COMPARISON OF THE EFFECTS OF NET BLOTCH AND LEAF REMOVAL ON YIELD IN BARLEY

1969 ◽  
Vol 49 (6) ◽  
pp. 731-735 ◽  
Author(s):  
L. Piening ◽  
M. L. Kaufmann
Keyword(s):  
Leaf Tissue ◽  
Causal Agent ◽  
Low Fertility ◽  
Leaf Removal ◽  
Net Blotch ◽  
Yield Losses ◽  
Leaf Clipping ◽  
Drechslera Teres ◽  
Time Required

Experiments were conducted in a growth cabinet to compare yield losses in barley caused by partial defoliation and foliar infection by Drechslera teres, the causal agent of net blotch. When Gateway barley was grown under a low fertilizer regime, infection of lower leaves caused greater yield reductions than the removal of comparable leaves. In contrast, infection or removal of upper leaves reduced yields to about the same extent. Under a higher fertilizer regime, yield reductions from infection or defoliation were about equal (14%). These losses were considerably lower than those from plants on the low fertility regime and were similar to those caused by net blotch in the field.In leaf clipping experiments, root weights and yields were reduced proportionately to the amount of leaf tissue removed. The time required to head was also increased with increasing amounts of leaf clipping.

scholarly journals Identification of Pyrenophora teres f. maculata, Causal Agent of Spot Type Net Blotch of Barley in North Dakota

Plant Disease ◽  
2010 ◽  
Vol 94 (4) ◽  
pp. 480-480 ◽  
Author(s):  
Z. H. Liu ◽  
T. L. Friesen
Keyword(s):  
North Dakota ◽  
Leaf Tissue ◽  
Causal Agent ◽  
Tan Spot ◽  
Pathogenicity Test ◽  
Pyrenophora Teres ◽  
Net Blotch ◽  
Hordeum Vulgare L ◽  
Single Spore ◽  
Spot Type

Net blotch of barley (Hordeum vulgare L.) caused by the fungus Pyrenophora teres (anamorph Drechslera teres) is found in two forms, net form net blotch (NFNB) and spot form net blotch (SFNB). When inoculated on susceptible varieties, P. teres f. teres produces lesions with a characteristic net-like pattern surrounded by necrosis or chlorosis (NFNB), whereas P. teres f. maculata produces lesions consisting of spots surrounded by necrosis or chlorosis (SFNB). Recently, epidemics of SFNB have occurred throughout the world (4). Currently, net blotch is a significant foliar disease of barley in the North Dakota-Northwestern Minnesota agricultural region, a leading barley-production area. Diseased barley leaf tissue was collected annually from 2004 to 2008 in Fargo and Langdon, ND. Diseased leaves were incubated to promote sporulation. Ten single-spore isolates of P. teres collected from each location each year were tested for virulence by inoculation on 20 commonly used barley net blotch differential lines. Among the 100 isolates collected, one isolate collected in Fargo in 2006 (FGOH06Pt-8) and one isolate collected in Langdon in 2008 (LDNH08Pt-4) were identified as P. teres f. maculata due to their induction of spot-type lesions across the differential set. Conidial morphology of the two isolates was similar to P. teres f. teres isolates. A pathogenicity test of all isolates was performed on regional barley cvs. Tradition, Robust, and Lacey as well as barley lines Rika and Kombar (1) as previously described (3). The net form isolate 0-1 and spot form isolate DEN2.6 (obtained from B. Steffenson, University of Minnesota) were used as controls. The P. teres f. teres isolate 0-1 produced typical net type symptoms on all barley lines except the resistant line Rika, in which only small, dark spots were observed. DEN2.6 produced pin-point spot-like lesions with an extensive yellow halo on Robust, Lacey, Rika, and Kombar, but without chlorosis on Tradition. The two newly identified isolates induced elliptical spot-type lesions measuring 3 × 6 mm, larger than those produced by P. teres f. maculata isolate DEN 2.6, suggesting a higher level of virulence. We constructed a neighbor-joining phylogenetic tree using ClustalW2 ( http://www.ebi.ac.uk/ ) based on sequence identity of the internal transcribed spacer (ITS) region from 0-1 (GenBank No. GU014819), DEN2.6 (GenBank No. GU014820), FGOH06Pt-8 (GenBank No. GU014821), and LDNH08Pt-4 (GenBank No. GU014822) as well as P. teres f. maculata, P. teres f. teres, and P. tritici-repentis (causal agent of tan spot of wheat) accessions obtained from GenBank (2). All P. teres isolates clustered together and were clearly separated from the P. tritici-repentis cluster. Isolates FGOH06Pt-8 and LDNH08Pt-4 had identical ITS sequences and differed from DEN2.6 by only a single nucleotide. To our knowledge, this is the first report of P. teres f. maculata in North Dakota. Resistance to SFNB should now be considered in local barley breeding programs and cultivar releases. Reference: (1) M. Abu Qamar. Theor. Appl. Genet. 117:1261, 2008. (2) R. M. Andrie et al. Fungal Genet. Biol. 45:363, 2008. (3) Z. Lai et al. Fungal Genet. Biol. 44:323, 2007. (4) M. S. McLean et al. Crop Pasture Sci. 60:303, 2009.

