scholarly journals Epidemiological Significance of Crown Rot in the Fruiting Field in Relation to Colletotrichum gloeosporioides Infection of Strawberry Nursery Plants

Plant Disease ◽  
2017 ◽  
Vol 101 (6) ◽  
pp. 907-915
Author(s):  
Mahfuzur Rahman ◽  
Frank J. Louws
Keyword(s):  
North Carolina ◽  
Colletotrichum Gloeosporioides ◽  
Disease Risk ◽  
Crown Rot ◽  
Research Station ◽  
Yield Losses ◽  
Marketable Yield ◽  
Percent Increase ◽  
Mother Plants ◽  
Fruit Harvest

Anthracnose crown rot (ACR), caused by Colletotrichum gloeosporioides, is a serious disease of strawberry (Fragaria × ananassa) in the southeastern United States, and there is a need to determine the link between nursery and fruiting-field disease risk. A 2-year study in 2007, repeated in 2008, was conducted at the North Carolina State University Horticultural Crops Research Station, Clinton, using ‘Chandler’, the most popular cultivar in North Carolina and one that is highly susceptible to ACR. Mother plants in a summer nursery were inoculated midseason with three pathogenic strains of C. gloeosporioides at an incidence level of 0, 5, 10, or 25%. Asymptomatic runner plants were selected at maturity (85 to 88 days after inoculation) from the nursery in early to mid-October from within a 0.5-m (inner) or 0.5- to 1.0-m (outer) radius around inoculated mother plants and planted into a plasticulture fruiting field system, with fruit harvest in April to June the following spring. Plants collected from the 25%-inner treatment had the greatest area under the disease progress curve (AUDPC) values, with a terminal ACR-related plant mortality of 32 and 20% by the end of fruit harvest and marketable yield losses of 30.5 and 30.2% in 2007–08 (Yr1) and 2008–09 (Yr2) seasons, respectively. All treatments increased AUDPC values compared with noninoculated treatments except the 10%-outer (O) and 5%-O treatments in Yr1 and Yr2, respectively. Marketable yield decreased 291.6 kg/ha for every percent increase in inoculum level (i.e., 0 to 25%, R2 = 0.696, P = 0.001). Levels of quiescent infection (QI) incidence (percentage of sampled leaves) assessed 25 to 28 days before digging runner plants also directly affected yield. For example, yield decreased 131.0 kg/ha for every percent increase in QI incidence in mother plants (R2 = 0.744, P = 0.001). Immersion of plants in fungicide solutions prior to planting decreased AUDPC values and improved plant stand by 7 to 11% but did not affect marketable yield compared with controls. This study provides results that can enable nursery and fruit growers to assess risk and implement mitigation measures to limit nursery plant and fruit yield losses.

scholarly journals Genetic Variation and Gains in Resistance of Strawberry to Colletotrichum gloeosporioides

2014 ◽  
Vol 104 (1) ◽  
pp. 67-74 ◽  
Author(s):  
L. F. Osorio ◽  
J. A. Pattison ◽  
N. A. Peres ◽  
V. M. Whitaker
Keyword(s):  
North Carolina ◽  
Genetic Variation ◽  
Genetic Control ◽  
Colletotrichum Gloeosporioides ◽  
Crown Rot ◽  
Additive Variance ◽  
Resistant Parent ◽  
Genetic Gains ◽  
The North ◽  
Diallel Mating Design

