people (and relevant businesses) together. An example is given in this issue's article on Pollinator Link.

Speaking of the old and new, they come together in the Virtual Library entry below. Do check it out if you're interested in horticultural history, or if you just like free stuff!


Plant & Garden News

Gardens make you feel better than balconies

In Austria, 811 people across a wide age range were questioned about their restorative value of their private lounges, terraces, balconies and gardens. Gardens were rated significantly better than balconies or terraces, with the restorative value increasing with the number of "natural elements" present in the garden. Age or gender made no difference, but the reported effectiveness of gardens did depend on the individual's ability to switch off from their worries and having a positive relationship with their gardens. "The message is that you should design your garden to be as close to nature as possible but, above all, you should enjoy it." A second study is further investigating the health-promoting effects of private gardens as well as more communal gardens. Source: Public Health Study: private gardens are more restorative than lounges

Australian wattle threatens Chinese flight safety

Black wattle (Acacia mearnsii) are rapidly spreading around airports in China's Yunnan province, endangering both the environment and flight safety. It is feared the fast-growing trees will provide shelter for birds and increase the likelihood of bird strikes. The species has been planted widely worldwide for its multiple uses, but is now poses an invasive threat in many locations. Source: Black wattle's new biogeographic distribution threatens flight safety in China

Saline soils have crop potential with Agave

Agave species could extend farming into hot, arid areas, producing a variety of edible and non-edible commercial products, but salinity could be a problem. When four types of Agave were tested, however, two species (Agave parryi and Agave weberi) performed well enough to demonstrate potential for cropping in saline soils. Source: Impacts of salinity determined for Agave

New symbiosis found

A new type of plant-fungus association with the potential to increase crop yields has been discovered in Europe. A type of Colletotrichum was found in wild Arabidopsis on phosphorus-poor soils. It lives within the whole plant and though it colonises via the roots, is not a mycorrhiza. However, function appearsto be similar moving phosphorous to leaves. Plants inoculated with the fungus produce more fruits and seeds. Source: A new plant – microorganism symbiosis discovered by UPM researchers

A wild defence

Wild tomatoes have some way of discouraging whitefly from settling on the surface of the plant, a study has shown. When pest was given a choice, they were 80% more likely to settle on the commercial variety 'Elegance' than wild type Lycopersicon pimpinellifolium. Such resistance is part of reason for popularity of wild and heritage varieties amongst home gardeners, but yields are too low for large-scale production. Researchers suggest returning some of these genes back into commercial varieties and emphasis the importance of preserving wild species. Source: Breeding wildness back into our fruit and veggies

Profusion Zinnia a space pioneer
Profusion Zinnia a space pioneer
Credit: Scott Kelly/NASA

A zinnia is the first ornamental plant to flower in space. This is part of the International Space Station's Vegetable Production System research. Although the primary aim is to produce fresh food on long missions, "space gardeners" have also reported how psychologically beneficial it is see and interact with live plants in this environment. News of the zinnia has been widely reported but with little mention of the variety. It was in fact a Profusion Orange. The Profusion series were developed by Sakata Ornamentals by hybridising Z. elegans and Z. angustifolia and have gained popularity around the world for heat, drought and disease resistance. Sources: ZINNIAS FROM SPACE! NASA Studies the Multiple Benefits of Gardening, Profusion Zinnias Become First Zinnias to Bloom in Space!

Clay sprays have potential

Kaolin (aluminosilicate clay) has been shown to have insecticidal properties in temperate regions, but this was largely untested in the tropics until Columbian researchers studied greenhouse whitefly on bean. They found that kaolin treatment was nearly as effective as synthetic chemical insecticides, Furthermore, a high application rate reduced transpiration and increased chlorophyll content compared to untreated plants, which could also make it useful in times of drought stress. Source: Kaolin effectively controls whitefly in beans

Childhood obesity intervention with gardens

A study of English children has shown that those in lower educated households, or those in higher educated households located in disadvantaged neighborhoods, that have no access to a garden between the ages of 3-5 years have an increased risk of obesity by age 7. Source: Study from England shows no garden access for young children linked to childhood obesity later in childhood

Floral density lures city bees

Insufficient pollination due to a lack of pollinators in an urban environment could potentially limit yield from city farms and gardens. An experiment in San Fransisco placed flowering tomato plants in various locations in the city, and flower clusters either covered (self-pollination only), covered and artificially pollinated (by tuning fork) or left open to pollination by local bees. Researchers were surprised to find that there were plenty of bees available to to the job, producing bigger and more numerous fruit than self pollination alone. Furthermore, the size of the garden nor the amount of green space in the surrounding area did not affect the amount of pollination occurring. Rather, it was the density of flowers in the garden that was important in attracting bees, meaning small city gardens can still be effective in this regard. it also debunks the notion that ornamental flowers will distract bees from visiting food-producing plants. Source: City buzz: Urban pollinators get the job done

The anti-aging effects of trees

A Toronto-based analysis of urban greenspace and health indicates that having 11 more trees in a city block decreases cardio-metabolic conditions equivalent to an increase in personal income or being 1.4 years younger. Just 10 trees produces a self-reported increase in health perception equivalent to being 7 years younger. Source: Neighborhood greenspace and health in a large urban center

