Koleroga or Mahali is a major disease of arecanut causing serious losses. The pathogen is a fungus Phytophthora palmivora. Spraying the. PDF | On Jan 1, , R Ramesh and others published Management of fruit rot ( Koleroga/ Mahali) disease of arecanut. Koleroga (kole = rotting, roga = disease) as it is called in Karnataka is in the same orchard (as found in Karnataka where arecanut, cocoa, cardamom, black.

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Disease symptoms “This disease occurs during South West monsoon. In water, chlamydospores germinate by producing short germ tubes, each with a sporangium at the tip. The zoospore-containing droplets may be further dispersed by wind and become the inoculum for infecting fruit and occasionally stems of papaya in the fields.

According to the xrecanut of the Deputy Commissioner, the district recorded an average rainfall of 4, Wind is required for dispersal of the inoculum once it reaches the air. Waterlogged conditions appear to weaken the defense mechanism of papaya roots against invasion by the pathogen. Sporangia are papillate and ovoid with the widest part close to the base.

Koleroga Disease of Areca Palms: Symptoms and Management | Plant Pathology

Chlamydospores produced in infected papaya fruit and pure papaya juice are thick-walled. Infected fruit on the trees and those that have fallen to the ground should be removed to reduce the inoculum for aerial infection of fruit and stems, and infection of seedling roots in subsequent plantings.

Coleman Orellana [2] Phytophthora parasitica var. The pathogen is considered to perennate in the infected tree tops during entire dry season ranging from January to June because of two reasons: The first appearance of the koleroga is on the nuts pf or three weeks after rains begin. Email will not be published required.

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In coconuts, the expected yield losses caused by P. Roots of papaya plants are protected by the virgin soil during the susceptible stage, and become resistant to the pathogen when they extend to the infested soil. Sawada [2] Phytophthora faberi Maubl. Therefore, wind-blown rain is essential for initiation of the primary infection and the development of epidemics in papaya orchards.

Arecantu Read Edit View history. Chemical control methods for P. Retrieved from ” https: One common symptom of P. During rainy periods, chlamydospores in soil may germinate in water to produce sporangia and release zoospores.

‘Kole roga’ strikes arecanut plantations in Dakshina Kannada again

Though the sexual reproduction is uncommon in nature, the formation of antheridia and oogonia producing oospores after fertilization has been found in cultures. The green colour of the nut-shell turns darker green and the early symptoms gradually spread ultimately covering the entire surface of the nut.

Copper fungicides such as 0. It severely affects the fruits nuts of the areca palm during June to September when there is heavy rainfall cm in these areas. A fine spray will be needed for effective spread of spray fluid over the surface of the nuts. Felty whitish qrecanut of fungal mycelia soon cover the entire surface of the fallen nuts. The source of primary inoculum, are the sporangia kolerooga by the perennating xrecanut structures, the chlamydospores formed in the infected fallen nuts, and, probably, the zoospores produced by the perennating oospores.

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‘Kole roga’ strikes arecanut plantations in Dakshina Kannada again – The Hindu

Phytophthora Water mould plant pathogens and diseases Coconut palm diseases. The pathogen produces abundant sporangia on the surface of infected fruit that are further dispersed by wind-blown rain and cause outbreaks of Phytophthora fruit rot in the same and nearby orchards. Similar diseases of palms are also known to occur in Kolerlga LankaMauritiusand Sumatra.

The signs of P. Root rots are another symptom of P. These are among the most serious diseases caused by fungi and moulds in South India. It is believed that where many crops are grown simultaneously in the same orchard as found kolerofa Karnataka where arecanut, cocoa, cardamom, black pepper, and citrus are grown simultaneously in the same plantationand they are infected by two to three species of the some pathogen e.

Trees established with the virgin soil method in the replant fields produce fruit as abundantly as those growing in afecanut first planting fields. All components of APSnet are copyrighted and may not be reproduced or distributed except by express permission of APS. Bud rots can also be seen in papaya and arecaunt infected with P. Contact Us – Report a Bad Link.

Sporangia produced from primary infection lesions serve as the source of secondary infections during the growing season.