Anthracnose crown rot is an important disease of strawberry primarily caused by Colletotrichum gloeosporioides in Florida and North Carolina. Information on the magnitude of additive and nonadditive genetic variation is required to define breeding strategies and to estimate potential genetic gains. However, little is known about the genetic control of resistance and its utility in breeding. Our objectives were to obtain estimates of heritabilities and of components of genetic variances, genotype–environment interactions, and gains for resistance, and to examine the effects of locations and transplant types on the estimates. An incomplete diallel mating design generated 42 full-sib families, which were propagated in plugs from seed (seedling tests) and as bare-root runner plants (clonal tests) of different genotypes of the same families. Both seedlings and clones were inoculated with C. gloeosporioides under field conditions in North Carolina and Florida during the 2010–11 season. Narrow-sense heritability (h2) and broad-sense heritability (H2) for both clones and seedlings were higher at the North Carolina location (h2 = 0.34 to 0.62 and H2 = 0.46 to 0.85) than at the Florida location (h2 = 0.16 to 0.22 and H2 = 0.37 to 0.46). Likewise, the seedling tests showed higher genetic control than the clonal tests at both locations. Estimates of dominance variance were approximately one-third of the additive variance at North Carolina and were even larger at Florida. Epistasis was negative at both locations and assumed zero for heritability (H2) calculations. Genotype–environment interactions were different by transplant type, suggesting rank changes across locations. ‘Pelican’ was the most resistant parent at both locations, followed by ‘NCH09-68’ at the NC location and ‘Winter Dawn’ at the Florida location. Selection and deployment of the most resistant clone within each of the five best families is estimated to produce average genetic gains of 53.0 and 73.7% at the North Carolina and Florida locations, respectively.

scholarly journals Initial Inoculum and Spatial Dispersal of Colletotrichum gloeosporioides, the Causal Agent of Strawberry Anthracnose Crown Rot

Plant Disease ◽  
2015 ◽  
Vol 99 (1) ◽  
pp. 80-86 ◽  
Author(s):  
Mahfuzur Rahman ◽  
Peter Ojiambo ◽  
Frank Louws
Keyword(s):  
Power Law ◽  
Colletotrichum Gloeosporioides ◽  
Exponential Model ◽  
Crown Rot ◽  
Plant Production ◽  
Inoculum Source ◽  
Initial Inoculum ◽  
Nursery Production ◽  
Mother Plants ◽  
Modified Power Law

Anthracnose crown rot (ACR), caused by Colletotrichum gloeosporioides, is a serious disease of strawberry (Fragaria × ananassa) in nurseries and fruiting fields in the southeastern United States. This study was conducted to determine the potential of alternative hosts for initial inoculum source and spread that causes ACR in strawberry nurseries. Results indicated that Parthenocissus quinquefolia is a noncultivated host of C. gloeosporioides in North Carolina and may serve as an initial inoculum source for planting material. Sources of inoculum data were complemented with a 2-year study of disease incidence and spread in simulated nursery production experiments. Sixty days after inoculation of the mother plants in the nursery, three different inoculation levels showed a significant positive correlation (r = 0.78, P < 0.004) with the quiescent infection (QI) incidence on the runner or daughter plants at the end of the nursery production cycle. Runner plant counts from different proportion of mother plants' inoculation treatments indicated that runner plant production was negatively and significantly (P < 0.001) affected by C. gloeosporioides. Infected tips used to produce transplants destined for fruit production resulted in 29.3 and 16.8% mortality in plug trays in 2007 and 2008, respectively. Tracking foliar QI incidence that resulted from dispersal of inoculum from an introduced point source in the nursery showed a sharp decline at 1 m and beyond from the inoculation focus. Although the exponential model (R2 = 0.92 to 0.94) had slightly higher coefficients of determination than the modified power law (R2 = 0.89 to 0.90), residual plots indicated that the modified power law model fit the disease gradient data better than the exponential model in both years. Results from our dispersal study indicated that rogueing of infected plants within a 4-m radius of infection foci would reduce the risk of transferring infected runner plants from the nursery to the fruiting field.

scholarly journals Effectiveness of Fungicides and Their Application Timing for the Management of Sorghum Foliar Anthracnose in the Mid-Atlantic United States

