Thesis (Ph.D. Biological Sciences)--University of Waikato, 2009. / Title from PDF cover (viewed July 10, 2009) Includes bibliographical references (p. 184-202)

Thesis (Ph. D.)--University of Canterbury, 2006. / Typescript (photocopy). Includes bibliographical references (leaves 109-118). Also available via the World Wide Web.

Thesis (MScFor)--Stellenbosch University, 2012. / ENGLISH ABSTRACT: The aim of this project was to determine the site effect- especially water availability - and the effect of cambial age on selected anatomical properties of Pinus radiata, in order to be able to predict possible changes in wood quality due to an expected change in climate. A second objective was to correlate ring and fibre properties, in order to determine, if ring properties could be used as a proxy to describe wood quality. The samples consisted of 12 trees, sampled at an age of 1 to 16 from six selected sites in the Western Cape, which ranged from water stressed to moist. Apart from the water availability all other external factors, such as elevation etc. were kept as equal as possible. Anatomical wood properties such as fibre length and fibre diameter, lumen diameter, cell wall thickness, ring width and earlywood/latewood ratio were determined and their change with cambial age and water availability was evaluated. Fibre length, fibre diameter and cell wall thickness increased with increasing cambial age, and ring width and earlywood/latewood ratio decreased with increasing cambial age. No significant correlations were found between any of the ring or fibre properties and water availability. Most of the fibre properties were significantly correlated with ring width and earlywood/latewood ratio when age was not considered as covariate, but showed no correlation when the age effect was excluded. / AFRIKAANSE OPSOMMING: Die doel van die projek was om die perseel se effek te bepaal, veral water beskikbaarheid, ten opsigte van die effek van kambium ouderdom en geselekteerde anatomiese eienskappe van Pinus radiata, om sodoende die moontike verandering in hout kwaliteit as gevolg van verwagte klimaatsverandering te voorspel. ‘n Tweede doelwit was om die ring en vesel eienskappe te korreleer en ook te bepaal of ring eienskappe gebruik kan word om hout kwaliteit te beskryf. Die monsters het bestaan uit bome van ses geselekteerde persele in die Wes Kaap en het gevarieer van ‘n water tekort na klam. Behalwe vir water beskikbaarheid is al die ander eksterne faktore, soos hoogte ens., konstant gehou waar moontlik. Anatomiese hout eienskappe soos vesel lengte en deursnee, sel deursnee, selwand dikte, ring wydte en E/L verhouding was bepaal asook die verandering met kambium ouderdom en water beskikbaarheid. Vesel lengte , vesel deursnee en selwand dikte het toegeneem met toename in kambium ouderdom, en ring wydte en E/L verhouding het afgeneem met toename in kambium ouderdom. Toename in water beskikbaarheid het gelei to afname in vesel lengte en selwand dikte, waar vesel deursnee, sel deursnee, E/L verhouding en ring wydte toegeneem het. Meeste van die vesel eienskappe het betekenisvol gekorrelleer met ring wydte en E/L verhouding wanneer ouderdom nie as ko-variant gebruik is nie.

