Abstract
Abstract A series of pot experiments were undertaken to assess the selectivity of the pre‐emergence herbicide 4‐(2, 6‐dichlorobenzyloxymethyl)‐4‐ethyl‐2, 2, ‐dimethyl‐1, 3‐dioxolan (WL 29,226) against a number of annual weeds in wheat. When applied at dose rates of 0.5–2 kg/ha it gave good control of a number of annual monocotyledonous weeds, including Alopecurus myosuroides (blackgrass), without any adverse effects on the crop. WL 29,226 is relatively immobile in soil, remaining at the soil surface and thus favouring uptake via the emerging shoot. Since WL 29,226 is transported predominantly via the xylem, to reach its site of action in the regions of cell division, and hence to be effective, the compound has to penetrate the shoot either at or below the stem apex. The roots are inhibited only when these come into direct contact with the compound. Selectivity of the herbicide is dependent upon the relative anatomical positions of the stem apices of the weeds and the crop with respect to the soil surface. Mesocotyl elongation in many of the weed species was such that the meristematic tissue was raised to the soil surface and into contact with the compound during the emergence of the shoot. In contrast, the stem apex of wheat remained some distance below the soil surface until considerably later, by which time the leaf sheaths offered protection to the meristematic tissue from direct contact with the herbicide. Selectivity is further enhanced in the field as a result of both the depth of planting for wheat and the tendency of many annual weed species to germinate more readily when near the soil surface. Tolerance of the wheat is lost where it germinates in direct contact with the herbicide, due to the lack of any biochemical selectivity. Under field conditions WL 29,226 gives good control of many dicotyledonous species. In pot experiments, however, these exhibit some tolerance to the compound. Radio‐tracer studies indicate that the tolerance shown by the shoots of these plants is due to limited transport of the herbicide from the shoot to its site of action at the apex. This suggests that control of broad‐leaved weeds occurs predominantly through an inhibition of root growth. However, in species such as sugar‐beet, soyabean and cotton a rapid rate of root elongation confers increased tolerance to the compound. Availability of WL 29,226 for uptake by young seedlings is favoured by soil moisture. Low temperatures further improve performance by reducing the rate of shoot emergence and hence prolonging contact with the compound at the most sensitive stage of growth. After emergence uptake of the compound via the shoot becomes a less efficient mode of entry.
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Claims 20
Claim · model-written summary
WL 29,226 at 0.5–2 kg/ha controlled annual monocot weeds including Alopecurus myosuroides.
- Taxon
- wheat
Triticum aestivumt0 - Treatment
- 0.5–2 kg/hae0
- Interactor
- Alopecurus myosuroides
Alopecurus myosuroidese0weed - Outcome
- good control of a number of annual monocotyledonous weedse0
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“When applied at dose rates of 0.5–2 kg/ha it gave good control of a number of annual monocotyledonous weeds, including Alopecurus myosuroides (blackgrass), without any adverse effects on the crop.”
t0“against a number of annual weeds in wheat.”
Claim · model-written summary
The treatment caused no adverse crop effects at 0.5–2 kg/ha.
- Taxon
- wheatTriticum aestivumt0
- Treatment
- 0.5–2 kg/hae0
- Outcome
- without any adverse effects on the crope0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“When applied at dose rates of 0.5–2 kg/ha it gave good control of a number of annual monocotyledonous weeds, including Alopecurus myosuroides (blackgrass), without any adverse effects on the crop.”
t0“against a number of annual weeds in wheat.”
Claim · model-written summary
WL 29,226 remained at the soil surface and favored emerging-shoot uptake.
- Taxon
- wheatTriticum aestivumt0
- Treatment
- WL 29,226e0
- Outcome
- uptake via the emerging shoote0
- Qualifier
- remaining at the soil surfacee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“WL 29,226 is relatively immobile in soil, remaining at the soil surface and thus favouring uptake via the emerging shoot.”
t0“against a number of annual weeds in wheat.”
Claim · model-written summary
The herbicide was transported predominantly through xylem toward dividing tissue.
- Taxon
- wheatTriticum aestivumt0
- Organ / stage
- shoote0
- Treatment
- WL 29,226e0
- Outcome
- transported predominantly via the xyleme0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Since WL 29,226 is transported predominantly via the xylem, to reach its site of action in the regions of cell division, and hence to be effective, the compound has to penetrate the shoot either at or below the stem apex.”
t0“against a number of annual weeds in wheat.”
Claim · model-written summary
Roots were inhibited only on direct contact with the compound.
- Taxon
- wheatTriticum aestivumt0
- Treatment
- the compounde0
- Outcome
- roots are inhibitede0
- Direction
- inhibitede0
- Qualifier
- direct contacte0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The roots are inhibited only when these come into direct contact with the compound.”
t0“against a number of annual weeds in wheat.”
Claim · model-written summary
Stem-apex position relative to the soil surface determined crop-weed selectivity.
- Taxon
- wheatTriticum aestivumt0
- Organ / stage
- stem apicese0
- Interactor
- weedse0weed
- Outcome
- Selectivity of the herbicidee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Selectivity of the herbicide is dependent upon the relative anatomical positions of the stem apices of the weeds and the crop with respect to the soil surface.”
t0“against a number of annual weeds in wheat.”
Claim · model-written summary
Weed mesocotyl elongation brought meristems to the soil surface and herbicide during emergence.
Verbatim
e0“Mesocotyl elongation in many of the weed species was such that the meristematic tissue was raised to the soil surface and into contact with the compound during the emergence of the shoot.”
