Developing interactive diagnostic support tools for tropical root crops
V. dR. Amante and G. A. Norton
Centre for Biological Information Technology
Level 6 Hartley-Teakle Building
The University of Queensland
Brisbane Qld 4072
Australia
Key words: sweetpotato, taro, yam, insect pests, diseases, nutritional disorders, Lucid
ABSTRACT
Information and Communication Technology (ICT) offers exciting new possibilities
for providing diagnostic support tools for farmers, advisors and others interested in
tropical root crops. A CD-ROM that provides diagnostic support for those attempting
to diagnose disorders in sweetpotato crops has recently been released. This CD has
been funded by the Australian Centre for International Agricultural Research
(ACIAR) and has involved collaboration among The University of Queensland, The
International Potato Centre (CIP) Office in Indonesia, and PhilRootcrops in the
Philippines. The process of developing this diagnostic support tool is described. Four
major steps are involved: (1) collection of information in text and graphic form, (2)
development of fact sheets (3) construction of the diagnostic key and (4) technical and
field testing. Construction of the key is discussed in detail, including the development
of a list of Possible Causes to be included in the key, formulation of Possible
Observations and states that describe the sick or damaged plant, and scoring Possible
Causes against Possible Observations. Field testing is an important part of developing
computer–assisted tools, and the response to a prototype by users from the
Philippines, Indonesia and Africa, is described. The possibility of developing a
similar diagnostic key for taro and yam problems in Asia, Africa and the Pacific
Regions is discussed.
INTRODUCTION
Sweetpotato, taro and yam are traditionally important crops in tropical agriculture.
Until recently, they had been grown mainly for home consumption and to provide a
source of additional cash. In the case of sweetpotato, recent developments in the
Asian region, which recognise its growing importance for food and industrial
processing as well as for production of processed feeds, tend to create a new market.
A similar trend is noted for taro and yam. To exploit and cope with this market
opening, production systems are being changed from small to large scale operations.
However, the consequence of changing production systems not only involves an
increase in production inputs and a change in cultural management to obtain higher
production but these changes also modify the crop’s macro and micro environments.
With an increased production area and more extensive cultivation, an increase in pest,
disease and other problems can be expected. These problems need to be addressed to
ensure these changes in production systems are beneficial and sustainable. The worst
thing that could happen is to give hope to small farmers for a better income and then
allow them to experience and cope with the problems that come with a larger scale of
production of which they will have difficulty in handling.
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Diagnosing crop problems is something that most farmers in Asia, the Pacific and
Africa find difficult. Technical help is sometimes available from government
institutions but, more often, they do not have the required specific skill and expertise
and pass on the task to experts located in major towns or cities. More often than not,
problems are either identified only after the crop has been too severely affected to
merit management or they have not been identified at all because affected plants were
not in a good condition for diagnosis.
Advances in information and communication technology (ICT) provide an
opportunity to bring expertise closer to the local people who are directly involved in
crop production. The email list-server – PestNet – that has over 400 subscribers in the
Pacific region, is one way in which IT is linking experts, extension agents and other
parties (See - www.pestnet.org). These advances in ICT also allow the development
of creative and innovative teaching, learning and diagnostic support tools that could
result in a better understanding of crop problems, their identification and
management. This in turn could lead to higher yields, more efficient production and
consequently increased farmers’ income.
This paper describes the process involved in developing a CD-ROM diagnosticsupport tool for sweetpotato, the Sweetpotato DiagNotes (Fig.1), aimed at educating
and supporting those directly or indirectly involved in managing the crop. It is
suggested that this sweetpotato diagnostic support tool could provide a model for a
similar product for taro and yam.
Fig 1. Sweetpotato DiagNotes - a diagnostic-support tool produced by the
Centre for Biological Information Technology, The University of Queensland,
Australia.
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DEVELOPING “SWEETPOTATO DIAGNOTES”
Four major steps were involved in developing Sweetpotato DiagNotes - a sweetpotato
diagnostic support tool - (1) collecting relevant information in text and graphic form,
(2) developing fact sheets (3) constructing the key and (4) technical and field testing.
1. Collection of information in text and graphic form
Information about the sweetpotato crop was obtained from collaborating international
experts from the International Potato Center (CIP) in Indonesia and Peru, Louisiana
State University in the United States of America (USA), Natural Resources Institute
in the United Kingdom (UK), The University of Queensland (UQ), Australia and the
Philippine Rootcrops Research and Training Center (PhilRootcrops), Philippines.
These collaborators were requested to provide information based on a common format
and were frequently consulted to confirm or verify details. Further information was
obtained from the literature, and web searches and from the authors’ knowledge and
experience of the crop.
