Rubber leaf disease – Board initiated control measures
Kottayam 11 August 2016
The Rubber Board has initiated measures to control Thread Blight, a fungal disease, noticed in certain rubber plantations in some areas of Idukki and Ernakulam Districts. Incidence of the disease has come to the notice of the Rubber Board last week. The Board has already given advice to growers regarding its control measures. The matter came to the notice of the Board through WhatsApp messages, the facility recently introduced by the Board for identifying pests and diseases.
The disease can be controlled through normal protection operations. So there is no need for growers to panic. As the first step towards creative awareness, the Board has arranged meetings at different locations under its Regional Offices at Muvattupuzha, Kothamangalam and Thodupuzha, with the help of Rubber Producers’ Societies (RPSs). The meetings will be attended by Board’s extension officers and scientists. The first meeting was held at Kalloorkkad under Muvattupuzha Regional Office. Further meetings will be held at Ayavana, Kumaramangalam, Kodikkulam and Paingottoor on Saturday, 13 August 2016. The Rubber Board has requested rubber growers to attend any one of these meeting.
Thread Blight disease is sporadic and may not affect plantations as a whole. So spraying against the disease can be limited to affected plants and its surrounding ones. Copper oxychloride and spray oil, required for spraying against the disease, are made available at Periyar Latex, Muvattupuzha, a Rubber Board owned company. Rubber Board advises Rubber Producers’ Societies to procure these inputs from the company and make necessary arrangements for spraying in holdings. Field Officers of the Board have been directed to give necessary technical guidance to the growers.
The occurrence of the disease that normally affects rubber bud wood nurseries, starts with the onset of monsoon. Infection is more in trees with dense foliage. Affected leaves turn pale yellow and the disease spreads rapidly to nearby leaves also. The fungal mycelia will spread over the leaves like branched threads, and in due course, leaves will dry up and fall subsequently. The fallen leaves that remain hanging in the mycelia are a characteristic feature of Thread Blight and this helps in distinguishing this disease from abnormal leaf fall disease of rubber. The disease is common in cocoa, nutmeg etc., but not widely found in rubber plants.
Marasmiellus spp., Thanatephorus spp., and Corticium spp. are the causative agents of this disease. Prophylactic spraying with copper fungicide is effective in preventing the disease. Affected branches should be cut and burned. In nurseries, application of one percent Bordeaux mixture, or water dispersible copper oxychloride (Fytolan, Fytran or Blitox) at the rate of 2.5 g/ litre of water is effective. In mature plantations, spraying with oil based copper oxychloride dispersed in spray oil (1:5 proportion) is effective.
Rubber growers can use the WhatsApp facility provided by the Rubber Board for diagnosing the occurrence of pests and diseases. The mobile number earmarked for the purpose is 9496333117. Rubber growers can also seek the service of Rubber Clinic, being operated by Rubber Research Institute of India. The address of Rubber Clinic is http://clinic.rubberboard.org.in