Meeting the Phytosanitary Requirements in Tree Germplasm Exchange in East Africa: Awareness on Importance, Challenges and Opportunities of Tree Seed Health among Stakeholders

Abstract

Globally, over 90% of tree species are propagated through seed and raised as seedlings. Other propagation materials include cuttings, wildings, grafts, tissue culture and air-layering. Since seed is the main source of planting material and medium of tree germplasm exchange, it is also the major source of disease and pest introduction in new localities worldwide. Seed microflora usually comprises of fungi, bacteria and to lesser extent viruses, and can be external or internally seed borne. Some tree nurseries have reported over 80% losses to seed related diseases. There has been an increase in tree diseases and pest incidences affecting the main plantation and agroforestry tree species in Kenya. Most pathogens are transmitted through seeds and cuttings while endophytes are transmitted through healthy looking host materials. For example, four major diseases and pests of eucalypts are reported to be on the increase within Africa. Their invasions are closely related to the continuous importation of Eucalyptus clones which have been traced to South Africa, Latin America and Australia. The future of local landraces of eucalypts are therefore unpredictable unless suitable biocontrol agents are introduced soon. In similar circumstances, the Dothistroma needle blight has almost stopped the growth of Pinus radiata in East Africa. The latent pathogen group; Botrosphaeriaceae is reported to be spreading fast on the popular Grevillea robusta and other tree species in Kenya. Tree germplasm production and exchange unlike the food crops faces phytosanitary challenges that include inadequate sources of high genetic quality, low seed production due to unpredictable flowering patterns, uncontrolled movement of live germplasm and forest products, inadequate enforcement of the relevant legislations on tree seed trade, inadequate formal quarantine standards especially for indigenous tree seeds and inability to trace the origin of seeds within E.Africa. In addition, inadequate tree seed testing facilities and poor formal distribution networks of forestry seed contributes significantly to the challenges in undertaking phytosanitary measures. Efforts and investments should therefore be made to ensure that stakeholders access high quality tree germplasm to guarantee sustainability of our forest resources. This paper 89 therefore aims to create awareness on the status, challenges and opportunities that exist to ensure that phytosanitary measures are instituted for clean germplasm exchange.