Shotgun disease is a fungal plant disease that primarily affects Prunus plants such as cherries, plums, peaches or cherry laurel. Read how you can recognize the dangerous infection in good time and fight it sustainably.

Shotgun disease is a serious disease that is difficult to cure

Table of Contents

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  1. the essentials in brief
  2. What is shotgun disease?
  3. Damage and course of the disease
  4. Combat shotgun disease
  5. Prevent shotgun disease
  6. frequently asked Questions

    7. the essentials in brief

    • Shotgun disease is a fungal plant disease that primarily affects Prunus plants.
    • It first appears on perforated leaves, but also affects shoots and branches.
    • Strong pruning is necessary to combat it, and spraying with horsetail broth or preparations based on copper or clay in the spring.
    • The disease occurs mainly after a cool and damp spring.

    What is shotgun disease?

    Due to the perforated foliage (which gave the disease its name), many hobby gardeners initially suspect a pest infestation. Shotgun disease is actually a fungal plant disease caused by the ascomycete Wilsonomyces carpophilus (also: Stigmina carpophila).

    This occurs mainly after a damp and cool spring, since the pathogen is spread by rain and the finest water droplets (such as those that appear in fog, for example). In May and June in particular, initial infection of young leaves and shoots is common, whereas from around July older parts of the plant are only rarely infected due to their higher resistance - especially since the weather conditions for the fungus in summer are no longer ideal anyway.

    In humid and rather cool summers, however, the new infection of young shoots continues into autumn. Even after the leaves have fallen in autumn, late infections are still possible, which usually only show up in the following spring. The fungus hibernates on and in the plant, penetrates deep into the tissue and causes numerous problems - up to and including the death of the affected trees.

    Damage and course of the disease

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    Typically, these symptoms occur in infested trees:

    • initially round, reddish-brown spots on the leaves
    • often have a red edge
    • Stains can also appear transparent or yellowish
    • later develop into black pustules
    • and later to reddish-edged holes
    • Leaves appear to be perforated
    • Leaves eventually dry up and fall off
    • infested trees are more or less bare at the beginning of summer

    In addition to the leaves, other parts of the plant such as shoots and branches are often affected. This is where an infection shows up, for example through gum flow or through cancerous growths. The latter occur mainly on older trees and show a defense reaction of the plant. Any fruits are also affected, but soon dry up or rot and are discarded prematurely.

    The fungus overwinters on affected plants, primarily on

    • already infected shoots and branches
    • on old, infected foliage
    • in fruit mummies

    From here it spreads to new shoots and young leaves the following spring. Over time, there is not only stunted growth and reduced formation of flowers and fruits, whole shoots and branches die - until finally the whole plant can no longer withstand the disease and dies.

    Commonly Affected Plants

    Cherries are particularly susceptible to shotgun disease

    Stone fruit trees are particularly often affected by shotgun disease

    • sweet and sour cherries
    • plums and prunes
    • plums
    • almonds
    • Peaches and Nectarines
    • apricots

    In addition, an infection is an ornamental tree, mainly on other Prunus species such as

    • cherry laurel
    • ornamental cherries
    • ornamental plums

    and probably on hydrangeas and peonies. In terms of houseplants, palms such as the Kentia palm are particularly at risk.

    digression

    Confused with bacterial blight

    Especially on older stone fruit trees, the so-called bacterial blight occurs, which is quickly confused with shotgun disease due to the similar damage pattern. Here, too, there are bullet-like leaf holes, but the tree bark is typically characterized by sunken, blackish injuries. In the spring, gum flow occurs from these. However, the pathogen here is not a fungus, but a bacterium by the name of Pseudomonas syringae pv.morsprunorum. As with shotgun disease, it is controlled by severe pruning, but fungicides are ineffective.

    Combat shotgun disease in the hobby garden

    There are two possible periods of the year when infection with shotgun disease is possible. Since the fungus prefers a damp and cool climate, the first wave of disease sets in in spring and the second in autumn - here often only after the leaves have fallen, because then the tiny fungal spores have enough opportunities to invade. Once in the trees, the fungi destroy the buds that have already been laid for the following year. With the onset of winter, they finally retreat deep into the interior of the plant.