Plant Disease ◽  
2019 ◽  
Vol 103 (11) ◽  
pp. 2804-2811 ◽  
Author(s):  
Bhupendra Acharya ◽  
Thomas N. O’Quinn ◽  
Wesley Everman ◽  
Hillary L. Mehl
Keyword(s):  
United States ◽  
North Carolina ◽  
Grain Yield ◽  
Disease Onset ◽  
Yield Losses ◽  
Single Application ◽  
Application Timing ◽  
Sorghum Anthracnose ◽  
Percent Increase ◽  
Dough Stage

Sorghum anthracnose (Colletotrichum sublineola) reduces grain yield up to 50% but suggested management tactics have not yet been developed for the mid-Atlantic United States, where warm, wet conditions favor disease. Under factorial arrangement, five fungicides plus a nontreated control and four application timings were compared for foliar anthracnose control, yield, and profitability of fungicide use in grain sorghum over eight site-years in Virginia and North Carolina. Anthracnose severity was rated at the hard dough stage, and grain yield was determined at harvest. Every percent increase in disease severity resulted in yield losses of 27 to 85 kg/ha. Pyraclostrobin and pyraclostrobin plus fluxapyroxad reduced anthracnose (P < 0.01), and three applications resulted in less disease and greater yield compared with single applications (P < 0.01). However, three applications exceed the labeled maximum application for the fungicides and are not economical. Among single applications, boot or flowering timings reduced disease, and flowering applications resulted in the overall greatest yield. Results suggest that when disease onset occurs at or prior to boot, a single application of pyraclostrobin-containing fungicide at or just prior to flowering reduces anthracnose, protects yield, and increases income. However, when disease is absent or severity is low prior to flowering, fungicide application may not be profitable.

scholarly journals Pre-harvest field application of enhanced freshness formulation reduces yield loss in orange

2020 ◽  
Vol 7 (1) ◽  
Author(s):  
Jaspa Samwel ◽  
Theodosy Msogoya ◽  
Abdul Kudra ◽  
Hosea Dunstan Mtui ◽  
Anna Baltazari ◽  
...  
Keyword(s):  
Yield Loss ◽  
Sweet Orange ◽  
New Technology ◽  
Significant Negative Correlation ◽  
Field Application ◽  
Yield Losses ◽  
Factorial Experiments ◽  
Marketable Yield ◽  
Pest Damage ◽  
Marketable Fruit

Abstract Background Orange (Citrus sinensis L.) production in Tanzania is constrained by several pre-harvest factors that include pests. Hexanal, sprayed as Enhanced Freshness Formulation (EFF) is a relatively new technology that has been reported to reduce pre-harvest loss in fruits. However, the effects of hexanal on pre-harvest yield loss of orange are not known. We studied the effects of hexanal as EFF on yield losses of three sweet orange cultivars namely, Early Valencia, Jaffa, and Late Valencia. Factorial experiments tested the effects of EFF concentration, variety, and time of EFF application on number of dropped fruit, percentage of non-marketable fruit and incidence of pest damage. Results Results showed significant negative correlation (p < 0.001) between EFF and the percentage of dropped fruit, non-marketable yield, and incidence of pest damage. An increase in hexanal concentration by 1%, is expected to reduce number of dropped fruit by 50, percentage of non-marketable by 35.6, and incidences of pest damage by 36.5% keeping other factors constant. Results also show significant association (p < 0.001) between time of hexanal application and non-marketable yield. Percentage of dropped fruit is expected to increase by 1 for each day away from harvest, keeping other factors constant. Conclusion Pre-harvest application of hexanal as EFF can significantly reduce number of dropped fruits, percentage of non-marketable fruit and incidence of pest damage.

