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South Africa has 1.2 million hectares of plantations developed progressively through the 20th century. These occur from 23° to 34°S, from near sea level to 2 000 m above sea level and in both Mediterranean winter rainfall and summer subtropical rainfall climates. Plantations supply pulp mills, sawmills, treated pole and mining timber production, and wattle tannin production. The diversity of sites and markets requires planting of a range of taxa of pine, eucalypt and wattle. A survey of planted area by taxa in South African forest plantations is reported and compared to statistics available from national annual reporting on the commercial timber resources in the country. The survey found a similar number of taxa are currently planted (15) as in the 1950s but only 6 of the earlier options remain in use. Changes have occurred in the last 30 years, with 40% of planted area in 2019 using options not available before 1990. From the 1990s, Eucalyptus grandis has been extensively replaced by eucalypt hybrids and E. dunnii and Pinus elliottii × P. caribaea var. hondurensis has become an important pine planting option. Over the past decade, E. nitens replacement with other existing frost tolerant eucalypt planting options has occurred, use of P. radiata has reduced and P. patula has been replaced on a significant scale with P. patula hybrids. Many of these changes have been to mitigate the impact of new pests and pathogens and, on lower productivity sites, periodicsevere droughts. However, the new planting options also provide increased yields and have wood properties acceptable to the intended markets. Meeting all three criteria is likely to remain a requirement for successful introduction of future new planting options. The survey indicates a need to revise current national reporting requirements to better reflect use of species and hybrids in South African plantations.

Table 1 P values of the OD values for the peptide-treated samples after different treatment duration.

Figure 1 The sequence and spatial structure of peptide 1 (P1). The sequence of the peptide is ACTSNADNKYLPKTCQT (disulfide 2-15) with purity of 95%.

Fusarium circinatum is an important fungal pathogen of Pinus species. In South Africa, it is the most significant pathogen of Pinus patula seedlings in forestry nurseries where it presents a substantial constraint to productivity and can continue to cause mortality in-field for up to two years after establishment. This study describes the results from two trials where P. patula seedlings were inoculated with F. circinatum to determine the impact of the pathogen on nursery and field performance. Seedlings were also subjected to water stress treatments to ascertain whether this would trigger the onset of disease symptoms. Inoculum load and timing of inoculation had significant effects on seedling survival in both the nursery and field. High inoculum concentrations caused greater levels of mortality and, where seedlings were inoculated at a young age, they showed higher levels of susceptibility to F. circinatum. Temporary water-stress in the nursery produced smaller plants and improved in-field survival, but this treatment did not trigger higher mortality in inoculated treatments. On the other hand, transplant stress was a major contributor to the higher levels of mortality observed in inoculated treatments. Overall, these studies confirmed that infection in the nursery leads to the disease problems observed during early plant establishment in the field.Keywords: Fusarium circinatum, inoculation, nursery-to-field, Pinus patula, seedlings, survivalSouthern Forests 2014, 76(3): 125–136

Fusarium circinatum is a pathogen causing serious post-planting mortality of Pinus patula seedlings in southern Africa. Containerised planting stock that is asymptomatic but associated with F. circinatum in the nursery is thought to be the cause of this problem. The aim of this study was to determine if re-use of seedling containers could be a source of inoculum resulting in asymptomatic planting stock and increased post-planting mortality of P. patula. Two experiments were conducted in successive years comparing nursery cull of symptomatic seedlings, seedling growth, association of F. circinatum with asymptomatic seedlings and post-planting mortality for crops raised in re-used containers, with and without sanitation, and factory-new containers. Each experiment consisted of a nursery production trial followed by out-planting into pots to assess post-planting mortality. Our results show that re-use of containers without sanitation increases the cull of symptomatic seedlings, incidence of F. circinatum associated with asymptomatic seedlings and post-planting mortality compared with the re-use of containers after steam sanitation or factory-new containers. Growth of asymptomatic seedlings was unaffected by container treatment or association with F. circinatum and in the absence of wilt symptoms the root system did not exhibit typical discolouration. Watering frequency did not influence post-planting mortality in pots. The comparison of two open-pollinated seed mixes of P. patula that, based on seedling stem inoculation screening, represented susceptible and tolerant material did not show differences in nursery cull or post-planting mortality. This work demonstrated that natural contamination of re-used containers can be a primary source of inoculum producing asymptomatic seedlings associated with F. circinatum that will succumb to the pathogen after field planting. The process of seedling infection, apparent latent infection in the seedling and expression of disease after planting needs greater understanding to improve nursery hygiene measures to control this disease.Keywords: containerised seedling nursery, Fusarium circinatum, Pinus patula, post-planting mortalitySouthern Forests 2014, 76(3): 177–187

