Welcome to my website where I gather information about plant pests and pathogens preying on gardens in my local area in Melbourne. I want to live in harmoney with nature and so I use exclusion techniques and natural predators to protect my edible and ornamental plants instead of using poisonous chemicals...................John Ashworth 27th July 2015.
Geranium Rust is fungus that grows on living plants and plant
debris. Movement of infected plant tissue can spread this fungus, and infection occurs readily if leaves are wet for 5 or 6 hours at 13°C to 24°C. Spores could remain infectious for at least 3 months.
variation exists between cultivars, and immunity varies considerably.
Both leaf surfaces first develop white or yellowish spots and those on the
lower surface enlarge and look like blisters (see photo). These brown
powdery markings are evident on leaves and sometimes on stems.
Why Geranium Rust is a Pest.
Severe leaf infection causes total yellowing and
defoliation. Eventually the plant will die.
Organic Pest Control.
Avoid wetting the plant's foliage.
Reduce humidity by spacing plants wide enough apart to provide good air circulation.
Inspect all plants regularly for signs of the disease, including new ones. Destroy diseased
leaves and severely affected plants. Do not recycle them unless you are
confident the fungi will be killed in the process (e.g. hot
Fungal plant pathogens like Puccinia pelargonii-zonalis are vulnerable to microbial predators in the soil. For this reason it is important to maintain an active community of micro-organisms in the soil by adding plenty of homemade compost before planting your Geranium.
There are also communities of beneficial microbes living on the surface of the Geraniums leaves, and the activity of these can be boosted by applying a foliar spray of aerated compost tea regularly.