Abstract
Abstract Severe defoliation of cassava by Zonocerus variegatus (L.) can occur every year during the dry season in southern Nigeria, but the effect of such defoliation on tuber yield was not known. Experiments simulating different forms of damage and direct observation on damage by Z. variegatus indicated that tuber yield is reduced significantly by defoliation only towards the end of the dry season after natural leaf regeneration has begun, when its effect is to delay regeneration so that damaged plants lag behind those which are undamaged. Continuous defoliation over six weeks at the end of the dry season caused a mean crop loss of 63%, and simulated debarking a mean loss of 49%. Z. variegatus confined in plots until the end of the dry season caused a mean loss of 36%, losses being less than those caused by simulated defoliation because cropping took place sooner after the end of defoliation. Defoliation during the dry season caused no significant crop loss when damage occurred before leaf regeneration at the beginning of the following wet season. Monitoring of natural defoliation by Zonocerus in successive years showed there were considerable differences in amount and timing. It is concluded that crop loss due to Zonocerus damage is significant only occasionally despite defoliation occuring every year.
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Claims 9
Claim · model-written summary
Defoliation significantly reduced tuber yield only late in the dry season after leaf regeneration began.
- Taxon
- cassava
Manihot esculentat0 - Treatment
- defoliatione0
- Outcome
- tuber yielde0
- Direction
- reducede0
- Qualifier
- only towards the end of the dry season after natural leaf regeneration has begune0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“tuber yield is reduced significantly by defoliation only towards the end of the dry season after natural leaf regeneration has begun”
t0“cassava”
Claim · model-written summary
Late dry-season defoliation delayed leaf regeneration.
- Taxon
- cassavaManihot esculentat0
- Outcome
- regeneratione0
- Direction
- delaye0
- Comparator
- those which are undamagede0
Not reportedTreatment
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“its effect is to delay regeneration so that damaged plants lag behind those which are undamaged”
t0“cassava”
Claim · model-written summary
Six weeks of continuous end-of-season defoliation caused 63% mean crop loss.
- Taxon
- cassavaManihot esculentat0
- Treatment
- Continuous defoliation over six weeks at the end of the dry seasone0
- Outcome
- crop losse0
- Direction
- losse0
- Value
- 63%e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Continuous defoliation over six weeks at the end of the dry season caused a mean crop loss of 63%”
t0“cassava”
Claim · model-written summary
Simulated debarking caused 49% mean crop loss.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“simulated debarking a mean loss of 49%”
t0“cassava”
Claim · model-written summary
Confined grasshoppers caused 36% mean crop loss.
- Taxon
- cassavaManihot esculentat0
- Treatment
- Z. variegatus confined in plots until the end of the dry seasone0
- Interactor
- Z. variegatus
.jpg?width=60)
Zonocerus variegatuse0pest - Outcome
- losse0
- Direction
- losse0
- Value
- 36%e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
.jpg?width=500)
Verbatim
e0“Z. variegatus confined in plots until the end of the dry season caused a mean loss of 36%”
t0“cassava”
Claim · model-written summary
The grasshopper-associated loss was less than simulated defoliation loss.
- Taxon
- cassavaManihot esculentat0
- Outcome
- lossese0
- Direction
- lesse0
- Qualifier
- cropping took place sooner after the end of defoliatione0
- Comparator
- simulated defoliatione0
Not reportedTreatment
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“losses being less than those caused by simulated defoliation because cropping took place sooner after the end of defoliation”
t0“cassava”
Claim · model-written summary
Defoliation before wet-season leaf regeneration caused no significant crop loss.
- Taxon
- cassavaManihot esculentat0
- Treatment
- Defoliation during the dry seasone0
- Outcome
- crop losse0
- Direction
- no significante0
- Qualifier
- before leaf regeneration at the beginning of the following wet seasone0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Defoliation during the dry season caused no significant crop loss when damage occurred before leaf regeneration at the beginning of the following wet season.”
t0“cassava”
Claim · model-written summary
Natural grasshopper defoliation differed considerably in amount and timing across years.
- Taxon
- cassavaManihot esculentat0
- Outcome
- natural defoliation by Zonoceruse0
ZonocerusOrganisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Monitoring of natural defoliation by Zonocerus in successive years showed there were considerable differences in amount and timing.”
t0“cassava”
Claim · model-written summary
The authors conclude grasshopper damage causes significant crop loss only occasionally.
- Taxon
- cassavaManihot esculentat0
- Outcome
- crop loss due to Zonocerus damagee0
- Qualifier
- only occasionallye0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“crop loss due to Zonocerus damage is significant only occasionally despite defoliation occuring every year”
t0“cassava”
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