The curl disease is feared by fruit tree growers. It causes all foliage to die and causes a reduced harvest. In order to fight against the infectious disease, knowledge about the cause and their preferences is important. This is the only way to interrupt the life cycle.
How to combat curl disease on peaches and nectarines?
To combat curl disease on peaches and nectarines, preventive spraying with milk, horsetail, vinegar or baking soda is recommended, depending on the season. It is also important to have a sunny, airy location and the right care to maintain the resistance of the plants.
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 grow new growth. Effective plant protection can be sprayed the following year before the buds begin to swell.
| Period | Phase | Medium |
|---|---|---|
| November to February | Winter rest | Milk, horsetail, vinegar |
| February to March | Bud swelling | Milk, horsetail, baking soda, copper lime |
| March to April | Sprout and growth | Milk, horsetail, baking soda |
Year-round anti-fungal agent: milk
Milk helps against fungal infections in plants
Whole milk contains fungicidal active ingredients and has proven effective in the fight against mildew. Regular injections can have a positive effect in the event of an infection with curling disease. 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 combated, you can create an anti-fungal environment with regular spraying.
To strengthen plants: horsetail
Field horsetail contains silica, which has a supporting effect on leaf tissue and cell walls. Collect the herb in August as the active ingredient content is 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 plant parts and spray the affected trees with a diluted solution in a ratio of 1:5.
How to use field horsetail:
- Use all year round as a plant-strengthening watering 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 anti-fungal effect and should be injected undiluted as a preventive measure. Avoid using solutions with soap, as this neutralizes vinegar and renders the substance ineffective. Put the liquid in a spray bottle and spray the tree between November and February. Make sure that furrows in the branch bark and buds are well wetted, as this is where the fungal spores overwinter.
Only for agriculture: copper sprays
A spray with copper lime proves to be effective when the buds swell. This happens between February and March when temperatures rise above ten degrees Celsius. Applications are possible from just five degrees to effectively prevent the growth of the spore cells. Sprays containing copper are not permitted to combat leaf curl in private gardens. Therefore, use commercially available and approved plant protection products.
In case of infestation: baking soda
Baking soda dissolves in water with a weak alkaline reaction. This makes the raising agent valuable for use against fungal diseases on plants. 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 curl disease. The pH value changes so that the growth of the spore cells is restricted.
The recipe to try:
- mix one liter of water with two to three splashes of spirit
- add some dish soap
- sprinkle in a packet of Bach powder
Accompanying measures
The preferred trees can only be infected in spring when the weather is mild and rainy. For this reason, a sunny and airy location is recommended where the fungus does not find optimal living conditions. A later infection is not possible because the fungus has a special life cycle and lasts most of the year.
First aid for an infestation:
- Attach glue rings to the trunk
- prevent further weakening by aphids
- Rain protection on cool days with temperatures below 16 degrees
- sufficient watering on hot days
- regular nitrogen fertilization
- Fruit thinning
Background
Life cycle of fungal spores
The fungus only attacks living plant parts from February to June
Taphrina deformans feeds exclusively on dead plant material from June to February and poses no danger to fruit trees and woody plants during this time. From the end of February, the fungus develops numerous shoot cells, which are washed into the opening buds with the spring rain. They infect the freshly emerging leaves and overgrow flower buds as soon as the thermometer rises above eight degrees Celsius.
After the leaves of the first shoot fall off as a result of the disease, the trees sprout again between June and July. Above 16 degrees the fungus is no longer infectious. It hibernates until the 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 months of late winter. If you cannot ensure roof protection, you should protect the tree from moisture with a tarp during the peak infection period. Remember to remove the cover for ventilation purposes on sunny days. You can adjust the measure from temperatures of 16 degrees.
Once the frizz disease has broken out, the progression 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 from a genus of parasitic fungi that predominantly spread on ferns and dicots. They do not kill the host tissue, but rather cause deformation of the affected parts of the plant. The fungus responsible for curling disease, like its relatives, has specialized in certain species. This means that the species is not always responsible for curled leaves on plants.
Common causes of curled leaves:
- Cherry: Aphids
- Apple tree: apple powdery mildew, fruit tree spider mite, apple aphid
- currant: currant aphid, currant leaf gall midge, currant gall mite
- Pear: pear leaf sucker, mealy pear aphid
- Tomatoes: care errors, tomato rust mites, spider mites
- Roses: psyllid wasp, rose aphid
- Cherry laurel: aphids, powdery mildew
Excursus
Attention, risk of confusion
If the eye is untrained, observing terminal curled leaves can quickly lead to a misdiagnosis. In summer, such deformed leaves also appear after an insect attack. 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 taking a close look at the underside of the leaf, you can quickly determine whether leaf pests were at work.
