Status of pests, pathogens and pesticide use in South African forestry nurseries and plantations

Abstract

In South Africa, pesticides represent an important component of integrated pest management (IPM) solutions for the management of especially nursery pests and pathogens. However, a limited number of pesticides, which comply with South African Government legislation and regulations set by certification schemes such as the Forest Stewardship Council® (FSC®) and the Sustainable African Forestry Assurance Scheme (SAFAS), are available for use in forestry. This study aimed to identify the key pests and pathogens currently affecting forestry nurseries and plantations in South Africa and to document the pesticides used for their management, thereby providing a foundation for identifying alternative pest management products for integration into forestry IPM programmes. Information was obtained from 16 plantation forestry nurseries and five plantation forestry companies. A total of five diseases, namely, the rooting tunnel disease complex (Botrytis cinerea, Rhizoctonia sp. and/or Calonectria sp.), powdery mildew (Podosphaera sp.), rooting disease caused by Fusarium circinatum, wattle rust (Uromycladium acaciae), and Quambalaria leaf and shoot blight (Quambalaria eucalypti), and five arthropod pests, comprising the Eucalyptus gall wasp (Leptocybe invasa), cutworm (Agrotis sp.), leaf roller caterpillars, red spider mite and aphids, were identified as key pests in the nurseries surveyed. In plantations, five diseases, comprising Destructans leaf blight (Teratosphaeria destructans), Coniothyrium stem canker (Teratosphaeria zuluensis), Phytophthora root and collar rot (Phytophthora sp.), wattle rust (U. acaciae), Eucalyptus scab and shoot malformation (Elsinoë masingae), and three insect pests, namely, Eucalyptus gall wasp (L. invasa), Eucalyptus snout beetle (Gonipterus sp. n. 2) and a soil pest complex (various species of whitegrub and cutworm), were identified as key pests affecting the majority of plantation forestry companies surveyed. A limited number of pathogen and pest-specific pesticides consisting of eight fungicides and six insecticides were reported to be used in nurseries, whilst only two fungicides and 12 insecticides were used in plantations. Across these products, approximately 17 active ingredients were identified, with those most commonly used (prochloraz manganese chloride, fludioxonil, azoxystrobin, difenoconazole, deltamethrin, cypermethrin, alpha-cypermethrin and imidacloprid) classified as restricted or highly restricted under FSC® guidelines. This information will provide the basis for the testing and registration of alternative (biological, natural and synthetic) products for the control of key pests and pathogens in the forestry industry.