Symptoms
- Small yellow spots, which later die causing a 'shothole' effect when the dead tissue falls out. Symptoms of this virus show only in winter or spring (Cause: pelargonium leaf curl tombusvirus, usually spread via infected cuttings)
- Leaf mottling, pale spots and unexpected flower colours (Cause: pelargonium flower break tombusvirus, mechanically transmitted).
- Line patterns along the veins and flecks on the veins (Cause: pelargonium line pattern virus, natural transmission unknown, not carried by insects but can be mechanically transmitted).
- Pale chlorotic rings, line patterns and yellow spots (Cause: pelargonium ringspot disease, several viruses carried on seeds and pollen).
- Yellow spots and ringspots, most commonly on ivy-leaved pelargoniums (Cause: tomato spotted wilt virus, transmitted by a number of thrips species, particularly the western flower thrips).
Control
There is no chemical control available, but good hygiene can prevent their spread. Many viruses can be spread on knives or when handling. Disinfect knives and secateurs between each cut when propagating, by flaming or washing in a strong detergent solution. Destroy and avoid propagating from plants showing virus-like symptoms and wash your hands after touching any suspect plants. Endeavour to buy virus-free plants.
Virus prevention through the control of insect vectors, such as thrips, usually requires a much higher level of control than can be achieved with the control measures available to home gardeners. For general information on thrips click here