Leaf Spot

“Leaf spot” is a common descriptive term applied to a number of diseases affecting the foliage of ornamental shrubs and trees. The majority of leaf spots are caused by fungi, but some are caused by bacteria. Leaf spots on trees are very common and generally do not require spraying. Leaf spot may result in some defoliation of a plant. An established plant can tolerate almost complete defoliation if it happens late in the season or not every year. Small or newly planted trees that become defoliated are more at risk of suffering damage until they become established. Here is a link that might be helpful:
http://www.ipm.ucdavis.edu/PMG/GARDEN/PLANTS/englishlaurel.html
You might want to consider pruning out and properly disposing of affected plant parts to give the plant a fresh start. You might want to consider treating with a fungicide as the new growth appears. Or you may want to consider replacing the plant.