Brown spot of oleander, a medicinal plant
Oleander scientific name NeriumindicumMill. It belongs to the woody plant of Apocynaceae. Used in medicine with leaves and flowers; poisonous. It has the effect of strengthening heart and diuresis, eliminating phlegm and killing insects. It is distributed in most provinces and autonomous regions of the country.
The main symptoms were harmful leaves, the purplish red dots appeared at the tip or edge of the leaves, and then expanded to form round, semicircular or irregular brown spots. There are wheel marks on the disease spot. In the later stage, the center retreated to white, and the edge was wider in reddish brown. When the humidity is high, the grayish brown mildew layer can grow on both sides of the disease spot, that is, the conidiophores and conidia of the pathogen.
Pathogen CercosporaneriellaSacc. Cercospora of oleander is called Cercospora, which belongs to the subphylum of semiknowns. The constellation is dark brown, 25-125 μ m in size. The conidiophores are light in color, uneven in thickness, clustered into bundles, with 0-3 septum, unbranched, and with small spore scars at the tip, the size of which is 5 ~ 35 × 3 ~ 5 (μ m). The conidia are cylindric, with 5 diaphragms of 1 Mel, and the size of the conidia is 15 mi 50 × 3 mi 5 (μ m). In addition, C.nerii-indiciYaman called Cercospora oleander, which is also the pathogen of the disease.
The pathogen overwintered by mycelium on the diseased leaves or on the soil surface with the fallen leaves. Conidia are produced in the next spring and spread to oleander through wind and rain, and the germinated spores invade from stomata or wounds, causing the disease. It occurs from March to July, when the seedlings grow too dense or the disease is weak and serious.
Prevention and control methods (1) strengthen the management of seedlings, not too dense planting, removal of diseased leaves and centralized burning. (2) spraying 1000 times of 50% carbendazim wettable powder or 25% carbendazim wettable powder and 36% thiophanate methyl suspension at the initial stage of the disease.
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Control methods of APHIS gossypii in ornamental trees
Distribution and damage of oleander aphid AphisneriiBoyerdeFonscolomde, also known as oleander yellow aphid. Belongs to Homoptera, Aphididae. Distributed in Changchun, Shenyang, Baotou, Taiyuan, Ningbo, Guiyang and Urumqi. Prickling is harmful to the new shoots and tender leaves of oleander plants, affecting the normal growth and flowering of plants. Morphological characteristics wingless female aphid body length 2 mm, body apricot yellow, antennae dark brown, foot black, tail tongue-shaped, with 11-14 curls. The winged female aphid is oval with black head and chest.
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Medicinal flowers: oleander
First, the source is NeriumindicumMill. Alias willow leaf peach, half a year red, peach bamboo, pen peach. It has been introduced into our country for a long time, and the bamboo was recorded in the Pingfang Spectrum of the Ming Dynasty. Although our country is not the hometown of oleander, it has been cultivated for more than 500 years. It is easy to grow oleander, so potted plants are very common in the south and north. It can be cultivated in open fields in the south of the Yangtze River Basin in China, and it is close to wild in Chongqing.
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