Critical Period for Palmer Amaranth (Amaranthus palmeri) Control in Pickling Cucumber

2018 ◽  
Vol 32 (5) ◽  
pp. 586-591
Author(s):  
Samuel J. McGowen ◽  
Katherine M. Jennings ◽  
Sushila Chaudhari ◽  
David W. Monks ◽  
Jonathan R. Schultheis ◽  
...  
Keyword(s):  
North Carolina ◽  
Critical Period ◽  
Relative Yield ◽  
Field Studies ◽  
Palmer Amaranth ◽  
Amaranthus Palmeri ◽  
Marketable Yield ◽  
Yield Data ◽  
Pickling Cucumber ◽  
Cucumber Yield

AbstractField studies were conducted in North Carolina to determine the critical period for Palmer amaranth control (CPPAC) in pickling cucumber. In removal treatments (REM), emerged Palmer amaranth were allowed to compete with cucumber for 14, 21, 28, or 35 d after sowing (DAS) in 2014 and 14, 21, 35, or 42 DAS in 2015, and cucumber was kept weed-free for the remainder of the season. In the establishment treatments (EST), cucumber was maintained free of Palmer amaranth by hand removal until 14, 21, 28, or 35 DAS in 2014 and until 14, 21, 35, or 42 DAS in 2015; after this, Palmer amaranth was allowed to establish and compete with the cucumber for the remainder of the season. The beginning and end of the CPPAC, based on 5% loss of marketable yield, was determined by fitting log-logistic and Gompertz equations to the relative yield data representing REM and EST, respectively. Season-long competition by Palmer amaranth reduced pickling cucumber yield by 45% to 98% and 88% to 98% during 2014 and 2015, respectively. When cucumber was planted on April 25, 2015, the CPPAC ranged from 570 to 1,002 heat units (HU), which corresponded to 32 to 49 DAS. However, when cucumber planting was delayed 2 to 4 wk (May 7 and May 21, 2014 and May 4, 2015), the CPPAC lasted from 100 to 918 HU (7 to 44 DAS). This research suggested that planting pickling cucumber as early as possible during the season may help to reduce competition by Palmer amaranth and delay the beginning of the CPPAC.

Effect of inbreeding and individual increase in inbreeding on growth in Nilagiri and Sandyno breeds of sheep

2016 ◽  
Vol 58 ◽  
pp. 63-71 ◽  
Author(s):  
R. Venkataramanan ◽  
A. Subramanian ◽  
S.N. Sivaselvam ◽  
T. Sivakumar ◽  
C. Sreekumar ◽  
...  
Keyword(s):  
Growth Traits ◽  
Inbreeding Coefficient ◽  
Pedigree Information ◽  
Research Station ◽  
Sheep Breeding ◽  
Inbreeding Coefficients ◽  
Equivalent Number ◽  
Breeding Research ◽  
Percent Increase ◽  
Two Populations

SummaryIndividual increase in inbreeding coefficients (ΔFi) has been recommended as an alternate measure of inbreeding. It can account for the differences in pedigree knowledge of individual animals and avoids overestimation due to increased number of known generations. The effect of inbreeding (F) and equivalent inbreeding (EF) calculated fromΔFi, on growth traits were studied in Nilagiri and Sandyno flocks of sheep. The study was based on data maintained at the Sheep Breeding Research Station, Sandynallah. The pedigree information and equivalent number of generations were less in Sandyno compared with Nilagiri sheep. The average F and EF for the Nilagiri population were 2.17 and 2.44, respectively and the corresponding values for Sandyno sheep were 0.83 and 0.84, respectively. The trend of inbreeding over years in both the populations indicated that EF was higher during earlier generations when pedigree information was shallow. Among the significant effects of inbreeding, the depression in growth per 1 percent increase in inbreeding ranged from 0.04 kg in weaning weight to 0.10 kg in yearling weight. In general, more traits were affected by inbreeding in Nilagiri sheep, in which greater regression of growth traits was noticed with F compared with EF. Higher values of EF than F in earlier generations in both the populations indicate that EF avoided the potential overestimation of inbreeding coefficient during recent generations. In the Sandyno population, the magnitude of depression noticed among growth traits with significant effects of inbreeding was higher. The differences in response to F and EF noticed in the two populations and possible causes for the trait wise differences in response to F and EF are appropriately discussed.

