Methods of improving the survival ofPinus patulaplanted into harvesting residues

Abstract

SYNOPSISThe aim of this trial was to investigate ways of improving the survival of Pinus patula seedlings when planted into areas characterised by high levels of harvesting residues (slash). The trial consisted of three non-randomised planting date treatments which spanned the 1997 -1998 summer planting season. On each of these dates, trees were planted into slash lines or areas where little or no slash had been left after harvesting. Sub-plot treatments tested whether the application of insecticide, fungicide or water combinations could improve the survival of P. patula seedlings.Within two of the planting dates tested, the presence of slash was found to significantly decrease the survival of Pinus patula. The relative magnitude of these differences varied between planting dates and diminished as the summer season ended. The impact of the sub-plot treatments was minimal in the cleared areas. In contrast, some of the sub-plot treatments, particularly the insecticide and fungicide combination treatment, improved survival in the slash to a level which equalled the best survival obtained in the cleared plots on each date.Water planting in the slash areas produced particularly poor survival at each planting date.

Post establishment survival ofPinus patulain Mpumalanga, one year after planting

“…The contrast of the water treatment with the control indicated that a single application of water at planting did not affect mean survival in any of the two sets of trials. This corresponded with earlier findings by Atkinson and Govender (1997), , Allan and Higgs (2000) and Rolando and Allan (2004).…”

“…In this study the application of pesticides generally improved survival significantly, as was found in other earlier trials (Atkinson and Govender, 1997;Allan and Higgs, 2000;Rolando and Allan, 2004;Rolando and Little, 2004). The application of fungicide improved survival by 12.8% on average over the control (10% significance level) and a combination of fungicide and insecticide improved survival by 29% on average over the control (5% significance level) at 365 dap.…”

“…This was possibly as a result of higher temperatures and lower rainfall associated with the sites on lower altitudes. Various researchers have found that increased seedling stress levels associated with high maximum temperatures shortly after planting increased mortality (Morris, 1991;Allan and Higgs, 2000). However, Rolando and Little (2004) reported good survival in a trial despite recording air temperatures higher than 30 °C on five occasions during the first week after planting, but mentioned that above average planting practices as well as a higher rainfall might have been responsible for the good survival.…”

“…insect-related mortality was estimated by applying insecticide or fungus-related mortality by applying a fungicide and thereafter monitoring the improvement in survival. The previous research conducted by Atkinson and Laing (1996), Atkinson (1997), , Allan and Higgs (2000), Rolando and Allan (2004), Rolando and Little (2004) indicated that application of pesticides at planting improved post establishment survival in general. However, these studies were not conclusive in determining the exact manner in which the pesticides enhanced seedling performance or in identifying and quantifying which insect pests and/or pathogens were causing the mortality.…”

The pitch canker fungus,Fusarium circinatum: implications for South African forestry

“…Although there is no doubt that much of the poor survival is related to contamination/infection by F. circinatum in South Africa, it is notable that other factors also play a contributing role in survival, especially with regards to P. patula. The effects of high temperatures, drought, insects and other pathogens have all been known to affect the survival of P. patula (Morris 1990, 1991, Allan and Higgs 2000, Rolando and Allan 2004). An increase in herbicide damage to young P. patula plantings has also been noted (RGM unpublished data).…”