| Smiley,
R.W., and Patterson, L.-M. 1996. Pathogenic fungi associated with
Fusarium foot rot of winter wheat in the semiarid Pacific Northwest
USA. Plant Disease 80:944-949.
ABSTRACT
Winter
wheat plants and soil were collected from 288 non-irrigated fields
in the semiarid Pacific Northwest (PNW) during 1993 and 1994.
Fungi associated with 5,390 crown and subcrown internodes from
10 Oregon and nine Washington counties were identified. Fusarium
graminearum Group 1 was most widespread and the dominant
pathogen associated with a crown and root rot named Fusarium foot
rot or dryland root rot. F. culmorum was widely distributed
in soil but was detected in plants in only half as many locations
as F. graminearum. Other pathogens included Bipolaris
sorokiniana, Microdochium nivale and F. avenaceum.
Highly variable isolation frequencies for all five pathogens was
presumed related to a very dry and a very wet survey year. Each
pathogen was considered dominant or co-dominant at one or more
sites during one or more years. All five species and F. acuminatum
and F. oxysporum included isolates capable of
killing wheat seedlings in the greenhouse.
[Note:
Fusarium pseudograminearum is the currently accepted name
for the fungus discussed in this abstract as either "F.
graminearum Group 1" or "F. graminearum"
]
Paulitz,
T.C., R.W. Smiley, and R.J. Cook. 2002. Insights into the prevalence
and management of soilborne cereal pathogens under direct seeding
in the Pacific Northwest, USA. Canadian Journal of Plant Pathology
24:416-428.
ABSTRACT
Direct
seeding or no-till leaves the soil undisturbed, except where the
seed is planted and the soil fertilized. It offers several advantages
in small-grain cereal production, including reduction in labor
and other operating costs, reduction in soil erosion, and improvement
of soil quality. However, only about 10% of small grains in the
U.S.A., and 6% of the small grains in the Pacific Northwest region
of the U.S.A. are currently direct seeded. Root diseases are major
constraints to adoption of direct seeding; they increase because
of lack of tillage, increased crop residue left on the surface,
and typically cooler and wetter soil conditions in the spring.
This review covers some recent research on the four most important
root diseases of cereals in the Pacific Northwest and their causal
agents. These diseases are rhizoctonia root rot and bare patch
[Rhizoctonia solani AG-8, Rhizoctonia oryzae],
pythium damping-off and root rot [Pythium spp.], take-all
[Gaeumannomyces graminis var. tritici], and
fusarium foot rot [Fusarium pseudograminearum and Fusarium
culmorum]. We discuss how these diseases are affected by
direct seeding and the impact of management strategies, including
crop rotation, residue management, control of inoculum from volunteers
and weeds, fertilizer placement, genetic tolerance, biological
control, development of natural suppressiveness, and prediction
of risk through DNA-based detection methods.
Smiley,
R.W., J.A. Gourlie, R.G. Whittaker, S.A. Easley, and K.K. Kidwell.
2004. Economic impact of Hessian fly (Diptera: Cecidomyiidae)
on spring wheat in Oregon and additive yield losses with Fusarium
crown rot and lesion nematode. Journal of Economic Entomology
97:397-408.
ABSTRACT
Damage
caused by Hessian fly, Mayetiola destructor (Say), was
quantified in spring wheat, Triticum aestivum L., trials
near Pendleton and Moro, OR, during 2001 and 2002. Five field
experiments were established to examine genetic resistance to
Fusarium crown rot, Fusarium pseudograminearum (O'Donnell
& Aoki), and economic damage by lesion nematodes, Pratylenchus
neglectus ((Rensch, 1924) Filipjev Schuurmanns & Stekhoven,
1941) and P. thornei (Sher & Allen, 1941). Hessian
fly became the dominant factor affecting grain yield in four experiments.
Genotypes carrying the H3-resistance gene had grain yields 66%
and 68% higher than susceptible genotypes in cultivar trials during
2001 and 2002, respectively. Yield reductions were detected when
Hessian fly infestation rates exceeded 50% plants during 2001
and 15% plants (8% tillers) during 2002. In two trials during
2001, in-furrow application of aldicarb (Temik) at planting improved
yields of four Hessian fly-susceptible cultivars by 72% and 144%
(up to 1,959 kg/ha) and yields of one Hessian fly-resistant cultivar
by 2% and 3%. Resistant cultivars and aldicarb improved grain
quality as much as two market grades during 2001. The value of
increased grain production with Hessian fly-resistant cultivars
in four field experiments ranged from $112 to $252/ha, excluding
price incentives for improved market quality. Yield reduction
due to combined damage from Hessian fly and either Fusarium crown
rot or lesion nematode was additive. This report seams to be the
first quantitative yield loss estimate for Hessian fly in spring
wheat in the semiarid environment of the inland Pacific Northwest.
Smiley,
R.W., H.P. Collins, and P.E. Rasmussen. 1996. Diseases of wheat
in long-term agronomic experiments at Pendleton, Oregon. Plant
Disease 80:813-820.
