scholarly journals Interaction of Onion Cultivar and Growth Stages on Incidence of Pantoea ananatis Bulb Infection

Plant Disease ◽  
2017 ◽  
Vol 101 (9) ◽  
pp. 1616-1620 ◽  
Author(s):  
Spencer Stumpf ◽  
Ron Gitaitis ◽  
Timothy Coolong ◽  
Cliff Riner ◽  
Bhabesh Dutta
Keyword(s):  
Leaf Senescence ◽  
Lower Incidence ◽  
Growth Stage ◽  
Management Strategies ◽  
Economic Losses ◽  
Growth Stages ◽  
Pantoea Ananatis ◽  
Bacterial Diseases ◽  
Onion Bulbs ◽  
Onion Cultivar

Center rot, caused by Pantoea ananatis, has been one of the most important bacterial diseases of onion leading to considerable economic losses. Symptoms can be expressed in the onion foliage and bulb, with the pathogen moving from the infected leaves to bulb scales. However, little is known regarding which growth stage the plant is most susceptible to bulb infection and if there are differences in susceptibility to bulb infection among sweet onion cultivars. In this study, five cultivars of sweet onion (Pirate, Sweet Harvest, 1518, Granex YPRR, and 1407) were inoculated by clipping the tips of onion foliage and depositing 1 ml of 1 × 108 CFU/ml of P. ananatis suspension into the central leaf cavity. The inoculations were done at three growth stages (first leaf senescence, bulb initiation, and bulb swelling). Center rot incidence was assessed for precured and cured onion bulbs. In addition, total bulb incidence of center rot for each cultivar inoculated at three growth stages were also calculated. Total bulb center rot incidence was significantly higher for Granex YPRR (84%) compared with other cultivars. Also, cultivars 1518 (49%) and 1407 (33%) had significantly lower incidence of bulb infection compared with other tested cultivars. Onions were significantly more susceptible to bulb infection when inoculated during first leaf senescence (62%) as compared with bulb initiation (37%) and bulb swelling (31%) stages in precured bulbs (P = 0.041). Significantly higher incidence of center rot was observed for bulbs whose foliage were inoculated during first leaf senescence stage (64%) compared with bulb initiation (55%) and bulb swelling (52%) stages (P = 0.048). Interactions between onion cultivar and inoculation stage on center rot bulb incidence were not significant (P ≥ 0.218), when evaluated at different assessment periods. However, different cultivars displayed significant variability in susceptibility to bulb infection. The outcomes of this study may have implications in devising management strategies aimed at protecting most susceptible onion growth stages against P. ananatis.

scholarly journals Identification of Wheat Yellow Rust Using Optimal Three-Band Spectral Indices in Different Growth Stages

Sensors ◽  
2018 ◽  
Vol 19 (1) ◽  
pp. 35 ◽  
Author(s):  
Qiong Zheng ◽  
Wenjiang Huang ◽  
Ximin Cui ◽  
Yingying Dong ◽  
Yue Shi ◽  
...  
Keyword(s):  
Classification Accuracy ◽  
Growth Stage ◽  
Yellow Rust ◽  
Kappa Coefficient ◽  
Economic Losses ◽  
Growth Stages ◽  
Spectral Indices ◽  
Rust Disease ◽  
Late Growth ◽  
Different Growth Stages

Yellow rust, a widely known destructive wheat disease, affects wheat quality and causes large economic losses in wheat production. Hyperspectral remote sensing has shown potential for the detection of plant disease. This study aimed to analyze the spectral reflectance of the wheat canopy in the range of 350–1000 nm and to develop optimal spectral indices to detect yellow rust disease in wheat at different growth stages. The sensitive wavebands of healthy and infected wheat were located in the range 460–720 nm in the early-mid growth stage (from booting to anthesis), and in the ranges 568–709 nm and 725–1000 nm in the mid-late growth stage (from filling to milky ripeness), respectively. All possible three-band combinations over these sensitive wavebands were calculated as the forms of PRI (Photochemical Reflectance Index) and ARI (Anthocyanin Reflectance Index) at different growth stages and assessed to determine whether they could be used for estimating the severity of yellow rust disease. The optimal spectral index for estimating wheat infected by yellow rust disease was PRI (570, 525, 705) during the early-mid growth stage with R2 of 0.669, and ARI (860, 790, 750) during the mid-late growth stage with R2 of 0.888. Comparison of the proposed spectral indices with previously reported vegetation indices were able to satisfactorily discriminate wheat yellow rust. The classification accuracy for PRI (570, 525, 705) was 80.6% and the kappa coefficient was 0.61 in early-mid growth stage, and the classification accuracy for ARI (860, 790, 750) was 91.9% and the kappa coefficient was 0.75 in mid-late growth stage. The classification accuracy of the two indices reached 84.1% and 93.2% in the early-mid and mid-late growth stages in the validated dataset, respectively. We conclude that the three-band spectral indices PRI (570, 525, 705) and ARI (860, 790, 750) are optimal for monitoring yellow rust infection in these two growth stages, respectively. Our method is expected to provide a technical basis for wheat disease detection and prevention in the early-mid growth stage, and the estimation of yield losses in the mid-late growth stage.

