issues and constraints related to the development of cashew nuts ...

10• The loss of farmer income due to the different pests and diseasesIt would be useful if the collection of such data could be harmonised, co-ordinated and jointlyanalysed across the region. Such region-wide data would be of greater value than the sum of theparts.Knowledge of cashew pests and diseases was generally very limited among field workers.2.2 Environmental constraints‘Natural’ drying of flowersPanicles can dry out naturally, to give a perfectly formed flowering panicle, which is brown incolour and devoid of potentially useful nuts.Although entire trees are often affected, this particular problem is not caused by a disease. Thepresence of dried flowers was seen quite frequently and reported as a problem by a number offarmers. In Nigeria, the harmattan was blamed for a number of problems, but the drying offlowers was the most frequently mentioned by farmers. However, in one location it was apparentthat the seriousness of dried flowers could vary dramatically from tree to tree. Sardinha et al(1993) reported that in Guinea Bissau, … “since it is well known the negative impact in cashewyield (by affecting its fertilisation) of the dry wind spells from the Sahara, that normally occursfrom 10-30 April, one selection criteria must be set to choose those clones or lines that showearly blossom period.” The problem of flowers drying out and giving no production issufficiently serious and widespread to warrant further immediate research.Natural drying of panicles can be a serious problem in East Africa in some areas or years. Littleresearch has been done on this problem but the possible causes could be genetic, environmental,lack of pollination, rainfall during flowering or nutrient deficiency.Nutrient deficienciesSymptoms of nutrient deficiencies were seen only occasionally, and the symptoms displayedwere similar at all sites – mottled (like marble) yellow and green leaves. This was thought topossibly be a nitrogen and/or zinc deficiency, but a precise diagnosis would require leaf and soilanalyses.FireFire was probably the major cause of lost cashew production in West Africa, and was frequentlyreported by farmers as one of their major problems in all countries visited. Fires do not onlyreduce yields in the year of the fire, but also cause reduction of yield in the subsequent years,deform the tree and, in some cases, kill trees outright.Various reasons were given for why fires were started, such as: to enable the hunting of smallmammals; accidentally; because of grudges; to increase new grass for cattle; or to remove weedsfor land preparation. Annual crop farmers and herders have no interest in the problem. However,it has been demonstrated that as a ‘cashew culture’ develops with more and more farmersgrowing cashew, fires are more likely to be brought automatically under control.