ABSTRACT
Diseases
of winter wheat were evaluated over 3 years in four long-term
(27- to 60-year) cropping system experiments. Disease incidence
and severity were evaluated with respect to seasonal precipitation
and soil chemical and microbiological parameters. Take-all and
eyespot were associated with increasing precipitation, and Rhizoctonia
root rot and Fusarium crown rot were favored by drought. Eyespot
and crown rot increased with rate of applied nitrogen and were
inversely proportional to soil pH. Surface residue from previous
crops had variable effects on diseases. Crown rot increased with
amount of surface residue and was directly correlated with soil
organic nitrogen and carbon. Surface residue also had a variable
effect on Rhizoctonia root rot, depending on magnitude of soil
microbial respiration; root rot increased directly with amount
of residue in a wheat-summer fallow rotation and was unaffected
by residue and/or tillage in a wheat-pea rotation. Repeated burning
of wheat stubble caused variable disease response, depending on
precipitation and nitrogen rate. At high fertility, burning suppressed
Pythium root rot and Rhizoctonia root rot, and enhanced eyespot
and take-all. Effects of crop rotations on diseases appeared related
to soil microflora effects on pathogen survival or virulence.
Rhizoctonia root rot was most damaging in wheat-fallow rotation,
Pythium root rot in wheat-fallow and annual wheat, and eyespot
and crown rot in annual wheat. Diseases were collectively least
prevalent where nitrogen in a wheat-fallow rotation was applied
as pea vines or manure, rather than as inorganic fertilizer. Diseases
also were generally less damaging in a wheat-pea rotation than
in annual wheat or wheat-fallow rotation. Soilborne plant pathogenic
fungi appeared to suppress wheat yield by 3 to 12%. Long-term
experiments provided insights to crop management and seasonal
effects that are unlikely to be identified in short-term experiments.
Smiley,
R.W., J.A. Gourlie, S.A. Easley, L.-M. Patterson, and R.G. Whittaker.
2005. Crop damage estimates for crown rot of wheat and barley
in the Pacific Northwest. Plant Disease 89:595-604.
ABSTRACT
Crown
rot of wheat and barley in the Pacific Northwest is caused by
a complex of Fusarium pseudograminearum, F. culmorum
and Bipolaris sorokiniana. Yield-loss estimates
were made by evaluating yield components on tillers collected
from commercial fields and sorted by disease severity classes,
and by comparing yields for field plots inoculated with F.
pseudograminearum with yields in naturally infested soil.
Increasing crown rot severity caused an increase in grain protein
content and reduction in grain yield, kernels per head, kernel
weight, test weight, tiller height, and straw weight. Crown rot
reduced winter wheat yield as much as 1,550 kg/ha (35%, $219/ha)
in commercial fields, with a 13-field mean of 9.5% ($51/ha). Inoculation
reduced yields as much as 2,630 kg/ha (61%, $372/ha) over that
caused by the native pathogen flora. Rain-induced crusting of
the soil surface greatly amplified pre-emergence damping-off caused
by F. pseudograminearum. Crown rot caused greatest losses
during seasons of lowest precipitation but also damaged crops
under wet conditions. Above-ground symptoms were not always apparent
under conditions of moderate infection and yield constraint. Damage
from crown rot in the Pacific Northwest is more widespread and
damaging than previously recognized.
Smiley,
R.W., J.A. Gourlie,
S.A. Easley, and L.-M. Patterson.
2005. Pathogenicity of fungi associated with the wheat crown rot
complex in Oregon and Washington. Plant Disease 89:949-957.
ABSTRACT
Crown
rot of wheat in the Pacific Northwest is caused by a complex including
Bipolaris sorokiniana, Fusarium avenaceum, F. culmorum,
F. pseudograminearum and Microdochium nivale. Relative
pathogenicity was examined under greenhouse conditions for 178
isolates of the five species, and under field conditions for 24
isolates of B. sorokiniana, F. culmorum and
F. pseudograminearum. In the greenhouse, all five species
reduced (P < 0.05) plant height relative to noninoculated
controls. Disease severity was inversely correlated with plant
height for the three Fusarium species. In one or more
of four experiments with spring wheat in the field, all three
species reduced stand establishment and density of mature heads,
and increased the incidence and severity of crown rot. Fusarium
culmorum and F. pseudograminearum caused the greatest
disease severity and plant damage and were the only pathogens
that reduced grain yield. Virulence ratings were variable among
isolates for each species in all greenhouse and field experiments.
Isolate variability was especially high for the location and year
variables in field experiments. Mixtures of multiple isolates
are required for future research.
Smiley,
R., M. Siemens, T. Gohlke, and J. Poore. 2005. Small Grain Acreage
and Management Trends for Eastern Oregon and Washington. Oregon
Agric. Exp. Sta. Spec. Pub. 1061:30-50.
ABSTRACT
Small
grain acreage and management trends over the past 20 years were
evaluated for counties and regions in eastern Oregon and Washington.
Data were obtained from surveys conducted by the Conservation
Technology Information Center (CTIC) and National Agricultural
Statistics Service (NASS). Small grain acreages of dryland and
irrigated winter wheat, spring wheat, and barley are reported
as a percent of the total acreage in each region of each state.
Also reported are trends for tillage practices, cropping frequency,
and timing in terms of percent of total acreage. Winter wheat
acreage has remained relatively constant over the last 20 years
for most regions and comprised over 60 percent of the nearly 3.5
million acres planted to small grains in eastern Oregon and Washington.
Acreage planted to barley has generally declined by 5 percent,
with production shifting to spring wheat. Use of intensive tillage
has decreased by over 50 percent in most regions, with production
shifting to reduced tillage and no-till. No-till acreage for all
wheat in Oregon increased from 1 percent in 1996 to 17 percent
in 2004 and from 3 percent to 13 percent in Washington. For spring
wheat, no-till acreage increased from 2 to 21 percent in Oregon
and from 2 to 18 percent in Washington.
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