Integrated nutrient management for root (wilt) diseased coconut (Cocos nucifera) palms

An experiment was conducted during 2004-08 at the Regional Station of Central Plantation Crops Research Institute, Kayamkulam, Kerala on root (wilt) disease affected palms of West Coast Tall variety. The entire field was divided into 2 parts and applied with full dose of fertilizers (500:300:1000 g NPK/palm/year) and with 50 % fertilizers + organic manures as vermicompost and incorporation of local variety of green manure cowpea (Vigna unguiculata L. Walp.) raised in the palm basin. All the coconut palms were indexed for the disease during December May (2005 to 2008). There was not much variation in the nutrient content in leaves of palms under various treatments except P and K which are slightly high in palms supplied with both fertilizers and organic manures. Presence of higher population of function-specific micro-organisms was found in the rhizosphere soils of disease early palms than in the other categories. Comparison of treatment after accounting for variations in disease index separately for various years was found non-significant. Though the post-treatment yield in both the treatments was non-significant, there was an increase of 17 % in yield in palms receiving both fertilizers and organic manures compared to 7 % increase in palms receiving only fertilizers. Negative correlation existed between yield and disease index in 2005, 2006 and 2007 and was respectively -0.223, -0.268 and -0.284 (P<0.05). In general, copra content was higher in palms applied with both fertilizers and organic manures and the overall increase was 4.57 % over the other treatment. The results indicated that through an integrated nutritional management, soil health as well as health of palms could be improved over the years or maintained without further deterioration.