There’s been some talk on the Oleandar Page about leaf scorch spreading here from other areas on leaf hopper insects.
But this is a rose bush, in a bed with three other roses who are doing quite well. The markings of leaf scorch are distinctive. If you see a triangle of brown on the end, surrounded by yellow, that’s definitely leaf scorch. The discoloration of the leaf is caused by a lack of water reaching the edges of the leaf. The causes for the lack of water are not so easily identified. This plant looked like it was wilting a few days ago and the wilt has continued to progress.
We’ve had no serious rain for a long time here. We’ve had 3.5″ of rain in 60 days most of it about 60 days ago. It has also been windier than normal here which also dries out the soil and plants. Leaf scorch usually appears during dry, windy spells.
Other causes of leaf scorch are a lack of roots on your plant from root rot ( over watering ) or lack of drainage ( clay soil ); from a wilt disease such as oak wilt; or from a bacteria spread by insects such as the leaf hopper.
If you see this symptom look for insect damage. Leaf hoppers are very tiny insects. Look on the underside of the leaf to find them. Damage from leaf hoppers on your roses will give the leaves a speckled appearance as if you had splattered yellow paint on your rose leaves. Or it may give your roses a tiny white dots all over the tops of the leaves. It will look like you spilled salt on the leaf. If you have the bacterial leaf scorch you will want to remove that plant as soon as possible to prevent the spread to your other plants. Other nearby plants should be sprayed on the underside of the leaves with an insecticide.
Since we have been in a dry, windy spell and the other three bushes in the bed are fine, I’m going to guess I just need to water more. If you are seeing this be sure you have a few inches of mulch around your plants to hold the water in the soil as long as possible.