The major diseases of barley in Uruguay are: net blotch, caused by Drechslera teres, spot blotch caused by Bipolaris sorokiniana, leaf rust caused by Puccinia hordei, scald, caused by Rhynchosporium secalis and Fusarium head blight, incited by Fusarium graminearum. Since 1992, screening nurseries are handled under high pressure of inoculum of the pathogen, in order to (a) identify sources of resistance for the above mentioned diseases and use them in adapted germplasm with malting quality (in the Barley Breeding Program) and (b) characterize the advanced lines of the Barley Breeding Program and those cultivars in final evaluation and currently grown.

Conditions for the 1996 growing season favoured development of spot blotch and scald, the latter mainly in the southwestern region.

Screening nurseries for scald, spot blotch, net blotch and leaf rust were sown in the field, with susceptible checks every 20 plots. The first two were artificially inoculated with conidial suspensions of the corresponding pathogen. Leaf rust collection was sown with susceptible checks every 10 plots and with susceptible borders to ensure infection. Materials came from the INIA Barley Breeding Program, National Cultivars Evaluation Program, ICARDA-CIMMYT, Australia, Canada, USA, Europe (mainly, Germany and Sweden), Argentina, Brazil, Ethiopia, and Morocco.

The Fusarium nursery was sown under a shading shelter, with sucessive inoculations of F. graminearum and manually sprinkled three times a day. Evaluated accessions came from the Barley Breeding Program, National Cultivar Evaluation Program, ICARDA-CIMMYT, and cultivars currently grown in Uruguay.

Net Blotch

Yield losses from NB in Uruguay have been estimated to be between 13 to 33% in susceptible cultivars. Of the 348 accessions, 33% presented low infection (Table 1).

Spot Blotch

21% of the 312 accessions had low infection of this disease (Table 1).

Leaf Rust

Yield losses from LR in the country have been estimated to be between 17 to 25% in susceptible cultivars. Of the 485 accessions, 62% had low infection rates (Table 1).

Scald

27% of the 308 accessions had low infection (Table 1).

Table 1 summarizes the accessions that had the lowest infections of the four diseases.

Table 1. Materials with best disease performance, 1996.

Material	Origin	NB?	SB	LR	SC
F594 1229 (Buck M8-88/CLE 119)	Uruguay	R?	MRMS	MRMS	MR
F594 1219 (Buck M8-88/CLE 119)	Uruguay	R	MRMS	MR	MR
F594 2081 (CLE 117/NE738)	Uruguay	R	MR	MR	MR
F593 3687	Uruguay	R	R	R	R
CLE 176	Uruguay	R	MRMS	R	MR
NE 175	Europe	R	MS	R	MR
Nadja/Shyri//Gloria's'/Copal's'	ICARDA-CIMMYT	R	MR	R	R
Emir/3/Api/CM67//Bus/4/Shyri/5/Sen's'	ICARDA-CIMMYT	R	R	R	R
Shyri/ABN//Gloria's'/Copal's'	ICARDA-CIMMYT	R	MR	R	R
Cerise/Arupo//Aleli	ICARDA-CIMMYT	R	MR	R	R
Arupo/K8755//Aleli	ICARDA-CIMMYT	R	MR	R	R

?NB: Net Blotch; SB: Spot Blotch; LR: Leaf Rust; SC: Scald

?R: Resistant; MR: Moderately resistant; MS: Moderately susceptible

Fusarium Head Blight:

Line Shyri//Gloria-bar/Copal/3/Shyri/Grit from ICARDA-CIMMYT, Defra and Aphrodite (Europe), exhibited the lowest FHB severity, while CLE 170 and Quilmes Sur (Uruguay and Argentina, respectively) had the highest FHB severities. DON concentrations in each material are being processed.

Since one of the main objectives of the Barley Breeding Program in Uruguay is malting quality, resistance (from those materials lacking malting quality) will be incorporated by one or more backcrosses with a recurrent parent with good malting quality.