Phytophthora cactorum
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Phytophthora cactorum |
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| ( Lebert & Cohn ) J. Schröt. |
Phytophthora cactorum is a protist species from the egg mushroom division (Oomycota). It attacks a large number of different plants and is responsible, among other things, for collar rot in apples, leatherberry and rhizome rot in strawberries, root rot in rhododendrons, azaleas, garden pansies and ginseng .
The fungus was first described as Peronospora cactorum by Hermann Lebert and Ferdinand Julius Cohn in 1870 as a cactus pest. The fungus occurs on all inhabited continents, but has its greatest occurrence in temperate climates. The fungus spreads in moist soil. It develops zoospores that can penetrate the infested plants and remain in the ground for a long time as permanent spores .
The discovery that Phytophthora cactorum is also responsible for collar rot in apples comes from Baines in 1939, and was made in England on the basis of infected Cox orange apples . The disease had its first major appearance in the 19th century in the United States when it affected large populations of the Grimes Golden apple . The disease, first mentioned in 1858, was originally known as Grimes' collar rot.
Collar rot in apples occurs particularly after harsh winters and was originally thought to be simple frost damage. In the apple, it develops over several years. The signs of decay in the tree increase over the years until it finally dies of the disease. The most effective countermeasures proved to be good drainage of the soil and, in particular, the use of resistant underlays such as M9 .
Symptoms
In the case of apples, the infestation shows up in spring with the general symptoms of an apple tree under stress: the late development of the buds is particularly noticeable here. The flowering is normal, but in late summer and autumn chlorosis shows up , the foliage changes color early, the fruits remain small and the foliage falls from the tree early. The symptoms are similar to those of other plant diseases such as fire blight or winter damage. An indication of collar rot is a discoloration of the bark a few centimeters below the surface of the earth and the clear boundary between infected and non-infected parts of the tree. However, collar rot can only be diagnosed with certainty in the laboratory.
Infested strawberries stop growing and only produce small leaves. If the plant is cut open, the crown or roots will turn brown. During the year, the plant dies from the disease. In pansies, the roots appear healthy, while the aerial parts of the plant wither and the leaves show chlorosis.
literature
- Luis Lindner: Phytophthora cactorum as the cause of bark and fruit damage on apples . (PDF) In: Obstbau und Weinbau , 9/2009, pp. 312–319
Web links
- Entry at Q-Bank
- Entry in the Phytophthora Database
- Cary Rivard: description. Department of Plant Pathology at NC State University
Individual evidence
- ↑ a b L Blindeman, K Heungens, F Goossens, B. Gobin: Efficacy of fungicides against Phytophthora cactorum on viola . In: Commun Agric Appl Biol Sci. , 2009, 74 (3), pp. 749-754, PMID 20222560 .
- ↑ SN Hill, MK Hausbeck: Virulence and fungicide sensitivity of Phytophthora cactorum isolated from American ginseng gardens in Wisconsin and Michigan . (PDF) In: Plant Disease , 92, 2008, pp. 1183–1189, here p. 1183.
- ↑ H. Lebert, F. Cohn: About the rot of the Cactus trunks . In: Ferdinand Cohn (Ed.): Contributions to the biology of plants . Volume 1, Issue 1, 1870, pp. 51-57.
- ↑ Cary Rivard: Pathogen Profile: Phytophthora cactorum.
- ↑ a b UC Pest Management Guidelines: Strawberry Phytophthora Crown Rot . University of California.
- ↑ William W. Turechek: Apple diseases and Management . In: SAMH Naqvi: Diseases of Fruits and Vegetables: Volume I: Diagnosis and Management . Springer, 2004, ISBN 1-4020-1822-3 , p. 35.
- ↑ a b William W. Turechek: Apple diseases and Management . In: SAMH Naqvi: Diseases of Fruits and Vegetables: Volume I: Diagnosis and Management . Springer, 2004, ISBN 1-4020-1822-3 , p. 36.
- ↑ Luis Lindner: Phytophthora cactorum as the cause of bark and fruit damage on apples . (PDF) In: Obstbau und Weinbau , 9/2009, p. 315.