Effects of stubble-borne fungal inoculum on incidence of leaf diseases and yields of barley in Western Australia

1988 ◽  
Vol 28 (4) ◽  
pp. 529 ◽  
Author(s):  
TN Khan
Keyword(s):  
Powdery Mildew ◽  
Yield Loss ◽  
Rhynchosporium Secalis ◽  
Net Blotch ◽  
Yield Losses ◽  
Hordeum Vulgare L ◽  
Leaf Disease ◽  
Drechslera Teres ◽  
Barley Crop ◽  
Number Of Seeds

Effect of stubble residues on leaf diseases and yield of barley (Hordeum vulgare L. cv. Dampier) were studied by adding small quantities of infested stubble to test plots grown on land where a non-barley crop or pasture had been grown in the previous year. Experiments conducted at 5 locations in 198 1 and 1982 showed that stubble residues increased leaf disease. The severity of leaf disease varied with location and year. High levels of scald (Rhynchosporium secalis) were recorded at all locations, but substantial levels of net blotch (Drechslera teres) occurred only at northern locations. Halo spot (Selenophoma donacis) and a leaf spot caused by Drechslera verticillata were either absent or occurred in minor proportions. The incidence of powdery mildew (Erysiphe graminis f.sp. hordei) at Mt Barker in 1982 was not related to the presence of stubble residues. Grain yield losses of 9 and 28% occurred in the stubble amended plots in 1981 and 1982, respectively. Reductions in number of heads and number of seeds per plot appeared to be the major components of yield loss.

scholarly journals Field efficacy of different fungicide mixtures in control of net blotch on barley

2016 ◽  
Vol 31 (1-2) ◽  
pp. 51-57 ◽  
Author(s):  
Milos Stepanovic ◽  
Emil Rekanovic ◽  
Svetlana Milijasevic-Marcic ◽  
Ivana Potocnik ◽  
Biljana Todorovic ◽  
...  
Keyword(s):  
Disease Control ◽  
Effective Treatment ◽  
Net Blotch ◽  
Yield Losses ◽  
Yield Increase ◽  
Growing Seasons ◽  
Drechslera Teres ◽  
Field Efficacy ◽  
Fungicide Mixtures

Seven fungicide mixtures (epoxiconazol + metconazole, boscalid + epoxiconazole, pyraclostrobin + epoxiconazole, prothioconazole + tebuconazole, picoxistrobin + cyproconazole, azoxystrobin + cyproconazole and spiroxamine + tebuconazole + triadimenol) were evaluated for control of net blotch of barley caused by Drechslera teres, as well as yield losses, over the 2010 and 2011 growing seasons. Two applications of the fungicide combination pyraclostrobin + epoxiconazole at the rate of 1.0 l ha-1 were the most effective treatment in controlling the disease and improving yield in both experimental years. Treatments with the fungicide mixtures epoxiconazol + metconazole and spiroxamine + tebuconazole + triadimenol showed the least effectiveness in disease control, as well as yield increase.