scholarly journals Sour cherry anthracnose and possibilities of the control with special regard to resident Glomerella population in sour cherry plantations of East Hungary

2010 ◽  
pp. 12-17 ◽  
Author(s):  
Gyula Oros ◽  
László Vajna ◽  
Klára Balázs ◽  
Zoltán Fekete ◽  
Zoltán Naár ◽  
...  
Keyword(s):  
Fruit Ripening ◽  
Fungal Pathogen ◽  
Colletotrichum Gloeosporioides ◽  
Rapid Development ◽  
Sour Cherry ◽  
Control Measures ◽  
Yield Losses ◽  
Trichoderma Species ◽  
Special Regard

Anthracnose is considered one of the most destructive diseases for sour cherry production due to the rapid development of the disease on fruits. Glomerella cingulata (Stoneman) Spauld. & H. Schrenk (anam.: Colletotrichum gloeosporioides (Penz.) Penz. & Sacc. in Penz.) has been the fungal pathogen responsible for anthracnose in last decades. Yield losses greater than 90% may occur under epidemic conditions. C. acutatum (J.H. Simmonds, 1968) strains were isolated of sourcherry plantations in East Hungary and this pathogen, new for Hungarian microbiont became recently dominant. Contrarily to the former species it is certainly transmitted with ants during fruit ripening. About third of strains proved to be cutinase producers that enable them to actively penetrate via cuticule, and these strains infect directly berries of blackberry, grape and tomato as well as plum and apple. Most of cutinase negative strains could also infect these fruits after mechanic injury. All strains of both species produce amylase, cellulase, lecithinase, lipase, polyfenoloxydase and protease in vitro, although the activity of these enzymes highly varied in the medium. The only C. acutatum strains produced noticeable amount of chitinase. Strains, tolerant to recently applied fungicides to control the anthracnose, could be isolated of sour cherry plantations that might be the cause of ineffectiveness of control measures in 2010. The mycofungicide containing mixture of three Trichoderma species in oil carrier could efficiently depress the development of anthracnose in ripening sour cherry.

Critical timing of Palmer amaranth (Amaranthus palmeri) removal in sweetpotato

2020 ◽  
Vol 34 (4) ◽  
pp. 547-551 ◽  
Author(s):  
Stephen C. Smith ◽  
Katherine M. Jennings ◽  
David W. Monks ◽  
Sushila Chaudhari ◽  
Jonathan R. Schultheis ◽  
...  
Keyword(s):  
North Carolina ◽  
Logistic Model ◽  
Yield Loss ◽  
Relative Yield ◽  
Field Studies ◽  
Palmer Amaranth ◽  
Amaranthus Palmeri ◽  
Marketable Yield ◽  
Yield Data ◽  
Critical Timing

AbstractPalmer amaranth is the most common and troublesome weed in North Carolina sweetpotato. Field studies were conducted in Clinton, NC, in 2016 and 2017 to determine the critical timing of Palmer amaranth removal in ‘Covington’ sweetpotato. Palmer amaranth was grown with sweetpotato from transplanting to 2, 3, 4, 5, 6, 7, 8, and 9 wk after transplanting (WAP) and maintained weed-free for the remainder of the season. Palmer amaranth height and shoot dry biomass increased as Palmer amaranth removal was delayed. Season-long competition by Palmer amaranth interference reduced marketable yields by 85% and 95% in 2016 and 2017, respectively. Sweetpotato yield loss displayed a strong inverse linear relationship with Palmer amaranth height. A 0.6% and 0.4% decrease in yield was observed for every centimeter of Palmer amaranth growth in 2016 and 2017, respectively. The critical timing for Palmer amaranth removal, based on 5% loss of marketable yield, was determined by fitting a log-logistic model to the relative yield data and was determined to be 2 WAP. These results show that Palmer amaranth is highly competitive with sweetpotato and should be managed as early as possible in the season. The requirement of an early critical timing of weed removal to prevent yield loss emphasizes the importance of early-season scouting and Palmer amaranth removal in sweetpotato fields. Any delay in removal can result in substantial yield reductions and fewer premium quality roots.

