Dry Bulb Onions Research Articles

Escherichia coli Survival on Dry Bulb Onions Treated with Crop Protection Sprays Prepared using Contaminated Water in the Treasure Valley Growing Region

Contaminated agricultural water has been implicated in produce-associated outbreaks, including dry bulb onions (Allium cepa). This study was designed to quantify risks associated with t contaminated water used to prepare crop protection sprays applied immediately before the onset of field curing of dry bulb onions. Laboratory experiments determining the behavior of Salmonella and Escherichia coli in crop protection chemical solutions were performed to guide selection for field use. Field trials were conducted (2022, 2023) in eastern Oregon (Treasure Valley) using two onion cultivars (‘Red Wing’ and ‘Cometa’) inoculated with a rifampicin-resistant E. coli cocktail (3–4 log CFU/100 mL) suspended in fungicide solution or clay suspension, and applied with a backpack sprayer at the end of the growing season. Onions were sampled through the next 4 weeks of field curing and after 1 and 4–5 mos of postharvest storage. In 2022, onions were initially contaminated at a maximum cell density of 48 MPN/onion (Geometric mean (GM): 3.7 MPN/onion). At the end of curing, a single onion (out of 320) tested positive at 2 MPN/onion. In 2022, E. coli was not detected during postharvest storage (n = 160). In 2023, the application of contaminated sprays resulted in a maximum contamination of 275 MPN/onion (GM: 8.6 MPN/onion). At the end of the 2023 curing period, three out of 320 onions (0.9%) had detectable levels of E. coli (1–2 MPN/onion). Three ‘Cometa’ onions from the same plot that were treated with fungicide were positive for E. coli after 5 months of postharvest storage (2, 11, and 83 MPN/onion). These field trials indicate field curing conditions in the Treasure Valley help mitigate risks associated with contaminated water used for applying crop protection sprays. E. coli was detected on a small percentage of onions at low cell density after curing. The single onion with elevated E. coli populations after postharvest storage had internal damage characteristic of bacterial rot.

Localization of Iris Yellow Spot Virus in Naturally Infected Onion Plants: A Sampling Approach for Reliable Diagnosis

Iris yellow spot virus (IYSV) from the genus Orthotospovirus of the family Tospoviridae can cause considerable yield reduction and crop loss in allium crops, especially dry bulb onion. While infected plants may or may not express symptoms of iris yellow spot disease, these onion plants can test negative for the virus because not all tissues contain detectable levels of IYSV due to its uneven distribution. The purpose of this study was to identify tissue locations of symptomatic onion plants that have the highest likelihood of testing positive for IYSV in DAS-ELISA using specific antibodies. Results revealed that the greatest likelihood of detecting IYSV from a single symptomatic plant occurred with tissue near foliar lesions located on the distal portions of older leaves (range: 42-71%). These low to moderate probability detection levels can predictably be overcome by testing pooled tissue samples from the same plant or from multiple plants. Indeed, the likelihood of distal and proximal youngest leaf tissue testing positive for IYSV from a single plant to a four-plant composite sample would increase from 44% to 90% and from 50% to 94%, respectively. Implications of these results for IYSV detection and surveillance in onion production systems are discussed.

Irrigation Method Matters: Contamination and Die-off Rates of Escherichia coli on Dry Bulb Onions After Overhead and Drip Irrigation in Washington State (2022–2023)

Two U.S. outbreaks of salmonellosis in 2020 and 2021 were epidemiologically linked to red onions. The 2020 outbreak investigation implicated the production of agricultural water as a likely contamination source. Field trials were designed to investigate the prevalence and survival of Escherichia coli (surrogate for Salmonella) on dry bulb onions after the application of contaminated irrigation water at the end of the growing period. Irrigation water was inoculated at 3 log most probable number (MPN)/100 mL (2022 and 2023) or 5 log MPN/100 mL (2023, drip only) with a cocktail of rifampin-resistant E. coli and applied with the final irrigation (0.4 acre-inch/0.4 ha-cm) to onions. Onion bulbs (40 or 80) were sampled immediately after irrigation and throughout field curing (4 weeks) and E. coli was enumerated using an MPN method. For drip irrigation, at 3 log MPN/100 mL E. coli was detected on 13% of onions at 24 h but not detected at 0 h; at 5 log MPN/100 mL for drip irrigation applied to saturated soil, E. coli was detected in 63% of onions at 0 h. Prevalence significantly (P < 0.05), decreased after 7 d of curing with cell densities of 1–1,400 MPN/onion. At the end of field curing in 2023, 1/80 of onions had detectable E. coli (2.04 MPN/onion). E. coli was detected in a significantly smaller percentage of onions (2022: 13%; 2023: 68%) after a contaminated drip irrigation event compared to overhead irrigation (98–100%; P < 0.05). After overhead irrigation, E. coli was detected in onions (1–1,000 MPN/onion) on day 0. Prevalence decreased significantly (P < 0.05) after 7 d of field curing in both years (2022: 15%; 2023: 7%). E. coli was not detected on Calibra onions (80/year) at the end of field curing in either year but was detected at <12 MPN/onion in 2.5–3.75% of onions (n = 80) for other cultivars. These data confirm limited contamination risk associated with drip irrigation water quality and begin to quantify contamination risks associated with overhead irrigation of dry bulb onions.

