Abstract
The onion industry in the United States is worth about US $1.6 billion, and onion bacterial diseases cause annual losses of approximately US $60 million. Chemical controls have limited effectiveness in most regions, which calls for a holistic approach that integrates cultural practices including nitrogen and irrigation management. High nitrogen application rates or late-season nitrogen application may delay maturation of onion plants, providing a window for pathogenic bacteria to establish in the necks of plants when the necks are beginning to senesce and are most susceptible to infection. However, this has not been investigated under the high-yielding, irrigated production conditions of the western United States. Furthermore, late-season sprinkler irrigation has proven detrimental for onions as free moisture on the plants favors bacterial growth, yet whether the frequency of sprinkler irrigation affects bacterial diseases is less clear. Trials were conducted in the Columbia Basin of Washington State to assess the impact of N application rates, in-season N application timing, and irrigation frequency on the incidence of onion bacterial diseases, bulb size distribution, and yield. The N application rate trial was conducted in 2021, 2023, and 2024 with total available N ranging from residual N only (0 kg N ha-1 applied) to 403 kg N ha-1. Results demonstrated that N application rates can affect total yield and the incidence of onion bacterial bulb rot, such that N application rates needed to maximize marketable yield (total yield minus bulbs culled for rot or other causes) are likely lower than those required to maximize total yield, though carefully managing N application rates to minimize bacterial bulb rot and maximize marketable yield can be challenging in practice. In contrast, late-season N application (up to two weeks after bulb initiation) did not affect yield or bacterial bulb rot incidence compared to stopping N application at bulb initiation or two weeks before bulb initiation. Irrigating twice as frequently but for half the duration each time had mixed effects, with both total yield and bacterial bulb rot incidence increasing in plots with more frequent irrigation in one of the two years; it was posited that the observed response to irrigation frequency was a result of late termination of irrigation and that irrigation frequency is unlikely to affect the incidence of onion bacterial diseases if irrigation is stopped before 50% of the tops of the onion plants fall over (a natural part of the senescence of onion leaves). In conclusion, careful management of irrigation and nitrogen is recommended for onion production for many reasons, though adjusting N application timing or irrigation frequency throughout the season may be less impactful than other cultural management practices like optimizing N application rates, terminating sprinkler irrigation sufficiently early, or switching to drip irrigation.
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Claims 9
Claim · model-written summary
N application rates affect total onion yield and the incidence of onion bacterial bulb rot.
- Taxon
- onion
Allium cepae0 - Treatment
- N application ratese0
- Outcome
- total yield and the incidence of onion bacterial bulb rote0
- Setting
- Columbia Basin of Washington Statee1
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Results demonstrated that N application rates can affect total yield and the incidence of onion bacterial bulb rot”
e1“Trials were conducted in the Columbia Basin of Washington State”
Claim · model-written summary
Nitrogen rates needed to maximize marketable onion yield are likely lower than those needed to maximize total yield.
- Taxon
- onionAllium cepat0
- Treatment
- N application ratese0
- Outcome
- marketable yielde0
- Direction
- lowere0
- Comparator
- those required to maximize total yielde0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“COMBATING ONION BACTERIAL DISEASES THROUGH NITROGEN AND IRRIGATION MANAGEMENT”
e0“N application rates needed to maximize marketable yield (total yield minus bulbs culled for rot or other causes) are likely lower than those required to maximize total yield”
Claim · model-written summary
Late-season N application up to two weeks after bulb initiation did not affect onion yield or bacterial bulb rot incidence compared with stopping N application at bulb initiation or two weeks before.
- Taxon
- onionAllium cepat0
- Treatment
- late-season N application (up to two weeks after bulb initiation)e0
- Outcome
- yield or bacterial bulb rot incidencee0
- Direction
- did not affecte0
- Comparator
- stopping N application at bulb initiation or two weeks before bulb initiatione0
- Setting
- Columbia Basin of Washington Statee1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“COMBATING ONION BACTERIAL DISEASES THROUGH NITROGEN AND IRRIGATION MANAGEMENT”
e0“late-season N application (up to two weeks after bulb initiation) did not affect yield or bacterial bulb rot incidence compared to stopping N application at bulb initiation or two weeks before bulb initiation”
e1“Trials were conducted in the Columbia Basin of Washington State”
Claim · model-written summary
Irrigating twice as frequently for half the duration increased total onion yield in one of the two years.