scholarly journals ​​Performance of Cereals under Need based Nitrogen Management Strategies: A Review

2021 ◽  
Author(s):  
Rayapati Karthik ◽  
Devilal Dhaker ◽  
L. Peace Raising
Keyword(s):  
Precision Agriculture ◽  
Environmental Sustainability ◽  
Management Strategies ◽  
Crop Growth ◽  
Nitrogen Management ◽  
Nitrogen Fertilizers ◽  
Economic Losses ◽  
Growth Stages ◽  
Canopy Reflectance ◽  
Economic Returns

Cereals have large nitrogen requirement, but the demand for fertilizer is variable. Divergence between the supply and requirement of nitrogen can potentially hamper the crop growth as well as the environment, resulting in poor nitrogen use efficiency leads to economic losses. A balance between supply and utilization is required to optimize crop growth, economic returns and to maintain environmental sustainability which can be solved through need based nitrogen management which is nothing but application of inputs is according to the needs of the farm. Spatial variability is present in the fields but often they receive a same dose of fertilizers because they are treated by farmers as a homogenous unit. Through need based strategies, farmers will supply nitrogen fertilizers according to the demand of the crop which reduce the losses of N fertilizer. A precision agriculture approach to address the disparate spatial N requirements across a field is the use of a variable rate application guided by crop canopy reflectance sensors. Sensors like SPAD chlorophyll meter, greenseeker, rapid SCAN etc are used for determining the nitrogen need of the field crops. Many researchers across the globe are working on standardization of these sensors for different growth stages of the crop. Precision input management in cereals is lacking at present in most of the growing areas. A good amount of information on crop nutrition is available, but information regarding need based N management is lacking. This article reviews the work done on need based nitrogen management strategies in cereals.

scholarly journals Foliar chemical protection against Pantoea ananatis in onion is negated by thrips feeding

2020 ◽  
Author(s):  
Spencer Stumpf ◽  
Leanna Leach ◽  
Rajagopalbab Srinivasan ◽  
Tim Coolong ◽  
Ron Gitaitis ◽  
...  
Keyword(s):  
Growth Stage ◽  
Cost Effective ◽  
The United States ◽  
Thrips Tabaci ◽  
Growth Stages ◽  
Pantoea Ananatis ◽  
Chemical Treatments ◽  
Frankliniella Fusca ◽  
Cupric Hydroxide ◽  
Bulb Rot

Center rot of onion, caused by Pantoea ananatis, is an economically important disease in onion production in Georgia and elsewhere in the United States. Growers rely on frequent foliar applications of bactericides, and in some cases, plant defense inducers to manage this disease. However, regular prophylactic applications of these chemicals is not cost-effective and may not be environmentally friendly. Thrips (Thrips tabaci and Frankliniella fusca) are vectors of P. ananatis, and their feeding may compromise the effectiveness of foliar applications against P. ananatis. In this study, foliar treatments of acibenzolar-S-methyl (Actigard 50WG), cupric hydroxide (Kocide 3000), and Actigard + Kocide were evaluated for their effectiveness in the presence and absence of thrips infestation at two critical onion-growth stages; bulb initiation and bulb swelling. Onion growth stage had no impact on effectiveness of either Kocide or Actigard. In the absence of thrips, Kocide application resulted in reduced center rot incidence compared with Actigard, regardless of the growth stage. However, when thrips were present, the efficacy of both Kocide and Actigard was reduced with bulb incidence not significantly different from the non-treated control. In independent greenhouse studies in the presence or absence of thrips, it was observed that use of protective chemicals (Kocide or Actigard and their combinations) at different rates also affected the pathogen progression into the internal neck tissue and incidence of bulb rot. These results suggest that thrips infestation can reduce the efficacy of protective chemical treatments against P. ananatis.