INHERITANCE OF RESISTANCE TO NET BLOTCH IN BARLEY. I. FACTORS AFFECTING THE PENETRANCE AND EXPRESSIVITY OF GENE(S) CONDITIONING HOST RESISTANCE

1969 ◽  
Vol 11 (3) ◽  
pp. 587-591 ◽  
Author(s):  
T. N. Khan
Keyword(s):  
Environmental Conditions ◽  
Net Blotch ◽  
Host Reaction ◽  
Susceptible Parent ◽  
Breeding Programs ◽  
Genetic Studies ◽  
Factors Affecting ◽  
Drechslera Teres ◽  
Resistant Varieties ◽  
High Level

Variability in the host-reaction of barley to infection by Drechslera teres was examined in the parents and progeny of selected crosses under different environmental conditions of testing.The Ethiopian variety C.I. 5791 exhibits a consistently high level of resistance under a range of environmental conditions, which is in contrast to the Manchurian variety C.I. 2330. The sensitivity of the genes for resistance possessed by these varieties to environmental modifications is considered to depend upon their respective genetic backgrounds. Furthermore, variability of host reaction in the progeny of these resistant varieties was shown to be influenced by the genetic background of the susceptible parent used.The implications of these findings in the conduct and interpretation of genetic studies and in backcross breeding programs is discussed.

scholarly journals Environmentally Induced Variability in the Host Reaction of Barley to Net Blotch

1969 ◽  
Vol 22 (5) ◽  
pp. 1237 ◽  
Author(s):  
TN Khan ◽  
WJR Boyd
Keyword(s):  
Environmental Conditions ◽  
Susceptible Variety ◽  
Post Inoculation ◽  
Net Blotch ◽  
Host Reaction ◽  
Drechslera Teres ◽  
Resistant Varieties

The host reaction of two Ethiopian and four Manchurian resistant varieties, and one susceptible variety of barley to isolate 177 of Drechslera teres was studied under a range of environmental conditions. The effects were specific to the variety(ies) used, with the exception of the factor of post-inoculation temperature. High post-inoculation temperatures brought about the breakdown of resistance in all the varieties.

scholarly journals Tracing the Origin and Evolutionary History of Pyricularia oryzae Infecting Maize and Barnyard Grass

2020 ◽  
pp. PHYTO-09-20-042
Author(s):  
Adel Pordel ◽  
Sebastien Ravel ◽  
Florian Charriat ◽  
Pierre Gladieux ◽  
Sandrine Cros-Arteil ◽  
...  
Keyword(s):  
Comparative Genomics ◽  
Host Range ◽  
Range Expansion ◽  
Pyricularia Oryzae ◽  
Causal Agent ◽  
Blast Disease ◽  
Yield Losses ◽  
Barnyard Grass ◽  
Host Range Expansion ◽  
Recent Emergence