Prunus persica
Prunus persica is particularly often affected 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 to prevent the disease from spreading further. A biological spraying makes sense at the end of January. The “Neudo-Vital fruit and fungus protection” product from Neudorff (€28.00 on Amazon) has proven itself to be effective. Repeat the spray three to four times in the coming weeks.
Varieties that cope well with curl disease:
- Nectarine: 'Snow Queen', 'Flavortop', 'Independence', 'Nectarine'
- 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 to provide peach trees with slow-release mineral or organic fertilizers. This makes the trees more resilient. Regular spraying with field horsetail tea helps prevent infection. To protect the plants, we recommend underplanting with horseradish, nasturtium or garlic.
Tip
Lime milk is used to protect tree bark from frost and disease. The aqueous solution with a consistency similar to milk can also be used for spraying. It reduces the risk of the fruit tree being attacked by curl disease.
Prunus armeniaca
Although the apricot is not one of the preferred host plants of Taphrina deformans, the tree in suboptimal locations is occasionally affected by the fungal disease. The spores spread in mild, humid weather and penetrate the opened buds. Planting in the right location is therefore the first step to prevent infection.
Identifying curl disease on apricots:
- young leaves curl and develop light green to reddish spots, slightly raised
- Leaves rotate around their own axis as the disease progresses
- Leaves turn whitish and appear rubbery before falling off
How to recognize frizz disease
The leaves not only curl, they also have ugly bubbles
The symptoms appear in spring after damp and mild weather. As a result of the disease, the leaves die. If the tree is strong and he althy, it will survive the fungal attack well and replace the fallen leaves with he althy foliage in summer. Old and severely weakened trees can die due to the disease.
| Leaf shape | Leaf coloring | |
|---|---|---|
| Initial stage | curled | scattered light green or red bubbles |
| Middle stage | knotted and thickened | reddish or light green to whitish |
| Final stage | greatly enlarged, rubbery to brittle | increasingly darker |
As soon as the first deformed leaves are visible in April, the fungus has already settled in the tissue. In June, the affected leaves fall off, so severe infestation can result in bald damage. A strong gum flow is characteristic of the curl disease. Fruits are rarely affected. If the tree is weakened by the disease over several years, death is possible.
Tip
If you spray the buds with an ecological color spray in winter, you can closely monitor the time of swelling. The paint then cracks and peels off. At this time, you should carry out plant protection measures.
Consequences of an illness
If the tree had to shed almost all of its leaves, there is a reduction in overall photosynthesis performance. If the fungal infestation is widespread, branches die completely. Trees that are weakened in this way reduce their ability to produce flowers, so that the harvest yield also decreases. The effects are often still noticeable in the following year because the bud setting is also restricted after the disease.
Frequently asked questions
Can I eat the fruit if it has been affected by curl disease?
The disease extremely rarely spreads to the fruit, so the consequences of the disease can only endanger your harvest. If the leaves are curled and fall off, the tree is missing a lot of leaf area for photosynthesis. As a result, it can drop unripe fruits or not allow them 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 curl disease that every single leaf becomes heavily knotted 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, because young trees heal faster than old trees. Carefully remove the affected leaves and pick fruits from the crown that no longer appear he althy. 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 he althy leaves will sprout and the fruits will remain.
Are there varieties that are resistant to curl disease?
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 about completely resistant peaches and nectarines. So far there is no variety to which the fungus cannot spread. However, many cultivars prove to be less sensitive or survive infection better than other cultivated forms. These are tolerant peach varieties:
- white-fleshed: 'Fidelia', 'Amsden', 'Roter Ellerstädter'
- gelbfleischig: 'Record from Alfter'
- red-fleshed: 'Vineyard Peach'
Is my plum tree affected by curl disease?
If your plum has curled leaves, it is not the curl disease pathogen but probably a leaf pest such as the plum aphid that is responsible. Taphrina deformans has specialized in certain woody plants and only attacks peach, nectarine and almond trees. A related parasitic fungus from the same genus mainly targets the species Prunus domestica and its varieties and cultivars. This also includes mirabelle plum and plum tree. Taphrina pruni is responsible for pocket disease and rarely causes misshapen and twisted leaves and shoots.
