Garlic – A Call to Arms

Currently there is a high public demand for organically grown produce and there are strict controls as to the use of plant protection chemicals from industry so that produce can be labelled as “organically-grown”. Although “good agricultural practice” can help to keep plant disease at low levels, the dilemma for the organic farmer is that cultural methods alone have only limited success without agrochemicals and yields and quality of organically produced fruits and vegetables suffer as a consequence. Plants, however, are the best chemists and produce a huge variety of organic molecules, or so-called “secondary plant products”, which we enjoy because they impart flavour and aroma to the foods we like to eat. Some of these natural chemicals are used by plants for their own defence. Furthermore, these familiar plant products, or 'botanicals', can be excellent in controlling infections in other plant species. Many members of the general public may have bought extracts of the tropical Neem tree from their local Garden Centre to dilute and spray to control insect pests. Well, perhaps in a low-tech application the hobby gardener will soon be using garlic from their own kitchen to keep the mildew off their roses and the scab off their apples. Garlic is something that you either love or that you hate, and the reason is the sulfur-containing substance called “allicin”. It may surprise you to learn that garlic is actually “odourless”, and as anyone who cooks with garlic knows from experience, the wonderful aroma only develops when you slice or crush the garlic clove. This is because allicin, which is the first major volatile given off by damaged garlic tissue, gives garlic its characteristic flavour and odour.