Curling disease is feared by fruit tree growers. It kills all foliage and causes a reduced harvest. In order to fight against the infectious disease, it is important to know who is responsible and what his or her preferences are. This is the only way to interrupt the life cycle.

Infection with leaf curl only takes place in the damp spring

Table of Contents

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  1. the essentials in brief
  2. Prevent with home remedies
  3. Accompanying measures
  4. Commonly Affected Plants
  5. detect damage
  6. frequently asked Questions

    7. the essentials in brief

    • Aqueous solutions with milk or horsetail have a preventive effect against frizz. Vinegar is sprayed in winter while baking soda is used when the buds swell.
    • To ensure that the plant survives an infestation, accompanying measures are useful. Choosing the right location ensures high resilience.
    • The curling disease occurs with a typical damage pattern mainly on peaches and nectarines. Curled leaves on other plants indicate different causes.

    Home remedies that help against frizz

    If the fungus has settled in the leaf tissue, no countermeasures will help. You can only remove the affected leaves to encourage the tree to sprout again. An effective crop protection can be sprayed the following year before the buds begin to swell.

    Period phase medium
    November to February hibernation milk, horsetail, vinegar
    February to March bud swelling Milk, horsetail, baking soda, copper lime
    March to April sprouting and growth milk, horsetail, baking soda

    Year-round antifungal agent: milk

    Milk helps against fungal infections in plants

    Whole milk contains antifungal agents and has been shown to be effective in fighting powdery mildew. Regular spraying can have a positive effect on an infection with frizz. Milk changes the environmental conditions and deprives the fungal spores of their livelihood. Mix milk with water in a 1:1 ratio and treat buds, shoots and leaves with the solution once a week. Although the infestation cannot be completely eliminated, you can create an anti-fungal environment with regular spraying.

    To strengthen plants: horsetail

    Field horsetail contains silicic acid, which has a supporting effect on leaf tissue and cell walls. Collect the herb in August, as the active ingredient content is at its highest at this time. Pour ten liters of water over one kilogram of fresh herb and let the mixture steep for 24 hours. Then boil the broth for half an hour. Sieve off the coarse parts of the plant and spray the affected shrubs with a diluted solution in a ratio of 1:5.

    How to use field horsetail:

    • year-round use as a plant-strengthening pouring agent
    • spray on the plant in case of an acute infestation
    • use as a preventive spray in winter

    Preventive home remedy: vinegar

    According to EU regulation 2015/1108, vinegar can be used as a fungicide. The agent has a caustic and antifungal effect, although it should be sprayed undiluted as a preventive measure. Avoid solutions with soap, because this neutralizes vinegar and renders the substance ineffective. Put the liquid in a spray bottle and spray between November and February. Make sure that furrows in the branch bark and buds are well moistened, because this is where the fungal spores overwinter.

    Only for agriculture: copper spray

    When the buds swell, spraying with copper lime proves effective. This happens between February and March when temperatures rise above ten degrees Celsius. Applications are possible from as little as five degrees to effectively prevent the growth of spore cells. Sprays containing copper are not approved for combating leaf curl in private gardens. Therefore, use commercially available and approved pesticides.

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    In case of an infestation: baking soda

    Baking soda dissolves in water with a weak alkaline reaction. This makes the raising agent valuable when used against fungal diseases on plants. Powdery mildew and gray rot can be treated biologically with baking soda, and the agent can also have a negative impact on the living conditions for the fungal spores in the case of curling disease. The pH changes so that the growth of the spore cells is restricted.

    The recipe to follow:

    • Mix one liter of water with two to three dashes of spirit
    • add some dish soap
    • sprinkle in a packet of Bach powder

    Accompanying measures

    The preferred trees and shrubs can only be infected in the spring when the weather is mild and rainy. For this reason, we recommend a sunny and airy location where the fungus does not find optimal living conditions. Later infection is not possible because the fungus has a special life cycle and survives most of the year.