AC Nordica alfalfa

1994 ◽  
Vol 74 (1) ◽  
pp. 145-147 ◽  
Author(s):  
B. P. Goplen ◽  
B. D. Gossen
Keyword(s):  
Medicago Sativa ◽  
Winter Hardiness ◽  
Crown Rot ◽  
Research Station ◽  
Snow Mold ◽  
Peace River ◽  
Tap Root ◽  
Cultivar Description ◽  
Medicago Sativa L ◽  
Moderately Resistant

AC Nordica alfalfa (Medicago sativa L.) was developed by the Agriculture Canada Research Station at Saskatoon, Saskatchewan. It is similar to Beaver alfalfa in having a broad crown and a tap root with many branches. AC Nordica is 1–2 d earlier in maturity than Beaver. It is shorter than Beaver at 10% bloom, is slightly slower in regrowth following harvest, and displays less spring vigor. However, it excels in winter hardiness, rating similar to Anik and Drylander alfalfa. AC Nordica is highly resistant to bacterial wilt (Clavibacter michiganense subsp. insidiosum [McCulloch] Davis, Gillaspie, Vidaver & Harris), and moderately resistant to snow mold (Coprinus psychromorbidus Redhead & Traquair). AC Nordica is intended as a special-purpose cultivar for the northern prairies, the Peace River area of Alberta, and other high snowfall areas where snow mold (winter crown rot) may occur and where extreme winter hardiness is required. Key words: Alfalfa, Medicago sativa, winter hardiness, winter crown rot, snow mold, cultivar description

scholarly journals Impacts of Crop Variety and Time of Inoculation on the Susceptibility and Tolerance of Winter Wheat to Wheat streak mosaic virus

Plant Disease ◽  
2014 ◽  
Vol 98 (8) ◽  
pp. 1060-1065 ◽  
Author(s):  
Z. Miller ◽  
F. Menalled ◽  
D. Ito ◽  
M. Moffet ◽  
M. Burrows
Keyword(s):  
Winter Wheat ◽  
Mosaic Virus ◽  
Great Plains ◽  
Disease Risk ◽  
Wheat Yield ◽  
Wheat Streak Mosaic Virus ◽  
Northern Great Plains ◽  
Yield Losses ◽  
South Central ◽  
The Impact

Plant genotype, age, size, and environmental factors can modify susceptibility and tolerance to disease. Understanding the individual and combined impacts of these factors is needed to define improved disease management strategies. In the case of Wheat streak mosaic virus (WSMV) in winter wheat, yield losses and plant susceptibility have been found to be greatest when the crop is exposed to the virus in the fall in the central and southern Great Plains. However, the seasonal dynamics of disease risk may be different in the northern Great Plains, a region characterized by a relatively cooler fall conditions, because temperature is known to modify plant–virus interactions. In a 2-year field study conducted in south-central Montana, we compared the impact of fall and spring WSMV inoculations on the susceptibility, tolerance, yield, and grain quality of 10 winter wheat varieties. Contrary to previous studies, resistance and yields were lower in the spring than in the fall inoculation. In all, 5 to 7% of fall-inoculated wheat plants were infected with WSMV and yields were often similar to uninoculated controls. Spring inoculation resulted in 45 to 57% infection and yields that were 15 to 32% lower than controls. Although all varieties were similarly susceptible to WSMV, variations in tolerance (i.e., yield losses following exposure to the virus) were observed. These results support observations that disease risk and impacts differ across the Great Plains. Possible mechanisms include variation in climate and in the genetic composition of winter wheat and WSMV across the region.

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