Ruud Kleinpaste: The smallest things in the air

Saturday Morning with Jack Tame

There are heaps of particles that fly in the air (apart from molecules of Oxygen, Nitrogen and Carbon Dioxide, of course). For instance, sea-salt is a biggie near the coast. Others are smoke from bush fires, soot, pollutants, dust. You name it and it flies. We all know about birds, insects, flying fish and sugar gliders, flying squirrels and such critters, plant seeds and helicopter seeds from maple trees. Then there are bio-aerosols (micro-organisms). I’ve read some amazing statistics about fungal spores in the air. Take a puffball. Drop some water on the outer skin and see it release its spores. It looks like smoke. Millions of spores float in the air – amazing dispersal! Fungal spores are very common in the air – you might not see them as easily as the “smoke” from puffballs, but there are estimates of concentrations as high as 10,000,000 spores per cubic meter!
Fungi in the groups Ascomycetes and Basidiomycetes can cause allergies in humans with over 13,000 spores per cubic meter considered a high concentration. Allergies for some humans! There are many different allergic troubles, such as rhinitis (nasal membranes inflammation), asthma and the famous hay fever. The density of spores in the air is also a pain in the neck for gardeners. Some plant pest fungi distribute themselves through airborne spores. These spores usually appreciate landing on wet leaves – the moisture allows them to “germinate” nicely on the leaves and will then penetrate those leaves.
Rust species are probably the best adapted to aerial bombardment. Look around for those orange rust pustules on you garlic/onions/spring onions at this time of the year. Prevention is to try and keep leaves dry, or regular treatment with organic fungicides such as Copper/Sulphur mixtures. These do not allow fungal spores to develop on the leaf surface.
A recent walk in the nearby forest during lockdown showed me the famous late-winter pollen dump. Pine flowers are out right now and the pollen which are shed are bright yellow and everywhere. This pollen is very noticeable on the ground, especially where there was the remnant evidence of rain flooding. The pollen literally stick to the “side” of the old “stream bed”. Pollen salso visible as a fine, yellow-ish film on your cars. Mind you – it’s not just pollen from pine trees – other trees are full of it too. Have a look around for flowering trees and shrubs. People can be allergic to all sorts of plant species, including grasses; especially when they are flowering. Christmas plums in flower… a wonderful surprise awaits around the festive season! LISTEN ABOVE

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