Thesis (MSc)--Stellenbosch University, 2015. / ENGLISH ABSTRACT: This study aimed to classify wood from trees that were exposed to forest fires with regards to their end use. Exposure to high temperatures over time is known to degrade wood in various ways. This degradation could limit the end use by altering mechanical, chemical and physical properties, leading to difficulty in processing or failing to meet required specifications for various grades. In this study wood from Pinus radiata trees that were exposed to forest fires of different levels of heat intensity was analysed with regards to its anatomical and physical changes. Trees were visually classified into three classes of burn severity. Moisture content measurements were taken from 135 standing trees, divided among the three classes. 30 trees, 10 from each of the three classes, were sampled and used for CT analysis. Samples were taken to include growth from before and after the fire. Two samples were taken from each tree, one from the charred and one from the uncharred side. The CT data was analysed and used to measure properties like growth ring width, cell wall thickness, lumen diameter and cell wall density. The data was used to compare properties from the charred and uncharred sides within a given year, as well as compare properties between years. The study showed that there were significant differences in the MC between the burnt and unburnt sides of trees from classes 2 and 3. The difference between the MC measurements on the burnt sides of three classes differed significantly from each other. Lightness measurements were taken on samples from classes 2 and 3. These samples showed no significant difference between the burnt and unburnt sides for either of the two classes. The samples from the less exposed class were lighter, but not significantly so. The macroscopic wood density was determined using core samples. A decrease in wood density was observed with an increase in fire exposure. The mean densities for all three classes however still fulfilled the requirements for structural timber set by the SABS. Growth ring width, cell wall thickness and lumen diameter analysis gave varied results, with some cases showing a decline in properties while others were seemingly unaffected. For many of the outcomes of this study, results found by previous studies could not be reproduced. / AFRIKAANSE OPSOMMING: Hierdie studie het gepoog om bome wat aan plantasiebrande blootgestel is volgens hul eindgebruik te klassifiseer. Dit is bekend dat blootstelling aan hoë tempreature hout in vele maniere afbreuk. Hierdie afbreuking kan die eindgebruik van die hout beperk deur die meganiese, fisiese en chemiese eienskappe sodanig te verander dat dit kan lei tot probleme met verwerking of ongeskiktheid vir sterktegrade. In hierdie studie is Pinus radiata bome wat aan plantasiebrande van verskillende grade blootgestel is ondersoek in terme van hul fisiese en anatomiese veranderinge. Bome is visueel in drie klasse van verskillende brandskade gegroepeer. Voglesings is op 135 staande bome, verdeel tussen die drie klasse, geneem. Monsters is van 30 bome, 10 uit elke klas, geneem vir CT analiese. Monsters is so geneem dat dit groei van voor en na die brand ingesluit het. Daar is twee monsters van elke boom geneem, een van die gebrande en een van die ongebrande kant. Die CT data is geanalieseer en gebruik om eienskappe soos jaarringwydte, selwanddikte, lumendiameter en selwand digtheid te meet. Die data is gebruik om eienskappe tussen die gebrande en ongebrande kante, sowel as tussen jare te vergelyk. Die studie het gewys dat daar noemenswaardige verskille is tussen die voginhoud van die gebrande en ongebrande kante van bome uit klasse 2 en 3. Die voginhoud van die gebrande kante van al drie klasse verkil ook noemenswaardig van mekaar. Ligtheidmetings is gedoen op monsters van klasse 2 en 3. Die monsters het nie ‘n noemenswaardige verskil tussen die gebrande en ongebrande kante getoon nie. Alhoewel die klas 2 monsters ligter vertoon het as die klas 3 monsters, was die verskil nie betekenisvol nie. Houtdigtheid is bepaal deur fisiese metings op die monsters wat vir die CT skandering gebruik is te doen. ‘n Daling in digtheid met ‘n toename in blootstelling aan die brand het duidelik na vore gekom. Die digtheid is egter nog hoog genoeg om aan die vereistes vir strukturele hout te voldoen, soos die die SABS bepaal. Jaarringwydte, selwanddikte en lumen diameter het wisselende resultate opgelewer, met sommige gevalle wat ‘n afname in eienskappe wys en ander wat ooglopend onveranderd was. Vir vele van hierdie uitkoms kon die resultate van vorige studies nie bevestig word nie.