Identifying Onion Fields at Risk of Iris Yellow Spot Virus in New York.

Iris yellow spot virus (IYSV) poses a significant threat to dry bulb onion, Allium cepa L., production and can lead to substantial yield reductions. IYSV is transmitted by onion thrips, Thrips tabaci (Lindeman), but not via seed. Transplanted onion fields have been major early season sources of IYSV epidemics. As onion thrips tend to disperse short distances, seeded onion fields bordering transplanted onion fields may be at greater risk of IYSV infection than seeded fields isolated from transplanted ones. Additionally, seeded onion fields planted early may be at greater risk of IYSV infection than those seeded later. In a 2-year study in New York, we compared IYSV incidence and onion thrips populations in seeded onion fields relative to their proximity to transplanted onion fields. In a second study, we compared IYSV incidence in onion fields with either small or large plants during midseason. Results showed similar IYSV incidence and onion thrips populations in seeded onion fields regardless of their proximity to transplanted onion fields, while IYSV incidence was over four times greater in large onion plants than in small ones during midseason. These findings suggest a greater risk of onion thrips-mediated IYSV infection in onion fields with large plants compared with small ones during midseason and that proximity of seeded fields to transplanted ones is a poor indicator of IYSV risk. Our findings on IYSV spread dynamics provided valuable insights for developing integrated pest and disease management strategies for New York onion growers.

A Cost–Benefit Analysis of Novel IPM-Based Approaches to Onion Thrips Management in US Dry Bulb Onions

Onion thrips, Thrips tabaci (Lindeman), is a major pest of dry bulb onion throughout the US and across the world. Yield and quality damage from thrips feeding and the expense of insecticides used for thrips management have jeopardized profitable and sustainable onion production. To improve approaches to thrips management, researchers in multiple US onion-producing regions developed novel, integrated pest management (IPM)-based strategies employing threshold-based insecticide treatments and reduced fertilization practices. The purpose of this study was to estimate the benefits from public investment in research to develop IPM-based onion thrips management techniques using a cost–benefit analysis. Benefits were extended over a 20-year timespan and were measured by reduced insecticide and fertilizer costs. The estimated net present value of benefits from improved pest management tactics will depend on the adoption and use of novel approaches to management. Using a scenario that assumes a maximum adoption rate of 58%, the estimated net present value of the research is $15.91 million, the benefit–cost ratio is 4.00, and the internal rate of return is 32%. Assuming a scenario with a maximum adoption rate of 29%, the estimated net present value of the research is $8.3 million, the benefit–cost ratio is 3.34, and the internal rate of return is 24%. Even when estimated assuming conservative adoption scenarios, results indicate a healthy return on investment in research to develop and refine new approaches to manage onion thrips and optimize dry bulb onion production.

Garlic Mite, Aceria tulipae (Acarida: Eriophyidae): A Review

Garlic (Allium sativum), belonging to the family Amarylidaceae, is a bulbous plant which is widely used as a condiment for its pungent flavour. India holds second position in garlic production after China. It is attacked by many insect pests. The most hazardous pest is Garlic mite (Aceria tulipae). This mite is also known as dry bulb mite or onion mite. It attacks in both field and storage condition. In field condition a typical pig tail appearance is seen in infected plants. In storage condition reddish brown spots appear on the garlic cloves due to the feeding of this mite. This article accrued different aspects of Aceria tulipae, viz., host range and host specificity, invasive history and distribution, morphology, taxonomic confusion, dispersal, biology and relationship with abiotic factors, population dynamics, damage symptoms in field and storage and its management.

