If the dark green foliage of the apple tree (Malus domestica) is covered by white deposits, quick action is required. In this article we will show you what these unsightly coatings are and what you can do about them.
Where does the white coating on the leaves of the apple tree come from?
If the entireleavesand entire shoots are covered by a whitecoating, this is thecaused by a fungus Apple Mildew. If a dark spot can be seen through the white flour dust, the mealy apple aphid has nested in.
How do the white apple powdery mildew coatings on the leaves develop?
The causative agent of apple powdery mildew, aharmful funguswith the Latin name Podosphaera leucotricha,overwinteresin theterminal budsthe shoots of the apple tree andinfectedin the spring the newly sproutingleaves:
- The leaves remain narrower and point steeply upwards.
- The affected flowers wilt and die.
- White, mealy spots appear on the leaves.
- The fruits are small and covered in a rusty net.
At the beginning of July, the fungus penetrates the terminal buds again and survives the winter here.
How can I combat apple mildew?
It is advisable to cut back allaffected shoot tips before budding and dispose of them in household waste. You can recognize these by the narrower, slightly wrinkled buds, the scales of which are not as tight as usual.
You can effectively prevent an infestation by choosing the right location and choosing resistant apple varieties. The so-called Re varieties are considered resistant, such as:
- Reka,
- Retina,
- Regine,
- Rewena.
Fighting apple powdery mildew with fungicides, which always interfere with the ecosystem, is only advisable in very severe infestation years.
What's behind the fluffy coverings on the apple orchard
The mealyapple aphid(Dysaphis plantaginea)looksat first glance like a delicatepuff of powderabove theleaves. The abdomen of the pink or grayish colored animals is protected by a white waxy layer, which creates this impression.
The leaves occupied by the pests curl up towards the midrib or from the tip due to the sucking activity. Since the fruits become crippled (louse apples), there are high harvest losses.
How can I fight the apple aphid?
The most effective way to prevent the infestation is to promote thesettlementof the very efficientantagonists of the apple aphid.
These include:
- Ladybug,
- lacewing larvae,
- Hoverfly larvae,
- predatory bugs,
- Birds.
In addition, remove all affected leaves in spring and dispose of them with household waste. This also applies to weeds in the garden, as the apple aphid migrates to many plantain species, for example.
To protect beneficial insects, no insecticides should be used in the home garden to combat apple aphids.
Tip
Caring for the tree disc keeps the apple tree he althy
Since the growth on the tree disc competes with the apple tree, it should remain unplanted. Cover the open area thinly with grass clippings, this reduces evaporation and provides additional nutrients. Remove the mulch again in late autumn to prevent pests or mice from overwintering in the loose material.