scholarly journals Growth Stages Classification of Potato Crop Based on Analysis of Spectral Response and Variables Optimization

Sensors ◽  
2020 ◽  
Vol 20 (14) ◽  
pp. 3995 ◽  
Author(s):  
Ning Liu ◽  
Ruomei Zhao ◽  
Lang Qiao ◽  
Yao Zhang ◽  
Minzan Li ◽  
...  
Keyword(s):  
Growth Stage ◽  
Spectral Response ◽  
Classification Model ◽  
Growth Stages ◽  
Potato Field ◽  
Spectral Bands ◽  
Svm Model ◽  
Selection Algorithms ◽  
Potato Crops

Potato is the world’s fourth-largest food crop, following rice, wheat, and maize. Unlike other crops, it is a typical root crop with a special growth cycle pattern and underground tubers, which makes it harder to track the progress of potatoes and to provide automated crop management. The classification of growth stages has great significance for right time management in the potato field. This paper aims to study how to classify the growth stage of potato crops accurately on the basis of spectroscopy technology. To develop a classification model that monitors the growth stage of potato crops, the field experiments were conducted at the tillering stage (S1), tuber formation stage (S2), tuber bulking stage (S3), and tuber maturation stage (S4), respectively. After spectral data pre-processing, the dynamic changes in chlorophyll content and spectral response during growth were analyzed. A classification model was then established using the support vector machine (SVM) algorithm based on spectral bands and the wavelet coefficients obtained from the continuous wavelet transform (CWT) of reflectance spectra. The spectral variables, which include sensitive spectral bands and feature wavelet coefficients, were optimized using three selection algorithms to improve the classification performance of the model. The selection algorithms include correlation analysis (CA), the successive projection algorithm (SPA), and the random frog (RF) algorithm. The model results were used to compare the performance of various methods. The CWT-SPA-SVM model exhibited excellent performance. The classification accuracies on the training set (Atrain) and the test set (Atest) were respectively 100% and 97.37%, demonstrating the good classification capability of the model. The difference between the Atrain and accuracy of cross-validation (Acv) was 1%, which showed that the model has good stability. Therefore, the CWT-SPA-SVM model can be used to classify the growth stages of potato crops accurately. This study provides an important support method for the classification of growth stages in the potato field.

scholarly journals Growth and Phenology of Vulpia Myuros in Comparison with Apera Spica-Venti, Alopecurus Myosuroides and Lolium Multiflorum in Monoculture and in Winter Wheat

Plants ◽  
2020 ◽  
Vol 9 (11) ◽  
pp. 1495
Author(s):  
Muhammad Javaid Akhter ◽  
Bo Melander ◽  
Solvejg Kopp Mathiassen ◽  
Rodrigo Labouriau ◽  
Svend Vendelbo Nielsen ◽  
...  
Keyword(s):  
Winter Wheat ◽  
Weed Management ◽  
Lolium Multiflorum ◽  
Management Strategies ◽  
Integrated Weed Management ◽  
Growth Stages ◽  
Neighborhood Design ◽  
Alopecurus Myosuroides ◽  
Winter Cereals ◽  
Arable Weed

Vulpia myuros has become an increasing weed problem in winter cereals in Northern Europe. However, the information about V. myuros and its behavior as an arable weed is limited. Field and greenhouse experiments were conducted in 2017/18 and 2018/19, at the Department of Agroecology in Flakkebjerg, Denmark to investigate the emergence, phenological development and growth characteristics of V. myuros in monoculture and in mixture with winter wheat, in comparison to Apera spica-venti, Alopecurus myosuroides and Lolium multiflorum. V. myuros emerged earlier than A. myosuroides and A. spica-venti but later than L. multiflorum. Significant differences in phenological development were recorded among the species. Overall phenology of V. myuros was more similar to that of L. multiflorum than to A. myosuroides and A. spica-venti. V. myuros started seed shedding earlier than A. spica-venti and L. multiflorum but later than A. myosuroides. V. myuros was more sensitive to winter wheat competition in terms of biomass production and fecundity than the other species. Using a target-neighborhood design, responses of V. myuros and A. spica-venti to the increasing density of winter wheat were quantified. At early growth stages “BBCH 26–29”, V. myuros was suppressed less than A. spica-venti by winter wheat, while opposite responses were seen at later growth stages “BBCH 39–47” and “BBCH 81–90”. No significant differences in fecundity characteristics were observed between the two species in response to increasing winter wheat density. The information on the behavior of V. myuros gathered by the current study can support the development of effective integrated weed management strategies for V. myuros.

