Stem bleeding

Stem bleeding
    Causal organism:Thielaviopsis paradoxa
    • This malady was first reported from Sri Lanka in 1906 and then from India in 1922. It is most common in Kerala, south coastal Tamil Nadu and Goa. Symptoms are the expression of abnormal conditions caused by mall factors that causes damage to the trunk and reduction in yield.
    Symptoms
    • The first symptom is the exudation of a dark reddish-brown fluid through cracks of outer tissue or wounds of lower parts of the trunk.
    • The tissue inside the trunk gets decayed and the epidermis destroyed.
    • The fluid turns black in colour as it dries up on the bark.
    • The crown becomes smaller.
    • This disease covers palms of all ages but the spread is more rapid in young palms.
    • Bleeding of the stem is associated with fungal infection.
    • The fungus associated with the disease is Thielaviopsis paradoxa, which is a wood parasite, isolated from infected stem tissues.
    • This parasite establishes itself inside tissues of the trunk after getting entry through cracks and wounds on the trunk.
    Epidemiology
    • Kharif season.
    • Unfavourable soil conditions play a major role.
    • Shallow laterite soils also develop stem bleeding symptoms in palms.
    • High relative humidity
    • Sources of inoculum
    • Primary source of inoculum- Dormant mycelia
    • Secondary source of inoculum- Airborne conidia
    Management
    • The rotting tissues should be removed with a sharp chisel and the exposed surfaces painted, with hot coal tar or 10•96 Bordeaux paste.
    • This is a serious disease caused by Bipolaris halodes. Normally, the leaf rot disease is found superimposed on root (wilt) infected palms.
    • If cavities are found, these have to be filled up with cement for reinforcing.
    • Since the pathogen is a wood parasite, mechanical injury to the healthy palm, should be avoided.
    • The organic matter content in the soil should be increased. Application of neem cake @ 5 kg/palm is beneficial.
    • Improvement in drainage system and soil conservation measure in drought areas are essential.
    • Application of Bavistin (%) in soil has been found to be beneficial in reducing infection

Last modified: Tuesday, 7 February 2012, 10:49 AM