Submitted by Reginaldo Soares de Freitas (reginaldo.freitas@ufv.br) on 2017-06-06T18:29:06Z No. of bitstreams: 1 texto completo.pdf: 1558482 bytes, checksum: 1a0c4385270f4da9acdf1b730e12eda4 (MD5) / Made available in DSpace on 2017-06-06T18:29:06Z (GMT). No. of bitstreams: 1 texto completo.pdf: 1558482 bytes, checksum: 1a0c4385270f4da9acdf1b730e12eda4 (MD5) Previous issue date: 2004-03-11 / Conselho Nacional de Desenvolvimento Científico e Tecnológico / Os objetivos do presente trabalho foram avaliar a qualidade fisiológica das sementes de feijão-mungo-verde; a influência do etileno e do ácido giberélico (AG3) no crescimento dos brotos; a relação entre a atividade da enzima peroxidase e o escurecimento dos brotos; e determinar o teor de água das sementes e dos brotos. Para analisar a qualidade fisiológica das sementes foram utilizados os testes de germinação, envelhecimento acelerado (42 °C/48 h e 42 °C/72 h), germinação a baixa temperatura (18 °C) e condutividade elétrica. A determinação da atividade da peroxidase foi realizada em raiz, hipocótilo e folha verdadeira dos brotos, em diferentes pHs (3, 4, 5, 6, 7, 8 e 9), provenientes de sementes germinadas a 25 °C e a 30 °C, em dois estádios de desenvolvimento (brotos com três e seis dias), enquanto a inativação da enzima, realizada por tratamento térmico (90 °C), em diferentes períodos (0; 2,5; 5 e 10 min). O etileno (Ethrel) e o ácido giberélico (AG3) foram aplicados isoladamente ou em conjunto, em diferentes estádios da germinação das sementes. O teor de água destas e dos brotos foi determinado em estufa a 70 °C até peso constante. As linhagens testadas foram Ouro Verde MG 2, VC 1973A, VC 5734A, V 3476, VC 4039A, VC 6148B16, VC 3890B e VC 3902A do banco de germoplasma do EPAMIG/CTZM, mas, para avaliação enzimática e aplicação dos hormônios de crescimento, utilizou-se apenas a cultivar Ouro Verde MG 2. Os testes de envelhecimento acelerado e de condutividade elétrica não foram eficientes na avaliação do vigor das sementes, sendo o mais adequado o teste de germinação à baixa temperatura. A atividade da peroxidase foi expressa por uma curva de formato semelhante nas diferentes partes amostradas do broto, sendo mais baixa nos extremos de pHs 3 ou 9 e mais elevada entre os pHs 4 e 6. Os picos máximos de atividade da enzima foram observados nos pHs 4 e 5 em raiz e 5 e 6 em folha e hipocótilo. Esse formato indica que existem diferentes isoenzimas ou proporções destas agindo nas diferentes partes do broto. A atividade máxima entre os pHs 4 e 6 evidencia tratar-se de uma enzima com atuação preferencialmente extracelular. A atividade específica enzimática foi maior na raiz, seguida das folhas e do hipocótilo. Com relação à atividade da raiz, houve diferença entre os tratamentos, em que a atividade dos brotos com seis dias foi maior que a de três, assim como nos germinados a 30 °C em relação a 25 °C. Os resultados indicaram que brotos cultivados a 25 °C e colhidos com três dias podem atenuar os efeitos indesejáveis da presença da peroxidase, como o escurecimento dos tecidos, e, assim, a vida útil do broto na pós-colheita. O tratamento térmico reduziu a atividade da peroxidase gradativamente com o aumento do tempo de inativação a 90 °C. A atividade peroxidativa dos brotos foi eliminada com o tratamento térmico a 90 °C/10 min. A aplicação de Ethrel a 20 ppm às 8 e 10 horas após o início da embebição resultou em melhor qualidade dos brotos, ou seja, maior espessura e comprimento do hipocótilo. A aplicação conjunta de Ethrel (20 ppm) e GA3 (500 ppm), nos mesmos períodos descritos anteriormente e produzidos a 25 °C + 2 °C, melhorou a espessura e comprimento do hipocótilo