Pitch canker fungus, Fusarium circinatum : implications for South African forestry

Fusarium circinatum, the causal agent of pitch canker of mature pines and root/collar rot of pine seedlings/cuttings, has resulted in large-scale losses to pine forestry in various parts of the world. The disease caused by this fungus is now regarded as one of the most important threats to pine plantations by a pathogen. Fusarium circinatum was first discovered in South Africa in 1990 where it infected Pinus patula seedlings in a nursery. Subsequently, the pathogen spread to pine nurseries in all other parts of the country, where it affects several Pinus species. Fusarium circinatum then appeared in the field where it has resulted in large-scale mortality of mostly young P. patula seedlings after planting. Pitch canker first appeared on mature P. radiata in 2006 and sporadic outbreaks of the disease have occurred subsequently on this species and on P. greggii in the western, southern and north-eastern Cape. Pinus patula is the most important softwood species grown in South Africa, comprising 50% of all softwoods planted, and is highly susceptible to F. circinatum. The pathogen, therefore, poses a potentially devastating threat to the future sustainability of the South African softwood industry. Strategic measures to minimise further spread are urgently needed. This review presents an overview of the impact that F. circinatum has had on South African forestry, and it considers the long-term prospects for pine forestry in the country as this relates to the presence of the pitch canker fungus.http://www.tandfonline.com/loi/tsfs2

Tolerance of Pinus patula full-sib families to Fusarium circinatum in a greenhouse study

The pitch canker fungus, Fusarium circinatum, has caused large scale mortality of young Pinus patula Schiede & Deppe ex Schltdl. & Cham. seedlings in nurseries in South Africa since 1990. Diseased seedlings have been inadvertently carried to the field, which in turn have died and has reduced stocking below an acceptable level. Tree breeders have suggested that the only long-term solution to limit infection by this pathogen is to identify and deploy tolerant P. patula families. A commonly used technique to identify tolerant clones is to artificially inoculate open-pollinated progeny from orchard clones with F. circinatum under greenhouse conditions. In these trials, large variation in tolerance to the pathogen among seedlings within open-pollinated families was observed and that this could be influenced by the pollen parent. Therefore, identifying individual full-sib families where both parents are known, should improve the identification of tolerant families, which can then be repeated. In this study, cuttings from control-pollinated P. patula seedling hedges were inoculated with F. circinatum in a greenhouse. The results showed large family variation where some of the full-sib families were similar in tolerance to P. elliottii Engelm var. elliottii seedlings. Therefore, it is recommended that breeders focus on identifying specific family combinations that are more tolerant to F. circinatum.http://www.tandfonline.com/loi/tsfs20hb2016Forestry and Agricultural Biotechnology Institute (FABI)Microbiology and Plant Patholog

Susceptibility of provenances and families of Pinus maximinoi and Pinus tecunumanii to frost in South Africa

The future of South Africa’s most important pine species, Pinus patula, is threatened by the pitch canker fungus, Fusarium circinatum. Pinus maximinoi and P. tecunumanii represent two subtropical species that provide an alternative to planting P. patula on the warmer sites of South Africa. Extending the planting range of P. tecunumanii and P. maximinoi to include higher and colder altitude sites will reduce the area planted to P. patula and the risk of F. circinatum. During 2007 progeny trials of P. tecunumanii and P. maximinoi were planted on a sub-tropical and sub-temperate site. Shortly after the establishment of these trials, unusually cold weather conditions were experienced across South Africa (-3 C at the sub-temperate site) resulting in severe mortality. This provided the opportunity to assess the variation in survival as a measure of frost tolerance within these two species to determine whether it could be improved upon through selection. Results indicated that the variation in survival was under genetic control in P. tecunumanii (h(0,1) 2 = 0.16, hL 2 = 0.27) and P. maximinoi (h(0,1) 2 = 0.11, hL 2 = 0.23) at the sub-temperate site. Correlations in provenance ranking for survival across sites were high for both species. Moderate correlations in family survival for P. tecunumanii (r = 0.52) were found at the two sites. Improvements in cold tolerance can thus be made in both species extending their planting range to include greater areas planted to P. patula thereby limiting the risk of F. circinatum.http://link.springer.com/journal/1105

