Colombia covers an area of approximately 114 million hectares (ha) of which the
potential forestly land has been estimated at 60.7 million ha, about 53% of the
total area. Only 54 million ha are considered as natural forest, leaving
approximately 29 million ha to be used for livestock and agriculture. In order to
provide an alternative source of timber, Colombian groups have planted
approximately 327 000 ha to different species of Pinus, Eucalyptus and native
species. This clearly represents only a small proportion of the total area that
might be used for forestry, which is set to grow in the future.
In general, trees established in plantations have been grown as monocultures
that allow for substantial productivity per management unit. But this is also a
homogeneous genetic resource that is highly susceptible to damage caused by
insect pests and diseases. It is therefore, surprising that relatively little work has
been conducted on pests and pathogens negatively affecting plantation foresty in
Colombia. In this regard, the studies presented in this thesis present the first
comprehensive treatment of the topic for the country. It is consequently hoped
that these will form a basis for the future management and sustainability of
forestry in Colombia.
In the first Chapter of this thesis, I provide a historical background and the
current pest and disease situation for the forestry sector in Colombia. This
includes an overview of the main pest and diseases affecting commercial nonnative
trees, especially species of Pinus and Eucalyptus. A wide range of sites
occurring in Colombia were considered and the document also includes the
impact of different climatic conditions on the incidence and management of the
various pests and diseases treated.
Some of the most important defoliators in Colombia reside in the order
Phasmatodea and one of these, Litosermyle ocanae, was treated in studies
presented in chapter two. The overall aim was to contribute basic knowledge of
L. ocanae including an understanding of the biology, egg population dynamics,
and potential biological control assessments based on early detection of the
insect. vi
Chapter three includes the discovery of one of the members of the
Geometridae that causes serious damage due to defoliation of Pinus and
Eucalyptus plantations. This pest, known as Chrysomima semiluteraria, has been
known in Colombia for many years and this study included a comprehensive
evaluation of its biology and field monitoring contributing to an Integrated Pest
Management strategy for it. The insect was studied under field and laboratory
conditions and a special emphasis was placed on its biological control using the
egg parasitoid Telenomus alsophilae.
Pinus plantations in Colombia have been affected by numerous pests, including
recently, the adelgid Pineus sp. To establish management strategies to assist
commercial forestry operations, the life cycle of this insect and the susceptibility
of different Pinus species were determined in Chapter four. In addition, the
possible role of a Ceraeochrysa sp. as a biological control agent was
investigated.
In chapter five, Fusarium circinatum is recorded for the first time on Pinus spp.
in Colombia. The discovery of this fungus, known to cause the disease Pitch
Canker has had an important impact on forestry, especially with regard to
management strategies aimed at reducing its impact. Studies in this chapter
included those to evaluate the susceptibility of families and provenances of Pinus
spp., which are currently used in forestry planting programs in Colombia.
The first emergence of the foliage pathogen Dothistroma septosporum as an
important constraint to pine forestry in Colombia is treated in chapter six. This
fungus is a serious pathogen of many species of Pinus around the world. It was,
however, not recognised as a serious threat to forestry in Colombia until it
emerged as a serious source of damage to Pinus tecunumanii. In this chapter,
the aim was firstly to confirm the identity of the pathogen based on DNA
sequence data. Subsequently, the host range and distribution of the pathogen
was established in different Colombian forestry areas. The impact of the disease
and the susceptibility of different provenances of P. tecunumanii was also
assessed. In chapter seven, the main objective was to described the susceptibility of E.
grandis clones to a new species of Ceratocystis and to identify clones resistant to
it. The fungus was described as Ceratocystis neglecta and management
strategies are suggested for it.
This thesis includes two Appendices treating new reports of insect pests and an
important Eucalyptus pathogen. In Appendix 1, I report on the importance of
three different pest insects. Appendix 2 includes a description of a new disease,
as well as the potential risks that this disease poses for the Colombian forestry
sector. / Thesis (PhD)--University of Pretoria, 2013. / gm2013 / Forestry and Agricultural Biotechnology Institute (FABI) / Unrestricted
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:up/oai:repository.up.ac.za:2263/32968 |
| Date | 13 January 2013 |
| Creators | Rodas Pelaez, C.A. (Carlos Alberto) |
| Contributors | Wingfield, Michael J. |
| Publisher | University of Pretoria |
| Source Sets | South African National ETD Portal |
| Language | English |
| Detected Language | English |
| Type | Thesis |
| Rights | © 2013 University of Pretoria. All rights reserved. The copyright in this work vests in the University of Pretoria. No part of this work may be reproduced or transmitted in any form or by any means, without the prior written permission of the University of Pretoria. |
Page generated in 0.0022 seconds