Education
Ph.D., University of California, Riverside, Plant Pathology, 1998
M.S., University of Göttingen, Germany, Agricultural Sciences,
1993
Research
Interests
Soil-borne plant pathogens and pests persist in a myriad of interactions
in the soil environment. Management of these yield-reducing organisms
is highly dependent upon a thorough understanding of their ecology.
Our program has set out to study these interactions as they
relate to the soybean cyst nematode, to sudden death syndrome of
soybean (SDS), root knot nematodes in watermelon, and an unidentified
soil-borne disease of watermelon.
Soybean
cyst nematode
The soybean cyst nematode, Heterodera glycines, is one of
the major yield-reducing agents in soybean throughout the US. Although
efforts for resistance
breeding have been ongoing for many years, the management of the nematode
remains challenging because it occurs in populations that can overcome
specific sources of resistance. This makes management of the nematode
challenging. Virulence patterns of the nematode are laborious to determine
and probably too costly to be conducted for every field under soybean
production. Integrated management of this nematode problem includes
the use of crop rotation and of natural population density regulation.
Cases
of specific soil suppressivenes of other cyst nematodes have been studied,
and the hope remains that certain agronomic inputs will support the
development of soil suppressiveness against this obligate parasite.
In various areas,
the shift to no-tillage practices has been beneficial in reducing soybean
cyst nematode reproduction. Similar observations have been made in
long-term tillage plots at Purdue University. The aim of Westphal's
program is
to determine whether specific soil suppressiveness similar to the one
found in related cyst nematodes is present in soybean cyst nematode
and to investigate if the reduced population densities under no-tillage
are
based on biological phenomena. This work is done in collaboration with
Virginia Ferris, Tony Vyn, and Terry West.
Sudden death syndrome of soybean (SDS)
This fungal disease of soybean is causing major damage to soybean in
the North Central Region. The disease has been damaging for several
years and still is increasing. SDS is characterized by its sporadic
occurrence
and unpredictable pattern. While the causal organism has been known
for some time, conditions that favor infection in the greenhouse and
in the
field have not been fully described. Westphal's program investigates
the interaction of the fungus with other soil-borne organisms. In particular,
the interaction of the fungus with the soybean cyst nematode appears
to be of major importance together with the effects of high moisture
content during early reproductive stages. Due to the difficulties with
predicting SDS development in field hot spots, the development of currently
used inoculation methods are refined. This work is done in close
collaboration with Scott Abney and Ellsworth Christmas.
Root knot nematodes on Watermelon and other crops in south Indiana
Southern Indiana growers take advantage of light soils for growing
vegetable crops. In Knox and adjacent counties, sandy soils permit
earlier warming
soils than other areas of Indiana. This benefit comes with the risk
of plant-parasitic nematodes that infect vegetable and field crops.
These
nematodes thrive in sandy soils and interfere with plant growth.
Unfortunately, crop sequences in southern Indiana depend almost exclusively
on host
crops of the nematode. Westphal confirmed that root knot nematodes
infect soybean and corn, rotational crops for watermelon in southern
Indiana.
He incorporates information on plant-parasitic nematodes into Extension
activities.
Additional research includes efforts to identify resistant soybean
cultivars to replace currently used susceptible ones. Westphal works
with Dan S.
Egel on these watermelon problems and with Allen LeRoy on the soybean
question.
Mature
watermelon vine decline
A number of late-season wilts or vine declines threaten the profitable
production of the high-value commodity watermelon throughout production
areas of the US and worldwide. While the etiologies of several root
rots and vine declines are well established, a new late-season disorder
of
watermelon, mature watermelon vine decline (MWVD) of yet unknown
etiology, has been observed in Indiana. In MWVD typically at the
end of the season,
watermelon vines collapse and wilt rapidly. At that time, exposing
mature watermelon fruit to sun results in sunburn of the fruit. The
direct yield
reduction is accompanied by a quality reduction in diminished sugar
content and decreased fruit surface quality. In preliminary tests,
the biological
nature of MWVD was demonstrated, since biocide treatments remove
MWVD from soil (Fig. 1).
Figure 1. Watermelon plants in MWVD soil: (1) Non-treated soil
(3) Methyl bromide-fumigated at 390 kg/ha.
Note the copious canopy increase
after soil fumigation.
Our program is made possible by the dedicated work and commitment
of our postdoctoral researcher Lijuan Xing, our technician
Farah Heraux and the undergraduate students Reuben Pillsbury and Dragan
Muvceski.
A number of graduate students will join the program shortly.
Assistantships
and Positions
A research
assistantship is available in the soil-borne disease program of Dr.
Andreas Westphal. The project of the highly motivated M.Sc. or Ph.D.
student will focus on the etiology of a late season vine decline of
watermelon for which the name 'Mature Watermelon Vine Decline' has been
coined. This disorder has been observed in Southern Indiana. The student
will be stationed at the West Lafayette campus. The project is a combination
of field, greenhouse and laboratory parts. Excellent facilities for
the field part of the project are in place at the South West Purdue
Agricultural Center (SWPAC) at Vincennes, IN. Please contact Andreas
Westphal for further information (765-496-2170; westphal@purdue.edu).
Please
contact me directly for information on assistantships and openings
in my program. Follow these links for general information on graduate
programs or employment announcements.
Selected
Publications
Xing, L.-J., and A.
Westphal. 2006. Interaction of Fusarium
solani f. sp. glycines and Heterodera glycines in
sudden death syndrome of soybean. Phytopathology: In Press.
Xing, L.-J., and A.
Westphal. 2005. A method for field
infestation with Meloidogyne incognita. Journal of Nematology
37:In Press
Creech, J. E., W.G. Johnson, J. Faghihi, V. Ferris and
A. Westphal 2005. First report of soybean cyst nematode reproduction
on purple deadnettle under field conditions. Crop Management doi:10.1094/CM-2005-0715-01-BR.
Robinson, A.F., R. Akridge, J.M. Bradford, C.G. Cook,
W.S. Gazaway, T.L. Kirkpatrick, G.W. Lawrence, G. Lee, E.C. McGawley,
C. Overstreet, B. Padgett, R. Rodriguez-Kabana, A. Westphal, and L.D.
Young. 2005. Vertical distribution of Rotylenchulus reniformis in
cotton fields. Journal of Nematology 37:265-271.
Robinson, A.F., C.G. Cook, A.
Westphal, and J.M. Bradford.
2005. Rotylenchulus reniformis below plow depth suppresses
cotton yield and root growth. Journal of Nematology 37:285-291.
Westphal,
A. 2005. Detection and description of soils
with specific nematode suppressiveness. Journal of Nematology 37:121-130.
Westphal,
A., and A.W. Scott. 2005. Implementation of
soybean in cotton cropping sequences for management of Rotylenchulus
reniformis in South Texas. Crop Science 45:233-239.
Westphal,
A., A.F. Robinson, A.W. Scott, Jr., and J.B.
Santini 2004. Depth distribution of Rotylenchulus reniformis under
crops of different host status and after fumigation. Nematology 6:97-107.
Westphal,
A., and T.E. Mirkov 2003. Need for improved
detection of ratoon stunting disease in sugarcane in South Texas. Subtropical
Plant Science 55:68-71.
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