Future outlook for Pinus patula in South Africa in the presence of the pitch canker fungus (Fusarium circinatum)

Approximately 50% of the area planted to softwood trees in South Africa has been established with Pinus patula making it the most important pine species in the country. More effort has gone into developing this species for improved growth, tree form and wood properties than with any other species. This substantial investment has been threatened in the last 10 years by the pitch canker fungus, Fusarium circinatum. The fungus infects and contaminates nursery plants and, once transferred to the field, causes severe mortality of young trees in the first year after establishment. Although nurserymen have some control of the disease, it is recognized that the best long-term solution to mitigate damage due to F. circinatum infection is to identify tolerant species, clones and hybrids for deployment in plantations in the future. Research has shown that alternatives such as P. tecunumanii, P. maximinoi and P. elliottii are suitable for warm sites. Pine hybrids, particularly between P. patula and the high elevation sources of P. tecunumanii, appear to be a suitable replacement on sub-temperate and temperate sites. Although these alternative species and hybrids are more sensitive to sub-freezing temperatures than P. patula, their planting range can be increased by including cold tolerance as a selection criterion. Future breeding efforts will most certainly focus on improving the tolerance of pure P. patula to F. circinatum, which can be achieved by identifying specific family crosses and tolerant clones. The commercial deployment of disease tolerant control-pollinated P. patula and hybrid families will most likely be established as rooted cuttings, which requires more advanced propagation technology. In the long term, new seed orchards comprised of P. patula clones tolerant to F. circinatum will be used to produce seed for seedling production.http://www.tandfonline.com/loi/tsfs20hb201

Tolerance of Pinus patula x Pinus tecunumanii, and other pine hybrids, to Fusarium circinatum in greenhouse trails

The field survival of Pinus patula seedlings in South Africa is frequently below acceptable standards. From numerous studies it has been determined that this is largely due to the pitch canker fungus, Fusarium circinatum. Other commercial pines, such as P. elliottii and P. taeda, show good tolerance to this pathogen and better survival, but have inferior wood properties and do not grow as well as P. patula on many sites in the summer rainfall regions of South Africa. There is, thus, an urgent need to improve the tolerance of P. patula to F. circinatum. Operational experience indicates that when P. patula is hybridized with tolerant species, such as P. tecunumanii and P. oocarpa, survival is greatly improved on the warmer sites of South Africa. Field studies on young trees suggest that this is due to the improved tolerance of these hybrids to F. circinatum. In order to test the tolerance of a number of pine hybrids, the pure species representing the hybrid parents, as well as individual families of P. patula x P. tecunumanii, a series of greenhouse screening trials were conducted during 2008 and 2009. The results indicated that species range in tolerance and hybrids, between P. patula and these species, are intermediate in tolerance to F. circinatum. Within P. patula x P. tecunumanii, large family variation exists when pollen from the high elevation source of P. tecunumanii is used. The results of these studies illustrate the importance of developing pine hybrid breeding programs to overcome the susceptibility of our pure species to pathogens such as F. circinatum.The members of the Tree Protection Co-operative Programme (TPCP) and the THRIP initiative of the Department of Trade and Industry (DTI).http://www.springerlink.com/content/102971

Selection of Pinus spp. in South Africa for tolerance to infection by the pitch canker fungus

