scholarly journals Quantification of Airborne Inoculum as an Aid in the Management of Leaf Blight of Onion Caused by Botrytis squamosa

Plant Disease ◽  
2005 ◽  
Vol 89 (7) ◽  
pp. 726-733 ◽  
Author(s):  
O. Carisse ◽  
H. A. McCartney ◽  
J. A. Gagnon ◽  
L. Brodeur
Keyword(s):  
Leaf Growth ◽  
Control Plot ◽  
Leaf Blight ◽  
Yield Reduction ◽  
Lesion Development ◽  
Botrytis Squamosa ◽  
Airborne Inoculum ◽  
Significant Yield ◽  
Epidemic Development ◽  
The Relationship

Botrytis leaf blight, caused by Botrytis squamosa, is a common and frequently damaging disease of onion crops, but the severity of epidemics varies widely from year to year. The disease is initiated and spread by airborne conidia. The relationship between airborne conidium concentration (ACC) and lesion development was studied in the field. A linear relationship was found between ACC and number of lesions per leaf: ACC values of 10 to 15 and 25 to 35 conidia m-3 were associated with 1 and 2.5 lesions per leaf, respectively. In 2000 and 2001, at three sites, four different criteria were used to start a fungicide spray program and their effect on epidemic development was compared with that of a grower's conventional schedule. The criteria were: at the fourth-true-leaf growth stage; according to an inoculum production index; when the ACC reached 10 to 15 conidia m-3; and when the ACC reached 25 to 35 conidia m-3. A nonsprayed control plot was included in the trial. Fungicide programs started when the ACC reached 10 to 15 conidia m-3 were as effective as the conventional program, but used fewer sprays. A fungicide spray program based on measurements of ACC and disease severity was evaluated in 2002 and 2003 in five and three commercial onion fields, respectively. At each site, half of the field was sprayed according to the grower's schedule and, in the other half, fungicide sprays were initiated when a threshold of 10 to 15 conidia m-3 or five lesions on the lower leaf (whichever came first) was reached. Overall, the number of fungicide applications was reduced by 75 and 56% in 2002 and 2003, respectively, without causing significant yield reduction. In both years, the reduction in number of fungicide applications was due mainly to the delay in initiation of the fungicide program.

scholarly journals Sensitivity and Recovery of Grain Sorghum to Simulated Drift Rates of Glyphosate, Glufosinate, and Paraquat

Agriculture ◽  
2019 ◽  
Vol 9 (4) ◽  
pp. 70 ◽  
Author(s):  
Ralph Hale ◽  
Taghi Bararpour ◽  
Gurpreet Kaur ◽  
John Seale ◽  
Bhupinder Singh ◽  
...  
Keyword(s):  
Growth Stage ◽  
Leaf Growth ◽  
Flag Leaf ◽  
Grain Sorghum ◽  
Yield Reduction ◽  
Leaf Stage ◽  
Herbicide Treatments ◽  
Significant Yield ◽  
Glyphosate Drift ◽  
Herbicide Drift

A field experiment was conducted in 2017 and 2018 to evaluate the sensitivity and recovery of grain sorghum to the simulated drift of glufosinate, glyphosate, and paraquat at two application timings (V6 and flag leaf growth stage). Paraquat drift caused maximum injury to sorghum plants in both years, whereas the lowest injury was caused by glyphosate in 2017. Averaged over all herbicide treatments, injury to grain sorghum from the simulated herbicide drift was 5% greater when herbicides were applied at flag leaf stage, as compared to herbicide applications at the six-leaf stage in 2017. In 2018, injury from glyphosate drift was higher when applied at the six-leaf stage than at the flag leaf stage. Paraquat and glufosinate drift caused more injury when applied at flag leaf stage than at six-leaf stage at 14 days after application in 2018. About 21% to 29% of injury from the simulated drift of paraquat led to a 31% reduction in grain sorghum yield, as compared to a nontreated check in 2017. The simulated drift of glyphosate and glufosinate did not result in any significant yield reduction compared to the nontreated check in 2017, possibly due to the recovery of sorghum plants after herbicides’ drift application.

scholarly journals Development of a TaqMan Real-Time PCR Assay for Quantification of Airborne Conidia of Botrytis squamosa and Management of Botrytis Leaf Blight of Onion

2009 ◽  
Vol 99 (11) ◽  
pp. 1273-1280 ◽  
Author(s):  
O. Carisse ◽  
D. M. Tremblay ◽  
C. A. Lévesque ◽  
K. Gindro ◽  
P. Ward ◽  
...  
Keyword(s):  
Real Time ◽  
Disease Risk ◽  
Quantitative Polymerase Chain Reaction ◽  
Characteristic Curve ◽  
Damage Threshold ◽  
Leaf Blight ◽  
Qpcr Assay ◽  
Botrytis Squamosa ◽  
Airborne Inoculum ◽  
Field Samples

