Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_5327_Библиотеки_им_академика_М_И_Перельмана

A key weakness in high vanilla production in many regions of the world is stem and root rot disease mainly caused by Fusarium oxysporum. Vanilla crops are badly affected under poor management conditions and does not get high degree resistance against the stem rot. Fusarium is a ubiquitous soil borne fungus, also transmitted by water splash that also causes rot in many other species. Under severe environmental conditions, the fungus produces spores i.e., chlamydospores to extend their survival in the soil. In some conditions, the pathogen may incubate within plant body with­out showing any prominent symptoms. Because of general poor performance, due to adverse environmental conditions, of vanilla crop and inuence of various dis­eases, farmers lose their interest in vanilla production and abandon their farms within 10 years [58]. Some main diseases of vanilla are Anthracnose and Rust (Table14.2). Anthracnose is caused by fungus Colletotrichum sp. It attacks fruits, leaves, stems and owers of vanilla plant. Dark brown sunken spots are the symp­toms of this disease. Resultantly, the infected fruit falls off the plant thus causing a great loss. Sometimes, due to Anthracnose the yield drops by 50%. Fungicides such as copper oxy-chloride and Mancozeb could be used at a concentration of 2g/L mixed in distilled water or Bordeaux mixture. Spraying is done immediately after nortes begin. Moreover, the plants should be well nourished to prevent disease. Yellow- orange, round pustules on the abaxial surface of leaves are the symptoms of Rust in vanilla plant. Poor ventilation, excessive shade and high precipitation are the causes of Rust. Resultantly, the productive capacity of vanilla plant is greatly reduced. It may entirely defoliate the plant. Copper containing mixtures are used to prevent rust. Infected leaves are removed from vanilla plant and buried. Black rot is another disease caused by Phytophtora sp. that kills the plant only in few days. Greenish or blackish coloured watery injuries appear on the infected plant. Damage starts from the apical part of the plant and then spreads in rest of the body. Poor irrigation, high rains and excess shade leads to development of this disease. It causes excessive loss due to fruit loss and rotting [12]. This disease could be prevented by maintaining proper distance between the plants. Usually, a distance of 2m should be between plants and 2–2.5m among the rows of plants. Plants should be pruned regularly so that they could receive maximum sunlight. Infected parts of the plants should be burnt or removed. Another problem faced in vanilla cultivation is rotting of recently planted cuttings. This is mostly done by Fusarium oxysporum. In this infection, rotting of lower portion takes place which then spreads in the upper por­tion. A white cottony mycelium is observed to be formed at the point of infection. About 5–50% damage takes place due to this. It could be controlled spraying car­bendazim on plants [69].