See:
Geranium (Pelargonium spp.) - Mosaic (Impatiens Necrotic Spot)
Cause Over 20 viruses have been found in Pelargonium cultivars including beet curly top virus (leaf hopper transmitted), cucumber mosaic virus, (CMV, mechanical and aphid transmitted), impatiens necrotic spot virus (INSV, thrips transmitted), tomato bushy stunt virus (TBSV), tomato ringspot virus (nematode transmitted), tomato spotted wilt virus (TSWV, thrips transmitted), tobacco mosaic virus (TMV, mechanical transmitted), tobacco necrosis virus (TNV), tobacco rattle virus (nematode transmitted), arabis mosaic virus (nematode transmitted), pelargonium flower break virus (PFBV, mechanically transmitted), and pelargonium line pattern virus. All can be transmitted to the next crop through propagation procedures. Many can produce various leaf spots that could be mistaken for bacterial blight.
Symptoms Although ringspot, mosaic, line pattern, and flower break may occur, greenhouse temperatures often mask symptoms. If present, symptoms often develop only in winter and spring.
CMV - flower breaking disease.
INSV and TSWV - Mosaic, mottling, stem and leaf necrosis, leaf deformation, ringspots, and stunted growth.
PFBV - Ivy-leaf geraniums are symptomless but many zonal geranium cultivars, especially those with red flowers, show flower break symptoms consisting of red petals with whitish streaks. Chlorotic spots on leaves and stunting can also occur.
TBSV and TNV - Pelargonium necrotic spot including stunted growth, leaf deformation and splitting, extensive spots that are first hyaline and then necrotic, yellowing and necrosis of leaves.
TMV - mosaic and small light-colored or brown lesion on leaves.
Cultural control
- Use virus-tested (and found to be free of all known viruses) certified stock plants for propagation.
- Remove and destroy infected plants.
- Control or avoid insect and nematode vectors.
References Rosa, C., and Moorman, G.W. 2017. Diseases of Geranium. In McGovern, R.J. and Elmer, W. H. (eds.) Handbook of Florists' Crops Diseases. Springer Int.
Valverde, R.A., Sabanadzovic, S., and Hammond, J. 2012. Viruses that Enhance the Aesthetics of Some Ornamental Plants: Beauty or Beast? Plant Disease, 96:600-611.