The use of a DNA-based method for quantifying airborne inoculum of Botrytis squamosa, a damaging pathogen of onion, was investigated. A method for purifying DNA from conidia collected using rotating-arm samplers and quantifying it using a TaqMan real-time quantitative polymerase chain reaction (qPCR) assay is described. The sensitivity of the qPCR assay was high, with a detection limit of 2 conidia/rod. A linear relationship between numbers of conidia counted with a compound microscope and those determined with the qPCR assay was obtained. Receiver operating characteristic curve analysis was used to evaluate the reliability of the two methods of conidia quantification (microscope examination and qPCR assay) to predict the risk of disease being below or above a damage threshold (Dth). In total, 142 field samples from commercial onion fields were analyzed. At damage thresholds of 5 or 10 lesions/leaf, conidia quantification with the qPCR assay was more reliable at predicting disease risk than conidia quantification based on microscope counts. The proportion of decisions where the disease was present and predicted was higher for the qPCR assay than for the microscope counts, with values of 0.95 and 0.89 compared with 0.79 and 0.81 for Dth of 5 and 10 lesions/leaf, respectively. The proportion of decisions where the disease was present but not predicted was lower for the qPCR assay than for microscope counts, with values of 0.05 and 0.11 compared with 0.20 and 0.19 for Dth of 5 and 10 lesions/leaf, respectively. The results demonstrated that this new qPCR assay was reliable for quantifying B. squamosa airborne inoculum in commercial onion fields and that molecular conidia quantification could be used as a component of a risk management system for Botrytis leaf blight.

scholarly journals GENETIC VARIATION FOR REACTION TO Cephalosporium gramineum IN FOUR CROSSES OF WINTER WHEAT

1983 ◽  
Vol 63 (3) ◽  
pp. 623-630 ◽  
Author(s):  
J. M. MARTIN ◽  
D. E. MATHRE ◽  
R. H. JOHNSTON
Keyword(s):  
Genetic Variation ◽  
Winter Wheat ◽  
Variance Components ◽  
Yield Reduction ◽  
Host Reaction ◽  
Resistant Parent ◽  
Yield Trial ◽  
Significant Yield ◽  
Cephalosporium Gramineum ◽  
The Relationship

The objectives of our research were to determine the magnitude of genetic variation for reaction to Cephalosporium gramineum and to investigate the relationship among indices measuring host reaction to C. gramineum in four winter wheat crosses. PI 278212 and MT 7579 (resistance sources) were each crossed with Marias and Winalta (adapted tester lines). Seventy random F2-derived F3 progenies per cross were planted in nonreplicated rows and were inoculated with C. gramineum. Visual disease scores were recorded on a scale of 0 to 5 (0 = no white heads and 5 = 100% white heads). The F2-derived F4 progenies were planted in a replicated yield trial with control and adjacent inoculated plots the following season. Cephalosporium gramineum caused significant yield loss in all crosses and in all parents except PI 278212. Comparisons among cross means showed that mean symptom expression approached the resistant parent in all crosses. Crosses from MT 7579 had greater yield in both control and inoculated conditions but had greater yield reduction than crosses from PI 278212. Parents performed similarly in cross combinations, as there was no significant resistance source × tester line interaction. F3 disease score was not a reliable predictor of F4 inoculated yield or yield reduction. Estimates of genetic variance components and heritabilities pooled over crosses were largest relative to their standard errors for inoculated yield and smallest for yield reduction. Phenotypic and genotypic correlations were of the same sign and nearly the same magnitude with inoculated yield being positively correlated with control yield and negatively correlated with yield reduction.Key words: Cephalosporium stripe, winter wheat, host reaction

scholarly journals Characterization of Maize Genotypes (Zea mays L.) for Resistance to Striga asiatica and S. hermonthica and Compatibility with Fusarium oxysporum f. sp. strigae (FOS) in Tanzania

Agronomy ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 1004
Author(s):  
John Lobulu ◽  
Hussein Shimelis ◽  
Mark D. Laing ◽  
Arnold Angelo Mushongi ◽  
Admire Isaac Tichafa Shayanowako
Keyword(s):  
Grain Yield ◽  
Fusarium Oxysporum ◽  
Biocontrol Agent ◽  
Zea Mays L ◽  
Control Treatment ◽  
Yield Reduction ◽  
Maize Genotypes ◽  
Significant Yield ◽  
The Mean

