I have a small mulberry tree. It was named ‘white shahtoot’ and was listed as Morus macroura but is likely just an alba hybrid. It appears to only set female catkins.
Last year it was small, got damaged by late frosts, was growing in a pot, and infested with beetle grubs eating the roots. It broke dormancy in spring and had heaps of catkins, then many withered and several of the branches died off. The mulberries it did set were delicious.
This spring it is growing in the soil, did not get any frost damage nor did we have late frosts, and should not have had issues with grubs. It was utterly covered in catkins as it was breaking dormancy, but again many of them are withering and the branches have started to die off.
What can be causing this and what can I do to prevent it?
Sorry to hear of your misfortune. There are many causes of dieback due to stress factors, but mulberries are pretty tough, and if you have given it reasonable care, I would suspect a soil born pathogen (there are hundreds of possible soil born pathogens that can infect mulberry). Most can be recognized by cutting off an infected branch and examining the cross-section for darkened vascular staining which usually forms a ring of darkened wood. The vascular tissue becomes so clogged that water and nutrients can’t reach the leaves and the stem “dies back”.
Not knowing the exact cause, it is difficult to suggest a treatment, but adding a good amount of organic material or compost usually helps. Work some into the top five centimeters of soil and then blanket the area with a good carpet of compost, leaves, straw, or whatever is available.
I hope your tree can flourish…Update us on its progress or demise.
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I cut off a branch today between a good node and a dead one to inspect it. There was no darker ring.
I had thought perhaps it is too hot and dry too early in spring? I have been watering it and I mulched heavily with guinea pig bedding over winter so the soil doesn’t dry out too much between watering (it hasn’t rained here in a long while). It is growing between a feijoa and a pomegranate which are both growing well.
Interestingly enough I had a look on the forum for the place that sells these trees. Many people were complaining that their tree was doing similar things. Most people complained of all the immature fruit dropping before it ripened. I am happy to say that any branches that survive tend to bear good numbers of really good fruit.
I will let you know how it goes.
That is good news, since one of the most common pathogens causing dieback in mulberry is Fusarium wilt, caused by Fusarium solani fungi. It is very difficult for the tree to ever fully recover from this disease without strong fungal treatment of the soil, as the fungus is very persistent in the soil.
Sounds like you are providing a healthy environment for you plant, so hopefully it will make a full recovery. Do me a favor though…If it doesn’t recover, and dies, pull up the plant and rinse off the roots with a hose. Examine them for a heavy infestation of root knot nematodes (little balls on the roots) and for blackened roots, indicating root rot disease (healthy roots are yellow-orange)…Finding the roots in good shape, the final thing to do would be to cut the trunk into (near the soil line) and examine the cross-section for a darkened path or ring, since Fusarium wilt often does not show in the individual branches.
Good luck…I hope your patient makes a full recovery!
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