e produziu os brotos de cor mais clara. A qualidade do produto foi depreciada quando as sementes foram germinadas em temperatura constante de 30 °C, resultando em brotos muito tenros e com coloração mais escura em comparação com aqueles produzidos a 25 °C. Não houve diferença significativa entre as linhagens quanto ao teor de água dos brotos. O menor valor absoluto de 92,72% no teor de água das sementes foi observado na linhagem VC 3902A. O teor de água das sementes não influenciou o conteúdo de água dos brotos colhidos com cinco dias após a germinação. / The goals of the present work were to evaluate the physiological quality in seeds of mung bean, the influence of ethylene and gibberellic acid (GA3) on sprouts growth, relationship between peroxidase activity and browning and to determined the water content of seeds and sprouts. To evaluate the physiological of seeds it was used the germination test, accelerated ageing (42 °C/48 h and 42 °C/72 h), germination at low temperature (18°C) and electric conductance. The activity of peroxidase was determined in the root, hypocotyl and true leaf of the sprouts at different pHs (3, 4, 5, 6, 7, 8 and 9) from seeds germinated at 25 °C and at 30 °C, grown for 3 and 6 days, and inactivation of the enzyme by thermal treatment (90 °C) for different periods (0, 2.5, 5 and 10 min). The ethylene (Ethrel) and GA3 were applied alone or mixed at different stages of seed germination. The content of water in the seeds and sprouts were determined after drying at 70 °C until constant weight. It was tested the accesses Ouro Verde MG 2, VC 1973A, VC 5734A, V 3476, VC 4039A, VC 6148B16, VC 3890B and VC 3902A belonging to the germoplasm bank from EPAMIG/CTZM, but the peroxidase analysis was done in the cultivar Ouro Verde MG 2. The accelerated ageing and electric conductance were not efficient in evaluating the seeds vigor, but the germination at low temperature was able to evaluate it. The peroxidase activity was represented by similar curves in all tissues analyzed. The activity was lower at pHs 3 and 9, and higher at pHs 4 and 6. The highest activities were present at pHs 4 and 5 for roots, and pHs 5 and 6 for leaf and hypocotyl. These data suggest that there are different isoforms or proportions of peroxidase acting in the different parts of the sprout. The maximum activity between pHs 4 and 6 suggest that the peroxidase is present mainly outside the cell. The specific activity of the enzyme was higher in the root, followed by leaves and hypocotyl. In the roots, the peroxidase activity was higher in sprouts grown for 6 days at 30 °C compared to those grown for 3 days at 25 °C. Sprouts grown for 3 days at 25 °C showed less browning due to lower peroxidase activity, increase the shelf life. Thermal treatment reduced the peroxidase activity at 90 °C proportional to the length of treatment. The peroxidative activity was eliminated when the sprout extract was treated at 90 °C/10 min. The use of 20 ppm Ethrel at 8 and 10 hours after the beginning of germination resulted in better quality for the sprouts or thicker and longer hypocotyls. The combined treatment with 20 ppm Ethrel and 500 ppm GA3, at 25 °C improved the thickness and length of the hypocotyl, and resulted in lighter color. The quality of the sprout was reduced when the seeds were germinated at 30 °C, resulting in softer and darker sprouts, compared to those grown at 25 °C. There was not difference among the accesses regarding the water content of the sprouts. A lower value of 92,72% was present in the seeds of VC 3902A. The water content in the seeds did not affect the water present in the sprout five days after germination.