Striga species cause significant yield loss in maize varying from 20 to 100%. The aim of the present study was to screen and identify maize genotypes with partial resistance to S. hermonthica (Sh) and S. asiatica (Sa) and compatible with Fusarium oxysporum f. sp. strigae (FOS), a biocontrol agent. Fifty-six maize genotypes were evaluated for resistance to Sh and Sa, and FOS compatibility. Results showed that FOS treatment significantly (p < 0.001) enhanced Striga management compared to the untreated control under both Sh and Sa infestations. The mean grain yield was reduced by 19.13% in FOS-untreated genotypes compared with a loss of 13.94% in the same genotypes treated with FOS under Sh infestation. Likewise, under Sa infestation, FOS-treated genotypes had a mean grain yield reduction of 18% while untreated genotypes had a mean loss of 21.4% compared to the control treatment. Overall, based on Striga emergence count, Striga host damage rating, grain yield and FOS compatibility, under Sh and Sa infestations, 23 maize genotypes carrying farmer preferred traits were identified. The genotypes are useful genetic materials in the development of Striga-resistant cultivars in Tanzania and related agro-ecologies.

scholarly journals STATISTICAL MODEL FOR THE RELATIONSHIP BETWEEN MAIZE KERNEL ORIENTATION AND SEED LEAF AZIMUTH

2015 ◽  
Vol 52 (3) ◽  
pp. 359-370
Author(s):  
ADRIAN KOLLER ◽  
GUILHERME TORRES ◽  
MICHAEL BUSER ◽  
RANDY TAYLOR ◽  
BILL RAUN ◽  
...  
Keyword(s):  
Simulation Models ◽  
Circular Statistics ◽  
Von Mises Distribution ◽  
Canopy Closure ◽  
Canopy Architecture ◽  
Maize Kernel ◽  
Angular Data ◽  
Significant Yield ◽  
Von Mises ◽  
The Relationship

SUMMARYHand-planted plots of across-row-oriented corn seeds (Zeamays L.) produce highly structured leaf canopies and have shown significant yield advantage over randomly planted plots in prior studies. For further investigation of the phenomenon by simulation, the objective of this study was to develop a probabilistic model for the correlation between seed orientation and initial plant orientation. In greenhouse trials, the azimuthal orientation of kernels of four different hybrids was recorded at planting. At collar setting of the seed leaf, the orientation of the seed leaf was determined and the angular data subjected to the analytical methods of circular statistics. The results indicate that the correlation between seed azimuth and seed leaf azimuth can be described by a von Mises distribution. The probabilistic seed to seed leaf azimuth model described herein may be implemented in simulation models to investigate the effect of canopy architecture, canopy closure and light interception efficiency of corn under conditions of seed oriented planting.

scholarly journals A BRIEF REVIEW FOR IDENTIFICATION AND DETECTION OF POTATO VIRUSES

2016 ◽  
Vol 1 (1) ◽  
pp. 33 ◽  
Author(s):  
Madiha Urooj ◽  
Uzma Arif ◽  
Anisa Intikhab
Keyword(s):  
Potato Crop ◽  
Abiotic Factors ◽  
Review Article ◽  
Pivotal Role ◽  
Yield Reduction ◽  
Human Consumption ◽  
Yield Losses ◽  
Food Crop ◽  
Potato Viruses ◽  
Significant Yield

Potato is ranked fourth among the food crop and fifth for human consumption. It provides more yield and calories production as compare to cereals. Fungal, viral, viroid, bacteria, nematode, phytoplasmas and abiotic factors play a pivotal role for yield reduction of potato crop. Viruses known to infect potato in Pakistan include PVA, PVM, PVS, PVX, PVY, PLRV and PMTV. Increasing incidence of PVX and PVY in main potato growing areas of Pakistan is getting an alarming position and PLRV has caused significant yield losses. Present review article demonstrate different techniques for diagnostics of major potato viruses.

scholarly journals Brown and Yellow Rust of Wheat in India –Significance of Climate on It’s Races and Resistance

2021 ◽  
pp. 72-91
Author(s):  
Katravath Srinivas ◽  
Shaik Moizur Rahman ◽  
Manu Yadav ◽  
Mamta Sharma
Keyword(s):  
Puccinia Striiformis ◽  
Yellow Rust ◽  
Yield Potential ◽  
Dominant Factor ◽  
Yield Reduction ◽  
Rust Disease ◽  
Comprehensive Overview ◽  
Economic Significance ◽  
Grain Damage ◽  
Significant Yield

