See Impatiens for a detailed discussion of these problems. These diseases are the most important problems on impatiens and can be extremely damaging. They are particularly troublesome on double-flowering varieties. Symptoms can appear as black ringspots, mosaics, and necrotic spots with tan centers and brown margins. Petals can develop a color breaking and leaves can pucker, become distorted, yellow, and abscise.
Stems occasionally develop distinctly black areas or lesions and plants can be stunted.
These pathogens are transmitted by the western flower thrips. Control of these diseases is focused on prevention since once plants are infected, they cannot be cured. It is important to eliminate and remove infected plants as soon as they are recognized and to eliminate other symptomatic plants since these viruses have very broad host ranges. It is also critical to manage the thrips population. When planted in full sun, many cultivars of New Guinea impatiens develop a marginal necrosis or brown patches on the leaves.