November 10, 2018
We have 27 ligustrum shrubs and 2 ligustrum trees. They have been afflicted with black spot for a few years now and we have tried Neem oil and hired a professional service to spray these plants to no avail. They keep losing leaves. The shrubs surround our wrap-around porch/deck and they are so thin you can see through them. They range in height from 4 to 6 feet and have spread width wise to form a hedge. The trees in the front yard have a rounded topiary shape and they are 10 to 12 feet tall sculpted to form trees. We cannot afford to replace 27 shrubs and especially replace the two trees as they were quite expensive. Can pruning them down to a height of 3 feet and start the treatment over help? Also, I have read that if you don't clean your hedge trimmers that they can re-infect shrubs and potentially spread diseases to other shrubs. Is that true? I read that pouring rubbing alcohol on the trimmer blades can kill the diseases on trimmers.
I believe your wax leaf ligustrums are suffering from a disease called Cercospera leaf spot. It can be difficult to reverse. For this winter, rake up any leaves that have fallen from the plants and destroy them. In late February, cut your plants back and remove all debris. Keep in mind that rapid new growth can occur with severe pruning, and this new growth can be more susceptible to the disease. Spray with a systemic fungicide such as Fertilome F-Stop, Immunox or Bayer Advanced Disease Control for Roses, Flowers & Shrubs. Follow the spray schedule on the label. You can mechanically transmit the disease from shrub to shrub with your pruners. Cleaning between bushes is helpful, but if they are electric trimmers, use caution with anything liquid. Bleach solutions or alcohol can help on regular pruners. Make sure when you are done trimming that you clean the pruners and lightly oil them before storing, as any bleach solution will cause corrosion over time.
September 16, 2017
Can you tell me what is wrong with this ligustrum? I have 6 of these in different locations and they all have it.
Your ligustrum has a great case of a leaf-spotting disease called cercospera. This late in the year I don’t think a spray program will be very effective. If foliage falls this late in the year rake it up and dispose of it. Next spring, you may want to lightly prune and then spray with a general fungicide such as Daconil.
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