GrainGenes
A Database for Triticeae and Avena
ITEMS FROM THE UNITED STATES
MINNESOTA
CEREAL DISEASE LABORATORY
(formerly CEREAL RUST LABORATORY)USDA-ARS, University of Minnesota, 1551 Lindig, St. Paul, MN 55108, USA.
D.L. Long, J.A. Kolmer, Y. Jin, M.E. Hughes, and L.A. Wanschura.
Wheat rusts in the United States in 2005.
[p.169-181]
Wheat stem rust (Puccinia graminis f. sp. tritici). The first reports of wheat stem rust were in late April, when trace levels of infection were found in plots of susceptible wheat at Giddings in central Texas. The next report of wheat stem rust was in late May, in plots of susceptible wheat at Castroville in south Texas that had high severity levels.
In early July, susceptible winter wheat plots had trace to 10 % severities at the soft dough stage in east central Minnesota. In mid-July, trace levels of stem rust were found on the susceptible spring wheat cultivar Baart in south central Minnesota and in an east central South Dakota plot of the susceptible cultivar Morocco. In late July, wheat stem rust was found in plots of Baart at Crookston in northwestern Minnesota. Stem rust was not found on any of the commonly grown cultivars in the spring wheat region. All current spring wheat cultivars grown in the region are resistant to the predominant stem rust race.
Stem rust on barberry. Aecial infections on common barberry in southeastern Minnesota in 2005 were heavy, similar to the level of infections in 2003 and 2004. Light aecial infections were found on barberry in Wisconsin. Aecial infections from Minnesota and Wisconsin were mostly due to P. graminis f. sp. secalis (the form attaching rye) as P. graminis f. sp. tritici (the form attacking wheat) or P. graminis f. sp. avenae (attacking oats) was not identified from the barberry samples. Common barberry plants with aecial infections were also found in the state of New York, but isolates did not infect wheat, rye or oat.
Virulence of wheat stem rust. Relatively few collections of wheat stem rust were made in 2005 due to the rarity of stem rust infections, which may indicate that many of the winter and spring wheat cultivars possess effective resistance to the predominant race. Race QFCS was the predominant race, identified on 21 of the 24 collections. One collection from Texas was race TTTT. Race QCCS, previously identified from collections in Washington, was found in Idaho (Table 1).
| State | Number of * | **Percentage of isolates of Pgt- race ** | |||
|---|---|---|---|---|---|
| Collections | Isolates | QCCS | QFCS | TTTT | |
| TX | 10 | 10 | 9 | 1 | |
| SD | 1 | 1 | 1 | ||
| MN | 11 | 11 | 11 | ||
| ID | 2 | 2 | 2 | ||
| U.S. Total | 24 | 24 | 2 | 21 | 1 |
|
|||||
Wheat leaf rust (Puccinia triticina). Southern Plains. In late January, leaf rust infections were found in central Texas plots. The most severe rust was reported on the cultivars TAM 110 and Cutter. Warm temperatures and wet weather in February allowed for good leaf rust development. In mid-February, cultivars such as Jagger in southern and central Texas varietal plots had 80 % severities. By late February, leaf rust was widespread across central Texas in fields of cultivars Coronado, Cutter, and Jagalene. Some of the fields in central Texas were sprayed for rust control (Figure 1). In early March, leaf rust was increasing rapidly in south Texas plots at Castroville, and cultivars like Cutter, Jagalene, and TAM 107 had 40-60 % severity ratings. Thunderbolt, Overley, both with Lr41, had little rust. In early March, leaf rust was at high severity levels in a nursery at McGregor in central Texas. At the same location, plots of Cutter that were planted in early September had completely brown leaves due to leaf rust. In mid-March leaf rust was the major disease of wheat in central Texas. Temperatures and rain were ideal for leaf rust development throughout Texas in March.
In mid-January, leaf rust was found in southern Oklahoma and conditions were conducive for sporulation, spread and development of the disease. In mid-February pustules were observed on lower leaves of susceptible varieties, which indicated that leaf rust had survived the winter in much of Oklahoma. By the first week in March, pustules were observed in the wheat varietal plot at Stillwater, Oklahoma.
In late March in southern, central, and northern Texas, low to moderate levels of leaf rust infections were found in most commercial wheat fields. High severities (80 %) of leaf rust were observed on susceptible cultivars in nursery plots and trace-20 % severity levels were found in wheat fields. In late March, in southern Oklahoma, fields had high severity levels of leaf rust, but severity levels were much lower in north central Oklahoma.