- Taxon
- onionAllium cepat0
- Treatment
- Irrigating twice as frequently but for half the duration each timee0
- Outcome
- total yielde0
- Direction
- increasinge0
- Qualifier
- in one of the two yearse0
- Setting
- Columbia Basin of Washington Statee1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“COMBATING ONION BACTERIAL DISEASES THROUGH NITROGEN AND IRRIGATION MANAGEMENT”
e0“Irrigating twice as frequently but for half the duration each time had mixed effects, with both total yield and bacterial bulb rot incidence increasing in plots with more frequent irrigation in one of the two years”
e1“Trials were conducted in the Columbia Basin of Washington State”
Claim · model-written summary
More frequent irrigation increased onion bacterial bulb rot incidence in one of the two years.
- Taxon
- onionAllium cepat0
- Treatment
- Irrigating twice as frequently but for half the duration each timee0
- Outcome
- bacterial bulb rot incidencee0
- Direction
- increasinge0
- Qualifier
- in one of the two yearse0
- Setting
- Columbia Basin of Washington Statee1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“COMBATING ONION BACTERIAL DISEASES THROUGH NITROGEN AND IRRIGATION MANAGEMENT”
e0“Irrigating twice as frequently but for half the duration each time had mixed effects, with both total yield and bacterial bulb rot incidence increasing in plots with more frequent irrigation in one of the two years”
e1“Trials were conducted in the Columbia Basin of Washington State”
Claim · model-written summary
The observed response to irrigation frequency was posited to result from late termination of irrigation.
- Taxon
- onionAllium cepat0
- Outcome
- response to irrigation frequencye0
- Qualifier
- late termination of irrigatione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“COMBATING ONION BACTERIAL DISEASES THROUGH NITROGEN AND IRRIGATION MANAGEMENT”
e0“it was posited that the observed response to irrigation frequency was a result of late termination of irrigation”
Claim · model-written summary
Irrigation frequency is unlikely to affect the incidence of onion bacterial diseases when irrigation is stopped before 50% of the tops fall over.
- Taxon
- onionAllium cepae0
- Treatment
- irrigation frequencye0
- Outcome
- incidence of onion bacterial diseasese0
- Qualifier
- if irrigation is stopped before 50% of the tops of the onion plants fall overe0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“irrigation frequency is unlikely to affect the incidence of onion bacterial diseases if irrigation is stopped before 50% of the tops of the onion plants fall over”
Claim · model-written summary
Careful management of irrigation and nitrogen is recommended for onion production.
- Taxon
- onionAllium cepae0
- Outcome
- careful management of irrigation and nitrogene0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“careful management of irrigation and nitrogen is recommended for onion production”
Claim · model-written summary
Adjusting N application timing or irrigation frequency may be less impactful than optimizing N application rates, terminating sprinkler irrigation early, or switching to drip irrigation.
- Taxon
- onionAllium cepat0
- Treatment
- adjusting N application timing or irrigation frequencye0
- Outcome
- less impactfule0
- Direction
- less impactfule0
- Comparator
- other cultural management practices like optimizing N application rates, terminating sprinkler irrigation sufficiently early, or switching to drip irrigatione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“COMBATING ONION BACTERIAL DISEASES THROUGH NITROGEN AND IRRIGATION MANAGEMENT”
e0“adjusting N application timing or irrigation frequency throughout the season may be less impactful than other cultural management practices like optimizing N application rates, terminating sprinkler irrigation sufficiently early, or switching to drip irrigation”
The same questions in other papers
nitrogen · disease · Allium cepa (onion)Positive and negative results
1 paper in the same direction as this paper · 3 reporting no difference from an alternative
- positive
- positive
- positive
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See all 5 papers →irrigation · disease · Allium cepa (onion)Positive and negative results
8 papers in the same direction as this paper · 5 in the opposite direction
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See all 14 papers →irrigation · yield · Allium cepa (onion)Positive and negative results
105 papers in the same direction as this paper · 22 in the opposite direction · 5 reporting no difference from an alternative
- negative
- negative
- negative
129 papers more in this group
See all 133 papers →Claims are grouped by organism, treatment and what was measured or targeted. A paper counts as positive when any of its claims in the group is positive.