Weeping Mulberry tree with patches of bare branches

(Question)

Tree over 20 years old in fairly sheltered spot, facing North and in Upper Beaches area. Since Spring complete branches devoid of leaves. Buds started to form but died. Rest of tree fine and bore fruit. Some crinkly browning of leaves many other leaves have tan blobs some with a white centre. Sorry my camera’s broken. Can you help me on this. Many thanks – Sue

(Answer)

Thank you for contacting the Toronto Master Gardeners with your inquiry.

Every year, trees maintain a set growth cycle, and they rely on the weather to keep them on track. Certain trees need to rest in cool temperatures before they can safely produce new growth in spring. When the dormant season is interrupted by unseasonal elements, trees begin to grow as though spring has arrived. They start sprouting leaves, flowers and fruits–no matter how short the resting period was. This winter we experienced numerous freeze thaw cycles. When temperatures are mild one day then plunge the next new growth is shocked by the sudden freeze and could be damaged. From your description it sounds that the damage to the buds is probably due to cold which we experienced this spring.

When pruning any trees or shrubs, the first rule is to cut out any dead and/or crossing branches. The same thing applies with the weeping mulberry. When pruning, it is important to not cut out more than one-third of the branches at a time.

Without a photo of the infected leaves it is difficult to say with 100% certainty what could be affecting your mulberry, however it sounds as if your tree your weeping mulberry may have Cercospora fungus (Leaf Spot) that attacks Mulberry trees usually via splashing water in rainy weather.

We have had a lot of rain this spring so the environment has been perfect for it’s growth. You will need to cut off the infected leaves, twigs and branches and any dead woody material. It would also be good to clean up all plant debris on the ground as well and dispose of it in the garbage. This should be done in the fall as well since the Cercospora fungus will overwinter in plant material left around near the tree. Any pruning equipment you use  on the tree should be disinfected  before using it again on the tree or other plants. It is best to spray a fungicide – sulphur based in the early spring on the tree as a preventative every 1.5 – 2 weeks however, the fungicide will not work as well later in the season. At this time, it is best to just clean up the tree and ensure that it has optimal growing conditions. Has the tree been fertilized? It likes a bit of All Purpose Fertilizer such as  10-10-10 or 20-20-20 twice a year – once in the late winter and again in midsummer or a slow release fertilizer once in the late winter.

Good Luck!