In mid-April, leaf rust was found in the Great Plains from Texas to Nebraska (Figure 1). During the first week in April, leaf rust was found on the mid and upper canopy leaves of susceptible cultivars in central and southern Oklahoma. In early April, high levels of leaf rust were found in variety trails and fields in the panhandle of Oklahoma, which is unusual since low moisture conditions in this area usually are not conducive for rust to develop.
In late April, plots of susceptible wheat cultivars had leaf rust severities up to 80 % in the area from central Texas to the Florida panhandle. In late April in central Texas, susceptible cultivars had moderate to severe rust infections, while in northern Texas wheat at milk stage had light to moderate leaf rust infection (Figure 1). By the last week in April, 100 % leaf rust severities were observed on flag leaves of Ae. cylindrica (common goatgrass) growing in roadside ditches in north central Texas. In central Texas and east central Louisiana, fields that had been sprayed with fungicides had 40 % leaf rust severities. By late April, leaf rust was increasing throughout Oklahoma. Cultivars such as 2174, Jagger (Lr17), and Jagalene (Lr24) were heavily rusted and there was some yield reduction. During the second week in May, moderate levels of leaf rust were reported in central Texas and low levels in the Panhandle area (Figure 1). In north central Texas, stripe rust was more common at the boot and heading growth stages, but leaf rust was more prevalent at the dough stage.
In early May, plots and fields of susceptible wheat in Oklahoma had 60-90 % severities. In mid-May, flag leaves of Ae. cylindrica growing in roadside ditches in north central Oklahoma had 60 % leaf rust severities.
In mid-May, leaf rust in the southern Great Plains was not as severe as last year, because the cooler temperatures in late April and early May slowed leaf rust development.
Central Plains. In late March, over wintering leaf rust infections were observed on lower leaves in southern Nebraska. Leaf rust over wintered in Colorado throughout the eastern half of the state, but dry conditions in the spring slowed leaf rust development.
In mid-April, trace levels of leaf rust were found across south central to southwest Kansas. In mid-May, plots and fields of susceptible wheat in south central Kansas had 40 % severities while in central Kansas fields 5 % severities were observed. In south central Kansas wheat plots, 40 % rust severities were observed on Jagger, Jagalene, Cutter, and Karl 92 cultivars. No leaf rust was observed on Overley, Deliver, and Santa Fe. In late May, leaf rust was found on susceptible cultivars in fields in northern Kansas. Hot dry weather slowed the rust development in Kansas and Oklahoma in late May. A two percent loss due to wheat leaf rust was estimated for Kansas in 2005 (Table 4).
In early June, traces of leaf rust were found in wheat fields in southern Nebraska. In mid-June wheat leaf rust was found in winter wheat fields from southern Nebraska to North Dakota (Figure 1). Rust severities on flag leaves in fields ranged from 20 % in Nebraska to trace levels in North Dakota fields. In late June, susceptible winter cultivars such as Jagalene in western Nebraska had 60 % rust severities.
Northern Plains. On 11 May, leaf rust infections that had over wintered were found on the lowest leaves of winter wheat plants of the susceptible cultivar Cheyenne at the Rosemount Experiment Station in east central Minnesota. In early June, leaf rust was increasing in winter wheat in southern Minnesota; susceptible cultivars had severities of 20-60 % on lower leaves and 5-10 % on flag leaves. The spring wheat crop had trace to 10 % levels of leaf rust infections on lower leaves. In early June, rain and warm temperatures were ideal for the increase and spread of leaf rust in the north central region.
Trace amounts of leaf rust were found on winter wheat lines in plots at Brookings in east central South Dakota in early June. Trace levels of leaf rust infections were also found in spring wheat in the Red River Valley of Minnesota in early June.
In late June in susceptible winter cultivars such as Jagalene, in east central Minnesota and central South Dakota had 60 % rust severities, but the resistant cultivars had only trace levels of infections on the flag leaves (Figure 1). In late June, susceptible spring wheat cultivars in southern Minnesota plots had 60 % rust severities with most infections on the lower leaves.
In early July, flag leaves of winter wheat in southeastern North Dakota fields had leaf rust severities up to 90 %. In mid-July, flag leaves of spring wheat cultivars in fields from north central South Dakota to west central Minnesota had trace-60 % leaf rust severities. Many wheat fields were sprayed with fungicide to prevent losses due to rust and scab. In 2005, 2-4 % losses to wheat leaf rust were common in the northern spring wheat states (Table 4).