Wheat is one of the most important staple food crops having global economic significance. Grown globally around 215 million hectares area with production of more than 600 million tons. Wheat is constrained in its production due to several biotic factors, among them yellow rust of wheat, Puccinia striiformis Westend. f.sp. tritici Eriks and Henn. (Pst) and brown rust of wheat, Puccinia recondita f.sp. tritici (Eriks. and E. Henn.) D.M. Henderson (Ptr) continues to be a serious threat and dominant factor limiting its yield potential globally. The estimated yield losses range from 10-70%, while in a severe epidemic the grain damage can be as great as 100%. Pathogens are considered to be favoured by the cooler areas but current races are more adaptable to high temperatures causing significant yield reduction in wheat. In India, prevalent pathotypes for yellow rust include 46S119, 110S119, and 238S119. Yr5, Yr10, Yr15, YrSp, and YrSk genes are resistant to Pst pathotypes in Indian conditions, while in the case of leaf rust of wheat, prevalent pathotypes are 77-5, 77-9, and 104-2. Lr9, Lr19, Lr24, Lr25, Lr29, Lr32, Lr39, Lr45, and Lr47 are the genes having resistance to Ptr pathotypes in Indian conditions. This publication provides a comprehensive overview of the stripe and leaf rusts of wheat in India and their virulent races, types of host resistance and provides a tool for effective management of wheat rust disease.

scholarly journals Effect of furrow irrigation methods and deficit irrigation levels on yield and water productivity of onion (Allium cepa L.) at Amibara, Middle Awash Valley, Ethiopia.

2021 ◽  
Author(s):  
Nigusie Abebe Sori ◽  
Kebede Nanesa Tufa ◽  
Jemal Mohammed Hassen ◽  
Wondimu Tolcha Adugna ◽  
Fikadu Robi Borana
Keyword(s):  
Deficit Irrigation ◽  
Water Productivity ◽  
Furrow Irrigation ◽  
Yield Reduction ◽  
Irrigation Methods ◽  
Middle Awash ◽  
Significant Yield ◽  
Irrigation Levels ◽  
Alternate Furrow Irrigation ◽  
Bulb Yield

Abstract Background: Deficit irrigation is one of the techniques used to enhance water productivity without significant yield loss in semiarid areas. Methods: A field experiment was conducted at Werer, Middle Awash Valley during the dry season of 2017/18, 2018/19 and, 2019/20 for three consecutive years to investigate the effects of deficit irrigation levels and furrow irrigation methods on onion yield and water productivity. Split plot design with three replications, in which the irrigation methods (Conventional, Fixed and Alternate Furrow) were assigned to the main plot and the three deficit levels (100% ETc, 75% ETc and 50% ETc), were in the sub-plot. Results: Results indicate that marketable onion bulb yield and water productivity were highly affected by the interaction effect of furrow irrigation methods and irrigation levels (p < 0.05). The highest bulb yield (17580.43 kg ha-) and water productivity (11.79 kg/m3) were obtained from conventional furrow irrigation method with100% ETc and alternate furrow irrigation with 50% ETc respectively. Considering water saved and maximum yield, Onion irrigated by AFI 100% ETC resulted in a 15% yield reduction with up to 50% irrigation water saving as compared to CFI 100% ETc. Conclusion: The present study suggests that, under water limiting conditions, adopting alternate furrow irrigation with 100% ETc can be an alternative to increase water productivity without significant yield reduction.

Effect of Potato virus Y on Yield of Three Potato Cultivars Grown Under Different Nitrogen Levels

Plant Disease ◽  
2006 ◽  
Vol 90 (1) ◽  
pp. 73-76 ◽  
Author(s):  
Jonathan L. Whitworth ◽  
Phil Nolte ◽  
Chris McIntosh ◽  
Robert Davidson
Keyword(s):  
Potato Virus ◽  
Potato Virus Y ◽  
Total Yield ◽  
Russet Burbank ◽  
Yield Reduction ◽  
Symptom Expression ◽  
Russet Norkotah ◽  
Nitrogen Levels ◽  
Foliar Symptoms ◽  
Significant Yield

Previous studies have shown that Potato virus Y (PVY) reduces yield in many cultivars. Typical foliar symptoms can include veinal necrosis, leaf drop, and a mosaic pattern sometimes accompanied by leaf roughness. Infection by PVY in Russet Burbank produces identifiable PVY symptoms, whereas cv. Russet Norkotah expresses mild, almost latent symptoms. Yield also is influenced by nitrogen fertilizer levels. This research was conducted to determine whether increased nitrogen mitigates yield reduction caused by PVY. Russet Norkotah, CO80011-5, and Russet Burbank were used in replicated plots of non-PVY-infected and PVY-infected plants at three nitrogen levels in 1995 and 1996. There was a significant yield reduction between PVY-negative and PVY-positive plots in all cultivars, at most nitrogen levels. PVY yield reduction was similar (approximately 38%) in the mild symptom expression clones of Russet Norkotah and CO80011-5, whereas the yield reduction in Russet Burbank, which exhibits typical symptom expression, was 63.5%. We conclude that increased nitrogen can influence total yield, but does not significantly mitigate the yield reduction due to PVY infection.

Sign in / Sign up

Export Citation Format

Share Document