Os inseticidas neonicotinóides são atualmente o principal grupo químico utilizado para o controle de insetos sugadores, constituindo-se uma boa opção para o controle de Diaphorina citri Kuwayama. Outra opção de controle do psilídeo tem sido a exploração do parasitóide Tamarixia radiata (Waterson). A compatibilidade dessas duas estratégias de controle poderia auxiliar na implementação de programas de manejo integrado de pragas na cultura do citros. No entanto, faltam estudos sobre a caracterização da suscetibilidade de D. citri para os inseticidas neonicotinóides e o impacto desses inseticidas sobre T. radiata. Sendo assim, os objetivos do trabalho foram o de caracterizar a suscetibilidade de D. citri a inseticidas neonicotinóides, realizar o monitoramento da suscetibilidade a esses inseticidas em populações de D. citri coletadas em pomares de diferentes regiões do Estado de São Paulo e avaliar os efeitos letais e subletais desses inseticidas sobre o parasitóide T. radiata. Os inseticidas avaliados foram: thiamethoxam, thiacloprid e imidacloprid. O método de bioensaio adotado foi o de contato residual para a caracterização da suscetibilidade de D.citri a esses inseticidas. O monitoramento da suscetibilidade a esses inseticidas em diferentes populações de D. citri foi realizado com concentrações diagnósticas baseadas na concentração letal 95 (CL95) de cada inseticida. Para avaliar os efeitos letais e subletais desses inseticidas sobre T. radiata foram realizados bioensaios de contato direto em adultos e pupas, toxicidade residual em adultos, e persistência da atividade biológica desses inseticidas sobre a superfície de folhas de citros. Entre os neonicotinóides testados, a maior toxicidade a D. citri foi observado com thiametoxam, seguidos por imidacloprid e thiaclopid. Os resultados do monitoramento apresentaram diferenças significativas na suscetibilidade das populações de D. citri aos inseticidas neonicotinóides. Para thiamethoxam, a sobrevivência estimada para as populações de D. citri testadas na concentração diagnóstica variou entre 5,5 e 16%, para thiacloprid variou entre 4,5 e 22,5 % e para imidacloprid entre 4 e 14%. Uma alta toxicidade desses inseticidas foi observada para adultos e pupas de T. radiata. No entanto, os efeitos subletais desses inseticidas a 10% da concentração recomendada sobre o estágio de pupa causou redução significativa no parasitismo somente com thiamethoxam. A emergência, longevidade e razão sexual de T. radiata não foram afetadas pelos inseticidas avaliados. A toxicidade residual de thiametoxam, thiacloprid e imidaclopid em folhas de mudas de citros foi relativamente elevada para adultos de T. radiata e com persistência de pelo menos 14 dias. / The neonicotinoids insecticides are currently the main chemical group used for controlling sucking pests and represent a good option for the control of Diaphorina citri Kuwayama. Another control alternative of this pest is the exploitation of parasitoid Tamarixia radiata (Waterson). The compatibility of these control strategies could be very helpful for the implementation of integrated pest management program in citrus. However, there are few studies on the characterization of the susceptibility of D. citri to neonicotinoid insecticides and the evaluation of the impact of these insecticides on T. radiata. Therefore, the objectives of this research were to evaluate the susceptibility of D. citri to neonicotinoid insecticides, to monitor the susceptibility to these insecticides in D. citri populations collected from different citrus groves in the State of São Paulo, and to evaluate the lethal and sublethal effects of these insecticides on T. radiata. The insecticides evaluated in this study were: thiamethoxam, thiacloprid e imidacloprid. A residual contact bioassay was used to characterize the susceptibility of D. citri to these insecticides. A diagnostic concentration bioassays based on lethal concentration 95 (LC95) of each insecticide were used for monitoring the susceptibility of D. citri populations. The lethal and sublethal effects of these insecticides on T. radiata were conducted by using direct contact bioassays on adult and pupal stages of T. radiata, residual contact bioassays and persistence of biological activity of these insecticides on citrus leaf surface. Among the neonicotinoid insecticides tested, the highest toxicity was observed with thiametoxam, followed by imidacloprid and thiaclopid. A significant difference in the susceptitibity to neonicotinoid insecticides was detected in D. citri populations. For thiamethoxam, the survivorship at diagnostic concentration varied from 5.5 to 16%, for thiacloprid varied from 4.5 to 22.5 %, and for imidacloprid from 4 to 14%. The toxicity of these insecticides was high to adult and pupal stages of T. radiata. However, the sublethal effects of these insecticides at 10% of the recommended rate on pupae stage caused the reduction of the parasitism capacity only with thiamethoxam. The emergence, longevity and sexual ratio of T. radiata were not affected by any insecticide tested. The residual toxicity of thiametoxam, thiacloprid and imidaclopid sprayed on citrus seedling leaves was relatively high to D. citri adults and lasted at least 14 days.

