Phytophthora cactorum
Phytophthora cactorum
Phytophthora cactorum is a Protistenart from the Department of Eipilze ( Oomycetes ). It attacks a variety of plants and is responsible among other things for collar rot in apples, berries, leather and crown rot on strawberries, root rot in rhododendrons, azaleas, garden pansies and ginseng.
For the first time the fungus was described in 1870 as Peronospora cactorum by Hermann Lebert and Ferdinand Julius Cohn as cacti pests. The fungus is found on all inhabited continents, has its greatest occurrence but in temperate climates. The fungus spreads in moist soil. He developed zoospores, which can penetrate into the infected plants and can remain in the soil as resting spores long.
The discovery that Phytophthora cactorum is also responsible for collar rot of apple, dates 1939 by Baines, and was made in England on the basis of infested Cox Orange apples. His first major appearance had the disease in the 19th century in the United States when she was seized large stocks of apple Grimes Golden. The 1858 first -mentioned disease was known as original as Grimes ' collar rot.
Collar rot in apples occurs especially after harsh winters, and was originally thought to be a simple frost damage. It develops the apple over several years. The decay in the tree to take over the years, until he finally dies from the disease. As effective countermeasures proved a good drainage of the soil, and especially the use of resistant documents such as M9.
Symptoms
With apples, the infestation shows in the spring with the general symptoms of an apple tree under stress: particularly striking here is the late development of the buds. Flowering is normal, but in the late summer and fall, you will chlorosis, premature discoloration of the foliage, the fruits remain small and the leaves fall from the tree early. The symptoms resemble those of other plant diseases such as fire blight or winter damage. One indication of collar rot is a discoloration of the bark a few inches below the surface and the clear boundary between infested and non- infested parts of the tree. Certainly collar rot can diagnose but only in the laboratory.
Infested strawberries stop growing and produce only small leaves. If the plant is cut, is shown by the crown or the roots of a brown discoloration. During the year, the plant dies from the disease. In pansy roots seem healthy while wither the aerial parts of the plant and the leaves show chlorosis.