Abstract
The aim of this investigation was to evaluate criteria for the forecast and targeted control of basal stem canker (blackleg) caused by Leptosphaeria maculans on oilseed rape. Ascospore discharge, ratio of aggressive and non‐aggressive isolates and leaf and stem infestations were determined during 1991/92–1993/94 at 6–10 sites in Northern Germany. On a 1–9 scale, blackleg intensity varied from 2.3 to 6.3 at BBCH 81 between different sites and years. Ascospore discharge started in September or October, and reached maxima 1 or 2 months later, without an apparent relationship to blackleg or leaf infestation. There was a positive relationship between leaf infestation and blackleg. However, correlation coefficients were too low to be used as a basis for forecasting. On plant residues from the stem base, aggressive isolates were dominant (>80%) on all sites. From higher parts of the stem and from leaves also, non‐aggressive isolates were isolated with higher frequencies on some locations, but the proportion of aggressive isolates was not related to the blackleg intensity. Taken all together, the three criteria alone seem to be insufficient for the development of a system of blackleg forecasting and targeted control. Further factors (e.g. climatic factors, seed‐and soilborne inoculum, cultural practices) have to be included in models for forecasting the impact of blackleg on oilseed rape.
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Claims 9
Claim · model-written summary
Blackleg intensity ranged from 2.3 to 6.3 across sites and years.
- Taxon
- oilseed rape
_Brassica_napus_-_Habit.jpg?width=60)
Brassica napuse1 - Organ / stage
- BBCH 81e0
- Interactor
- Leptosphaeria maculans
Plenodomus lingame1pathogen - Outcome
- blackleg intensitye0
- Value
- 2.3 to 6.3e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
_Brassica_napus_-_Habit.jpg?width=500)
Verbatim
e0“blackleg intensity varied from 2.3 to 6.3 at BBCH 81 between different sites and years”
e1“Leptosphaeria maculans on oilseed rape”
Claim · model-written summary
Ascospore discharge started in September or October and peaked one or two months later.
- Taxon
- oilseed rapeBrassica napuse1
- Interactor
- Leptosphaeria maculansPlenodomus lingame1pathogen
- Outcome
- Ascospore dischargee0
- Value
- 1 or 2 monthse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Ascospore discharge started in September or October, and reached maxima 1 or 2 months later”
e1“Leptosphaeria maculans on oilseed rape”
Claim · model-written summary
Ascospore discharge showed no apparent relationship to blackleg or leaf infestation.
- Taxon
- oilseed rapeBrassica napuse2
- Interactor
- Leptosphaeria maculansPlenodomus lingame2pathogen
- Outcome
- blackleg or leaf infestatione0
- Direction
- without an apparent relationshipe0
- Comparator
- Ascospore dischargee1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“without an apparent relationship to blackleg or leaf infestation”
e1“Ascospore discharge started in September or October”
e2“Leptosphaeria maculans on oilseed rape”
Claim · model-written summary
Leaf infestation was positively associated with blackleg, but correlations were too low for forecasting.
- Taxon
- oilseed rapeBrassica napuse1
- Organ / stage
- leafe0
- Interactor
- Leptosphaeria maculansPlenodomus lingame1pathogen
- Outcome
- blacklege0
- Direction
- positivee0
- Qualifier
- correlation coefficients were too low to be used as a basis for forecastinge0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“There was a positive relationship between leaf infestation and blackleg. However, correlation coefficients were too low to be used as a basis for forecasting”
e1“Leptosphaeria maculans on oilseed rape”
Claim · model-written summary
Aggressive isolates dominated plant residues from the stem base at all sites.
- Taxon
- oilseed rapeBrassica napuse1
- Organ / stage
- stem basee0
- Interactor
- Leptosphaeria maculansPlenodomus lingame1pathogen
- Outcome
- aggressive isolates were dominante0
- Value
- >80%e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“On plant residues from the stem base, aggressive isolates were dominant (>80%) on all sites”
e1“Leptosphaeria maculans on oilseed rape”
Claim · model-written summary
Nonaggressive isolates occurred more frequently in upper stems and leaves at some locations.
- Taxon
- oilseed rapeBrassica napuse1
- Organ / stage
- higher parts of the stem and from leavese0
- Interactor
- Leptosphaeria maculansPlenodomus lingame1pathogen
- Outcome
- non‐aggressive isolatese0
- Direction
- higher frequenciese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“From higher parts of the stem and from leaves also, non‐aggressive isolates were isolated with higher frequencies on some locations”
e1“Leptosphaeria maculans on oilseed rape”
Claim · model-written summary
The proportion of aggressive isolates was unrelated to blackleg intensity.
- Taxon
- oilseed rapeBrassica napuse1
- Interactor
- Leptosphaeria maculansPlenodomus lingame1pathogen
- Outcome
- blackleg intensitye0
- Direction
- not relatede0
- Comparator
- proportion of aggressive isolatese0
Not reportedOrgan / stage
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the proportion of aggressive isolates was not related to the blackleg intensity”
e1“Leptosphaeria maculans on oilseed rape”
Claim · model-written summary
The authors judged the three criteria alone insufficient for blackleg forecasting and targeted control.
- Taxon
- oilseed rapeBrassica napuse1
- Interactor
- Leptosphaeria maculansPlenodomus lingame1pathogen
- Outcome
- blackleg forecasting and targeted controle0
- Qualifier
- three criteria alone seem to be insufficiente0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the three criteria alone seem to be insufficient for the development of a system of blackleg forecasting and targeted control”
e1“Leptosphaeria maculans on oilseed rape”
Claim · model-written summary
The authors recommend including climatic factors, seed- and soilborne inoculum, and cultural practices in blackleg forecasts.
- Taxon
- oilseed rapeBrassica napuse0
- Interactor
- Leptosphaeria maculansPlenodomus lingame1pathogen
- Outcome
- included in models for forecasting the impact of blacklege0
- Qualifier
- climatic factors, seed‐and soilborne inoculum, cultural practicese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Further factors (e.g. climatic factors, seed‐and soilborne inoculum, cultural practices) have to be included in models for forecasting the impact of blackleg on oilseed rape”
e1“Leptosphaeria maculans on oilseed rape”