Education
| 1998 |
Ph.D.
(Ecology), University of California, Davis
Dissertation: Improving the competitive ability of water-seeded
rice: the influence of cultivar, density and the relative importance
of root and shoot competition. |
| 1992 |
M.S.
(Biology), San Diego State University, San Diego
Thesis: The response of cordgrass (Spartina foliosa)
to soil amendments in a constructed marsh. |
| 1990 |
B.S.
(Biology and English), Indiana University, Bloomington, Indiana
Honors project: The impact of clearcutting in the Hoosier
National Forest on migratory songbirds. |
Research
Interests
General
description: The principal tenet of integrated weed management
is that, by presenting weeds with a more complex pattern of management
practices, weed populations can be decreased, resistance to management
tactics delayed and herbicide inputs reduced. The complexity of integrated
weed management systems requires that work be conducted from a whole-systems
perspective. However most research conducted on weed management occurs
at organizational levels below that of whole-systems and so is often
of limited value to farmers and resource managers interested in adopting
new approaches to weed management. The primary goal of my research
program is to develop a better understanding of the relationships between
management systems and the distribution and abundance of weed species
within agricultural and forest ecosystems. We have ongoing collaborative
projects in four main areas: 1) weed management systems in tomato,
2) biology and management of glyphosate-resistant horseweed site-specific
weed management, 3) the susceptibility of forests to plant invasion
and 4) the use of remote sensing to explore relationships between the
spatial distribution of weeds and management systems. In addition to
these major projects, we also have projects addressing garlic mustard
population dynamics, and the role of seed predation in tomato cropping
systems. Each project is discussed below.
Weed
management systems in tomato: Weed management is a critical
component of tomato crop production and most growers rely heavily
on chemical applications
for weed control in vegetables. Recently, concerns about human and ecosystem
health, as well as economic constraints in the development, registration and
re-registration of herbicides for minor acreage crops, have limited the availability
of effective herbicides for vegetable cropping systems. The adoption of effective
multi-option integrated weed management systems by farmers is essential to
the sustainability of tomato production in the North Central
region. However, farmers
are unlikely to alter current practices without a clear understanding of how
adopting an alternative management system might affect weed communities and
their ability to control problematic weed species. David
Hillger,
a doctoral student,
joined our research team in spring 2003. Dave is working to 1) quantify the
relationships between weed management systems and weed communities
with particular regard to
problematic weed species and 2) use this information to develop a paper and
web-based extension manual that discusses the relative advantages
and limitations of various
weed management systems in vegetable crops. We are using on-farm sampling and
detailed questionnaires to determine the effect of conventional and alternative
weed management systems on weed communities and weed control. This information
will be used to develop a paper and web-based extension manual that will be
unique in its emphasis on delineating weed management options
within the context of
conventional and alternative vegetable crop production systems. (click
to see Dave's poster).
Biology and management of glyphosate-resistant horseweed (Conyza canadensis):
Glyphosate-resistant horseweed, also known as marestail, is now widespread
in southern Indiana, Kentucky and Ohio and poses a serious threat to the sustainable
use of glyphosate-tolerant soybean in the North Central region. We are currently
working on a multi-state, multi-investigator project to assess the biology
of
this weed, to map areas at risk for resistance, to determine the economic impact
of glyphosate-resistant horseweed, and to develop viable alternative management
practices to limit the effect of horseweed on soybean production. My responsibilities
include conducting research on the fitness of resistant and susceptible biotypes,
on horseweed population dynamics, including its germination ecology and co-supervising
the identification of risk zones for Indiana.
Susceptibility of forests to plant invasion: Eastern deciduous forests are
undergoing an invasion of non-native plant species that threatens species biodiversity
and
ecosystem functions. There is some evidence that old-growth stands are less
susceptible to invasion than more recently disturbed stands. Jeremy Weber joined
our lab
in summer 2003 and has begun work to evaluate the relationship between forest
invasibility and a number of factors including stand age and isolation (degree
of patchiness). This research will improve our understanding of plant invasions
and will contribute to efforts to manage plant invasions at the landscape level.