scholarly journals Low Light/Darkness as Stressors of Multifactor-Induced Senescence in Rice Plants

2021 ◽  
Vol 22 (8) ◽  
pp. 3936
Author(s):  
Ahmed G. Gad ◽  
Habiba ◽  
Xiangzi Zheng ◽  
Ying Miao
Keyword(s):  
Leaf Senescence ◽  
Crop Yields ◽  
Crop Improvement ◽  
Light Response ◽  
Development Stage ◽  
Regulatory Mechanisms ◽  
Economic Losses ◽  
Low Light ◽  
Chlorophyll Breakdown ◽  
Premature Leaf Senescence

Leaf senescence, as an integral part of the final development stage for plants, primarily remobilizes nutrients from the sources to the sinks in response to different stressors. The premature senescence of leaves is a critical challenge that causes significant economic losses in terms of crop yields. Although low light causes losses of up to 50% and affects rice yield and quality, its regulatory mechanisms remain poorly elucidated. Darkness-mediated premature leaf senescence is a well-studied stressor. It initiates the expression of senescence-associated genes (SAGs), which have been implicated in chlorophyll breakdown and degradation. The molecular and biochemical regulatory mechanisms of premature leaf senescence show significant levels of redundant biomass in complex pathways. Thus, clarifying the regulatory mechanisms of low-light/dark-induced senescence may be conducive to developing strategies for rice crop improvement. This review describes the recent molecular regulatory mechanisms associated with low-light response and dark-induced senescence (DIS), and their effects on plastid signaling and photosynthesis-mediated processes, chloroplast and protein degradation, as well as hormonal and transcriptional regulation in rice.

scholarly journals The Effect of Gut Bacteria on the Physiology of Red Palm Weevil, Rhynchophorus ferrugineus Olivier and Their Potential for the Control of This Pest

Insects ◽  
2021 ◽  
Vol 12 (7) ◽  
pp. 594
Author(s):  
Qian-Xia Liu ◽  
Zhi-Ping Su ◽  
Hui-Hui Liu ◽  
Sheng-Ping Lu ◽  
Bing Ma ◽  
...  
Keyword(s):  
Molecular Mechanisms ◽  
Current Knowledge ◽  
Management Strategies ◽  
Gut Bacteria ◽  
Economic Losses ◽  
Rhynchophorus Ferrugineus ◽  
Intestinal Immunity ◽  
Red Palm Weevil ◽  
Nutrient Metabolism ◽  
Palm Weevil

Red Palm Weevil (RPW), Rhynchophorus ferrugineus Olivier, is a notorious pest, which infests palm trees and has caused great economic losses worldwide. At present, insecticide applications are still the main way to control this pest. However, pesticide resistance has been detected in the field populations of RPW. Thus, future management strategies based on the novel association biological control need be developed. Recent studies have shown that the intestinal tract of RPW is often colonized by multiple microbial species as mammals and model insects, and gut bacteria have been found to promote the growth, development and immune activity of RPW larvae by modulating nutrient metabolism. Furthermore, two peptidoglycan recognition proteins (PGRPs), PGRP-LB and PGRP-S1, can act as the negative regulators to modulate the intestinal immunity to maintain the homeostasis of gut bacteria in RPW larvae. Here, we summarized the current knowledge on the gut bacterial composition of RPW and their impact on the physiological traits of RPW larvae. In contrast with metazoans, it is much easier to make genetic engineered microbes to produce some active molecules against pests. From this perspective, because of the profound effects of gut bacteria on host phenotypes, it is promising to dissect the molecular mechanisms behind their effect on host physiology and facilitate the development of microbial resource-based management methods for pest control.

scholarly journals Effect of Herbicides on the Management of the Invasive Weed Solanum rostratum Dunal (Solanaceae)

Plants ◽  
2021 ◽  
Vol 10 (2) ◽  
pp. 284
Author(s):  
Jackline Abu-Nassar ◽  
Maor Matzrafi
Keyword(s):  
Growth Stage ◽  
Late Summer ◽  
Early Spring ◽  
Growth Stages ◽  
Weed Species ◽  
Invasive Weed ◽  
Solanum Rostratum ◽  
Stage 4 ◽  
Chemical Solutions ◽  
Late Growth