Performance of a semi-glossy onion hybrid in certified organic onion fields infested with Thrips tabaci and bulb-rot causing bacteria

More than one-third of the certified organic farms that produce dry bulb onions in the USA are in the Great Lakes region, while onion thrips, Thrips tabaci Lindeman, and bulb-rot causing bacteria are important onion production constraints. Onion cultivars with semi-glossy foliage have been reported to support fewer thrips and suffer less thrips damage and therefore may provide a non-chemical option for thrips management. However, inconsistent results regarding efficacy of semi-glossy onions to reduce thrips densities have been reported in field studies. Bacteria causing bulb rot can infect onion plants through wounds in leaves, but the relationship between thrips damage and bacterial bulb rot disease needs further investigation. In this study, the performance of a semi-glossy onion hybrid, ‘USDA Maia’, was compared with the commonly grown waxy, thrips-susceptible cultivar ‘Bradley’ on certified organic farms in New York and Wisconsin from 2019 to 2021. Results indicated that thrips abundance was not different between ‘USDA Maia’ and ‘Bradley’. Bacterial bulb rot incidence in ‘USDA Maia’ was either similar or lower than the incidence in ‘Bradley’ in four of six trials, but higher in the other two. Marketable bulb yield in ‘USDA Maia’ was similar to yield in ‘Bradley’ in four of seven trials, but lower in the other three. Positive relationships between thrips density and bacterial bulb rot incidence occurred in one of three trials for both onion cultivars. Similarly, negative relationships between thrips density and marketable bulb yield only occurred in one of three trials, regardless of onion cultivar. ‘USDA Maia’ did not reduce thrips infestations as anticipated, but it was similar in susceptibility to bacterial bulb rot disease and produced similar large bulb yields as ‘Bradley’. While high thrips abundance can potentially increase incidence of bacterial bulb rot disease, wet growing conditions during bulbing was more important.

Bi-national outbreak of Salmonella Newport infections linked to onions: the United States experience.

From 2016-2019, dry bulb onions were the suspected cause of three multistate outbreaks in the United States. We investigated a large multistate outbreak of Salmonella Newport infections that caused illnesses in both the United States and Canada in 2020. Epidemiologic, laboratory and traceback investigations were conducted to determine the source of the infections, and data were shared among U.S. and Canadian public health officials. We identified 1127 U.S. illnesses from 48 states with illness onset dates ranging from 19 June to 11 September 2020. Sixty-six per cent of ill people reported consuming red onions in the week before illness onset. Thirty-five illness sub-clusters were identified during the investigation and seventy-four per cent of sub-clusters served red onions to customers during the exposure period. Traceback for the source of onions in illness sub-clusters identified a common onion grower in Bakersfield, CA as the source of red onions, and onions were recalled at this time. Although other strains of Salmonella Newport were identified in environmental samples collected at the Bakersfield, CA grower, extensive environmental and product testing did not yield the outbreak strain. This was the third largest U.S. foodborne Salmonella outbreak in the last 30 years. It is the first U.S. multistate outbreak with a confirmed link to dry bulb onions, and it was nearly 10-fold larger than prior outbreaks with a suspected link to onions. This outbreak is notable for its size and scope, as well as the international data sharing that led to implication of red onions as the primary cause of the outbreak. Although an environmental assessment at the grower identified several factors that likely contributed to the outbreak, no main reason was identified. The expedient identification of the outbreak vehicle and response of multiple public health agencies allowed for recall and removal of product from the marketplace, and rapid messaging to both the public and industry on actions to protect consumers; these features contributed to a decrease in cases and expeditious conclusion of the outbreak.

Seaside Petunia Susceptibility to Herbicides Used in Dry Bulb Onion

Seaside petunia (Calibrachoa parviflora) is a mat-forming plant species that was recently reported in fall-seeded onion (Allium cepa) in the southwestern United States. To initiate development of herbicide recommendations for seaside petunia in onion, we conducted a study to determine seaside petunia susceptibility to commonly used herbicides for broadleaf weed control after onion emergence. Our study included herbicides applied at below-label rates, which provided insights on seaside petunia responses to reductions in the amount of herbicide available for plant absorption. For herbicides with preemergence activity, our growth chamber study indicated that soil applications of flumioxazin or oxyfluorfen (0.06 and 0.25 lb/acre, respectively) prevented seaside petunia seedling emergence when applied at 0.125×, 0.25×, 0.5×, and 1.0× the labeled rates for onion. Labeled rate treatments of dimethenamid-P (0.84 lb/acre) and S-metolachlor (0.64 lb/acre) inhibited seedling emergence similar to labeled rate treatments of flumioxazin and oxyfluorfen; however, below-label rate treatments of dimethenamid-P and S-metolachlor resulted in diminished control of seaside petunia compared with the labeled rate treatments. Following labeled rate applications of dimethyl tetrachloroterephthalate [DCPA (6 lb/acre)] and pendimethalin (0.71 lb/acre), more than 50% of seaside petunia seedlings emerged compared with the nontreated control. For herbicides with postemergence activity on weeds, our greenhouse study indicated that bromoxynil at 0.37 lb/acre, flumioxazin at 0.06 lb/acre, and oxyfluorfen at 0.25 lb/acre equally reduced growth of seaside petunia plants that were small at the time of spraying (stem length, 1–2 cm). Postemergence control of seaside petunia with oxyfluorfen and flumioxazin decreased as plant size at spraying increased; however, bromoxynil effects on seaside petunia remained high as stem length at spraying increased from 5 to 12 cm. Based on the results of this study, we conclude that promising herbicide programs for seaside petunia in onion include oxyfluorfen or flumioxazin for preemergence control and bromoxynil for postemergence control. These herbicides, alone and in combination, should be evaluated for seaside petunia control and onion phytotoxicity in future field trials.