2. Developing the fact sheets and other relevant information
There are two fact sheets for each pest, disease and nutrient disorder included in
Sweetpotato DiagNotes. The first fact sheet provides (Fig.2) a summary of diagnostic
information, including common signs and symptoms and, when available, information
on conditions that aggravate or reduce the occurrence of the disorder. The second fact
sheet, which is linked to the diagnostic summary, gives more detailed information on
Fig. 2. Each disorder has a fact sheet providing a diagnostic summary.
taxonomy, economic importance, geographical distribution, morphology, signs and
symptoms, biology and ecology, confusion with other symptoms, detection and
inspection, management and references. Both fact sheets contain images, most of
which were taken in the field.
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In addition to fact sheets, general information about the crop and its production is
included in the product.
3. Constructing the key
Lucid Professional is a software tool developed by the Centre for Biological
Information Technology (CBIT) at UQ for creating and publishing interactive
identification or diagnostic keys (See the Box for more information on the two types
of identification and diagnostic keys). This software tool, which was used to develop
the matrix key for diagnosing sweetpotato problems, consists of a Builder, which
allows keys to be easily constructed, including the incorporation of multimedia
(images, audio and video) and a Player, which allows users to operate the key. When
a user selects in the key those features they have observed in the “sick” crop, the
Player filters these information, reduces the list of Possible Causes and lists the
eliminated problems under Unlikely Causes (Fig. 3).
Box – Dichotomous and Matrix keys
There are two types of identification and diagnostic keys – dichotomous (or pathway)
keys and matrix keys. Dichotomous keys are the traditional keys used for
identification of biological organisms. A dichotomous key presents the user with a
hierarchical set of questions or “couplets”, concerning more general to more specific
features of the specimen to be identified or diagnosed. Depending on which of the
couplets they choose, users are either directed to another couplet or to a solution – an
identification or a diagnosis. A major problem with dichotomous keys is the
“unanswerable couplet” problem. If the user is unable to decide which couplet best
describes the specimen, he or she is unable to continue.
By contrast, matrix keys are more flexible than dichotomous keys since they allow the
user to consider and choose features describing the specimen in any order they wish.
This allows users to ignore features that are not clear and still be able to get a reliable
diagnosis or at least a short list of likely causes. Lucid Professional is a matrix key
system. For more information go to - www.lucidcentral.com.
Constructing the key used in Sweetpotato DiagNotes involved the following:
3.1. Developing a list of Possible Causes or problems
A list of insect and mite pests, diseases and nutritional disorders affecting the
sweetpotato crop was made. The project staff and collaborators discussed and
deliberated on the final list of Possible Causes or problems to be included in the
key based on their current importance in the countries/regions covered, the
potential for introduction and increased importance of these problems in these
countries/regions and the existence of sufficient information on these problems.
3.2. Determining the Possible Observations associated with a “sick” crop
Possible observations and “states” that characterise the identified problems were
determined. The list included all the descriptions or interpretations of signs and
symptoms as well as the conditions where the problems occur. A lot of
deliberation was involved on how possible observations and “states” were to be
presented. Possible observations were put in question form and “states” under
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each possible observation were made to be easy to understand and be able to
describe what the users observe or think they observe in the field in order to allow
for a quicker and easier identification of the problem using the Lucid Player.
Hence, aside from using simple words to describe the “sick” plant and the field
conditions, notes and images were further added (Fig. 4). A glossary was also
included to help with difficult or technical words used in the key and the fact
sheets.
Fig. 3. The Lucid Player allows users to operate the key. It has 4
windows: clockwise from top left: Possible Observations,
Observations Chosen, Possible Causes and Unlikely Causes.
Fig. 4. Notes on possible observations provide users with useful help in
describing the features of a “sick” plant, such as leaf colour changes.
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3.3. Interpreting information for scoring using a data matrix
Lucid Builder was used to build the key. This software allows the key builder to
score the matrix that lies behind the diagnostic key in a number of ways. Possible
Observations are related to Possible Causes by a score in the key’s matrix (Fig.5).
The score is “common”, when the feature in question is a common, frequently
exhibited expression or condition of that particular cause; “rare”, when a specific
feature may or may not be exhibited or expressed, depending on factors such as
cultivar and environment; and “misinterpreted”, when users may incorrectly select
a feature (e.g. choosing reduction in leaf size rather than leaf curling).
Fig. 5. Construction of the sweetpotato key involved scoring Possible Causes
against Possible Observation states using a data matrix provided by the Lucid
Builder (blue= common; green= rare).
4. Field testing
Field testing of diagnostic support tools is critical in providing the authors with
insights into how the product will perform with respect to critical success criteria namely: technical accuracy, relevance and acceptability (Table 1). Sweetpotato
DiagNotes was field tested in the Philippines, Indonesia and Africa.