The increasing threats from pests and diseases demand that the South African forest industry explores options to deploy alternative pine species in plantation development. This is especially true for species, such as Pinus patula Schiede and Deppe ex Schltdl. and Cham., which are highly susceptible to the pitch canker fungus Fusarium circinatum. Losses due to F. circinatum have been confined mostly to nurseries and at field establishment resulting in a significant cost to the industry. Although, the fungus has not as yet resulted in stem and branch infections on established P. patula in South Africa, it has caused pitch canker on other, more susceptible species such as P. radiata D. Don., and P. greggii Engelm. ex Parl. As alternatives to P. patula, on the warmer and cooler sites in South Africa, families of P. elliottii Engelm var. elliottii, P. tecunumanii (Schw.) Eguiluz and Perry, P. maximinoi H. E. Moore and P. pseudostrobus Lindl. were screened for tolerance to infection by F. circinatum in greenhouse studies. Seedlings were wounded and inoculated with spores of F. circinatum. Lesion development following inoculation was used to differentiate the levels of tolerance between families. The results showed that P. maximinoi, P. pseudostrobus, and the low elevation variety of P. tecunumanii are highly tolerant to infection with very little family variation. The narrow sense heritability estimates for these species were less than 0.06. In contrast, P. elliottii showed good tolerance with some family variation and a heritability of 0.22, while the high elevation source of P. tecunumanii showed a high degree of family variation and a heritability of 0.59. These results provide the industry with valuable information on pine species tolerant to F. circinatum that could be used as alternatives to P. patula in South Africa.Members of the Tree Protection Co-operative Programme (TPCP) and members of the Technology and Human Resources for Industry Programme (THRIP), an initiative of the Department of Trade and Industry (DTI).http://www.springerlink.com/content/102971/nf201

Comparison of the tolerance of Pinus patula seedlings and established trees to infection by Fusarium circinatum

Since the first appearance of Fusarium circinatum in South Africa in 1990, foresters have been challenged with poor field survival of seedlings at establishment. One of the best long-term solutions is to improve the genetic tolerance of Pinus patula to infection by the pathogen. Currently, large numbers of families are routinely screened for their tolerance to F. circinatum by infecting open-pollinated seedlings from orchard clones in a greenhouse and assess-ing lesion development. In this study, nine-year-old P. patula trees from 96 families were inoculated with F. circina-tum in the field. Their levels of tolerance were assessed and compared to those observed in seedlings originating from seed harvested from the same trees. The field results were also compared with those from previous greenhouse screening trials where seedlings from a number of the same families had been inoculated with F. circinatum. The results showed that there was a strong phenotypic (r = 0.71) and genetic (rg = 0.94) correlation in the performance of the families common in both the greenhouse studies. A comparison of the tolerance of the families, screened as both seedlings and as trees, was also meaningful (r = 0.40). Furthermore, the seedlings raised from seeds collected from the infected P. patula trees, that ranked more tolerant than the mean of the P. elliottii trees, were similar in tolerance to P. elliottii seedlings in the greenhouse trial. Our results indicate that utilising seedlings from clones known to be tolerant should improve the tolerance of mature trees to infection by F. circinatum.Tree Protection Co-operative Programme (TPCP)http://www.tandfonline.com/loi/tsfs202015-06-30hb201

Factors Associated with Revision Surgery after Internal Fixation of Hip Fractures

Background: Femoral neck fractures are associated with high rates of revision surgery after management with internal fixation. Using data from the Fixation using Alternative Implants for the Treatment of Hip fractures (FAITH) trial evaluating methods of internal fixation in patients with femoral neck fractures, we investigated associations between baseline and surgical factors and the need for revision surgery to promote healing, relieve pain, treat infection or improve function over 24 months postsurgery. Additionally, we investigated factors associated with (1) hardware removal and (2) implant exchange from cancellous screws (CS) or sliding hip screw (SHS) to total hip arthroplasty, hemiarthroplasty, or another internal fixation device. Methods: We identified 15 potential factors a priori that may be associated with revision surgery, 7 with hardware removal, and 14 with implant exchange. We used multivariable Cox proportional hazards analyses in our investigation. Results: Factors associated with increased risk of revision surgery included: female sex, [hazard ratio (HR) 1.79, 95% confidence interval (CI) 1.25-2.50; P = 0.001], higher body mass index (fo