In South Africa, the limited extent of indigenous forests accelerated the development of fast-growing introduced species plantations, on which the country is now heavily reliant for its fibre and timber products. However, the plantation forestry industry is challenged with limited freshwater resources, the need for sustainable management of introduced tree species in commercial forest production systems, and a diversity of plant ecological production factors such as soils that have to be manipulated for the purposes of increasing production capacities. Additionally, plantations are established in the limited high rainfall regions of the country and the industry’s water use has been regulated since 1972. Conversely, natural forests also provide valuable goods, however, their slow growth rates have restricted their development as commercial tree production systems. In this regard the forestry industry is continuously seeking to provide for the country’s timber and fibre needs while ensuring the provision of other ecosystem services from tree production systems. Recent developments in the forestry industry have therefore been focused on water use efficiency in current and alternative tree production systems. There is also widespread unsubstantiated belief that indigenous tree species are efficient users of water. Against this background this study sought to explore the single tree water use and water use efficiencies of introduced commercial plantation species (Pinus radiata) and that of important indigenous species (Ilex mitis, Ocotea bullata and Podocarpus latifolius) for timber and fibre production in the southern Cape region of South Africa. Single tree water use measurements were carried out for a year using the heat pulse velocity method. Growth measurements for utilisable stem wood were done on a quarterly basis for the specimen trees and growth increments over the year were determined. Single tree water use efficiency was a calculated as a function of grams of stem wood gained per litre of water transpired. Measurements of daily weather conditions and soil water content were concurrently taken during the year. The relationships between the variables that express daily climatic conditions, soil water content and daily volumes of transpired water were explored. Empirical models for the prediction of daily transpiration as a function of climate and soil water content were then developed using multiple linear regression analysis. Pinus radiata trees exhibited higher totals of volumetric transpiration than the indigenous species. The water use patterns of Pinus radiata showed higher peaks of maximum and minimum daily and seasonal water use while the indigenous species showed temperate patterns of water use throughout the year. Podocarpus latifolius attained the lowest water use efficiency in the year (0.49g/L) while Pinus radiata, Ocotea bullata and Ilex mitis had comparable water use efficiency values ranging between 1g/L to 2.50g/L. Significant positive correlations existed between climatic variables and daily sapflow volumes of the tree specimens. Daily total solar radiation showed the highest positive correlation with daily transpiration and the average value of the correlation coefficient for solar radiation and water use for all tree species was 0.70 (p < 0.001). Empirical models for predicting daily water use integrated the variables expressing plant available moisture and energy. The study enhances our understanding of single tree water use, water use efficiency, the drivers of transpiration and the applicability of such studies in developing rapid estimation techniques for water use in current and alternative South African tree production systems.

Memoria para optar al Título Profesional de Ingeniero Forestal / La madera de pino radiata, principal recurso maderero del país, es de baja durabilidad. Hongos e insectos, entre otros factores de su deterioro, son usualmente los más relevantes. Del grupo de los insectos, en particular la termita subterránea “Reticulitermes flavipes”, representa hoy la mayor preocupación, por su agresividad y avance permanente en áreas pobladas del país. El arseniato de cobre cromado (CCA) fue, por décadas, el preservante más utilizado en todo el mundo para proteger la madera, sin embargo, preocupaciones medioambientales, hace más de diez años, dieron paso a un cambio hacia otros productos. El uso de cobreazoles (CA) y en particular el de tipo B, junto con cobreazol micronizado, han sido los cambios más importantes desde entonces a nivel mundial. Su incorporación al mercado local, sin embargo, ha sido muy lenta, básicamente por costo y por no existir un marco legal que regule el uso de madera tratada con CCA. Sobre la base de los requisitos exigidos por la Australian Standard®, AS 1604.1-2012, para madera tratada con CA-B, el objetivo del estudio fue evaluar el comportamiento de madera de Pino radiata tratada con CA-B, a retenciones menores a las exigidas por la Norma Chilena, frente al ataque de hongos de pudrición y termita subterránea. Los métodos empleados fueron; “Standard Test Method for Wood Preservatives by Laboratory Soil-Block Cultures”, descrito en la ASTM Designation: D1413 − 07ɛ1 y la Norma Chilena NCh 3060.Of 2007, para el estudio con hongos y termita subterránea respectivamente. En el estudio con Lentinus lipideus, todos los grupos de retención presentaron efecto positivo en el control del hongo y diferencias estadísticamente significativas respecto a las probetas testigo. En el caso de Coriolus versicolor, solo los grupos de retención 1,4 y 1,8 kg/m3 se diferenciaron estadísticamente del testigo en el control del hongo. En el estudio contra termita subterránea, la retención necesaria de CA-B para el control de Reticulermes flavipes se ubicó entre las retenciones 1,4 y 1,8 kg/m3 (concordante con la Norma NCh 819:2012). Una retención menor en pino radiata tratado con CA-B, no pudo ser validada para el control de termita subterránea, Reticulermes flavipes.

