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MANDARIN ORANGE Gummosis

Name of Crop	MANDARIN ORANGE
Scientific Name	Citrus reticulate
Local Name	Santra
Family	Rutaceae
Distribution state/World wide	Sikkim, Assam, Meghalaya, Nagpur, Darjeeling Nepal, Bhutan
Common Name of Disease	GUMMOSIS
Local Name of Disease	Foot rot, color rot, trunk rot
Causal Organism	Phytopthora palmivora, Phytopthora citropthora, Phytopthora parasitica
Distribution of Disease in Sikkim	Orange grown in paddy land where the soil is heavy due to spring water source
Disease Incidence	Low
Site of Infection	Infection appears on the bark first
Dissemination of the Disease	Phytopthora is a soil inhabited fungi, they produce sporangia and zoospores on the soil surface during rainy season. These spores are carried out by drops of rain water or irrigation water or wind from infected plant to healthy one. The pathogen enters into the plant through bud joints or any other injured parts of the host and thereby causes infection
Symptoms	Profuse gumming on the surface of the affected bark is the main symptom. When the stems are affected, droplets of gum trickles down the stems. Conspicuous brown staining along the harden masses of gum are also seen on the surface of the bark. The affected bark gradually turns dark brown and develops longitudinal cracks when scraped. When gumming starts close to the soil, the disease spreads on the main roots and then around the base of the trunk. Exudation of gum at this stage is less noticeable as portion gum is absorbed by the soil. As a result of severe gumming, the bark is completely rotten and the tree dies due to girdling affect
Favourable enviromental condition for disease	Ill drain soil. Excessive irrigation leading to prolong contact of the trunk and crown with water. Low budding practices, deep planting etc are the factors responsible for disease. Varietals susceptibility is also one of the factors
Mode of Transmission	Transmission can be through rain water, irrigation, wind and soil
Plant Protection Measures	Selection of proper site with adequate drainage. Use of resistant root stocks with high budding and high planting. Scrape out the diseased portion with sharp knife and paste with Bordeaux paste on the cut portion