EFFECT OF SALICYLIC ACID APPLICATION ON GROWTH AND DEVELOPMENT OF GREEN ONIONS GROWN UNDER SALT STRESS

Soil salinity negatively affects crop production and leads to loss of agricultural lands worldwide. In Iraq, poor agricultural practices, such as inadequate drainage facilities and low water quality, are known to be caused soil salinization. Onion (Allium cepa L.) is an economic crop that is consumed heavily as green or dry bulb onion. The cultivated area of green onion was statistically decreased in the Kurdistan region, Iraq, lately. Therefore, this study was conducted in the Directorate of Agriculture, Ankawa, Erbil, to examine whether salicylic acid (SA) mitigate the effect of salt stress and improve the growth and development of green onions. Two different concentrations of NaCl (20 and 40 mM) were injected around the base of each plant and after 24h, SA (0.5 and 1mM) was sprayed to the vegetative parts of each plant, evenly. The results showed that the short-term application of SA was reduced the impact of NaCl. The number of green leaves, leaf area, plant height, root growth, bulb diameter, plant weight and total yield (t. ha-1) was improved by the application of SA. It has been suggested the application of a commercial or SA analogue to the agricultural saline land may alleviate the salt stress and improve the product. Soil salinity negatively affects crop production and leads to loss of agricultural lands worldwide. In Iraq, poor agricultural practices, such as inadequate drainage facilities and low water quality, are known to be caused soil salinization. Onion (Allium cepa L.) is an economic crop that is consumed heavily as green or dry bulb onion. The cultivated area of green onion was statistically decreased in the Kurdistan region, Iraq, lately. Therefore, this study was conducted in the Directorate of Agriculture, Ankawa, Erbil, to examine whether salicylic acid (SA) mitigate the effect of salt stress and improve the growth and development of green onions. Two different concentrations of NaCl (20 and 40 mM) were injected around the base of each plant and after 24h, SA (0.5 and 1mM) was sprayed to the vegetative parts of each plant, evenly. The results showed that the short-term application of SA was reduced the impact of NaCl. The number of green leaves, leaf area, plant height, root growth, bulb diameter, plant weight and total yield (t. ha-1) was improved by the application of SA. It has been suggested the application of a commercial or SA analogue to the agricultural saline land may alleviate the salt stress and improve the product.

Evaluation of Foliar Insecticides for the Control of Onion Thrips in Dry-Bulb Onion in Wisconsin, 2019

Evaluation of Foliar Insecticides for the Control of Onion Thrips in Dry-Bulb Onion in Wisconsin, 2019

Field Evidence Supporting Conventional Onion Curing Practices as a Strategy To Mitigate Escherichia coli Contamination from Irrigation Water

The Produce Safety Rule of the U.S. Food Safety Modernization Act includes restrictions on the use of agricultural water of poor microbiological quality. Mitigation options for poor water quality include the application of an irrigation-to-harvest interval of <4 days; however, dry bulb onion production includes an extended irrigation-to-harvest interval (<30 days). This study evaluated conventional curing practices for mitigating Escherichia coli contamination in a field setting. Well water inoculated with rifampin-resistant E. coli (1, 2, or 3 log CFU/mL) was applied to onion fields (randomized block design; n = 5) via drip tape on the final day of irrigation. Onions remained undisturbed for 7 days and were then lifted to the surface to cure for an additional 21 days before harvest. Water, onions, and soil were tested for presence of rifampin-resistant E. coli. One day after irrigation, 13.3% of onions (20 of 150) receiving the poorest quality water (3 log CFU/mL) tested positive for E. coli; this prevalence was reduced to 4% (6 of 150 onions) after 7 days. Regardless of inoculum level, E. coli was not detected on any onions beyond 15 days postirrigation. These results support conventional dry bulb onion curing practices as an effective strategy to mitigate microbiological concerns associated with poor quality irrigation water.

