Inoculum pressure and the development of stem rust epidemics in barley

1991 ◽  
Vol 42 (5) ◽  
pp. 769 ◽  
Author(s):  
R Dill-Macky ◽  
RG Rees ◽  
GJ Platz

The effects of inoculum pressure on the development of epidemics of Puccinia graminis tritici in two barley cultivars with different levels of resistance were examined in two field experiments. Treatments were established by inoculation of foci within plots and/or the strategic use of fungicides. Additional 'rust-free' treatments were maintained to provide comparisons of grain yield and quality. Relationships between rust severity, rust incidence and grain yield and quality were also examined. Initial inoculum levels were important in determining disease severity and incidence for individual epidemics; however, severe epidemics developed under most 'rusted' treatments of the susceptible cultivar Galleon and reduced grain yield by up to 58%. Epidemics under corresponding treatments of the moderately resistant cultivar Grimmett were less severe, and the value of the resistance was evident with yield losses not exceeding 12%. Yield reductions were usually associated with reduced grain size and weight.

1985 ◽  
Vol 86 (2) ◽  
pp. 265-271 ◽  
Author(s):  
A. C. Dick ◽  
S. S. Malhi ◽  
P. A. O'Sullivan ◽  
D. R. Walker

2019 ◽  
Vol 20 (1) ◽  
pp. 238-250 ◽  
Author(s):  
Vera ĐEKIĆ ◽  
Jelena MILIVOJEVIĆ ◽  
Milomirka MADIĆ ◽  
Vera POPOVIĆ ◽  
Snežana Branković ◽  
...  

1990 ◽  
Vol 41 (6) ◽  
pp. 1057 ◽  
Author(s):  
R Dill-Macky ◽  
RG Rees ◽  
GJ Platz

The progress of epidemics of Puccinia graminis f. sp. tritici strain 343-Anz-1,2,3,5,6 was examined in field plots of the Australian barley cultivars Clipper, Corvette, Galleon, Grimmett, Prior and Schooner. The barley Purple Nudum, reported to possess seedling resistance to Puccinia graminis f. sp. tritici, and the susceptible wheat Oxley were also examined. Additional rust-free treatments were maintained to provide comparisons of grain yield and quality. Differences in the rate of epidemic development between cultivars were found. Moderate epidemics developed in Clipper, Schooner, Grimmett and Prior and no significant losses in yield were detected in Grimmett or Prior. Severe epidemics developed in Galleon, Corvette and Oxley and reduced grain yield by about half. Yield reductions were generally associated with reduced grain size and weight.


2002 ◽  
Vol 138 (3) ◽  
pp. 317-331 ◽  
Author(s):  
M. J. GOODING ◽  
A. PINYOSINWAT ◽  
R. H. ELLIS

Four field experiments were conducted to investigate the effects of seed rate on yield and quality of wheat. Despite some small and inconsistent effects of seed rate on radiation-use efficiency and harvest index, the responses of PAR interception, above-ground biomass and grain yield generally followed similar asymptotic increases as seed rate increased. In one experiment, when nitrogen fertilizer was withheld, biomass and grain yields did not respond to increases in seed rate despite increases in PAR interception. In one experiment, grain yield followed a parabolic response to seed rate with apparent reductions in yield at very high seed rates. Plants compensated for low population densities by increased production and survival of tillers and, to a lesser extent, increased grain numbers per ear. Net tiller production continued until the main stems flowered or later. Effects of seed rate on grain specific weight and thousand grain weight were small and inconsistent. Hagberg falling number increased linearly with seed rate in three experiments, associated with quicker maturation of the crop. Grain protein concentration declined with increase in sowing rate according to linear divided by linear or linear plus exponential models depending on whether the grain yield response was asymptotic or parabolic. Discolouration of the grain with blackpoint increased with seed rate in the most susceptible cultivar, namely Hereward. The economic consequences of these effects on yield and quality are discussed.


1986 ◽  
Vol 92 (3) ◽  
pp. i-i
Author(s):  
A. C. Dick ◽  
S. S. Malhi ◽  
P. A. O'Sullivan ◽  
D. R. Walker

1997 ◽  
Vol 37 (2) ◽  
pp. 173 ◽  
Author(s):  
W. K. Anderson ◽  
D. Sawkins

Summary. The aim of our experiments was to determine whether the soft-grained, club-head wheats used for the Australian Soft grade (cvv. Tincurrin and Corrigin), required different management to maximise grain yield and quality than the standard-head wheats used for other grades. Two series of field experiments were conducted in the 300–500 mm rainfall zone in the southern wheatbelt of Western Australia between latitudes 32 and 34°S from 1989 to 1993. Agronomic variables examined in the experiments included sowing time, nitrogen (N) fertiliser and seed rate. Grain yield, grain protein concentration, hectolitre weight and small grain sievings (below a 2 mm slotted screen) were measured on the grain samples. It was concluded that the optimum time for sowing the soft wheats, both of which are of mid-season maturity, was May. Small grain sievings and grain proteins of the soft wheats exceeded the receival standards for the grade when sown outside this period and were more sensitive to earlier or later sowings in this regard than the other wheats. The soft wheats had smaller kernels and were more likely than other cultivars to produce grain samples with high levels of sievings associated with sowing at inappropriate times and the use of N fertiliser. They had consistently 1–1.5% lower grain protein concentrations than the other cultivars used in the experiments. Hectolitre weights seldom fell below the receival standard of 74 kg/hL for any of the grain samples. Increasing seed rate did not increase the level of sievings at all sites. Although sievings were affected by sowing time, N fertiliser and cultivar, there were large influences associated with site factors that also caused excessive sievings. Fertile sites where the crop did not respond to N fertiliser and sites where the crop was infected by leaf rust were associated with high levels of sievings. Standard-head wheats were less susceptible to dockages, but lower yielding than the club-head, soft wheats. Seed rates for the soft wheats should be chosen to maximise yield rather than to attempt to avoid price dockages at receival.


2019 ◽  
Vol 70 (1) ◽  
pp. 55 ◽  
Author(s):  
Mark S. McLean ◽  
Grant J. Hollaway

Net form of net blotch (NFNB), caused by Pyrenophora teres f. teres, is a major foliar disease of barley (Hordeum vulgare L.) worldwide that can cause grain yield and quality loss in susceptible varieties. Seed- and foliar-applied fungicides were evaluated in six field experiments infected with NFNB during 5 years, for suppression of NFNB severity and protection of grain yield and quality. Suppression of NFNB severity varied between treatments and experiments. Grain yield and quality improvements were recorded in two experiments. Foliar fungicide applications at stem elongation (Zadoks growth stage Z31) and flag leaf emergence (Z39) or ear emergence (Z55) significantly reduced NFNB severity, increased grain yield by up to 23%, and improved grain-quality measurements of retention, screenings and weight. The seed-applied fungicide fluxapyroxad provided significant reductions in NFNB severity, improvements in grain yield of up to 20%, and improved grain quality. Where NFNB was severe, none of the seed or foliar fungicide application strategies provided complete control of NFNB, indicating that more than two applications were necessary when conditions were favourable for disease development in susceptible varieties.


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