Clippings

Sniffer plants?
Researchers have produced plants that respond to certain chemicals in the air or soil by changing from green to white. They hope that further work will reduce the respponse time from hours to minutes, so that plants can be used to detect pollutants or explosives. More at www.news.colostate.edu/Release/5553 (26, January 2011, Colorado State University)

Sydney gets edible
The City of Sydney's has used vegetables in its summer planting program on various CBD locations including Martin Place. The displays are a tribute to the importance of local agriculture and will provide city dwellers with examples of how they might grow some of their own veggies in city conditions. Source: Fresh crops grow in the heart of the city (31 January 2011, City of Sydney Media)

New plants or products

International trends

For Your Virtual Library

Editorial

Welcome to Issue #1! Into Horticulture is aimed at the advanced amateur gardener as well as professionals in the nursery and garden industry, featuring news, opinion, and articles about plants, soil and gardening techniques.

There'll be an emphasis on issues concerning Queensland, but there should be something to interest any keen gardener in every issue.

Would you like to receive future editions of this newsletter (in a simple text-only format) delivered to your email inbox? Go to www.queenslandgardening.com/newsletters.html for subscription information and more about this initiative.

Pest and Disease News

First found in Australia in the central coast region of NSW last year, the disease has since been identified in Qld (Myrtle rust confirmed in South East Queensland, 5 January, 2011) and is spreading in NSW. At the time of writing, the NSW Department of Primary Industries Myrtle Rust website hasn't had a "weekly update" since 7 January. However, reportage in the media tells the tale:

And in case you missed it, three ornamental gingers were declared weeds in Qld in 2010

Hedychium flavescens is now a Class 1 weed
Hedychium coronarium is now a Class 3 weed
Hedychium gardnerianum is now a Class 3 weed

All are now illegal to sell or trade in Qld, while landowners who have H. flavescens on their properties must eradicate it. Media release here: Three Gingers banned in Queensland. More information at the Biosecurity Queensland website.

The Science of Horticulture

Cation exchange capacity (CEC) is a property of soils and growing mixes that is rarely discussed in mainstream gardening literature. However, it plays a very important role in nutrient-retention by soils which subsequently affects fertiliser efficiency and plant growth.

Many important plant nutrients, when added as fertilsers or released from breakdown of insoluble minerals and decomposition of organic matter, exist dissolved in in soil moisture (the soil solution) as negatively-charged ions (cations). Examples are potassium, magnesium, calcium and ammonium nitrogen.

In dissolved form, there's a limit to the amount of nurients that can be stored in the soil and they are vulnerable to leaching.

Fortunately, certain types of positively-charged substances in soil have the ability to cling onto cations, while keeping them relatively available for uptake by plant roots. Cations can re-enter the soil soilution by swapping places with other cations in solution.

The "cation exchange capacity" of a given soil will depend on the amount and type of such substancess it contains. Clays generally have a high CEC (although it it varies with the type of clay). Sand has none. Humus also has a high CEC, and is one of the ways in which organic matter improves soil.

Note that sodium is also a cation. Swamping the clay particles with positve charge affects soil structure and is one of the problems associated with salinisation of soils. More about this at a later date.