• Technical accuracy
The technical accuracy of the key was assessed by experts in a workshop held at
PhilRootcrops, Philippines, and by distributing a prototype CD to reviewers from
different countries. During the testing, one suggested weakness of the key was the
difficulty associated with situations where there is more than one causal agent
affecting a particular specimen (e.g. corky lesions on the stem and round holes in the
leaves caused by leaf and stem scab and tortoise beetle, respectively). In response to
this, the key has been modified so that when there are no possible causes left, the
users is prompted to consider that there is unlikely to be a single problem but that the
cause is most probably due to two or more different agents. One way to deal with this
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situation is to key out the observed symptoms separately, and refer to the fact sheets
to confirm the results of the diagnosis. In general, reviewers found that the key, with
the functions and special features it provides, was able to provide a valuable tool for
diagnosis.
Table 1. Matrix used for sweetpotato key field testing in the Philippines.
Criteria
Indicator
Methodology
Technical
accuracy
Software performance
Technical content
The key and other features of the CD
were reviewed by experts based on
guidelines provided.
Relevance
Usefulness of the key and
the information contained
in the CD to the users.
The use of the key were monitored
for a whole cropping season under
different testing/learning situations
such as:
• field/ office
• training
• classroom
• Farmer Field Schools
• Library/resource context
A simple monitoring tool was
developed and used for each
situation.
Acceptability Ease of use of the key and
comprehensibility of
information
This was tested together with
relevance, in this case with the focus
on the ease of using the key and how
user friendly it is.
• Relevance
The key and other information contained in the CD are only relevant or useful if they
meet the requirements of the target users and the conditions in which they would use
the product. For this reason, Sweetpotato DiagNotes was developed in accordance
with user requirements and specifically focussed primarily on extension workers in
Asia. The general profile of these extension workers (e.g. computer literacy, technical
knowledge, knowledge of technical language and proficiency in the English language)
was considered in the design and the language used in the key. As well as providing
diagnostic support and training for farmers and advisors, Sweetpotato DiagNotes also
constitutes a useful learning tool for students and researchers in getting acquainted
with the crop.
Feedback from extension workers who field tested the Sweetpotato DiagNotes during
a two-day training in the Philippines and field testing in Indonesia and the Philippines
during the actual growing season indicated that some problems were particularly
difficult to diagnose and modifications were made to the key to address these issues.
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More generally, there is often apprehension about the relevance of computer-based
tools for rootcrop growers when the majority of users would not have access to
computers. Acquisition of computers, however, is a top priority among all local
government offices in the Philippines and other third world countries. They are also
becoming a necessity among households particularly with students and office
workers. In the near future this is unlikely to be an important constraint.
• Acceptability
The training and field testing sessions in the Philippines and Indonesia and some
feedback from Africa indicated strong support for Sweetpotato DiagNotes. The main
reasons for this appear to be the ease of use of the key, the use of non-technical words
in the key and fact sheets and the preference of target users for more image-based
rather than text-based materials. Extension workers said this tool would enable them
to diagnose crop problems quicker and to easily learn more about them. These
extension workers would like similar tools to be available for other crops, including
taro and yam.
DISCUSSION
The continuing change in production systems of tropical root crops such as
sweetpotato, taro and yam brought about by expanding markets aggravates or creates
pests, diseases and soil problems. There is an increasing need to educate extension
workers and farmers who are directly involved in production to enable them to cope
with these problems. One way to do this is to take advantage of the advances in
information and communication technology and develop interactive diagnostic
support and learning tools such as Sweetpotato DiagNotes and “RiceDoctor” – a
similar key that is being developed for rice growers, in association with Philrice and
the International Rice Research Institute. As shown for Sweetpotato DiagNotes, these
products, with user-friendly interactive diagnostic keys, fact sheets, notes and images,
make diagnosis and learning about the crop and its problems much quicker and easier
for extension staff. Such tools are particularly appropriate for the South Pacific,
where books and advice from experts are not readily available.
REFERENCE
Amante, V.dR.; Norton, G.A.; O’Sullivan, J.N.; van de Fliert, E. and Pardales, J. Jr.
(2003). Sweetpotato DiagNotes: A diagnostic key to sweetpotato problems.
CD-ROM produced by the Centre for Biological Information Technology,
The University of Queensland, Brisbane, Australia.
ACKNOWLEDGEMENTS
We wish to acknowledge the other authors of Sweetpotato DiagNotes – Jane
O’Sullivan, Elske van de Fliert and the late Jose Pardales, Jr. We thank Erlinda
Vasquez of PhilRootcrops, Elske van de Fliert of CIP-Bogor and James Okoth of
FAO-Uganda, for their effort and feedback during the field testing in the Philippines,
Indonesia and Africa respectively. Their involvement in the project has enabled this
paper to be written. We also wish to thank the Australian Centre for International
Agricultural Research (ACIAR) for the funds that made this project possible.
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