    In view of this life cycle, it has been shown that active control of the pathogen makes sense, especially in spring and autumn. While you attack the fungus at the beginning of the sprouting with - in the hobby garden if possible biological - sprays, cut back infected parts of the plant vigorously in the autumn. In this section, we will explain how best to proceed and which remedies work.

    Cut back affected plant parts

    Infested parts of the plant should be removed and discarded

    The first step in combating shotgun disease is always a vigorous pruning, cutting back all infected foliage and diseased shoots and branches well into the healthy wood.

    • Cut away all plant parts showing signs of disease
    • sweep up all leaves from the ground
    • Cut off any diseased foliage remaining on the wood
    • Remove fruit mummies
    • Do not compost clippings, but dispose of them with household waste or burn them

    In addition, regular pruning is useful as a preventive measure to prevent a renewed outbreak. Loose bushes and crowns dry faster after a downpour and thus offer the fungus less surface to attack.

    tips

    If possible, do not plant the cherry laurel (and other endangered trees) under taller trees. The dripping rainwater encourages infection, while a sunny and airy location is better for prevention.

    Make spray yourself - what really helps

    A self-made spray that is effective against shotgun disease is based on the fungicidal effect of field horsetail. Start spraying undiluted horsetail broth on plants that were sick the previous year as early as March - before they sprout - and continue this at intervals of 14 days until flowering begins.

    Recipe for making horsetail broth:

    1. Chop 500 grams of fresh field horsetail
    2. alternatively use 150 grams dried
    3. first soak in five liters of water for 24 hours
    4. then simmer for half an hour on a low flame
    5. let cool down
    6. strain out the rough parts
    7. Pour into a squeeze bottle and use fresh

    The broth described is also very effective against other fungal diseases, such as powdery mildew. When used as a preventative, dilute the concoction 1:5 with soft water. If you don't want to prepare it yourself, you can buy a ready-made herbal extract from specialist retailers.

    Nettle manure, on the other hand, is not suitable for combating the fungal disease, but can be used preventively to strengthen the plant.

    Fungicides allowed in home and hobby gardens - useful or not?

    Only a few fungicidal preparations are available for home and hobby gardens. Biologically active agents based on clay or copper, which are also used in organic farming, are available from specialist retailers. Only if these do not work do you use an approved fungicide. The preparation Celaflor Pilzfrei Ectivo, for example, is suitable, which you can use between March and April both for diseased plants and for prevention. However, its use needs to be carefully considered, because chemical pesticides harbor considerable risks:

    • Introduction of toxins into the environment
    • Killing beneficial insects and other important garden dwellers
    • penetration of the toxins into the groundwater
    • Disruption of the ecological balance

    Basically, caution is advised, because the list of funds permitted for private use is getting shorter and shorter. In addition, you must ensure that these fungicides are actually only used in accordance with their approval for the permitted plant species and against the fungal diseases described. The reason for this restriction is that a possible resistance of pathogens to carelessly used agents should be prevented. In any case, the preventive measures described and spraying with horsetail broth, clay or copper will work just as well - only without the disadvantages of toxic pesticides.

    Effectively prevent shotgun disease

    Regular pruning prevents shotgun disease

    "Avoid standing too close together! Air must be able to circulate between the plants!”

    Since shotgun disease, once it has broken out, is difficult to combat, preventive measures are the best choice. The means and maneuvers described here are not only useful in the fight against these, but also against other fungal diseases in fruit trees.

    • rain protection: Since infection occurs through rain, it can be prevented by using rain gear. Therefore, in spring, before flowering, install a rain cover wherever possible.
    • Adequate ventilation: In case of doubt, light and air cannot prevent an infection, but make it less likely due to the higher resistance of the plant. Therefore, when planting, pay attention to a suitable location and sufficient planting distances (follow recommendations!).
    • winter pruning: Prune trees and shrubs regularly in winter and remove dry branches, old leaves and fruit mummies in particular.

