Damage to Otto Luyken laurel shrubs
What is the problem with my Otto Luyken laurel shrubs? Two years ago they were treated for scale (2X with Talstar an insecticide). Last year, the shrubs with the worst damage did not improve. Several times throughout the year, new leaves and blooms would appear and then they would die off. They have started to grow this year and I am sending pictures. Is this scale or something else? What is the best way to treat these shrubs? Thank you!
Our entomologist could not see any scale, or determine if the shrubs have active scale. However, if the infestations were severe, they may have weakened the plants substantially, to the point that they cannot pull themselves out of decline. Be sure to do the basics: water during droughts, don't pile mulch on trunks, keep mulch no more than 2-3" deep. A single fertilization would be all right.
Some of the browning looks like winter burn.
The holes are made by cherry shothole fungus, which is very common on cherry laurel. It's called ‘shot hole’ because the infected tissue dries up and falls out causing the tiny holes. Mild, wet spring and early summer weather promotes this leaf spot. Rake up and dispose of infected leaves that fall off the plants. The disease is not serious but causes cosmetic damage. Spraying with a fungicide is not practical as the spraying regimen begins when the new leaves emerge and continues every two weeks or so throughout the summer. You can simply prune out the affected parts. Do not over-water or water the plants from above. Good water management and air circulation can help control this disease.