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Topics for discussion in the Crop Pests and Diseases Forum To participate in discussion, browse to www.africancrops.ipbhost.com or Contact the Moderator by email: jmsonga@africaonline.co.ke or Board Administrator, africancrops@wananchi.com ------------------------------ Integrated Pest Management For many years now, most research and development efforts on crop protection has focused on the use of pesticides and other pest management technologies such as cultural control, biological control and use of resistant varieties. My observation is that a number of these technologies have used the ‘Silver bullet approach’ which in my opinion is not sustainable. There have been too few efforts in the development and use of an Integrated Pest Management (IPM) approach, especially with respect to reducing pest and disease problems in small scale farmers’ fields and stores. Furthermore, even in the few cases where IPM technologies have been developed, there has been often no consideration of including indigenous technical knowledge methods in the IPM approaches. To address this concern, I have the following suggestions:
Crop husbandry A number of improved crop varieties with good attributes such as high yields, resistance/tolerance to major pests and diseases, tolerance to drought have been developed in Africa. In order for farmers to get optimal benefits from these varieties, the crops have to be managed properly, using recommended crop husbandry practices with respect to soil fertility and pest management. Crop losses due to damage by pests and diseases continue to be a major constraint in farmers’ fields. My opinion is that, for selected (high performing) crop varieties, there is need to develop a compatible pest management package that will ensure optimal crop yields under the target farming systems. What is the situation in your country with respect to this issue? Please give your suggestions. Indigenous knowledge “Old habits die hard”. It is a recognized fact in extension that implementation of new ideas is very difficult if the existing knowledge is not considered. Farmers know their time-tested ways, and are often unwilling to dump them completely. Therefore, any agricultural innovations are often blended with traditional methods at varying levels. For instance, the idea of selecting the largest cobs from an old harvest and using it as the next season’s seed is still practised, even with the advent of Hybrid seed. In fact, many farmers cite this as one weakness of this technology, and often have some selected line of grandmothers’ seed just in case the hybrid fails. I agree that there’s need to put more emphasis on addressing the small scale farmers’ disease and pest problems using an integrated approach. Cataloguing indigenous methods used in the management of pests and diseases in small scale farming systems, seeking funds for their scientific evaluation and including them in IPM packages is an important suggestion. Farmers, and especially so those producing organically have argued that these indigenous methods are effective. One news letter titled “The Organic Farmer” circulating in Kenya has a lot of information on some of these indigenous methods. Some of the diseases that have been managed using these methods include bacterial wilt, early and late blight, mildews and nematodes. It would be important to conduct investigations and give recommendations on these practices. Research therefore could benefit a lot from finding out the basis of these methods, and incorporating them in the IPM systems. First, it is ‘unscientific’ to discard tenets held to be true due to their very apparently-non-scientific basis, without a careful examination of their worth. More importantly, a recognition and incorporation of compatible traditional and ‘modern methods’ would serve to build the trust needed for the effective implementation of IPM approaches. In this case, perceived failure might be looked at more objectively even by rural farmers. Yes, there should be greater support for documentation and evaluation for the worth of traditional knowledge and management systems and their possible incorporation into IPM systems. Delaying the effects of build-up of resistance to pest control methods by pests From a genetic viewpoint, single-bullet solutions to pest problems serve as directional selection forces that favor the survival of few variants tolerant to the very control procedure used. The individuals left (no method really wipes out everything) enjoy an environment of abundance favoring faster multiplication and proliferation of their kind! A resurgence of a recalcitrant population ensues. We know that pests and diseases have a way of evolving resistance or tolerance to a specific control strategy (e.g. a pest resistant crop variety). What strategies can be used to delay this resistance evolution and thus prolong the useful period of the pest management strategy? We need, therefore, to play in the line of genetic diversity to limit unidirectional selection pressure and reduce the proliferation of survivors. This calls for the use a combination of physical, cultural and whatever approaches together, and hierarchically. For instance, a post-harvest insect pest population that is resistant to a pyrethroid-based insecticide might perhaps, not also stand environmental vagaries limitations like very dry grain or diatomaceous earth etc. Even if it does, these constrains could reduce its ability to unlimitedly exploit the niche created by a single method it has a way of overcoming. We have learnt this from the era of chemical control (especially DDT) and need not repeat the same cycle. Agricultural scientists therefore need to encourage the development of a multi-target system approach, that attacks the pest from as many points as possible, together and in rotation. The aim is to discourage the development of super-bugs. Post-harvest crop losses One of the most cited difficulties for post-harvest crop losses has been the development of high-yielding varieties, perhaps resistant to field pests and diseases, which are not quite tested against storage pests. Perhaps this cuts across several pest types too. To begin with, most breeders prefer to deal with a small group of genes (or inheritable characteristics) at a time, as do most scientists. This way, selection in a desirable direction is achieved faster and is easier to evaluate. Unfortunately, the organism comes as a suite of genes, each selected for in its own right. In a few cases, desirable production traits are also (or linked to) undesirable pest tolerance traits. On the other hand, it is unrealistic to imagine a simple super crop, that is highly nutritious and high-yielding to man (yet not as nutritious or abundant to insects for instance); able to stand harsh environmental conditions, and completing development in tandem with the crop season. We cannot discard the gains already gained in crop breeding. One way is the use of biotechnology to artificially introduce specific desirable genes into crops, with minimum interference with other desirable characteristics. On this end, we should also develop and adapt existing