Abstract
Early-season leaf loss due to damage by thrips (Thysanoptera: Thripidae) is considered an important issue by Australian cotton growers. To understand the potential impact of early-season leaf loss in the southern region of New South Wales, we investigated the effects of artificial defoliation on cotton growth, maturity timing and lint yield over four seasons (2013–14 to 2016–17) in commercial cotton crops in the Riverina district. Four defoliation scenarios were investigated: (i) complete defoliation, 100% removal of all true leaves from all plants; (ii) partial defoliation by plant, 100% removal of all true leaves from 75% of plants; (iii) partial defoliation by leaf, removal of 75% of leaf area from all individual true leaves on all plants; and (iv) no defoliation. Defoliation was done by hand at the onset of the 2-, 4-, and 6-node growth stages. Defoliated plants were initially shorter than undefoliated (control) plants, but by ~100-days post seedling emergence, height differences were no longer statistically significant in two of the four seasons. Defoliation did not affect the total number of bolls shortly before harvest. However, complete defoliation delayed crop maturity by up to 18 days and partial defoliation by plant delayed crop maturity by up to 8 days. Because of the delays, fully defoliated plants often had fewer open bolls shortly before harvest and yielded significantly less than undefoliated plants in three of the four seasons. A laboratory experiment with caged cotton seedlings showed that weekly introductions of up to10 thrips per seedling (predominantly onion thrips (Thrips tabaci), the most abundant species on cotton in the region) caused significant clubbing in true leaves, but the total leaf area was not significantly reduced at the 6-node stage. Implications of the results for southern cotton integrated pest management are discussed.
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Claims 9
Claim · model-written summary
Defoliated cotton plants were initially shorter than controls.
- Taxon
- cotton
Gossypium hirsutumt0 - Treatment
- Defoliatede0
- Outcome
- shortere0
- Direction
- shortere0
- Qualifier
- initiallye0
- Comparator
- undefoliated (control) plantse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Defoliated plants were initially shorter than undefoliated (control) plants”
t0“cotton”
Claim · model-written summary
Height differences were no longer significant by about 100 days in two of four seasons.
- Taxon
- cottonGossypium hirsutumt0
- Treatment
- Defoliatione1
- Outcome
- height differencese0
- Qualifier
- two of the four seasonse0
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“by ~100-days post seedling emergence, height differences were no longer statistically significant in two of the four seasons.”
t0“cotton”
e1“Defoliation did not affect the total number of bolls shortly before harvest.”
Claim · model-written summary
Defoliation did not affect total boll number shortly before harvest.
- Taxon
- cottonGossypium hirsutumt0
- Treatment
- Defoliatione0
- Outcome
- total number of bollse0
- Direction
- did not affecte0
- Qualifier
- shortly before harveste0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Defoliation did not affect the total number of bolls shortly before harvest.”
t0“cotton”
Claim · model-written summary
Complete defoliation delayed cotton crop maturity by up to 18 days.
- Taxon
- cottonGossypium hirsutumt0
- Treatment
- complete defoliatione0
- Outcome
- crop maturitye0
- Direction
- delayede0
- Value
- up to 18 dayse0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“complete defoliation delayed crop maturity by up to 18 days”
t0“cotton”
Claim · model-written summary
Partial defoliation by plant delayed cotton crop maturity by up to eight days.
- Taxon
- cottonGossypium hirsutumt0
- Treatment
- partial defoliation by plante0
- Outcome
- crop maturitye0
- Direction
- delayede0
- Value
- up to 8 dayse0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“partial defoliation by plant delayed crop maturity by up to 8 days”
t0“cotton”
Claim · model-written summary
Fully defoliated cotton plants often had fewer open bolls before harvest.
- Taxon
- cottonGossypium hirsutumt0
- Treatment
- fully defoliatede0
- Outcome
- open bollse0
- Direction
- fewere0
- Qualifier
- shortly before harveste0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“fully defoliated plants often had fewer open bolls shortly before harvest”
t0“cotton”
Claim · model-written summary
Fully defoliated plants yielded significantly less than controls in three of four seasons.
- Taxon
- cottonGossypium hirsutumt0
- Treatment
- fully defoliatede0
- Outcome
- yieldede0
- Direction
- lesse0
- Qualifier
- three of the four seasonse0
- Comparator
- undefoliated plantse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“fully defoliated plants often had fewer open bolls shortly before harvest and yielded significantly less than undefoliated plants in three of the four seasons.”
t0“cotton”
Claim · model-written summary
Weekly thrips introduction caused significant clubbing of cotton true leaves.
- Taxon
- cottonGossypium hirsutume0
- Treatment
- weekly introductions of up to10 thrips per seedlinge0
- Interactor
- Thrips tabaci
Thrips tabacie0pest - Outcome
- clubbing in true leavese0
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“weekly introductions of up to10 thrips per seedling (predominantly onion thrips (Thrips tabaci), the most abundant species on cotton in the region) caused significant clubbing in true leaves”
Claim · model-written summary
Weekly thrips introduction did not significantly reduce total cotton leaf area at six nodes.
- Taxon
- cottonGossypium hirsutumt0
- Organ / stage
- 6-node stagee0
- Treatment
- weekly introductions of up to10 thrips per seedlinge1
- Interactor
- Thrips tabaciThrips tabacie1pest
- Outcome
- total leaf areae0
- Direction
- not significantly reducede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the total leaf area was not significantly reduced at the 6-node stage.”
t0“cotton”
e1“weekly introductions of up to10 thrips per seedling (predominantly onion thrips (Thrips tabaci), the most abundant species on cotton in the region) caused significant clubbing in true leaves”
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See all 27 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.