Claim · model-written summary
Wheat stem apices remained deeper until leaf sheaths protected the meristem.
- Taxon
- wheatTriticum aestivume0
- Organ / stage
- stem apexe0
- Treatment
- herbicidee0
- Outcome
- leaf sheaths offered protectione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“In contrast, the stem apex of wheat remained some distance below the soil surface until considerably later, by which time the leaf sheaths offered protection to the meristematic tissue from direct contact with the herbicide.”
Claim · model-written summary
Planting depth and near-surface weed germination enhanced herbicide selectivity in the field.
- Taxon
- wheatTriticum aestivume0
- Interactor
- annual weed speciese0weed
- Outcome
- Selectivity is further enhancede0
- Qualifier
- depth of planting for wheate0
- Setting
- fielde0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Selectivity is further enhanced in the field as a result of both the depth of planting for wheat and the tendency of many annual weed species to germinate more readily when near the soil surface.”
Claim · model-written summary
Wheat lost tolerance when it germinated in direct contact with the herbicide.
- Taxon
- wheatTriticum aestivume0
- Treatment
- direct contact with the herbicidee0
- Outcome
- Tolerance of the wheate0
- Direction
- loste0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Tolerance of the wheat is lost where it germinates in direct contact with the herbicide, due to the lack of any biochemical selectivity.”
Claim · model-written summary
WL 29,226 controlled many dicot weeds under field conditions.
- Taxon
- wheatTriticum aestivumt0
- Treatment
- WL 29,226e0
- Interactor
- dicotyledonous speciese0weed
- Outcome
- good control of many dicotyledonous speciese0
- Setting
- field conditionse0
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Under field conditions WL 29,226 gives good control of many dicotyledonous species.”
t0“against a number of annual weeds in wheat.”
Claim · model-written summary
Dicot weeds displayed some tolerance in pot experiments.
- Taxon
- wheatTriticum aestivumt0
- Interactor
- thesee0weed
- Outcome
- some tolerance to the compounde0
- Setting
- pot experimentse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“In pot experiments, however, these exhibit some tolerance to the compound.”
t0“against a number of annual weeds in wheat.”
Claim · model-written summary
Limited shoot transport to the apex explained dicot shoot tolerance.
- Taxon
- wheatTriticum aestivumt0
- Interactor
- these plantse0weed
- Outcome
- tolerance shown by the shootse0
- Qualifier
- limited transport of the herbicidee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Radio‐tracer studies indicate that the tolerance shown by the shoots of these plants is due to limited transport of the herbicide from the shoot to its site of action at the apex.”
t0“against a number of annual weeds in wheat.”
Claim · model-written summary
Broadleaf weed control appeared to occur mainly through root-growth inhibition.
- Taxon
- wheatTriticum aestivumt0
- Interactor
- broad‐leaved weedse0weed
- Outcome
- control of broad‐leaved weedse0
- Qualifier
- inhibition of root growthe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“This suggests that control of broad‐leaved weeds occurs predominantly through an inhibition of root growth.”
t0“against a number of annual weeds in wheat.”
Claim · model-written summary
Rapid root elongation increased herbicide tolerance in sugar-beet.
- Taxon
- sugar‐beet
Beta vulgaris subsp. vulgarise0 - Organ / stage
- roote0
- Treatment
- compounde0
- Outcome
- tolerance to the compounde0
- Direction
- increasede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“However, in species such as sugar‐beet, soyabean and cotton a rapid rate of root elongation confers increased tolerance to the compound.”
Claim · model-written summary
Rapid root elongation increased herbicide tolerance in soyabean.
Verbatim
e0“However, in species such as sugar‐beet, soyabean and cotton a rapid rate of root elongation confers increased tolerance to the compound.”
Claim · model-written summary
Rapid root elongation increased herbicide tolerance in cotton.
- Taxon
- cotton
Gossypium hirsutume0 - Organ / stage
- roote0
- Treatment
- compounde0
- Outcome
- tolerance to the compounde0
- Direction
- increasede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“However, in species such as sugar‐beet, soyabean and cotton a rapid rate of root elongation confers increased tolerance to the compound.”
Claim · model-written summary
Soil moisture favored availability of WL 29,226 to seedlings.
- Taxon
- wheatTriticum aestivumt0
- Treatment
- soil moisturee0
- Outcome
- Availability of WL 29,226 for uptake by young seedlingse0
- Direction
- favourede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Availability of WL 29,226 for uptake by young seedlings is favoured by soil moisture.”
t0“against a number of annual weeds in wheat.”
Claim · model-written summary
Low temperature improved herbicide performance by slowing shoot emergence and prolonging exposure.
- Taxon
- wheatTriticum aestivumt0
- Treatment
- Low temperaturese0
- Outcome
- improve performancee0
- Qualifier
- reducing the rate of shoot emergencee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Low temperatures further improve performance by reducing the rate of shoot emergence and hence prolonging contact with the compound at the most sensitive stage of growth.”
t0“against a number of annual weeds in wheat.”
Claim · model-written summary
After emergence, shoot uptake became less efficient.
- Taxon
- wheatTriticum aestivumt0
- Organ / stage
- After emergencee0
- Outcome
- uptake of the compound via the shoote0
- Direction
- less efficiente0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“After emergence uptake of the compound via the shoot becomes a less efficient mode of entry.”
t0“against a number of annual weeds in wheat.”
The same questions in other papers
herbicide · disease · Triticum aestivum (wheat)Positive and negative results
10 papers in the same direction as this paper · 18 in the opposite direction
- positive
- positive
- positive
25 papers more in this group
See all 29 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.