    First aid in case of an infestation:

    • Attach glue rings to the trunk
    • prevent further weakening by aphids
    • Rain protection on cool days with temperatures below 16 degrees
    • adequate watering on hot days
    • regular nitrogen fertilization
    • thinning of the fruit

    background

    Life cycle of fungal spores

    The fungus only attacks actively living parts of the plant from February to June

    From June to February, Taphrina deformans feeds exclusively on dead plant material and does not pose a threat to fruit trees and shrubs during this time. From the end of February, the fungus develops numerous sprout cells, which are washed into the opening buds with the spring rain. They infect the freshly sprouting leaves and overgrow flower buds as soon as the thermometer rises above eight degrees Celsius.

    After the leaves of the first shoot fall as a result of the disease, the trees and shrubs sprout again between June and July. Above 16 degrees, the fungus is no longer infectious. It overwinters until next spring on the shoots and on the scales of the newly formed buds.

    Choose the right location

    Plant trees on a south-facing house wall so that they get enough sun. An overhanging roof protects against rain during the critical late winter months. If you cannot guarantee roof protection, you should protect the tree from moisture with a tarpaulin during the main infection period. Remember to remove the cover for ventilation on sunny days. From temperatures of 16 degrees, you can stop the measure.

    Once frizz has broken out, the course of the disease can hardly be slowed down. The right location deprives the fungus of the growth conditions.

    Commonly Affected Plants

    Taphrina deformans is a fungus in a genus of parasitic fungi found predominantly on ferns and dicots. They do not kill the host tissue, but cause deformation of the affected parts of the plant. Like its relatives, the fungus responsible for curling has specialized in certain species. That means the species isn't always responsible for ruffled leaves on plants.

    Common causes of curled leaves include:

    • Cherry: aphids
    • Apple tree: apple powdery mildew, fruit tree spider mite, apple aphid
    • Currant: Currant louse, currant leaf gall midge, currant gall mite
    • Pear: Pear leaf sucker, Mealy pear aphid
    • Tomatoes: Care mistakes, tomato rust mite, spider mites
    • Roses: scroll wasp, rose aphid
    • Cherry laurel: aphids, powdery mildew

    digression

    Attention risk of confusion

    If the eye is untrained, observing terminal stage ruffled leaves can quickly lead to misdiagnosis. In summer, such deformed foliage also shows up after an insect infestation. However, a pest infestation by aphids and other sap-sucking insects is not preceded by red blisters, which are typical of the infectious leaf curl disease in the early stages. By looking closely at the underside of the leaf, you can quickly determine whether leaf pests were at work.

    Prunus persica

    Prunus persica is particularly frequently attacked by the fungus

    The leaves of the peach tree and nectarine tree become infected early in the year as soon as the buds begin to swell. If you notice the typical symptoms,remove stunted shoots and fruit mummies. These should be disposed of with household waste so that the disease does not spread further. Biological spraying makes sense at the end of January. The remedy "Neudo-Vital Obst-fungusschutz" from Neudorff has proven itself. Repeat the spraying three to four times over the coming weeks.

    Varieties that do well with leaf curl:

    • nectarine: 'Snow Queen', 'Flavortop', 'Independence', 'Nectarose'
    • plate peach: 'White Frisbee', 'Yellow Frisbee'
    • peach: 'Fruteria', 'Benedicte'

    To prevent the fungal disease, you should plant all sensitive varieties of dwarf nectarine, flat peach or dwarf peach in the right location and thin out the crown regularly. It helps feed peach trees with slow-release mineral or organic fertilizers. This makes the trees more resilient. Regular spraying with field horsetail tea prevents infection. To protect the plants, we recommend underplanting with horseradish, nasturtium or garlic.

    tips

    Lime milk serves to protect the tree bark from frost and diseases. The aqueous solution with a milk-like consistency can also be used for spraying. It reduces the risk of the fruit tree being affected by leaf curl.

