Survival and growth of Pinus patula at two years in response to harvest residue and pest management, in Mpumalanga, South Africa

Abstract

Previous research has indicated that the presence of harvesting residues, post-planting tern perature and rainfall, and insect pests and diseases, are among the main causes of mortality during re-establishment of Pinus patula stands. The main objectives of this work were to confirm previous observations on the effects of these factors on initial survival and growth of P. patula seedlings. Three harvest residue management treatments (burning, harvesting residues left in situ or removed) and four pest management treatments applied at planting (fungicide, insecticide, fungicide and insecticide, and a control, where no pesticides were used) were tested in combination with each other. For the first two years after planting, there was a significant effect of harvest residue and pest management on survival. At two years, survival in the burned treatment was 59 %, possibly due to the presence of Rhizina undulata. Where the harvest residues were not burned, the survival was 88 %. Application of a fungicide and insecticide at planting improved survival in all harvest residue treatments, especially the burned treatment. Tree growth was the best where both a fungicide and insecticide had been applied at planting, followed by the individual application of either a fungicide or insecticide, with the poorest growth occurring in the control treatment.