Blast disease is a notorious fungal disease leading to dramatic yield losses on major food crops such as rice and wheat. The causal agent, Pyricularia oryzae, encompasses different lineages, each having a different host range. Host shifts are suspected to have occurred in this species from Setaria spp. to rice and from Lolium spp. to wheat. The emergence of blast disease on maize in Iran was observed for the first time in the north of the country in 2012. We later identified blast disease in two additional regions of Iran: Gilan in 2013 and Golestan in 2016. Epidemics on the weed barnyard grass (Echinochloa spp.) were also observed in the same maize fields. Here, we showed that P. oryzae is the causal agent of this disease on both hosts. Pathogenicity assays in the greenhouse revealed that strains from maize can infect barnyard grass and conversely. However, genotyping with simple sequence repeat markers and comparative genomics showed that strains causing field epidemics on maize and on barnyard grass are different, although they belong to the same previously undescribed clade of P. oryzae. Phylogenetic analyses including these strains and a maize strain collected in Gabon in 1985 revealed two independent host-range expansion events from barnyard grass to maize. Comparative genomics between maize and barnyard grass strains revealed the presence or absence of five candidate genes associated with host specificity on maize, with the deletion of a small genomic region possibly responsible for adaptation to maize. This recent emergence of P. oryzae on maize provides a case study to understand host range expansion. Epidemics on maize raise concerns about potential yield losses on this crop in Iran and potential geographic expansion of the disease.

CEPHALOSPORIUM SPECIES PARASITIC ON HELMINTHOSPORIUM (SENSU LATE)

1964 ◽  
Vol 44 (2) ◽  
pp. 182-187 ◽  
Author(s):  
R. Kenneth ◽  
P. K. Isaac
Keyword(s):  
Bipolaris Sorokiniana ◽  
Causal Agent ◽  
Direct Invasion ◽  
Drechslera Teres ◽  
Helminthosporium Sativum

Four species of Cephalosporium from Canada and one species from Israel were found to be hyperparasitic on Drechslera teres (Helminthosporium teres) and D. poae (H. vagans). Among these was C. acremonium, causal agent of black bundle disease of corn. Direct invasion of conidia, conidiophores, and hyphae of the host fungi by hyphae of the mycoparasites was observed. Appressoria were not found. Conidia of Drechslera spp. disintegrated shortly after penetration by hyphae of the hyperparasites. None of the three species tested on Bipolaris sorokiniana (Helminthosporium sativum) invaded conidia or conidiophores of this species, and parasitism was limited to occasional penetration of hyphae of the host. It is concluded that hyperparasitism on Drechslera species is likely to be general among Cephalosporium spp.

scholarly journals Cassava common mosaic virus causes photosynthetic alterations associated with changes in chloroplast ultrastructure and carbohydrate metabolism of cassava plants

2020 ◽  
Author(s):  
Andrea A. Zanini ◽  
Liliana Di Feo ◽  
Dario F. Luna ◽  
Pablo Paccioretti ◽  
Agostina Collavino ◽  
...  
Keyword(s):  
Viral Infection ◽  
Mosaic Virus ◽  
Leaf Tissue ◽  
Chloroplast Ultrastructure ◽  
Oxygen Evolving Complex ◽  
Reaction Centre ◽  
Yield Losses ◽  
Chloroplast Structure ◽  
Complex Activity ◽  
Mesophyll Cells

AbstractCassava common mosaic virus (CsCMV) is a potexvirus that causes systemic infections in cassava plants, leading to chlorotic mosaic and producing significant yield losses. To date, the physiological alterations and the mechanism underlying biotic stress during the cassava-CsCMV compatible interaction remains unknown. In this study, we found that CsCMV infection adversely modified chloroplast structure and had functional effects on chloroplasts in source leaves during the course of viral infection. Extrusion of the chloroplast membrane with amoeboid-shaped appearance was observed in infected mesophyll cells. These alterations were associated with lower relative chlorophyll content, and reduced PSII efficiency and CO2 fixation. Moreover, an oxidative stress process was observed in CsCMV-infected plants. Strong declines in the maximum quantum yield of primary photochemistry (Fv/Fm) were observed in infected plants. Furthermore, the analysis of Chlorophyll-a fluorescence (ChlF) evidenced a progressive loss of both oxygen evolving complex activity and “connectivity” within the tripartite system (core antenna-LHCII-Reaction Centre). Other effects of the pathogen included reduction of starch and maltose content in source leaves, and a significant increase of the sucrose/starch ratio, which indicates alteration pattern of carbon. Our results suggest that CsCMV induces chloroplast distortion associated with progressive chloroplast function loss and diversion of carbon flux in source leaf tissue, which should be key in inducing yield losses of infected crops.Main conclusionCsCMV infection adversely modified chloroplast structure and had functional effects on chloroplasts during the course of viral infection, associated with metabolic adjustment in cassava source leaves, which would partly explain cassava root yield losses.