desirable IPM practices for each of these varieties. As it is, we have clothes but no laundry instructions to match! Managing resistance development to transgenic crops I attended a workshop in which the issue of managing resistance development to transgenic crops came up. There seemed to be general agreement that use of refugia (areas planted with non-transgenic crops to generate susceptible individuals to mate with any resistant individuals) could be one of the strategies for delaying the evolution of resistance. In Bt maize for example, it was suggested that other cereals such as sorghum and millet could be considered as refugia. We were informed however that the stem borer species which attack these crops are different from those that attack maize hence they may not be suitable as refuge plants. It was also considered that it would be difficult to convince farmers to plant refuge crops (which may not be of as much value to them) alongside their main crops. I was of the opinion that farmers can be given seed mixtures of Bt and non-Bt maize (i.e. blended prior to distribution). This would ensure compliance as well as getting round the problem of stem borer species incompatibility between maize and the other possible refuge crops. It would however be worth noting that the value of the seed mixture approach could be greatly reduced by interplant movement of insects which could create a mechanism for increased survival of rare resistant insects exposed to the endotoxin (as the insects could ingest sub-lethal doses from Bt plants and then move to non-Bt plants to complete their development). Furthermore, farmers often save seed from their harvest for the subsequent crop-further complicating the practicability of the seed mixture strategy. It is evident therefore that there are still a number of ‘information gaps’ that need to be filled in order to be able to choose the most suitable resistance management approach for Bt maize crops in the small scale farming systems in Kenya.. Technology transfer Transferring technologies to farmers is as important to Researchers as is developing them, since the farmer is the target. In Kenya, the breakdown of the connection between the researcher and the extension services has played a big role in technologies failing to reach the farmer. More funding should be geared towards technology transfer. Dissemination methods such as farmer demonstrations, farmer training, field days, clearly written leaflets or bulletins would transfer messages to farmers. A number of pest management technologies have been developed in the African region and results published in scientific journals. However, in a number of cases, this information does not get to and have an impact on the end user, the farmer. Why do researchers not go further with these results and deliver them to the farmer through appropriate dissemination methods e.g. farmer leaf lets, farmer demonstrations and training, etc. Is it because researchers feel that delivery of information to the farmers is not their job? Is it because they feel that such additional efforts do not contribute much to their job appraisals? What is the cause of this gap and how can we address it? The bridge between technical products of research and their commercialization or practical utilization should be built from these two ends. While it is understandable that researchers avoid excess baggage and concentrate on pure research till some leads are obtained, the very expected users of these efforts and extension workers rarely seek innovations from publications where researchers 'dump' their product. Most farmers in Africa may not have reliable access to scientific publications, and if they do, publications are rarely intended for such use. It would be feasible to incorporate 'technological transfer' between scientists and the extension service, as part of capacity building; over and above training research students. Some ready-to-use mid-term technologies like pest recognition could then come earlier in the research activity. Finally, with a collaborative audience in mind, it would be a lot easier to produce a simple user manual and published product satisfying the need for practical application of research findings. Left on their own, even commercial horticultural establishments find it difficult to realize the benefits of research they so much need and are willing to invest in. Yet, working separately from the end users, the role of research becomes difficult to realize. Graduate students do a lot of work and come up with theses/dissertations which literally just ‘gather dust’ on shelves in the ‘reserve’ sections of university libraries. A lot of this material, despite being extremely valuable, does not even get published in reputable journals. Furthermore, there do not seem to be mechanisms for disseminating these research findings in order that they benefit potential end users. There are volumes upon volumes of Masters and PhD theses on our university shelves with very useful findings. Material that is disseminated by the various National Research Institutes is normally confined to information obtained from studies carried out by the institutions themselves. Universities appear, to me, to have no clear mechanisms for sharing their findings with the wider public-at least in my country. I have always pondered over this issue as a graduate student and what a better forum to share my concerns than this! Could you kindly share your experiences in this regard? In case such a situation prevails throughout the continent, what are the possibilities of lobbying African governments to set up institutions that would be tasked with the responsibility of looking through university research works and disseminating useful content to potential beneficiaries? Biopesticides Use of pesticides for pest and disease control is slowly being replaced by bio-pesticides that are environmentally friendly and affordable to our resource-limited farmers who constantly struggle to put food on the table. Little or minimal research efforts have been geared towards developing new or existing bio-pesticides. My opinion and suggestions are:
Intercropping and spread While searching for literature on the role of green manure legumes in the management of pest and diseases in East Africa, I discovered that there is inadequate information to this effect. Knowing that farmers intercrop or rotate priority crops (such as maize and beans) with these green manure legume crops, there is bound to be shared pests and diseases among these crops. Hence, it is of paramount importance to do the following:
To participate in discussion, browse to www.africancrops.ipbhost.com or Contact the Moderator by email: jmsonga@africaonline.co.ke or Board Administrator, africancrops@wananchi.com Disclaimer: This document is produced for the sole role of sharing useful information that can only be used for academic and development purposes only. We make no warranty, express or implied, of its completeness and therefore assume no legal liability or responsibility for the accuracy, completeness, reliability or usefulness of any information or process disclosed. |
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