In mid July wheat leaf rust was widespread throughout North Dakota and northwest Minnesota. Susceptible spring wheat cultivars such as Oxen, Ingot, Hanna, and Reeder, had leaf rust severities of 60 % or greater in southeast and central North Dakota. The heavy leaf rust infections combined with high temperatures killed the flag leaves of these cultivars. Alsen, the most commonly grown cultivar in North Dakota, had good to moderate resistance to leaf rust, and the cultivars Knudson, Steele, and Glenn were highly resistant. Leaf rust was at lower levels in northeast North Dakota and northwest Minnesota, being mostly found on the lower leaves of susceptible cultivars. By the end of July susceptible wheat cultivars in northwest Minnesota had leaf rust severities of 80-100 %.
This year leaf rust was widespread in the upper Midwest in spring and winter wheat. Rust inoculum arrived from the south in mid-May through mid-June with rain showers. Many of the wheat fields in the spring wheat region were treated with fungicide, which prevented losses due to leaf and stripe rust. However, in unsprayed fields of susceptible cultivars leaf rust losses were significant.
Southeast. In late January, heavy leaf rust (> 5 %) was observed in varietal plots in a nursery at Baton Rouge. By mid-February, leaf rust was severe on susceptible cultivars throughout the state in plots and fields. Temperature and moisture conditions in February and March were ideal for rust development throughout the southern red winter wheat region.
In late February, leaf rust was severe in fields of susceptible varieties in southwest Arkansas and some fields were sprayed for rust control. By mid-March, leaf rust infections were more severe and widespread than usual in southwestern Arkansas. In late March, susceptible cultivars in Baton Rouge, Louisiana, plots had 50 % leaf rust severities. Some of the fields infected with rust were sprayed for rust control in the southeastern U.S.
In early April from central Louisiana through Alabama to Georgia, moderate levels of leaf rust infections were observed in research plots and fields. Susceptible cultivars in south central Louisiana and southern Alabama nurseries had up to 60% severities. In late April, southeastern Alabama varietal plots had 80 % leaf rust severities, whereas 100 miles to the north only trace amounts of leaf rust were observed on the same varieties. In late April in east central Arkansas plots of susceptible cultivars, trace levels of leaf rust were on lower leaves while upper leaves did not have any leaf rust. By late May, 100 % rust severities were reported in plots of susceptible cultivars in central and southwestern Georgia.
East. In late April, traces of leaf rust were found in nursery plots in eastern Virginia at Warsaw and in fields in northeastern North Carolina. During the second week in May, traces of leaf rust were found in fields in north central Tennessee. In late May, 15 % leaf rust severities were observed on flag leaves of Saluda and McCormick cultivars in northeastern North Carolina research plots. Soft red winter wheat cultivars in eastern Virginia in late May had trace to 90 % severities.
In early June, leaf rust severities were low across the state of Virginia. However, a severe leaf rust epidemic occurred in a nursery at Warsaw, Virginia with multiple races that had virulence to Lr24 and Lr26. Cultivars with Lr26, e.g., USG 3209 and Sisson, had high leaf rust severities.
In mid-June, trace levels of leaf rust were found in south central New York plots. In early July, light levels of wheat leaf rust were found in western New York.
Mideast. In early June, leaf rust was found in fields from southern Illinois at 20 % severity to trace levels on flag leaves in northwestern Ohio, northwestern Indiana, and south central Wisconsin. In much of the Ohio Valley and Wisconsin, dry conditions in May and June slowed rust development.
California. In late April, traces of leaf rust were detected in yield trials in the Central Valley of California. In mid-May, susceptible cultivars in the San Joaquin Valley nurseries in California had 60 to 100 % severities. In late May, 70 % leaf rust severities were observed in a field of the cultivar Blanca Grande in Kern County, California.
Pacific Northwest. In early June, low levels of leaf rust was found in winter wheat in south central Washington. In mid- June, wheat leaf rust was at high levels in nurseries near Mt. Vernon in northwestern Washington and was increasing in central Washington, mainly in seed-production fields under irrigation. In early July, low levels of wheat leaf rust were found in southwestern Idaho and east central Washington.
Mexico. In the second week in March, leaf rust was present in low amounts on durum wheat and bread wheat throughout the Yaqui Valley. Plots of Morocco had light (5 %) levels of leaf rust. Isolated areas of high leaf rust infection were found on durum wheat.