scholarly journals First Report of Bud Rot Caused by Phytophthora palmivora on African Oil Palm in Colombia

Plant Disease ◽  
2010 ◽  
Vol 94 (9) ◽  
pp. 1163-1163 ◽  
Author(s):  
G. A. Torres ◽  
G. A. Sarria ◽  
F. Varon ◽  
M. D. Coffey ◽  
M. L. Elliott ◽  
...  
Keyword(s):  
Oil Palm ◽  
Leaf Tissue ◽  
Causal Agent ◽  
Phytophthora Palmivora ◽  
Its Sequencing ◽  
Fruit Tissue ◽  
First Report ◽  
Palm Heart ◽  
Blastn Analysis ◽  
Average Size

A bud rot disease, referred to as “pudricion del cogollo” or PC (for its name in Spanish), is a major disease of oil palm in four production areas of Colombia. Even though the disease has been studied for more than 40 years in Central and South America, the causal agent remained unknown (1). Infection first develops in the palm heart (cogollo) above the meristematic zone. Initial external symptoms appear as necrotic lesions on the sides of the spear leaf (youngest, unexpanded leaf) and the sizes of the lesions remain static as tissues emerge, expand, and mature. Under favorable environmental conditions (temperature around 26°C and relative humidity above 80%), further rotting of the heart eventually destroys the bud. A baiting technique with papaya and cocoa fruits was successfully used to trap the causal agent from symptomatic spear leaf tissue collected from the provinces of Nariño and Santander (2), where the disease is severe. Small, triangular-shaped pieces were removed from healthy fruits that had been surface sterilized, and a corresponding piece of diseased oil palm tissue was inserted into the hole and sealed with the removed fruit tissue. The whole fruit was wrapped with plastic and incubated at 25°C. Once the fruit traps showed initial necrotic symptoms, fruit tissue from the advancing point of the lesions was plated on Phytophthora-selective media. Four isolates of Phytophtora palmivora, all A2 mating type, were obtained during this study and each presented similar white and depressed mycelium when grown on oatmeal agar (OMA) medium. Papillated, ellipsoidal sporangia with short pedicels had an average size of 37.1 (breadth) × 52.8 μm (length). Chlamydospores averaged 35.1 μm in diameter and were similar to those observed in diseased palm tissue. DNA from the Phytophthora isolates was used as a template for PCR using ITS1/ITS4 primers. BLASTn analysis of the ITS sequences (GenBank Accession No. GQ398157) showed 99.9% homology with P. palmivora. The sequences of the four isolates were identical. For pathogenicity testing, cultures were grown on OMA. Two milliliters of distilled water containing 40,000 sporangia were injected into the base of the spear leaf of 105 nursery palms; the same number of palms was injected with 2 ml of distillated water as controls. Initial PC symptoms were observed 3 to 4 days after inoculation on 85% of inoculated palms and 15% of these palms developed typical bud rot symptoms under favorable conditions. No symptoms were observed on the controls. The presence of Phytophthora was confirmed by light microscopy and P. palmivora was reisolated from symptomatic palms with the fruit-baiting technique. The presence of Phytophthora in the four Colombian growing areas was also confirmed using Agdia (Elkhart, IN) immunostrips followed by DNA extraction from the Immunostrip wick and ITS sequencing to confirm the species. To our knowledge, this is the first report of P. palmivora causing PC on oil palm in Colombia. References: (1) H. de Franqueville. Exp. Agric. 39:225, 2003. (2) G. Sarria et al. Rev. Palmas, Colombia. 29(3):31, 2008.

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