Rhododendrum leaves curling

Russell Plumb

New Member
The photo above is a coupe of rhododendrons at my house. The one on the right has curled leaves on a 55 degree day. We have seen this on a few properties in the last two day and believe it may be Phytophthora.
Any input from anyone?
We’re thinking Agrifos soil drench of 12oz per 100 gl.


Most well-known member
Could be, or botryosphaeria perhaps. Check your soil moisture too.

Agrifos is a pretty good preventative but once rhodies start to decline here, that's usually not a good thing.

Are rhodies native to your area or plants with similiar cultural requirements?
Check to see if the symptomatic tree has stem cankers then check to see how the roots look. Are the roots white on the inside and firm? Or are they brown-black and squishy?
Phytophthora cannot be identified on symptoms alone. Lab work needs to be done for confirmation. You can send samples to your state's Extension Plant Disease Clinic. You can find your state's clinic's info here: www.npdn.org