Weeds a window on origins of agriculture

Discovery of weeds typical of cultivated soils, along with cereal species and grinding tools at an ancient settlement on the shore of the Sea of Galilee now puts the date for the origins of agriculture to about 23,000 years ago , some 11,000 years earlier than previously thought. Source: International collaboration uncovers proof of earliest small-scale agricultural cultivation

The rhythm of floral fragrance

An ordinary garden petunia, which releases its scent at night to attract pollinators such as months has been used to study the timing of fragrance. The LHY gene, which is associated with the circadian clock in many plants, was found to be active in the morning, regulating scent production through a suppressive effect. Scientists are now studying how pollinators respond to plants with and without altered LHY genes with a view to improving the pollination efficiency of crop species. Source: Researchers discover how petunias know when to smell good

Cucumber gender in the DNA

The genetic variation that causes some cucumber varieties to produce all-female flowers has been identified as a duplication of a particular piece of DNA. These "gyneoecious" plants are valued in horticulture because of their high yields (if conditions are good enough to support them), although pollination from a male flower is still required. Source: Extra DNA creates cucumber with all-female flowers

Managing contamination in urban gardens

In a study of contaminant risk of urban-grown food, gardens were tested in seven cities across the USA. Lead was the most common contaminant but arsenic, zinc and polycyclic aromatic hydrocarbons were also found at some sites. They were scarcely present, however, in food harvested from these gardens. There was elevated lead in root crops, but not sufficient to cause adverse effects at expected consumption levels. Proper washing of leaf and fruit crops will reduce contaminated dust. The gardeners themselves should take precautions against direct contact with the soil. Appropriate gardening practices can also help to reduce the risks. Source: Study: With proper care, contaminated urban soils are safe for gardening

Feature Article

   Blue Tiger butterfly
Blue Tiger butterfly (Tirumala hamata)

Pollinator Link

An environmental model for suburbia

Pollinator Link™ had its origins when Michael Fox, an active member of the Mt Gravatt Environment Group in Brisbane, tried to find ways to link the Mt Gravatt Conservation Reserve with Bulimba Creek. A number of groups are coordinating to restore and preserve the Bulimba creek catchment on the city of Brisbane's southside. It includes areas of remnant bush and wetlands as well as a network of creeks and their associated habitats.

Large continuous areas are better for supporting flora and fauna than many small ones, but this is rarely possible in a suburban landscape. Linking fragmented habitats via wildlife corridors, on the other hand, is more achievable because existing creek lines and remnant bushland can be incorporated.

The problem for Michael and the Mt Gravatt Environment Group was that many of the potential corridors to Bulimba creek were interrupted by urban development. By engaging the community and supporting them in the development of wildlife-friendly gardens, however, the vital connections could be made.

With this goal in mind, Michael developed the Pollinator Link concept. The goal is to establish at least 10% of private backyards and balconies, plus school grounds, community gardens and public parks, as Pollinator Link gardens. Even if not contiguous, a sufficiently dense mosaic could provide effective corridors for species that can fly.

A Pollinator Link garden aims to provide water, food and shelter for birds, butterflies and bees. These widely recognisable and desirable species are the main focus because the target market for this message is much broader than folk who typically become involved in environmental projects. This would include many time-poor families who would like to provide opportunities for the kids to learn more about nature but don't know where to start.

Once set up, Pollinator Link gardens will also help support a wide range of other, less celebrated species like moths and micro-bats. Furthermore, the knowledge and engagement created in the community can be built upon for future projects.

The Pollinator Link™ fence sign

Registered gardens are added to a digital map of certified gardens, receive a sign for their fence or front door and can opt-in to regular news via email. A small fee covers printing, postage and administrative costs.

The Pollinator Link name and logo have been trademarked to facilitate branding because the campaign also needs to reach organisations and businesses such as plant nurseries, landscapers, property developers and schools to be most effective. It is currently getting established in the Brisbane region, but the goal is to expand Australia-wide.

As urban development continues to encroach on natural areas in Australia and elsewhere in the world, new ways of living with nature will be important for human quality of life as well as flora and fauna. Pollinator Link is one strategy to help achieve that.

Learn more:
Bulimba Creek Catchment Coordinating Committee

Thank-you to Michael Fox, who supplied information and images for the above article.

For Your Virtual Library

Project Gutenberg hosts thousands of free electronic books that are not protected by U.S. copyright law, mostly due to expiration. Most books can be downloaded in a number of formats or read online. A vast array of fiction and non-fiction titles are available, but gardeners might like to start at the Horticulture Bookshelf or the Botany Bookshelf

Project Gutenberg Australia hosts works in the public domain in Australia. The number of works on offer is not as extensive and are not exclusively Australian, but there is a possibility of finding works here not available at the US site, such as three works by organic farming and composting pioneer Sir Albert Howard

(Note that works that are copyright-free in one jurisdiction aren't necessarily so in another.)

LibriVox is a library of public domain audiobooks, read by volunteers. There are a few gardening titles as well as some pertinent titles in the life sciences to listen to while you're getting other things done.

While much of the technical information in these works may be superseded, there will undoubtedly be gems of wisdom. Furthermore they provide historical background to the art and science of horticulture as we practise it today.

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