Wheat leaf rust virulence. In 2005, 72 races of wheat leaf rust were found in the U.S. Races with virulence to Lr24 increased in frequency throughout all wheat growing regions of the U.S, except for Washington state (Table 2). Virulence to Lr24 was highest throughout the Great Plains region, where a number of winter wheat cultivars have Lr24. Races with virulence to Lr9 were found in all regions except for California and Washington State. Virulence to Lr9 was highest in Texas and Oklahoma. Virulence to Lr26 occurred in all regions of the U.S. and was highest in the northeast region. Virulence to Lr16 occurred in all regions except for the northeast and was highest in the spring wheat region of Minnesota and North and South Dakota. Virulence to Lr17 was found in all regions of the U.S., with the highest frequency in the Northeast region. Virulence to Lr18 occurred in all regions, except California and was highest in the southeast region where a number of SRWWs have this gene. Virulence to Lr21 was not found in any region, whereas virulence to Lr41 was found in all regions except the Ohio Valley and California. Virulence to Lr42 was found in all regions except California.
In the southeast, the most common race, TCRKG (10.8 %), had virulence to Lr2a, Lr26, and Lr18. In the Northeast, the most common race MCDSB (41.7 %) had virulence to Lr26 and Lr17. In the Ohio Valley, the most common race TDBGG (14.8 %) had virulence to Lr2a and Lr24. In Texas and Oklahoma, the most common race TDBGH (14.5 %) had virulence to Lr2a, Lr24, and Lr42. In Kansas and Nebraska, the most common race MCDSB (13.2 %) had virulence to Lr26 and Lr17. In Minnesota, South Dakota, and North Dakota, the most common race TJDGH (11.8 %) had virulence to Lr2a, Lr16, Lr24, Lr17, and Lr42. In California, the most common race MBDSB (35 %) had virulence to Lr17. In Washington state, the most common race MBJJG (50 %) had virulence to Lr11 and Lr17.
Since 2003, races that are avirulent to Lr14a and virulent to Lr1, Lr2a, Lr2c, Lr3, and Lr24 have increased in frequency throughout the U.S. Previous to the detection of these races, virulence to Lr14a had been near 100 % in all regions of the U.S. for over 20 years. These races also are unique since they are avirulent to a second, previously undetected, gene in the Thatcher line with Lr1. Some of these races are also virulent to Lr16, Lr17, and Lr26. Virulence to Lr41 was most common in races that were also virulent to Lr9 and Lr24. These races were found mostly in Texas and Oklahoma (Table 3).
Wheat stripe rust (Puccinia striiformis f.
sp. tritici).
Southern Plains. During the second week in February, low levels
of stripe rust were found scattered throughout the varietal plot
in central Texas at College Station. Weather conditions were ideal
for stripe rust development. In mid-February in south Texas at
Castroville, stripe rust was severe on susceptible cutlivars,
whereas more resistant cultivars had low levels of rust. In early
March, stripe rust was increasing rapidly and was widespread throughout
the nursery at Castroville (Figure
2). Most infections sites were on lower leaves, with a few
on the upper leaves. In south Texas fields were sprayed for rust
control.
In late March, wheat stripe rust infections were at low to moderate severities in wheat fields in southern and central Texas. Stripe rust severities ranged from trace levels to 80 % severity in plots. This year, stripe rust was found at more locations and the weather conditions were more favorable for rust development than last year in Texas. However, in late March, higher day and night temperatures had slowed stripe rust development in southern and central Texas plots and fields.
During the third week in March, moderate levels of stripe rust were found throughout southern Oklahoma.
In early April, stripe rust was reported from central Texas, Louisiana, and Arkansas to southern Alabama (Figure 2). In the first week of April, susceptible entries had severity levels of 100 % in stripe rust-monitoring and breeding nurseries throughout Louisiana and central Texas. In early April, in southern Oklahoma, fields of 2174 and OK 102 had severe stripe rust and were sprayed for rust.
In mid-April, stripe rust was increasing throughout the Texas Panhandle (Figure 2) and by late April most plots of susceptible cultivars had rust severities over 80 % on flag leaves. In north central and central Texas, stripe rust was most common in April but by mid-May the warmer temperatures had caused stripe rust development to cease.
In late April, stripe rust was at moderate to severe levels in north central Texas and Oklahoma plots and fields. On 30 April, in a wheat-breeding nursery at Lahoma, in north central Oklahoma, the cultivars Custer, OK101, and 2137 had 80 % stripe rust severities. In the same nursery, Jagger and Jagalene had trace to 5 % stripe rust severities. In late April, Jagger and Jagalene in north central Texas had 30-40 % stripe rust severities.