The future resilience of Pinus radiata D. Don (Monterey pine) is dependent upon the development of a silviculture program inclusive of either preventative or management techniques for the potentially fatal pitch canker disease (Fusarium circinatum Nirenberg and O’Donnell [=F.subglutinans (Wollenw. & Reinking) Nelson et al. f. sp. Pini). As an ecologically and commercially valued species, a myriad of factors threaten the genetic resources of the geographically limited natural range. This study evaluated the effectiveness of uneven-aged forest management for regeneration success in the native, pitch canker infected Año Nuevo stand at Swanton Pacific Ranch in Davenport, California. Seedling survival and growth averages were used to evaluate the impact of the variables of gap size (0.20-hectare, 0.10-hectare, and 0.05-hectare), site-preparation treatment (pile and burn, lop and scatter), and parent tree (13 local seed sources). Pitch canker symptoms were quantified to conclude if there is indeed a range of expressed resistance according to parent tree. Statistical models (i.e. ‘mixed effect’) yielded moderately significant differences in odds of survival between site treatments, with pile and burn plots producing higher survival rates (p=0.066). No significant difference in survival was detected between gap-sizes (p=0.936 and 0.803, 0.05- and 0.10-hectare gaps respectively to 0.20-hectare reference). Significant variation was expressed (estimate=0.1219, SE=0.057) between the 13 parent trees, implicating usefulness in predicting seedling survival. ‘Mixed effect’ models only detected a significant effect from gap-size on growth measures: 0.20-hectare gaps yielded height and diameter measures significantly larger than 0.05-hectare gaps (p=0.027 and 0.0081 respectively). Contingency tables detected significant association between gap-size and number of pitch canker branch symptoms. The range of infection rates produced by the 13 parent trees did not prove significant by analysis. Pile and burn site preparation treatment increases the probability of survival for artificially regenerated seedlings and 0.20-hectare gaps yield significantly higher growth averages over 0.05-hectare gaps.

This study was a part of the international collaborative IMPACT project, which aims to address the potential threat that the pitch canker disease poses to the use of Pinus radiata D. Don in plantations in New Zealand, Australia, and Chile. A field trial of 264 seedstocks was planted adjacent to a native stand of pitch canker infected P. radiata on the central coast of California, and disease symptom development was recorded over a period of 3 years. The results did not correlate with a greenhouse study of the same seedstocks inoculated with Fusarium circinatum Nirenberg & O'Donnell, the causal agent of pitch canker. Three main types of symptoms were identified (branch flagging, pitchy buds, and chlorotic tips), and preliminary isolation analyses suggest that the disease observed is actually caused by Diplodia pinea (Desm.) Kickx. Survival analysis showed that the effect of tree genetic origin was significant to its time to disease, and that spatial location in the plantation was also significant. Average nearest neighbor analysis showed disease distribution to be significantly clustered, which also suggests that the disease is not pitch canker, but diplodia blight. This experiment illustrates the difficulty in performing naturally infected field trials when another similar-looking fungal disease is also present. It also provides data on seedstock resistance to diplodia blight, another fungal disease important to P. radiata forest managers.