MINNESOTA

 

Barley Rusts in the United States in 2003

 

D.L. Long¹, Y. Jin¹, M.E. Hughes¹,B.J. Steffenson², and L. A. Wanschura¹

 

¹Cereal Disease Laboratory, USDA-ARS and ²Department of Plant Pathology, University of Minnesota

 

Barley stem rust.  The first reports of stem rust in 2003 were of trace severities in plots of susceptible two-row cultivars in southern Minnesota.  By late July, trace-40% severities with very low incidence were observed in spring barley varietal plots throughout North Dakota, while traces were observed in commercial fields.  In plots in northwestern Minnesota, 10% severities were observed, most of which were on late tillers.  Stem rust caused minimal losses to barley in 2003, due mostly to its late arrival during the growing season, the lack of sufficient dew periods, and cooler than normal temperatures (Table 1).

 

The most common race of Puccinia graminis f. sp. tritici identified from barley and Hordeum jubatum was QFCS (Table 2).  This race is avirulent on barley cultivars with the stem rust resistance gene Rpg1.  Race QCCJ, which possesses virulence for Rpg1, was present in the stem rust population at a frequency of 12% of all isolates.  Race RFCN was detected in low frequency (5%) and appears to be a new race.  Its virulence spectrum on stem rust resistance genes in barley has not been characterized yet. 

 

Barley leaf rust.  In mid-May, 60% severities were observed on barley in a nursery in the San Joaquin Valley of California.  In mid-late May, low levels of leaf rust were observed in yield trials in the Central Valley of California.  By late May, leaf rust was severe on susceptible lines in nurseries at Davis, California.

 

In early June, leaf rust severities of 100% were found on susceptible lines in the eastern shore nursery at Painter, Virginia.  Barley leaf rust was much more severe than wheat leaf rust at this location.

 

In early July, traces of leaf rust were reported on lower leaves in susceptible spring barley plots in southern Minnesota and in commercial fields across southeastern North Dakota.  Losses to barley leaf rust were minimal in the U.S. in 2003 (Table 1).

 

Twelve differential barley genotypes were used to identify pathotypes of P. hordei (Table 3).  These pathotypes were designated according to a system similar to that of Roelfs and Martens (Phytopathology 78:526-533) as shown in Table 4.  Five pathotypes of P. hordei were identified from 5 viable collections in 2003 (Table 5).  The most common virulences identified were for Rph1, Rph2, Rph4, Rph8, Rph9, Rph11, and Rph13.

 

Barley crown rust.  In mid-June, barley crown rust was light in plots growing near the buckthorn nursery on the St. Paul campus of the University of Minnesota.  Wild barley (Hordeum jubatum) in south central South Dakota had rust severities of 20% in late June.  Susceptible barley cultivars in the buckthorn nursery at St. Paul had trace to 5% rust severities by late June.  In mid-July, trace to 40% severities were observed in plots in west central Minnesota.  These plots were near a shelterbelt that included common buckthorn with many crown rust infection sites.  In mid-July, traces of crown rust were found in barley plots in southern Minnesota.  In late July, trace to 10% rust severities were found in plots and commercial fields throughout North Dakota.

 

In early June, foci of crown rust were observed on smooth brome grass (Bromus inermis) in southeastern Minnesota.  In late July, crown rust on smooth brome grass was widespread in North Dakota and northwestern Minnesota.

 

Stripe rust on barley.  Stripe rust was first detected in Davis, California nurseries on February 27, which was earlier than normal.  In early May in the Western Regional Spring Barley Nursery at Davis, California, susceptible lines had 50-80% severities at early dough stage.  By late May, stripe rust had increased in these nurseries to 100% severity on susceptible lines.  Susceptible cultivars (Max, Commander) also had 100% severity by late May in yield trials in the Central Valley.

 

In early May, stripe rust was increasing in the barley nursery in northwestern Washington near Mount Vernon.  No stripe rust was found on barley in eastern Washington since most of the spring barley grown in this area is resistant to stripe rust.  In late May, stripe rust was severe on winter barley and was developing quickly on spring barley in northwestern Washington fields and nurseries.  The first report of barley stripe rust in eastern Washington (regions east of the Cascade Mountains) was on May 29 in a winter barley field of ‘Hoody’ at the Othello Experiment Station.  At the station, plots of the spring barleys ‘Bob’ and ‘Calpso’ had traces of stripe rust on the lower leaves.  In one of the spring barley nurseries near Pullman, Washington, one pustule of stripe rust was found on May 28.  In mid-June, stripe rust was increasing in experimental plots of susceptible barley cultivars in the Palouse region of eastern Washington.  Stripe rust was not a problem in most barley fields in eastern Washington because moderately resistant cultivars are widely grown.

