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.
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