April 2012. More images of coconuts with suspected nutritional deficiency from St Lucia. On this occasion the 6-8 year-old palm in question is in the north of St Lucia growing in a backyard. The area is relatively dry during December to May annually. There are neighbouring palms showing the same symptoms. The leaflets on these palms show chlorotic spots which coalesce and turn necrotic.
Note that a previous post, summarised at www.pestnet.org/SummariesofMessages/Crops/Plantationcrops/Coconutoilpalm/NutritionalproblemStLucia also showed a nutritional problem on cocnuts in St Lucia. On that occasion Mg or K were the two elements suspected as the cause from the symptoms described.
On this occasion too, a deficiency of the same elements, Mg and K, was suggested. For a deficiency of Mg, it was suggested that a NPKMg fertilizer (12-12-17-1.2) should be applied.
To distinguish between Mg and K, a member suggested looking at <lee.ifas.ufl.edu/Hort/GardenPubsAZ/PalmNutritionFertilizers.pdf> where the very different symptoms are described in some detail.
Consideration might also be given to “Bronze Leaf Wilt”. This as has been reported from the Caribbean (Dominican Republic, Jamaica, Trinidad and Venezuela) and elsewhere (Nigeria). In Nigeria, it is synonymous with Awka Wilt and considered to be a phytoplasma, but in Jamaica it was different from Lethal Yellowing and presumed to be a physiological condition. If you can access any of the publications listed below you might find some similarities.
1955 – Coconut Time Line
Bull, R.A. (1955) Bronze leaf wiltof coconut palms in Nigeria. Journal of West African Institute of Oil Palm Research 2, 69-72. [or 1(3) 70-72]?
| 1994 Jun 5, 2011…Benin with emphasis on possible vectors of Bronze Leaf Wilt(“Awka …Ganodermawiltdisease of coconut. pp 889-920 In: K.L.Chadha and … cocos.arecaceae.com/1994.html
| 1978 Agwu, S.I. & Okaye, H.C. (1978) The distribution of bronze leaf wiltdisease of coconuts in Anambra and Imo states of Nigeria. J. NIFOR 5, 79-85. Alcantara, J.A. … cocos.arecaceae.com/1978.html
| 1990 Aug 29, 2011 …Ekpo, E.N., and Ojomo, E.E. (1990) The spread of lethal coconut diseases in West Africa: Incidence of Awka Disease (or Bronze Leaf Wilt) in … cocos.arecaceae.com/1990.html
1969 – Coconut Time Line Nov 26, 2011 …Ohler, J.G. 1969. Bronze leaf, a new coconut disease in the Caribbean area. …( 1969)