Gunnera leaves going yellow

[aspidistra]

I have a Gunnera Tinctoria which has been growing very happily by my pond for about four years. It has lots of new leaves this year but they are covered in yellow marks. The newly emerging leaves are unaffected at the moment and I can't see any insects on the leaves.

Someone has suggested that it could be cucumber mosaic virus. Does anyone have any other suggestions?

[gardening_guru]

Hello,

I wonder if the yellow marks on the leaves are caused by a lack of soil nutrition. As the plant gets older it will develop a larger root system an dgo further in search of nutrients.
Is the soil deep and of good quality, these are hungry plants, you could try feeding it with a nitrogen rich fertiliser.

[aspidistra]

The soil is fairly heavy clay - I did improve the soil in the hole when I planted it four years ago but other than that it hasn't had any extra nutrition and te soil hadn't been cultivated before. I'll try feeding it and see if it helps. Thanks!