Solanum rostratum Dunal is an invasive weed species that invaded Israel in the 1950s. The weed appears in several germination flashes, from early spring until late summer. Recently, an increase in its distribution range was observed, alongside the identification of new populations in the northern part of Israel. This study aimed to investigate the efficacy of herbicide application for the control of S. rostratum using two field populations originated from the Golan Heights and the Jezreel Valley. While minor differences in herbicide efficacy were recorded between populations, plant growth stage had a significant effect on herbicide response. Carfentrazone-ethyl was found to be highly effective in controlling plants at both early and late growth stages. Metribuzin, oxadiazon, oxyfluorfen and tembutrione showed reduced efficacy when applied at later growth stage (8–9 cm height), as compared to the application at an early growth stage (4–5 cm height). Tank mixes of oxadiazon and oxyfluorfen with different concentrations of surfactant improved later growth stage plant control. Taken together, our study highlights several herbicides that can improve weed control and may be used as chemical solutions alongside diversified crop rotation options. Thus, they may aid in preventing the spread and further buildup of S. rostratum field populations.

Lethal and Sublethal Effects of Eucalyptus camaldulensis and Mentha piperita Essential Oils on the Khapra Beetle (Coleoptera: Dermestidae) in Terms of Feeding Inhibition, Oviposition, and Seed Damage

2021 ◽  
Author(s):  
Ehsan Borzoui ◽  
Ramin Khaghani ◽  
Gadir Nouri-Ganbalani
Keyword(s):  
Essential Oils ◽  
Sublethal Effects ◽  
Management Strategies ◽  
Eucalyptus Camaldulensis ◽  
Choice Test ◽  
Mentha Piperita ◽  
Growth Stages ◽  
Fumigant Toxicity ◽  
Khapra Beetle ◽  
Wheat Seeds

Abstract Trogoderma granarium Everts, the Khapra beetle, is a major pest of stored products, especially grains. In this study, fumigant toxicity and sublethal effects of Eucalyptus camaldulensis Dehnh. (Myrtaceae) and Mentha piperita L. (Lamiaceae) essential oils (EOs) were investigated against different growth stages of T. granarium. To assess the sublethal effects, insects were exposed to an LC20 or LC50 concentration of each essential oil, and the ability of these oils to deter feeding, oviposition, and damage to wheat seeds and overall mass were surveyed. At LC50 concentrations, M. piperita EO showed higher fumigant toxicity than E. camaldulensis EO against eggs, 2nd instar larvae, 4th instar larvae, and adults of T. granarium. Furthermore, the adults were more sensitive to the tested EOs than immatures. In free-choice tests, both larvae and adults showed a preference for control-treated wheat seeds than for seeds treated with an LC20 or LC50 concentration of EOs from E. camaldulensis or M. piperita. In a no-choice test, adult females exposed to EOs showed lower fecundity and fertility in comparison to control females not exposed to EOs. Treatment of wheat seeds with E. camaldulensis or M. piperita EOs resulted in a dose-specific reduction in the number of damaged seeds and seed weight loss when compared to control. According to our results, both tested EOs, especially EOs extracted from M. piperita, showed good potential for use in integrated pest management strategies against T. granarium.

scholarly journals Diversity of Colletotrichum Species Associated with Anthracnose Disease in Tropical Fruit Crops—A Review

Agriculture ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 297
Author(s):  
Latiffah Zakaria
Keyword(s):  
Management Strategies ◽  
Economic Losses ◽  
Fruit Crops ◽  
Tropical Fruit ◽  
Colletotrichum Species ◽  
Adequate Knowledge ◽  
Dragon Fruit ◽  
Causative Agents ◽  
Colletotrichum Spp ◽  
Fruit Plantations

In tropical fruit crops, anthracnose is mainly caused by species belonging to the fungal genus, Colletotrichum. These phytopathogens can infect several parts of the fruit crops; however, infection during postharvest or ripening stages is responsible for major economic losses. Due to the formation of black to dark brown sunken lesions on the fruit surface, anthracnose reduces fruit quality and marketability. Among the most common tropical fruit crops susceptible to anthracnose are mango, papaya, banana, avocado, guava, and dragon fruit; these are economically relevant products in many developing countries. It is important to document that the newly recorded Colletotrichum spp. associated with fruit anthracnose can infect multiple hosts, but some species may be host-specific. By using multiple markers, many phylogenetic species of Colletotrichum have been reported as anthracnose-causing pathogens. Taking into account that disease management strategies strongly rely on adequate knowledge of the causative agents, updated information on Colletotrichum species and the hazard posed by the most recently identified species in tropical fruit plantations and harvested fruits becomes vital. Besides, the newly recorded species may be important for biosecurity and should be listed as quarantine pathogens, considering that tropical fruits are traded worldwide.

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