Sour cherry

Bacterial canker

What you will see

Sunken dead patches on the bark with gummy ooze; leaves have ‘shot-hole’ holes.

The source says: in stone fruit it is a serious disease that can kill branches or whole trees.

How to protect

1. Prevention

   • Gummy ooze on its own is not a diagnosis – look for sunken dead bark.
2. By handCut affected branches back to healthy wood and let the wounds heal naturally.

No fungicide sprays are available to amateur gardeners; rely on cultural measures.

European cherry fruit fly

What you will see

Fruit is dull and sometimes soft; the maggot feeds near the stone, so the infestation is not visible at first. After the larva leaves, an exit hole and sunken spots remain near the stalk; fruit also rots on the tree.

The source says: it is a serious pest of cherries.

How to protect

1. Prevention

   • Choose early varieties (harvest in cherry weeks 1–3, e.g. 'Frühe rote Meckenheimer', 'Burlat') – they are usually not attacked, but they split more easily.
   • Harvest on time and completely; collect and dispose of fallen fruit.
   • The fly's flight (1 generation a year, the pupa overwinters in the soil) depends on the weather: it needs rain to soften the soil; cool, damp weather reduces the population.
2. By hand during the fly's flight (as the fruit colors)Netting with a mesh of at most 1.4 × 0 in is, according to the source, the most effective measure (it prevents egg-laying); covering for ~2 weeks during the flight is enough. Pocket nets are available for small trees up to ~13 ft 1½ in; there is a risk of birds becoming entangled.
3. By hand before the fruit colorsYellow sticky boards only for timing the flight – in a garden they do not reduce egg-laying.
4. Chemical — only when nothing else helpsA product authorized in your country against cherry fruit fly – in commercial growing from when the fruit changes color from green to yellow, 1–2 treatments; in organic growing, direct methods are insufficient.

Cherry leaf spot

What you will see

Red-purple spots on leaves, later brown with the centers falling out; leaves turn yellow and drop prematurely.

The source says: it is most common on sour cherry; sweet cherry is quite susceptible too.

How to protect

1. Prevention

   • Remove fallen overwintering leaves.
2. By hand before bud breakRemove overwintering leaves.
3. Chemical — only when nothing else helpsA product authorized in your country against cherry leaf spot (Blumeriella) (as per the label; only if the other steps are not enough).

Brown rot

What you will see

Fruit rots brown with cream-coloured spore pustules, drops or dries up as mummified fruit on the tree. At flowering, blossoms and fruiting spurs turn brown and wilt (blossom wilt). Severity varies with the weather at flowering time.

The source says: stone fruits like this one are susceptible to brown rot.

How to protect

1. Prevention

   • Protect fruit from birds with netting – the fungi enter through wounds (from birds, codling moths, scab).
   • Mummified fruit touching the bark causes small cankers and releases spores in spring – do not leave it on the tree.
2. By hand from midsummerPick up rotten fruit straight away; bury it at least 11¾ in deep or put it in biowaste if your council accepts it.
3. By hand at flowering and in winter dormancyRemove affected fruiting spurs and blossoms by pruning where possible.

Black cherry aphid

What you will see

Curled leaves, stunted shoots, honeydew and sooty mold, especially on young cherry trees.

How to protect

1. Gentle spray winter / early springOil in winter dormancy against overwintering eggs; in spring after hatching, insecticidal soap before the leaves curl.

Pesticides against cherry blackfly are not recommended (they reduce biodiversity); the aphid neither kills the tree nor prevents flowering.