Postemergence Weed Control in Onion with Bentazon, Flumioxazin, and Oxyfluorfen

Field experiments were conducted in 2008 and 2010 to determine crop tolerance and weed control efficacy of the POST herbicides bentazon, flumioxazin, and oxyfluorfen applied to direct-seeded dry bulb onions on organic soil. Postemergence application of oxyfluorfen at 0.071 kg ai ha−1resulted in less than 20% onion injury when applied at the 2 and 4 onion leaf stages and provided good control of ladysthumb and common lambsquarters. Oxyfluorfen EC caused slightly higher visual injury than oxyfluorfen SC, but there was no difference in onion yield among the treatments. Application of flumioxazin at 0.036 of 0.072 kg ai ha−1alone or in combination with pendimethalin ACS resulted in minimal onion injury and no yield reduction. Combining flumioxazin in a tank mix with pendimethalin EC, dimethenamid-P EC, orS-metolachlor EC resulted in significant onion injury and yield reduction. Flumioxazin plusS-metolachlor, dimethenamid-P, or pendimethalin improved ladysthumb control in one of two years. Bentazon applied at 0.56 kg ai ha−1produced moderate onion injury and did not control yellow nutsedge adequately. Bentazon applied at 1.12 kg ai ha−1provided good control of yellow nutsedge but caused serious onion injury and yield loss.

Thrips Managment on Dry Bulb Onions With the Use of Foliar Insecticide Applications, 2016

Thrips Managment on Dry Bulb Onions With the Use of Foliar Insecticide Applications, 2016

Drip vs. Furrow Irrigation in the Delivery of Escherichia coli to Onions

<abstract> <b><i>Abstract. </i></b> Surface irrigation systems that reuse water may deliver bacteria to produce destined for fresh consumption. Four irrigation systems delivered (1) well water free of via subsurface drip irrigation, (2) canal water with moderate levels of via subsurface drip irrigation, (3) canal water with moderate levels of via furrow irrigation, and (4) canal water with enhanced levels of via furrow irrigation. The four irrigation systems (replicated five times) applied water to onion on silt loam. Water was sampled hourly for , and the lateral movement of in the soil solution was tracked by soil samples following irrigations. Onion bulbs were sampled for contamination. The most probable numbers of E. coli in water and soil water were determined using IDEXX Colilert^® and Colisure^®, respectively, and Quanti-Tray/2000^®. Under both furrow and subsurface drip irrigation, a fraction of the was delivered to the soil immediately adjacent to the onion bulbs. The silt loam retained most of the content away from the onion bulbs and close to where the water entered the soil. No was detected inside of the onion bulbs from any irrigation treatment. Current subsurface drip or furrow (flood) irrigation practices do not appear to pose a significant risk for bacterial contamination of dry bulb onion grown on silt loam.

Evaluation of foliar insecticides for the control of onion thrips in dry-bulb onion, 2014: Table 1.

The objective of this experiment was to assess the efficacy of foliar insecticides applied at threshold levels for the control of immature stages of OT in dry-bulb onion. The trial consisted of 12 main effect treatments arranged in a randomized complete block (RCB) design with four experimental replicates. Onion was direct seeded on 5 May 2014 at Shiprock Farms, located 5.1 miles (8.1 km) west of Coloma, WI. Experimental plots consisted of 54 inch (1.4 m) raised formed beds containing 6 rows of onion …

Thrips Control on Dry Bulb Onions in Washington State, 2012: Table 1

Thrips Control on Dry Bulb Onions in Washington State, 2012: Table 1

Thrips Control on Dry Bulb Onions in Washington State, 2012: Table 1

Thrips Control on Dry Bulb Onions in Washington State, 2012: Table 1

Thrips Control on Dry Bulb Onions in Washington State, 2014: Table 1

Thrips Control on Dry Bulb Onions in Washington State, 2014: Table 1

Thrips Control on Dry Bulb Onions Using Overhead Chemigation of Insecticdes, 2014: Table 1

Onion thrips are a major pest of dry bulb onion production in Washington State. This trial began on June 14, 2014 in Pasco, WA in a field under drip irrigation. Designated plots were 11 feet wide and 25 feet long under a RCD design with four replicates. Applications were made with pull type sprayer fitted to mimic applications …