Geography

Germany (Berlin, Brandenburg, Bavaria), Italy (Bozen)

The disease was first confirmed in Germany to be associated with a novel emaravirus maple mottle-associated virus (MaMaV), but virus-like symptoms have been observed and reported earlier in maples not only in Germany (Bandte et al., 2008; Büttner et al., 2013), but also in Romania (Ploiaie and Macovei, 1968), Hungary (Szirmai, 1972), Turkey (Erdiller, 1986), North America (Brierley, 1944), United Kingdom (Cooper, 1979). Symptom descriptions such as “mosaic,” “chlorotic mottle,” “yellow-mottle,” “ring-mottle,” and “mosaic mottling with chlorotic spots” were used by earlier researchers. Whether the newly identified viruses might be associated with the symptoms described in these earlier studies remains to be determined, given in particular that electron-dense structures known as double-membrane-bound bodies with diameters differing within the range of 80–200 nm and typical of emaraviruses (Mielke-Ehret and Mühlbach, 2012) have never been reported in earlier electron microscopy samples from symptomatic maples, while more typical plant virus particles sometimes have.