Republic of Kenya Integrated Pest Management Framework (ipmf) For Kenya Agricultural Productivity and Agribusiness Project (kapap) and Kenya Adaptation to Climate Change in Arid and Semi-Arid Lands (kaccal) February 2009

7.3 Key Forestry pests and diseases

178. 
     One of the most significant recent pests in forestry is an exotic pest, identified as the gall- forming wasp, Blue Gum Chalcid. It has been reported as a threat to Eucalyptus trees in Western parts of Kenya. The pest is reported to cause serious damage to young trees and nursery seedlings.
     
179. 
     Another pest of significance is the Cyprus aphid which was reported to have invaded the county in 1991. The weed was estimated to kill as many as 50 percent of all Cyprus trees during the 30-year harvest cycle.
     

8. MANAGEMENT OF NEGATIVE IMPACTS OF CROP PROTECTION MEASURES

   1. Introduction

178. 
     The effective control of diseases and pests is pertinent for improved crop and livestock production. No single crop or plant is free from diseases and pests. There are pests and disease of economic importance that require cost effective control for improved productivity. Effective management can only be achieved when social, economic and environmental factors are taken in account’, particularly when you are making a choice of the appropriate control measure. This is important for increased adoption and effective use of the selected method. Some of the major social and economic activities to be considered are presented in the Table below. In addition, an understanding of the institutional and legal frame work is also important in assessing the impacts of the current pests and disease control measures.
     

178. 
     An environmental impact of pest managemnt is a change in the environment caused by applying or using a certain method of pest or disease control. This will involve a change in the properties of a natural or man-made resource in a way considered important. In this case, specific environmental areas of concern will include: the quality of ground and surface water, wetlands and terrestrial communities (flora and fauna), and aquatic communities including fishery and other animals and soil properties. While the social economic impacts include: the health and personal safety of the people using the various control methods. The primary goals of any control programme against pests or diseases are, first, to establish the "optimal" level of disease or pest presence to meet a country's goals and, next, to choose the most cost-effective way of achieving that level of control.
     

2. Implication of control measures

8.2.1 Control of plant pests and diseases

178. 
     The control of pests and diseases raises the most obvious concern of the resulting losses when there is no control, as pests populations can expand quickly from a localized outbreak to critical levels with serious infestations occurring simultaneously in several areas and neighbouring regions. The fast initial multiplication may occur unnoticed in remote and unpopulated areas and follow a natural (biologically induced) pathway. Once cropping areas are invaded, there is rarely sufficient time to prevent damage through control operations.
     
179. 
     The widespread loss associated with an outbreak of pests and diseases makes it imperative for control measures to be undertaken. In view of major pests and diseases losses occurring in the lake basin, there is added need to prevent impacts on scarce food resources. Normally a control is carried out as a response to the appearance of pests and disease, with the main effort aimed at eradicating them once they appear in significant or levels. The primary response is widespread pesticide spraying to target pests, manual removal, biological control such as use of preys, use of resistant varieties, etc. All these methods have different effects on the environment, health and safety and general social setting. The rapid identification of early stages of attacks in the lake basin is critically important to minimize the damage to neighbouring regions
     

8.2.2 Control of Livestock pests and diseases

178. 
     Animal diseases are spread either through natural pathways or human intervention. The transmission of certain diseases requires an insect to serve as a vector, dictated by external environmental conditions and possibly appropriate plant hosts to carry out its life cycle. Based on biological reasons, these disease pathways have limited geographical scope, which simplifies the task of identifying pathways for disease transmission compared with plant pest introduction. In the lake- basin movement of livestock and derived products is regulated and controlled to prevent the entry and subsequent spread of exotic disease agents. Furthermore, disease surveillance systems with laboratory diagnostic support are maintained to ensure the early detection of disease outbreaks and contingency plans are in place to respond rapidly to an epidemic. In addition to these there is immense use of pesticides through spraying to control the spread of the disease and the use of acaricides to treat the disease.