    Prunus armeniaca

    Although the apricot is not one of the preferred host plants for Taphrina deformans, the tree in the suboptimal location is occasionally afflicted by the fungal disease. The spores spread in damp, mild weather and penetrate the open buds. Planting in the right location is therefore the first measure to prevent infection.

    Recognizing Curling Disease On Apricots:

    • young leaves curl and develop light green to reddish spots, slightly puckered
    • Leaves turn around their own axis in the course of the disease
    • Foliage turns whitish and appears rubbery before falling

    How to recognize frizz disease

    Not only do the leaves curl, they also have ugly blisters

    Symptoms appear in spring after damp and mild weather. As a result of the disease, the leaves die off. If the tree is strong and healthy, it will withstand the fungal attack well and replace the fallen leaves with healthy foliage in the summer. Old and severely weakened trees can die from the disease.

    leaf shape leaf coloring
    initial stage curled isolated light green or red blisters
    middle stage knotted and thickened reddish or light green to whitish
    final stage greatly enlarged, rubbery to brittle progressively darker

    As soon as the first deformed leaves are visible in April, the fungus has already settled in the tissue. The affected leaves fall off in June, so that severe infestation can lead to balding damage. A strong gummy flow is characteristic of the frizz disease. Fruits are rarely attacked. If the tree is weakened by the disease over several years, it may die.

    tips

    If you spray the buds with an ecological paint spray in winter, you can carefully observe the moment of swelling. The paint will then crack and peel off. At this time, you should carry out plant protection measures.

    consequences of an illness

    When the tree has had to shed almost all of its foliage, there is a reduction in overall photosynthetic performance. If the fungal infestation is widespread, branches die off completely. Trees that are weakened in this way reduce their ability to produce flowers, which means that the crop yield also falls. The effects can often still be felt the following year, because the budding is also limited after the disease.

    frequently asked Questions

    Can I eat the fruit if it has been affected by leaf curl?

    The disease spreads to the fruit extremely rarely, so your harvest can only be threatened by the consequences of the disease. When the leaves are curled and dropping, the tree lacks much leaf area for photosynthesis. As a result, it can drop unripe fruit or not allow it to ripen properly. The small peaches are still suitable for consumption because they are not contaminated by fungal spores.

    My peach tree is so badly affected by leaf curl that every single leaf is tangled and I fear a crop failure. What to do?

    Whether you can still save the harvest depends on various factors. Some varieties prove to be resilient and regenerate comparatively quickly after an infestation. Age also plays a role in recovery, as young trees heal faster than old trees. Carefully remove the affected leaves and pluck fruit from the crown that no longer appears healthy. It is quite possible that the trees will appear very bare afterwards. Spray the tree with horsetail broth and with a bit of luck, after a while, fresh and healthy leaves will sprout and the fruit will remain.

    Are there varieties that are resistant to leaf curl?

    In general, white-fleshed peaches are less sensitive to the fungal disease than yellow-fleshed or reddish varieties. However, do not trust any advertising promises of fully resistant peaches and nectarines. To date, there is no variety to which the fungus cannot spread. However, many cultivars have proven to be less sensitive or survive an infection better than other cultivars. These are tolerant peach varieties:

    • white-fleshed: 'Fidelia', 'Amsden', 'Red Ellerstadter'
    • yellow-fleshed: 'Record from Alfter'
    • red-fleshed: 'vineyard peach'

    Is my plum tree affected by leaf curl?

    If your plum has curled leaves, it is not the causative agent of curling disease but probably a leaf pest such as the plum aphid that is responsible. Taphrina deformans has specialized in certain trees and only infests peach, nectarine and almond trees. A related parasitic fungus from the same genus mainly targets the species Prunus domestica along with its varieties and cultivars. These also include mirabelle plums and plum trees. Taphrina pruni is responsible for the pocket disease and less commonly causes malformed and crooked leaves and shoots.

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