Bacteria utilize multiple regulatory systems to modulate gene expression in response to environmental changes, including two-component signalling systems and partner-switching networks. We recently identified a novel regulatory protein, SypE, that combines features of both signalling systems. SypE contains a central response regulator receiver domain flanked by putative kinase and phosphatase effector domains with similarity to partner-switching proteins. SypE was previously shown to exert dual control over biofilm formation through the opposing activities of its terminal effector domains. Here, we demonstrate that SypE controls biofilms in Vibrio fischeri by regulating the activity of SypA, a STAS (sulphate transporter and anti-sigma antagonist) domain protein. Using biochemical and genetic approaches, we determined that SypE both phosphorylates and dephosphorylates SypA, and that phosphorylation inhibits SypA's activity. Furthermore, we found that biofilm formation and symbiotic colonization required active, unphosphorylated SypA, and thus SypA phosphorylation corresponded with a loss of biofilms and impaired host colonization. Finally, expression of a non-phosphorylatable mutant of SypA suppressed both the biofilm and symbiosis defects of a constitutively inhibitory SypE mutant strain. This study demonstrates that regulation of SypA activity by SypE is a critical mechanism by which V. fischeri controls biofilm development and symbiotic colonization.

The re-establishment of Pinus patula seedlings into sites with high harvesting residue (slash) loads can negatively affect the survival of these plants. Field trials have examined the role that insect pests and fungal diseases play in causing this phenomenon. Research has also indicated that temperatures at ground level tend to be higher in the slash during the day, compared to areas where slash had been removed. The current investigation aimed to determine whether the high temperatures experienced in the slash are likely to be the sole causal agent for the observed mortality. Pots containing P. patula seedlings were exposed to four different temperatures (26o, 32o, 38o and 44o C) in an illuminated growth chamber. The duration of exposure was 1, 2 or 3 hours. The exposure to the different temperatures was repeated on 7 days in a 10 day period. Respiration rates increased significantly at the high temperatures, while the chlorophyll a, b and total chlorophyll concentrations were significantly reduced at the highest temperature. Increasing temperature also significantly reduced both height and new root growth in the seedlings during the experiment. The results indicate that, although no mortality was observed during the experiment, continued exposure to high temperatures over an extended period has the potential to cause seedling mortality. However, it is hypothesised that high temperatures predispose the seedlings to attack by pests and pathogens on site. Keywords: Pinus patula, Heat stress, Chlorophyll concentrations, Re-establishment problems, Harvesting residues Southern African Forestry Journal No.200 2004: 27-38

Six fertiliser trials were established in separate stands in their 4th, 7th or 12th year on both granite and gabbro derived soils in the Usutu Forest, Swaziland. All trials compared the same factorial combination of N, P and K fertilisers. Tree growth response to fertiliser was measured five years after application. The trials demonstrate that meaningful responses to fertiliser can be obtained when applied to established pulpwood stands without thinning. Both stand age at application and soil parent material were found to influence response to fertiliser. With K, positive responses were obtained in the 3 and 6 year old stands but negative responses were evident applied to 11-year-old stands. Positive responses to K were also more pronounced on gabbro derived soils. Tree growth was improved by P applied in 6- and 11-year-old stands and by N applied in 11-year-old stands. Results are discussed in relation to nutrient cycling, stand development, soil fertility and records of long-term productivity at Usutu. It is proposed that observed declines in second rotation productivity in block A of the forest are associated with gabbro-derived soils and that this decline can be corrected by fertiliser application. Keywords: Fertiliser response, 2R decline, Pinus patula, Stand age, Soil nutrition Southern African Forestry Journal No.199 2003: 27-40