Gadenin日本語Get the appBirds take the largest share
No pest or disease costs you as much fruit as birds do. Mulberries ripen a few at a time over weeks, they are soft and highly visible, and every fruit-eating bird in the neighborhood learns the tree within a season. On a mature tree you should expect to lose a third to a half of the crop, and on a small tree birds can strip it entirely, working from the top down and often taking fruit a day before you would have judged it ripe.
There is no way to protect a full-sized mulberry. A mature canopy is far too large to net, and netting slung over a big tree traps birds and tears in wind. Accept the loss and pick early and often; the fruit you shake down each morning is fruit the birds do not get. On a small or container-grown tree, or a wall-trained one, netting works well if it is held clear of the foliage on a frame so birds cannot perch on the mesh and feed through it.
| Approach | Where it works | Realistic outcome |
|---|---|---|
| Netting over a frame | Trees under about 10 ft (3 m), wall-trained forms | Very effective if fully enclosed at the base |
| Netting thrown over a large canopy | Not recommended | Tears, traps birds, birds feed through it |
| Daily shaking onto a sheet | Any tree | The most practical defense on a big tree |
| Visual scarers and tape | Any tree | Works for a few days, then birds ignore it |
| Planting for the birds too | Large trees | Accept a share; the tree usually produces enough |
Dieback, canker and bleeding wounds
The commonest serious problem on a garden mulberry is self-inflicted: a branch cut while the sap was rising, which bled, failed to seal, and died back from the wound. You will see a branch that leafs out weakly or not at all, with sunken, discolored bark spreading back from an old cut, sometimes with sap staining below it. Cut the affected limb back into clean, sound wood at a natural junction and do it in deep dormancy. Sterilize the saw between cuts if you are working on more than one branch.
Bacterial blight shows differently, as angular black spots on the leaves with yellow haloes, blackened shoot tips and, in a wet spring, whole young shoots collapsing. Prune out affected shoots well below the damage in dry weather, clear fallen leaves, and thin any congested growth so air moves through the canopy. Established trees generally shrug it off; it is only a threat to very young ones.
Any wound that is still weeping sap a year later, or a branch with sunken bark on one side, should be dealt with in the next dormant season rather than watched for another year. Decay in a mulberry moves inward slowly, but wounds this size do not close on their own.
Fruit and leaf troubles
Popcorn disease is the one that alarms people: individual segments of a berry swell up hugely, go pale and hard, and the fruit ends up looking like a piece of popcorn. It is fungal, it is spread by infected fruit left on the ground and on the tree, and it does not kill the tree. Control it by sanitation alone: pick off and bin every affected berry you can reach, gather up fallen fruit under the canopy through the season, and clear the ground thoroughly after the crop. Two clean seasons usually reduce it to a nuisance.
Leaf spot appears as brown or purplish blotches, sometimes joining up, with early leaf fall in a wet summer. On a mature tree it is cosmetic and needs nothing beyond raking up fallen leaves. Powdery mildew as a white bloom on the leaf surface is likewise a late-season cosmetic problem, worse on trees that are crowded or dry at the root.
| Symptom | Likely cause | What to do |
|---|---|---|
| Berry segments swollen, pale, hard | Popcorn disease | Remove affected fruit and all fallen fruit; repeat yearly |
| Angular black leaf spots, dying shoot tips | Bacterial blight | Prune out in dry weather, well below the damage |
| Branch fails to leaf out, sunken bark | Dieback from a badly timed cut | Cut back to clean wood in deep dormancy |
| White bloom on leaves in late summer | Powdery mildew | Improve airflow; usually needs no treatment |
| Sticky leaves, black sooty film | Scale insects or aphids | Wash off; treat heavy scale in dormancy |
| Heavy green fruit drop | Drought at fruit set | Deep soak weekly until fruit starts coloring |
Insects, and why they rarely matter
Mulberries are not troubled by much. Scale insects are the most likely to need action: look for small limpet-like bumps along the undersides of twigs, with sticky honeydew and a black sooty mold on the leaves beneath. A light infestation can be rubbed off or washed down; a heavy one is treated with a plant-based winter wash while the tree is fully dormant and leafless.
Aphids cluster on soft shoot tips in spring and are almost always cleared up by predators within a couple of weeks, so leave them. Where spotted wing drosophila is present it will lay in ripening mulberries as it does in other soft fruit, and the only practical response in a garden is to pick often and remove every over-ripe and fallen berry, because that fallen fruit is what breeds the next generation.
Fruit that never ripens, and other disappointments
A young tree that flowers and sets nothing, or sets fruit that stays small and sour, is usually just young. Seedling mulberries can take many years to come into full bearing and there is no fixing that except patience. On an established tree, a poor crop nearly always traces to one of three things: a dry spell between fruit set and coloring, too much shade, or a heavy dose of nitrogen that pushed the tree into making leaf instead.
Suckers appearing from the base or from the root run are common on grafted trees and after any root disturbance. Pull them off while they are green and soft rather than cutting them, because a cut sucker regrows from the stub, and keep the mower and the spade away from the shallow roots that provoke them in the first place.
Record what happened and when
Note the date you first see each problem: the first popcorn berry, the first sign of blight, the day the birds started on the fruit. Problems on a long-lived tree repeat on almost the same schedule every year, so a note from last season tells you the week to start clearing fallen fruit or to get netting onto a small tree. Record which limb you cut out for dieback and where, so that if the same branch declines again you know the wound is not closing and the whole limb should go.