 

Table 1.  Pathotypes of Puccinia graminis f. sp. tritici identified from barley in 2003
				Number of
State			Source	collections			isolates				QCCJ		QFCS		RFCN
	MN	Nursery			4	8						100
		H. jubatum			4	9						89		11
	ND	Nursery			6	12				17		75		8
	SD	Nursery			1	2						100
		H. jubatum			6	12				25		75
	U.S.	Nursery			11	22				9		86		5
		H. jubatum			10	21				14		81		5
		Total			21	43				12		84		5

 

 

	Table 2. Estimated losses in barley due to rusts in 2003 in the United States.
				1000		Yield in		Production				Stem rust				Leaf rust					Stripe rust
			acres			bushels			in 1000					1000					1000					1000
State			harvested			per acre			of bushels		%			bushels			%		bushels			%		bushels
AZ			30		118.0		3,540			0.0			0.0		0.0			0.0		0.0			0.0
CA			58		64.0		3,712			0.0			0.0		1.0			38.3		2.0			76.5
CO			82		109.0		8,938			0.0			0.0		0.0			0.0		0.0			0.0
DE			21		59.0		1,239			0.0			0.0		0.0			0.0
ID			720		66.0		47,520			0.0			0.0		0.0			0.0		0.0			0.0
KS			8		57.0		456			0.0			0.0		0.0			0.0
KY			8		75.0		600			0.0			0.0		0.0			0.0
ME			27		65.0		1,755			0.0			0.0		0.0			0.0
MD			38		57.0		2,166			0.0			0.0		0.0			0.0
MI			14		56.0		784			0.0			0.0		0.0			0.0
MN			170		75.0		12,750			T*			T		T			T
MT			810		39.0		31,590			0.0			0.0		0.0			0.0		0.0			0.0
NE			4		50.0		200			0.0			0.0		0.0			0.0
NV			3		80.0		240			0.0			0.0		0.0			0.0
NJ			3		45.0		135			0.0			0.0		0.0			0.0
NY			12		50.0		600			0.0			0.0		T			T
NC			14		56.0		784			0.0			0.0		T			T
ND			1,980		60.0		118,800			T			T		T			T
OH			6		58.0		348			0.0			0.0		0.0			0.0
OR			60		64.0		3,840			0.0			0.0		0.0			0.0		T			T
PA			65		61.0		3,965			0.0			0.0		0.0			0.0
SD			55		53.0		2,915			T			T		T			T
UT			35		80.0		2,800			0.0			0.0		0.0			0.0
VA			45		62.0		2,790			0.0			0.0		T			T
WA			310		47.0		14,570			0.0			0.0		T			T		0.5			73.3
WI			35		55.0		1,925			0.0			0.0		T			T
WY			75		95.0		7,125			0.0			0.0		0.0			0.0
	Total from above
		4,688			58.9		276,087						T					38.3					149.8
	U.S. % Loss
												T			0.01					0.06
	U.S. Total
		4,688			58.9		276,087
	*T = Trace

 

Table 3.  Barley genotypes used to differentiate isolates of Puccinia hordei
Genotype			Resistance gene
Sudan			Rph1
Peruvian			Rph2
Estate			Rph3
Gold			Rph4
Magnif			Rph5
Bolivia-Rph6			Rph6
Cebada Capa			Rph7
Egypt 4			Rph8
Hor 2596			Rph9
Clip BC8			Rph10
Clip BC67			Rph11
Triumph			Rph12

 

 

Table 4. North American system of pathotype nomenclature for Puccinia hordei based on 12 differential barley linesa
		Infection phenotype
	Set 1	Rph1	Rph2	Rph3	Rph4
	Set 2	Rph5	Rph6	Rph7	Rph8
Ph-code	Set 3	Rph9	Rph10	Rph11	Rph12
	B	Low	Low	Low	Low
	C	Low	Low	Low	High
	D	Low	Low	High	Low
	F	Low	Low	High	High
	G	Low	High	Low	Low
	H	Low	High	Low	High
	J	Low	High	High	Low
	K	Low	High	High	High
	L	High	Low	Low	Low
	M	High	Low	Low	High
	N	High	Low	High	Low
	P	High	Low	High	High
	Q	High	High	Low	Low
	R	High	High	Low	High
	S	High	High	High	Low
	T	High	High	High	High
a Pathotype designations are based on the infection phenotypes of the pathogen isolate on the 12 differential barley hosts.  Low = incompatibility (infection phenotypes 0, 0;, 1, or 2) and High = compatibility (infection phenotypes 3 or 4).  The infection phenotypes from set 1 determine the first letter of the code, those from set 2 the second, etc.

 

Table 5.  Pathotypes of Puccinia hordei identified from the United States in 2003
	Number of
State	collections	Source	Pathotypes and (no. of collections) a
California	4	Nursery	RFN (1), RCD (1), RCL (1)
North Dakota	2	Field
Virginia	3	Nursery	RFL (1), MFD (1)
aSome collections did not yield any viable spores; thus, no pathotype determinations could be made.