Remote sensing: We have two major ongoing remote sensing projects. In the first
project, Rich Dirks, a Research Associate, is developing a tractor-mounted
mechanical vision system in which a Patchen weed-seeker, digital imagery and
GPS equipment
will be used to provide highly accurate, detailed maps of weed populations
in agronomic fields. The ultimate goal of this project is to combine weed maps
with
other precision technologies to evaluate the relationship between environmental
variables and weed species spatial distribution. (click
to see Rich's presentations).
In the second project, we are collaborating with Dr. Bill
Johnson to determine
the effect of weed removal and N application timing on weed growth and herbicide-resistant
corn yields. Environmental concerns associated with N fertilizer and soil-applied
herbicides are likely to limit their use in the future and growers will increasingly
adopt post-emergence management strategies. However, weed-corn competition
for N can occur early in the season and weed accumulation of N may suppress
corn
yields. We seek to use digital imagery acquired through remote sensing to determine
weed densities and to assess N stress in corn. If successful, this information
could be used to provide farmers with data necessary to make more informed
decisions regarding fertilizer and herbicide applications.
Garlic mustard population dynamics: Garlic mustard, (Alliaria petiolata), a
non-native biennial herb that displaces native species, particularly spring
ephemerals,
has become widespread in eastern deciduous forests of the United States. Efforts
to limit the spread of this invasive weed through conventional weed management
practices have been largely unsuccessful. The development of alternative practices
is clearly needed but will require a greater understanding of the processes
and factors facilitating or limiting garlic mustard survival and dispersal.
We initiated
a project to determine the relationship between abiotic factors and the survival
of garlic mustard cohorts in pine and oak forests in Purdue University’s
Martel Forest in 2002. An additional experiment designed to test the effect of
soil moisture availability on garlic mustard survival was initiated in 2003.
Seedbank dynamics in alternative vegetable cropping systems: Annual weeds are
the most costly and difficult pest problems for vegetable growers to manage
in the North Central region. Current weed management systems rely on the extensive
use of tillage and prophylactic herbicide applications that contribute to soil
erosion and pollute the environment. We are collaborating with Dr. Steve
Weller on an experiment initiated in 2001 to assess the effect of rye cover crop systems
with weed management strategies based on economic thresholds on weed control
and weed communities. Specific objectives are to: 1) determine the effect of
threshold and no-seed management practices on weed seed bank levels; 2) examine
the effect of soil management systems on seed predation and weed seed survival;
and 3) develop a weed management system for tomatoes that effectively reduced
weed occurrence and the soil seed bank population.
Teaching
BTNY
304 Introduction to Weed Science. The objectives of this course are
for students to 1) gain an understanding to the biological and ecological
factors affecting the distribution, abundance, persistence and dynamics
of weed species and populations, 2) become familiar with principles
of weed control strategies used in crop and non-crop systems, 3)
become familiar with the principles of herbicide classification,
application technologies and mode of action and 4) be able to identify
weeds of the Midwest.
BTNY
302 Plant Ecology. The primary objective of the course is
to introduce students to the subject of plant ecology. Through
labs and
lectures, students gain an in-depth understanding of ecological concepts
regarding the occurrence and distribution of plant species and populations.
The course is also designed to provide students with insight into
the application of ecological concepts to the conservation
and management
of plants. Lectures focused sequentially on 1) the interaction of
plants with their physical environment, 2) population and community
ecology,
3) ecosystem properties and 4) case studies. Offered in Spring semester
of alternate years.
Topics
in Plant Science. The 1 credit hour course was designed
to provide students with a more extensive background in weed
species
identification,
herbicide symptomology, calibration and problem-solving. Participants
are encouraged to compete in the annual North Central Weed Science
contest.
BTNY
390C Biodiversity in Natural and Agricultural Systems in the
Tropics.
