Leaf problems on Spirea and Salvia
Last year I noticed some of the leaves on both of the plants were half yellow and half green on one leaf. I thought it was a weather related issue, but it came back again this year on both plants. I tried to research it and came up with a possible deficiency in the soil but it seems odd to me that it's only on those plants. I have 4 varieties of Spireas and it is only on the ones that have the dark green curly serrated leaves. I have 4 May Night Salvia, and it is only on 2 of the plants. Advice please. Thank you.
I think the place to start is with the MSU Diagnostics Lab at MSU. You should send them a sample. Because the leaves with the odd color also seem to be distorted in comparison to the other leaves, you want to rule out some kind of a virus. Viral problems can cause weird growth and coloration. There are no treatment for viral problems except disposing of the plant. You don't want to do this on a guess. Plants with viral problems usually also have diminished growth. Another possibility would be herbicide damage but it should not happen two years in a row.
Is there a possibility that this is a cultivar with this color characteristic? Did the plants ever appear all green? If they have always looked like this, it may be normal but if they have changed, that could be the concern.
Diagnostic Lab to download forms: www.pestid.msu.edu There will be information about how to take a sample and you pack and ship the filled out forms, a check and the sample.