Sweet plums are robust, but in the event of maintenance errors they are susceptible to certain pests and plant diseases. You can find out what these are, how to recognize them and how to combat them here.© Sinuswelle - Fotolia.com
Although the plum (Prunus domestica subsp. Italica) is considered to be quite robust and many varieties can also be cultivated well in regions with a harsher climate, the fruit crop is not completely spared from diseases and pests.
However, if noble plums are cultivated according to their requirements for location and irrigation, diseases can largely be avoided because weakened plants are far more vulnerable to damage of all kinds.
The following diseases and pests have been observed on the plum:
- Plum pox virus
- Monilia peak drought
- plum fruit
Scharka virus - deadly danger for plums
The Scharka virus can occur on all plums. There is no disease that German orchards fear anymore, because the infestation extends to the entire tree and the Scharka virus cannot be effectively combated.
At first, the disease can hardly be recognized. Leaf discolouration occurs in midsummer, the shape of which resembles rings and clouds. The trees are sickly and grow worse than usual. When fruit ripens, pox-like deformations can be seen on the fruit. Therefore, Scharka disease is often referred to as smallpox. The otherwise yellowish flesh shows reddish discolouration. The plums fall off the tree earlier than usual. The fruits taste slightly bitter and are no longer edible.
If a noble plum is infected with the Scharka virus, there is no rescue. The trees must be felled and destroyed immediately. The occurrence of Scharka disease must be reported and reported to the responsible municipality.
" Tip: Plums are particularly susceptible to the Scharka virus. The varieties Große Grüne Reneklode and Graf Althanns are considered to be resistant to the pathogen.
Monilia peak drought - danger for fresh shoots
The Monilia peak drought is a fungal disease that begins with the flowers and then continues in the young shoots. The trees do not suffer any significant damage initially. Since the fungus nests in the fruit wood and hibernates there, trees can suffer from the disease for years. Over time, this weakens the plant until it grows stunted and eventually dies.
An infestation is visible on the flowers. These open as usual, but start to wilt a little later. Soon the leaves wither too. They lose color and wither visibly. The tips of the shoots also die. The infected plant parts do not fall to the ground, but remain on the tree and serve the fungus for the winter. The cycle then starts again in spring.
With good care, the Monilia tip drought can be largely avoided. If symptoms of the fungus appear, the infected shoots are generously cut back into the two-year-old wood.
" Attention: The cutting material must not be put on the compost, but should be disposed of with the residual waste or incinerated.
Infested prunes can be treated quite well with biological agents. Spraying with a broth of field horsetail herb or onion peel has proven itself here.
Plum wrapper - maggots on the move
As apple trees are not safe from the apple wrapper, the plum wrapper attacks the plum trees. The eggs are laid on the leaves, on the branches and on the fruits. The larvae hatch after only three weeks. They hibernate in the bark or in the ground and then plunge on the fruits in summer.
It is difficult. The maggots only become visible when the fruits are opened. The plums often fall off the tree prematurely and feel soft and mushy.
Here the hobby gardener can take preventive action. If a catch belt made of corrugated cardboard is laid out, the larvae will retreat there. The cardboard should be changed weekly. This means that the infestation cannot be completely destroyed, but can be significantly minimized.
The gall mite - small and mean
Gall mites cannot be seen with the naked eye. Therefore, an infestation initially goes unnoticed. In order to identify the infestation as early as possible, the orchardist should equip himself with a magnifying glass and take a close look at the plant.
" Tip: Gall mites spread especially in warm and dry weather.
In the case of an advanced infestation, reddish protrusions become visible on the leaves and on the fruits.
If the soil is always kept sufficiently moist, this not only benefits the growth and prosperity of the plants, it is also an effective remedy for gall mites, which appreciate a dry and warm environment. In lacewings and predatory mites, the gall mites have natural predators. In the case of an infestation, the use of biological pesticides based on rapeseed oil has also proven its worth.
Avoid diseases and pests caused by maintenance mistakes
Healthy and vigorous plants are less affected by diseases and pests.
The following measures serve as prevention: