Frizziness
The curl is caused by the fungus Taphrina deformans caused plant disease, the peach - nectarine - and almond trees attacks. The disease is also known under the name of "vesicular and puckered disease".
Damage
The young green leaves curl up when they shoot in spring and show light green and / or red blisters. In the further course the diseased leaves turn whitish-green and appear enlarged, rubbery and brittle in the final stage. The leaves are eventually thrown off. In June / July there is usually a healthy new shoot because the fungus is not infectious above 16 ° Celsius. Due to the strong loss of leaves, however, the overall photosynthesis performance is reduced . The number of blossoms and fruits in such weakened trees is reduced and the number of buds for the next year is also limited. If the infestation is severe, entire branches die off, so that the tree has to be cleared after a few years. In summer, the untrained eye can confuse the end-stage curl disease caused by fungus (that is, without the initially characteristic red blisters) and leaf curl caused by insect infestation. An inspection of the underside of the leaves for aphids etc. allows a clear diagnosis here.
Pests
The peach curl disease is caused by Taphrina deformans , a hose fungus . This mushroom is closely related to Taphrina pruni , the causative agent of the fool's or pocket disease on the plum. Taphrina deformans lives saprophytically from June to February - that is, it feeds exclusively on dead plant material - as a shoot mycelium on shoots and bud scales. At the end of February to the beginning of March, the sprout mycelium disintegrates into a multitude of sprout cells. When it rains, the sprout cells are washed into the buds of the tree that have just opened (in Western Europe around February). There they infect the not yet unfolded leaves and grow through the flower buds. If this has happened, no countermeasures will help and the disease will take its course in spring. From mid-May to early June, the fungus forms spore beds that can be recognized as delicate, plush-like fluff. The contained ascospores germinate on the shoots and overwinter again later as shoot mycelium.
An infestation with Taphrina deformans occurs particularly in damp winters, because the fungus needs 12.5 hours of continuous moisture on the tree bark (from rain, not from dew or fog) at temperatures below 16 ° C for infection. In an unusual case in Hungary in 2011, curl disease caused by Taphrina deformans was reported on an apricot tree . The peak drought caused by monilini fungus infestation is usually found on apricots .
Combat
There are several approaches:
- On the one hand, disease-resistant peach varieties are being investigated, for example peach Benedicte.
- The most effective method in horticulture is to plant the tree on the wall of a house under an overhanging roof, which protects the tree from rain in the critical winter months and thus prevents infection; if necessary, the tree is also covered with a tarpaulin until the spring temperatures reach 16 degrees Celsius and deactivate the fungus.
- In commercial cultivation it is common to spray peaches and nectarines with fungicides just before the buds break in January or February. These are often copper-containing agents; Recently, residue-free peracetic acid has been discussed (produced by mixing acetic acid and hydrogen peroxide). The use of fungicides, including peracetic acid, requires adequate protection against skin contact and inhalation and should not be carried out by untrained personnel.
- Several fungicides with the active ingredient difenoconazole have also been approved in Germany and Austria for use in home and allotment gardens .
If a tree shows symptoms of curl disease in spring, the disease will inevitably run its course until the diseased leaves fall off and are replaced with healthy ones in summer, or the weakened tree dies. Accompanying measures to maintain the tree during the infestation stage are: timely tying of glue rings to the trunk, especially against aphids, rain protection on cold days (<16 ° C), sufficient irrigation and nitrogen fertilization (liquid manure), and thinning of any fruit that may still be present. It is not clear whether removing the infected leaves from the tree or removing the fallen leaves from the ground makes sense.
Web links
Individual evidence
- ^ A b V. Rossi, M. Bolognesi, L. Languasco, S. Giosuè: Influence of Environmental Conditions on Infection of Peach Shoots by Taphrina deformans. In: Phytopathology. Volume 96, Number 2, February 2006, pp. 155-163, ISSN 0031-949X . doi : 10.1094 / PHYTO-96-0155 . PMID 18943918 .
- ^ The peach curl disease , leaflet 3357 , Bavarian State Institute for Viticulture and Horticulture (PDF; 83 kB)
- ↑ Leaflet on the peach curl disease in home and allotment gardens , Thuringian Ministry of Agriculture, Nature Conservation and Environment (PDF; 75 kB)
- ↑ Kovics, Gyorgi Janos. An unusual occurrence of Taphrina deformans on apricot trees in Hungary. University of Debrecen, Oct 2011. [1]
- ↑ Bavarian State Institute for Viticulture and Horticulture: Information brochure: The curl disease on peaches. Retrieved March 27, 2013 .
- ↑ Peach leaf curl. In: website Royal Horticultural Society . Retrieved January 7, 2013 .
- ↑ Patent DE 10241614 A1, http://www.freepatentsonline.com/DE10241614A1.html
- ^ V. Měrka, R. Urban: Study of inhalation toxicity of performic, peracetic and perpropionic acid in mice. In: Journal of hygiene, epidemiology, microbiology, and immunology. Volume 20, Number 1, 1976, pp. 54-60, ISSN 0022-1732 . PMID 944215 .
- ^ Directorate-General for Health and Food Safety of the European Commission: Entry on difenoconazole in the EU pesticide database; Entry in the national registers of plant protection products in Switzerland , Austria and Germany ; accessed on December 7, 2019.
- ↑ Peach Leaf Curl. In: Website University of California (UC) - Integrated Pest Management Program (IPM) Online . May 2012, accessed March 27, 2013 .