Where shotgun disease strikes, it puts hobby gardeners on high alert. And rightly so, because the Stigmina carpophilum fungus is characterized by such tenacity that it even overwinters. Its prey pattern ranges from stone fruit of all kinds to ornamental trees such as the cherry laurel. The plant disease owes its name to the circular holes that form rapidly as a result of the plant’s defense reaction against the spores. If the gardener does not intervene, sooner or later the tree will no longer be able to withstand the pressure of infestation and will die. In order to break this sophisticated mechanism of action, control and natural pesticides should follow a targeted strategy.
Table of Contents
course of the disease and damage
In ornamental and kitchen gardens, a large number of fungal diseases threaten to significantly impair the beauty of the plants or the joy of harvesting and enjoyment. The effectiveness of countermeasures depends crucially on a correct diagnosis. The more purposefully a hobby gardener acts against shotgun disease, the more promising the chances of healing and saving the affected plants. Typical signs of fungal infection are:
- In spring, light yellow dots appear on leaves and shoots.
- After a short time, the spots turn reddish-brown.
- A further 2 weeks later, circular spots fall out.
- Tiny holes with a red-brown edge remain.
- Eventually the leaves will yellow and die.
- Unchecked spread leaves trees bare in June and July.
The young shoots also reveal round infection wounds. On the other hand, they do not react by shedding the necrotic tissue, but excrete plant sap or gum as a defense or form ugly galls. The cooler and rainier the weather, the more invasive the spread of the spores, which also affect the fruit. Predominantly on cherries , plums, apricots and peaches, black, sunken spots spoil the gardeners’ appetites.
In the course of the summer, the pressure of infestation usually decreases slightly because the Stigmina carpophilum fungus prefers a damp, cool climate. In addition, mature summer foliage has more resilience. At the beginning of autumn, weather conditions set in again with wet and cold fog, which resulted in a second wave of disease. Now the attachment points of the fallen leaves are wide open as entry points for the microscopically small spores. Until winter sets in, they continue their destructive work, destroying the buds already laid for the next season. The fungi then retreat into the interior of the plant, where they overwinter.
Mechanical combat
If a hobby gardener is confronted with the disastrous shotgun disease, he uses the cutting tool as the first emergency measure.
- Immediately cut all affected plants down to healthy wood.
- Gather all the leaves from the ground and burn them.
- Cut off diseased leaves from Kentia palm and cherry laurel.
- Do not leave fruit mummies on the tree or on the ground.
Since shotgun disease fungi lurk in wet to damp conditions, diseased wood should also be thoroughly thinned out. As a result, the crown dries more quickly and prevents the spores from spreading further because they are often carried by raindrops to the lower part of the leaves.
Natural sprays
Shotgun disease predominantly affects fruit trees that bear stone fruit. Infection occurs less frequently in ornamental trees, such as the cherry laurel or the Kentia palm. Since hobby gardeners are extremely critical of the topic of fungicides on crops, they primarily use sprays that are harmless to health and ecologically.
horsetail manure
- 500 grams of horsetail
- 5 liters of water
Soak the plant parts in cold water for 3 hours. Then boil for 30 minutes, let cool and strain. In case of high infestation pressure, spray on undiluted every 2 weeks. Otherwise dilute to 30% and distribute every 4 weeks.
common yarrow
- 20 grams of dried yarrow
- 1 liter of water
Leave the yarrow in the water, pour it through a sieve and apply. The spray is also suitable for prevention in a diluted concentration.
Copper fungus free
- Finishing agents based on copper
The remedy unfolds its full effect especially when used in autumn. Sprayed regularly on plants affected by shotgun disease, copper prevents a second wave of infestation. The fungal spores are killed before they can penetrate the plant tissue via the roots of the fallen leaves.
horseradish
- 150 grams horseradish, fresh and roughly chopped
- 5 liters of water
Pour the boiling water over the fresh horseradish. Leave for 10 minutes and filter.
net sulfur
- Finished preparation as a water-soluble powder or granules
As the main component, sulfur acts on the leaf surfaces by converting into sulfur dioxide when moisture occurs. Even in low concentrations, a poison is produced that is deadly for fungal spores but harmless to humans. From March, the natural spray is used repeatedly. The harmful effect on beneficial insects, such as ladybugs or predatory mites, is likely to be disadvantageous.
clay preparations
- Biological combination of active ingredients stimulates the resistance of fruit trees.