This intensive course is designed to familiarize students with
emerging
issues in
tropical
biodiversity,
agriculture and agroforestry. The course is expressly interdisciplinary
and will integrate material from forestry, horticulture, entomology,
plant pathology, weed science, ecology, and agronomy. Specific
course objectives include: 1) exposing students to life in
Costa Rica, cultivating
an appreciation for tropical ecosystems and agriculture, 2) promoting
an awareness of connections between farmers, consumers and foreign
policy in the US and farming systems in the tropics, 3) seeing
how biodiversity issues are integrated into tropical agriculture
and
4) developing an appreciation for the goals and practices of sustainable
agriculture in the tropics relative to the US. Students will attend
lectures at Purdue during Spring semester and participate in a
2 week
tour of Costa Rican ecosystems. Offered in Maymester in alternate
years.
Assistantships
and Positions
Research
Graduate Assistantships:
Openings for assistantships in my program will not be available until 2006. Please follow these links for general information on graduate
programs or employment announcements.
Peer-Reviewed
Publications
Gibson,
K. D., A. J. Fischer and T. C. Foin. In press. Compensatory responses
of late watergrass (Echinochloa phyllopogon) and rice to resource
limitations. Weed Res.
Gibson,
K.D. and A.J. Fischer. In press. Competitiveness of rice
cultivars as a tool for crop-based weed management. Chapter
25. In: Inderjit
(ed) Weed Management in Agroecosystems, Kluwer Press.
Gibson,
K. D., A. J. Fischer, T. C. Foin and J. E. Hill. 2003.
Crop traits related to weed suppression in water-seeded rice.
Weed Sci.
51:87-93.
Gibson,
K.D., A.J. Fischer, T.C. Foin and J.E. Hill. 2002. Implications
of delayed Echinochloa germination and duration of competition
for integrated weed management in water-seeded rice. Weed
Research 42:351-358.
Fischer, A. J., K.D. Gibson and A. Merotto, Jr. 2002. Cultivares
de Arroz Competitivos con Malezas [Weed competitive Rice cultivars].
Proceedings of the XXIII Brazilian
Weed Science Congress, July 29-Aug.1, Gramado, State of Rio Grande do Sul,
Brazil. 7 pp.
Fischer,
A.J, M. Chatel and K.D. Gibson. 2001. Competitiveness of upland
rice cultivars against Brachiaria brizantha and B. decumbens. Agronomy Journal 93:967-973.
Gibson,
K.D. and A.J. Fischer. 2001. The relative growth and photosynthetic
response of water-seeded rice and E. oryzoides to shade. International
J. Pesticide Science. 47:305-309.
Gibson,
K. D., J. L. Breen, J. E. Hill, T. C. Foin, and B. P. Caton. 2001.
Sagittaria montevidensis is a weak competitor in water-seeded
rice. Weed Science 49:381-384.
Caton,
B.P., A.M. Mortimer, T.C. Foin, J.E. Hill, K.D. Gibson, and A.J.
Fischer. 2001. Weed morphology effects on competitiveness for light
in direct-seeded rice. Weed Research 41:155-163.
Gibson,
K. D., A.J. Fischer, and T. C. Foin. 2001. Shading and the growth
and photosynthetic responses of Ammannia coccinnea. Weed Research
41:59-67.
Gibson,
K. D., J. E. Hill, T. C. Foin, B. P. Caton, and A. J. Fischer. 2001.
Water-seeded rice cultivars differ in ability to interfere with watergrass.
Agronomy Journal 93:326-332.
Gibson,
K. D., T. C. Foin, J. E. Hill. 1999. The relative importance of
root and shoot competition between water-seeded rice and watergrass.
Weed Research 39:181-190.
Caton,
B. P., T. C. Foin, K. D. Gibson, and J. E. Hill. 1998. A temperature-based
model of direct-, water-seeded rice (Oryza sativa) stand establishment
in California. Agricultural and Forest Meteorology 90:91B102.
Gibson,
K. D., J. B. Zedler. 1994. Limited response of cordgrass (Spartina
foliosa) to soil amendment in a constructed marsh. Ecological
Applications 4:757-767.
|
Faculty 