In Oklahoma by mid-May, dry and warm weather had slowed stripe rust development throughout the state. Stripe rust did cause yield reductions in much of the wheat producing areas of Oklahoma (Table 4).
This year, stripe rust infections in the southern U.S. were more severe and extensive than last year due to more initial inoculum sources of infection and cooler than normal temperatures in early spring.
Central Plains. In mid-April in Kansas, trace levels of stripe rust were found in south central and southwestern regions. In early May, a field of Jagger at heading stage in south central Kansas had 30-40 % stripe rust severity. This was among the first reports of increased stripe rust severity levels on Jagger, Jagalene, and Cutter. In mid-May, wheat stripe rust was prevalent in much of Kansas at varying degrees of severity. Stripe rust was most severe in the southern and western areas of the state. Resistant cultivars such as Overley, Cutter, and TAM 111 were still resistant. In some areas of Kansas, the more susceptible cultivars such as 2137, OK102, and Trego had high levels of stripe rust. In 2005, the estimated overall loss to wheat stripe rust in Kansas was 8.0 %, which relates to a 34 x 106 bushel loss (Table 4).
In mid-May, wheat stripe rust was severe in central Nebraska plots and light in east central Nebraska plots. In early June, stripe rust was widespread from northern Kansas and across Nebraska and many fields were sprayed to control the disease. In mid-June, susceptible cultivars in winter wheat plots and fields in the panhandle of Nebraska had 60 % rust severities, but hot temperatures at the end of June stopped further rust development.
Northern Plains. In late May, traces of wheat stripe rust were found in winter wheat plots in east central Minnesota and south central South Dakota. Infections were mostly on the lower leaves. In early June, stripe rust infections were found in east central Minnesota winter wheat plots on flag leaves. In early June, trace amounts of stripe rust were found in spring wheat fields throughout North Dakota and in spring wheat plots in south central Minnesota. Soft red winter cultivars with Yr9 stripe rust-resistance gene, which is on the T1B·1R wheat-rye translocation that also has Lr26/Sr31, had 80 % severities in plots in east central Minnesota in mid-June. By mid-June, stripe rust had passed peak development in southern Minnesota and slowed down due to warmer weather and host resistance the spring wheat cultivars.
In late June, very hot weather slowed or stopped stripe rust development throughout the northern Great Plains. In late June, stripe rust severity levels were up to 20 % in east central South Dakota spring wheat plots (Figure 2). Most of the commonly grown spring wheats have good resistance to stripe rust. In mid-July, hot temperatures stopped development of stripe rust on spring wheat in the far northern Great Plains.
Lower Mississippi Valley. In early February, severe levels of stripe rust was observed in some varietal plots at Baton Rouge. During the third week in February, fields were sprayed for stripe rust control in central Louisiana.
In early March, in southwestern Arkansas plots, susceptible wheat cultivars averaged 30 % rust severity, whereas other cultivars had 0 to 5 % severities. In late March, stripe rust was active in Louisiana and some fields were sprayed for rust control. In wheat plots in south central Louisiana, 80 % stripe rust severities were recorded. Higher day and night temperatures during the last week of March slowed stripe rust development. In late March, stripe rust was severe in fields throughout Arkansas and fungicide application was recommended.
In mid-April, wheat stripe rust severities of 100 % were observed on susceptible entries in nurseries in southwestern Arkansas. By the third week in April, stripe rust was found throughout Arkansas. In late April, wheat plots with 90 % severities were observed at Marianna (east central Arkansas) and cool temperatures were still favorable for infection, but insufficient moisture was limiting spread. In mid-May, stripe rust development had slowed in Arkansas.
East. In mid-March, stripe rust over wintering foci were observed in plots in south central Georgia. Stripe rust had expanded outward from the foci and many of the cultivars in the nursery were infected. In late April, plots of susceptible cultivars had trace-80 % severities in the panhandle of Florida, southwestern Georgia, and southern Alabama. By late April, stripe rust was reported as far north as southeastern Virginia.
In early May, wheat stripe rust was found across the Atlantic coastal plain from Georgia to Virginia. North central Tennessee wheat fields had 15 % stripe rust severities. In mid-May stripe rust was found on Virginia's Eastern Shore and significant stripe rust was found in border rows in nurseries in Painter, Virginia.
In late May, severe stripe rust was found in a field in Washington county in central coastal North Carolina.
In mid-June traces of stripe rust were found in plots in south central New York.