Clay preparations based on natural ingredients are already effective at low temperatures below 10° Celsius, while copper only develops its effect from 16° Celsius. Mixing with copper, neem, seaweed or potash products should be avoided. The combination with wetted sulfur, on the other hand, improves the effectiveness.
The correct dosage makes a decisive contribution to the successful use of natural sprays. Since such preparations are essentially based on a contact effect, experienced hobby gardeners pay attention to a continuous wetting film. This also includes the use of carefully maintained and correctly adjusted devices in advance. If you want to be absolutely sure that the spray film has been applied in an adequate concentration, you can use simple application tools such as special, water-sensitive paper.
Efficient prevention
Ornamental gardens and kitchen gardens in rainy regions with a cool, harsh climate are particularly at risk of infestation with shotgun disease. Hobby gardeners based there are advised by plant disease experts to take preventive measures. This is all the more true if the garden has already been infested with fungal spores.
- Give preference to robust, resistant fruit varieties.
- Establish endangered plants in sunny, airy locations.
- Avoid locations under tall trees with dripping rainwater.
- Likewise, do not plant in the sprinkler area.
- Prune fruit trees generously immediately after harvest.
- Prune cherry laurel regularly in spring and autumn.
- Refrain from nitrogen-rich fertilization.
An annual coating of the trunk with Brisiacum, a herbal mixture with neempress cake and other valuable ingredients, has proven to be an effective preventive measure on fruit trees. The tree’s own defenses are strengthened and the bark is protected from damage so that fungal spores cannot gain access. In addition, it is advisable to protect endangered plants with a rain cover even before flowering, if the visual appearance of the garden is not impaired too much.
Resistant fruit varieties
The following types of stone fruit are rated as particularly resistant to shotgun disease:
cherries
- Hedelfinger Riesenkirsche (also called Abels Späte)
- Gerema Vistula (Prunus avium ‘Gerema Vistula’)
- Altenburg melon cherry (Prunus avium ‘Altenburg melon cherry’)
- Sweet cherry ‘Querfurt King Cherry’ (Prunus avium ‘Querfurt King Cherry’)
- Hausmüller’s medium thickness (Prunus avium ‘Hausmüller’s medium thickness’)
plums
- Zwetschge Hanita (Prunus domestica ‚Hanita ‘)
- Plum tree Kantinka (Prunus domestica ‘Katinka’)
- Plum Cacaks Schöne (Prunus domestica ‘Cacaks Schöne’)
- Bühler early plum (Prunus domestica ‘Brühl early plum’)
peaches
- Pfirsichbaum ‘Amsen’ (Prunus persica ‘Amsen’)
- Roter Ellerstädter (Prunus persica ‘Roter Ellerstädter’)
- Pfirsich ‘Revita’ (Prunus persica ‘Revita’)
- ‘Early Alexander’ peach tree (Prunus persica ‘Early Alexander’)
- Pfirsich ‘Dixired’ (Prunus persica ‘Dixired’)
It is in particular old stone fruit varieties that have proven to be largely resistant to fungal infections such as shotgun disease. In addition, breeders around the world are striving to develop new, hardy cherry, plum and peach varieties. In this context, it must not be overlooked that planting a resistant variety alone is not enough to contain shotgun disease. Rather, it is a sensible combination of variety selection, prevention and control that is crowned with success.
Planned weighting of combat
Hobby gardeners who devote their free time to ornamental and kitchen gardens naturally do not have nearly as much time capacity as commercial fruit growers. For this reason, they usually find themselves forced to filter out those methods that promise the greatest success from the numerous control methods. As a contribution to the decision-making process, experts from the Chamber of Agriculture have prepared an estimate of the effectiveness of preventive measures:
- Weather protection: 80%
- Variety selection: 70%
- Site selection: 60%
- Maintenance work: 50%
Since no directly effective fungicides are permitted for use in the house and small garden, the focus in combating fungal infections will continue to be on natural sprays and mechanical prevention in the future.
Conclusion
The shotgun disease joins the long list of fungal infections that are up to mischief in kitchen and ornamental gardens. The causative fungus Stigmina carpophilum has mainly specialized in infesting stone fruit trees. The disease can also be found on ornamental plants such as cherry laurel. Since the use of chemical fungicides is frowned upon among health-conscious and environmentally conscious hobby gardeners, control is concentrated on prophylactic measures and natural sprays that nip shotgun disease in the bud. Garden lovers who are careful when selecting the variety and location are said to have the best chances of success. Then there is targeted weather protection, in connection with plant-strengthening, natural sprays,