Reducing the risk of pitch canker disease (caused by Fusarium circinatum) to Pinus patula in South Africa

The principal objective of this research has been to reduce the potential impact of Fusarium circinatum on young and mature Pinus patula trees in South Africa. The results provide new knowledge concerning the genetic variation within P. patula, and suggest alternative species and hybrids, with resistance to infection by the pitch-canker pathogen F. circinatum. The infection of nursery plants is the principal cause of dying seedlings after planting and controlling the disease in the nursery is paramount to achieving good post-planting survival of P. patula. A large number of alternative pines, which are more tolerant to the pathogen, exist. Pinus elliottii is the most versatile alternative due to the ready availability of seed and the fact that it can be planted on a wide range of sites. Although the species is more tolerant than P. patula, individual families vary in their tolerance to F. circinatum and care should be taken to eliminate the more susceptible families. Pinus maximinoi and the low elevation (LE) source of P. tecunumanii are highly tolerant and provide an excellent alternative to P. patula on sites free of frost. The high elevation (HE) source of P. tecunumanii, which is more tolerant of cold than the low elevation source, is significantly more tolerant to F. circinatum than P. patula. However, large variation in the tolerance of individual P. tecunumanii (HE) families to F. circinatum exists and tolerant families of this source need to be identified before commercial deployment. Although P. maximinoi and P. tecunumanii are sub-tropical pines and sensitive to frost, meaningful variation in the tolerance of individual families to frost has been observed which indicates that these species can be bred for improved frost tolerance. On the colder sites, P. pseudostrobus may become an important alternative to P. patula due to its excellent tolerance to F. circinatum. In all cases hybrids between P. patula and pines more tolerant to F. circinatum, are significantly more tolerant than P. patula. Of these the P. patula x P. tecunumanii hybrid is the most promising. Due to the excellent tolerance of P. tecunumanii (LE) all families of the P. patula x P. tecunumanii (LE) hybrid are tolerant of F. circinatum. On the other hand, families of the P. patula x P. tecunumanii (HE) vary greatly in their tolerance to F. circinatum and the specific combination of the parents appears to play an important role in determining tolerance. Although only 5% of the current P. patula growing stock is of similar tolerance to F. circinatum as P. elliottii heritability for tolerance to F. circinatum is high in P. patula indicating that improvements can be achieved through breeding. Good control can also be achieved by identifying specific full-sib P. patula families that are tolerant to F. circinatum, rather than the use of open pollinated seed. It is anticipated that large areas, currently well suited to P. patula, will in the future be replanted with pine hybrids and species more tolerant of F. circinatum. Pinus patula, which has been bred for improved tolerance to F. circinatum, will be limited to the most temperate regions of South Africa.Thesis (PhD)--University of Pretoria, 2012.Microbiology and Plant PathologyPhDUnrestricte

Fracture fixation in the operative management of hip fractures (FAITH): an international, multicentre, randomised controlled trial

Background Reoperation rates are high after surgery for hip fractures. We investigated the effect of a sliding hip screw versus cancellous screws on the risk of reoperation and other key outcomes. Methods For this international, multicentre, allocation concealed randomised controlled trial, we enrolled patients aged 50 years or older with a low-energy hip fracture requiring fracture fixation from 81 clinical centres in eight countries. Patients were assigned by minimisation with a centralised computer system to receive a single large-diameter screw with a side-plate (sliding hip screw) or the present standard of care, multiple small-diameter cancellous screws. Surgeons and patients were not blinded but the data analyst, while doing the analyses, remained blinded to treatment groups. The primary outcome was hip reoperation within 24 months after initial surgery to promote fracture healing, relieve pain, treat infection, or improve function. Analyses followed the intention-to-treat principle. This study was registered with ClinicalTrials.gov, number NCT00761813. Findings Between Mar