    It also makes sense to strengthen the defenses of the trees from the moment they sprout with regular watering or spraying with horsetail tea. Spraying with net sulfur also has a preventative effect. This is a very finely ground sulfur powder, which can be easily dissolved in water.

    Spraying with net sulfur - how it works:

    • monthly from March until flowering (the last time in June)
    • Harmless to bees, but very odorous
    • Harmful to ladybugs, predatory mites and predatory bugs (beneficial!)
    • Dissolve 20 to 40 grams of potassium sulfite (network sulphur) in 10 liters of water
    • liver of sulfur (consists of potassium carbonate - potash - and sulphur) is also very suitable
    • add some soft soap (44.90€) as an adhesive
    • sharpen undiluted
    • do not spray in strong sunlight

    planting of resistant varieties

    Below you will find a list of fruit varieties that are largely resistant (i.e. particularly resistant) to shotgun disease. These are mainly old varieties, some of which were already cultivated in the 19th century. But be careful: planting insensitive varieties does not mean that the disease cannot break out. In addition to the choice of variety, you should also pay attention to targeted prevention (choice of location, planting distance, rain protection).

    cherries Plums / plums peaches
    'Abel's Late' 'Cacak's Beauty' 'Red Ellerstadter'
    'Gerema Vistula' 'Bühl early plum' 'Formerly Alexander'
    'House miller's medium thickness' 'katinka' 'Revita'
    'Altenburg melon cherry' 'hanita' 'amsden'
    'Büttner's Red Cartilage' 'Dixired'
    'Querfurt King Cherry' ('King Cherry Type Gatterstedt')

    digression

    With onions and garlic against shotgun disease

    Many a gardener plagued by shotgun disease swears by cultivating garlic and/or onions on the tree disc of particularly infested trees and shrubs. These have antiseptic ingredients that are intended to reduce the risk of infection. Alternatively, you can simply spray or water your fruit trees with garlic or onion broth as a preventive measure.

    frequently asked Questions

    Are fruits affected by shotgun disease still edible?

    The fruit from such a diseased tree should not be eaten

    If a tree is affected by shotgun disease, the fruit is usually affected as well. This is shown by dark brown, sunken scab spots that have a significant negative effect on the taste and also contain fungal toxins. Persons with a fungal or penicillin allergy should therefore particularly refrain from eating or processing infected fruit. However, infected fruit is usually discarded before maturity anyway.

    Also be careful when spraying with pesticides: Here you have to wait a few weeks (depending on the agent used between 14 days and four weeks) until the sprayed fruit can be harvested and released for consumption.

    What to do if the cherry laurel is attacked by shotgun disease every year?

    Shotgun disease is very stubborn and difficult to combat, sometimes reappearing every year - despite all precautionary measures. Only a radical pruning helps here, especially in the case of trees that tolerate pruning, such as the cherry laurel, in order to really eliminate all pathogens completely. This ornamental tree in particular recovers very quickly and sprout again healthy and strong. On the other hand, you should clear up other plants that are repeatedly afflicted by shotgun disease - such as the cherry - and replace them with a resistant variety.

    Does homeopathy help against shotgun disease?

    In fact, there are homeopathic elixirs (e.g. from Neudorff) that have been specially developed to strengthen plants' resistance to fungal diseases. However, these cannot be used directly to combat shotgun disease, as they are ineffective against it. In general, the benefit of homeopathy is highly controversial, since all scientific studies do not confirm an effect that goes beyond that of a placebo effect. Therefore, you should be much more successful with tried and tested home remedies such as self-made nettle manure, as they actually contain active ingredients.

    When is the best time for an injection?

    A spray is only effective for shotgun disease if it is carried out early enough. The first implementation takes place in spring with the beginning of budding, then two more sprayings are to be carried out at intervals of about ten to 14 days. On the day of the spraying, the weather should be frost-free and dry, and there should also be no wind - only then will the active ingredients get to where they are supposed to go.

    tips

    It is also helpful to prevent fruit trees and cherry laurels from being cultivated near a lawn sprinkler or similar. Watering - for example in very dry weather - should always be done directly on the tree disc and never over the leaves.

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Trees