Mideast. In early June, low levels of wheat stripe rust was found in a plot of Becker (older cultivar) in plots at Wooster Ohio. This was only the fourth time in 25 years that stripe rust was seen in the plots at Wooster.
In early June, fields and plots from northwestern Missouri to east central Indiana had 60 % severities (Figure 2). Traces of wheat stripe rust were found in nurseries in northwestern Ohio and central Michigan in early June.
In early June, stripe rust foci with 10 % severity were found in winter wheat plots and fields in northern Indiana and south central Wisconsin. In much of the Ohio Valley and Wisconsin, dry and hot conditions in June slowed rust development.
California. Stripe rust on wheat was first detected on 25 February in the nursery at UC Davis in border rows of the highly susceptible variety D6301. On 11 March, trace levels of stripe rust were detected in the Sacramento Valley and in the Sacramento/San Joaquin Delta nursery. Severity levels and incidence were less than last year on the same date. In early April, susceptible entries in nurseries in the Davis area of the Sacramento Valley had 60 % stripe rust severities. Cool and wet weather in late April were ideal for stripe rust infection, but rust levels remained low to moderate on most of the wheat acreage (dominated by resistant cultivars Summit and Blanc Grande). In late April in the Central Valley, plots of susceptible cultivars had severe stripe rust and severe rust was found in the screening nursery at UC Davis. In early May, stripe rust was increasing in fields and nurseries in the Sacramento Valley.
Pacific Northwest. In early February, stripe rust was
found in experimental plots near Corvallis, Oregon. On 10 March,
susceptible checks in winter wheat plots at Mount Vernon in northwestern
Washington had 20 % severities. The winter was warmer than normal
in the Pacific Northwest, and therefore, stripe rust started sporulating
earlier than normal in western PNW.
In early April, wheat stripe rust continued to increase in western
Oregon and northwestern Washington. During the first week of April,
wheat stripe rust was found on susceptible winter wheat entries
in south central Washington nurseries. In mid-April, traces of
stripe rust were found in winter wheat nurseries near Pullman
in southeastern Washington. An early appearance of stripe rust
in the Palouse region was expected according to the forecast based
on the higher than normal temperatures in December and January.
The wet weather in April was favorable for stripe rust infection.
During the third week in April wheat stripe rust was developing rapidly in the Pacific Northwest, because of moist weather, which was favorable for rust development. In northwestern Washington, wheat fields with 20 % rust severities were reported.
By early May, stripe rust was present throughout the Pacific Northwest and caused yield losses in susceptible winter wheat crops in northwestern Oregon and south central Washington. Fungicides were sprayed to control stripe rust in Washington wheat fields in an area that had the most stripe rust in the last 20 years. In early May, in east central Washington and northern Idaho, susceptible winter wheat experimental fields had 60 % stripe rust severities. In both Oregon and Washington nurseries stripe rust severities ranged from 0 to 60 % in winter wheat cultivars.
In mid-May, stripe rust was widespread throughout the Pacific Northwest. Susceptible entries in southeast Washington winter wheat nurseries had 100 % severities and susceptible entries in the spring wheat nurseries had 40 % severities. In eastern Washington, winter wheat fields with 5 % rust severities were sprayed with fungicides. Stripe rust was common in spring wheat fields with less than 2 % severity on the lowest leaves. The wet and cool weather in mid-May, were ideal for stripe rust infection in the Washington.
In early June, fields in northern Utah and southern Idaho had severe rust. In mid-July, significant levels of stripe rust were found on wheat in fields and plots in south central Idaho. Losses to wheat stripe rust were expected in southern Idaho.
In mid-June, wheat stripe rust occurred throughout the wheat areas of the Pacific Northwest. The disease passed peak development on winter wheat and was developing on spring wheat. By late June, stripe rust was severe in virtually every location wheat was grown in the Pacific Northwest, extending as far east as Bozeman (Figure 2). Most fields of moderately susceptible or susceptible winter and spring wheat cultivars were sprayed with fungicides.
Because the rust started very early in the season, and the weather was extremely favorable to the disease (cool and wet), and the inoculum load was heavy, cultivars with low to moderate levels of high-temperature adult-plant (HTAP) resistance, which is generally adequate in years of normal weather, showed heavy infection. This year wheat stripe rust losses were expected to be higher than average in the Pacific Northwest.
Mexico. Stripe rust was at moderate to high infection levels on a few bread wheat cultivars throughout the Yaqui Valley. Some fields were sprayed to prevent yield loss.