Physiological Basis for the Different Phloem Mobilities of Chlorsulfuron and Clopyralid

Weed Science ◽  
1990 ◽  
Vol 38 (1) ◽  
pp. 1-9 ◽  
Author(s):  
Malcolm D. Devine ◽  
Hank D. Bestman ◽  
William H. Vanden Born
Keyword(s):  
Leaf Tissue ◽  
Phloem Transport ◽  
Assimilate Transport ◽  
Herbicide Application ◽  
Irreversible Binding ◽  
Sensitive Species ◽  
Physiological Basis ◽  
Treated Leaf ◽  
Phloem Translocation ◽  
Leaf Disks

Foliar-applied clopyralid was translocated much more readily than chlorsulfuron in the phloem of Tartary buckwheat plants. This result was not due to greater penetration of clopyralid into the treated leaf or to greater retention of chlorsulfuron in the cuticle. Experiments with excised leaf disks indicated that chlorsulfuron was taken up more readily by the leaf tissue and accumulated in the tissue to a higher concentration than clopyralid. Both herbicides effluxed readily from the tissue after transfer to herbicide-free medium, indicating that the accumulation was not due to irreversible binding within the tissue. Chlorsulfuron (2.8 nmol) applied with14C-sucrose reduced14C export from the treated leaf. Chlorsulfuron also reduced export of14C following exposure of the treated leaf to14CO2at 6, 12, or 24 h after herbicide application. This effect of chlorsulfuron could be partially reversed by pretreating the plants with a combination of 1 mM valine, leucine, and isoleucine. In similar experiments clopyralid had no effect on assimilate transport. It is concluded that phloem translocation of chlorsulfuron in sensitive species is limited by a rapid, indirect effect on phloem transport that reduces both its own translocation and that of assimilate.

Fate of Fenoxaprop-Ethyl Applied to Moisture-Stressed Smooth Crabgrass (Digitaria ischaemum)

Weed Science ◽  
1993 ◽  
Vol 41 (3) ◽  
pp. 335-340 ◽  
Author(s):  
Frank S. Rossi ◽  
Joseph M. Di Tomaso ◽  
Joseph C. Neal
Keyword(s):  
Dry Weight ◽  
Membrane System ◽  
Moisture Stress ◽  
Antagonistic Effect ◽  
Herbicide Application ◽  
Matric Potential ◽  
Relative Level ◽  
The Third ◽  
Shoot Dry Weight ◽  
Treated Leaf

Investigations of smooth crabgrass growth and fenoxaprop-ethyl retention, foliar penetration, translocation, and metabolism were conducted at various soil moisture levels using a polyethylene glycol (PEG) semipermeable membrane system. The activity of fenoxapropethyl was significantly reduced at higher levels of moisture stress and this antagonistic effect was greater with increased duration of water deficit following herbicide application. Fenoxaprop-ethyl spray retention decreased linearly (23% total reduction) as soil matric potential (Ψm) decreased from −0.01 to −0.1 MPa. Foliar penetration and translocation of14C-fenoxaprop-ethyl applied on the third true leaf were not affected by level or duration of moisture stress. Only 2% of the absorbed radioactivity was translocated out of the treated leaf for each moisture stress level and duration. As the soil Ψm decreased (−0.01 to −1.0 MPa) the relative levels of fenoxaprop-ethyl increased by 76 and 65% after a 48- and 96-h postapplication moisture stress period, respectively. In contrast, fenoxaprop acid decreased by 59 and 44% after 48 and 96 h of moisture stress, respectively. The relative level of fenoxaprop acid was linearly correlated to the antagonistic effect on shoot dry weight. These results suggest that decreased spray retention and, particularly, alterations in fenoxaprop-ethyl metabolism contribute to reduced fenoxaprop-ethyl activity observed in moisture-stressed smooth crabgrass.

Differential Absorption and Distribution as a Basis for the Selectivity of Bifenox

Weed Science ◽  
1978 ◽  
Vol 26 (1) ◽  
pp. 76-81 ◽  
Author(s):  
G. R. Leather ◽  
C. L. Foy
Keyword(s):  
Zea Mays ◽  
Glycine Max ◽  
Leaf Tissue ◽  
Abutilon Theophrasti ◽  
General Distribution ◽  
Differential Absorption ◽  
Greenhouse Soil ◽  
Treated Soil ◽  
Treated Leaf ◽  
Soil Mix

The uptake and distribution of14C-bifenox [methyl 5-(2,4-dichlorophenoxy)-2-nitrobenzoate] was different among corn(Zea maysL.), soybean(Glycine max(L.) Merr.) and velvetleaf(Abutilon theophrastiMedic.) following preemergence application to a greenhouse soil mix. Autoradiographs of seedlings harvested 14 days after treatment, showed the14C to be in (or on) those areas of the crop plant in contact with the treated soil. Velvetleaf translocated14C residue throughout the shoot. Absorption of14C-compound(s) from treated nutrient solution accumulated in the roots of the three species but to a greater extent in soybean. There was no difference in the concentration of14C in the shoots. However, in corn and soybean the14C-compound(s) was confined to the primary and secondary leaf veins while velvetleaf showed a general distribution throughout the leaf tissue. Velvetleaf absorbed and translocated bifenox from shoot zones to a greater extent than the crop plants. Some acropetal movement was noted following leaf application to corn and velvetleaf but movement was only 3% of applied14C from the treated leaf. No movement was detected in soybean.

scholarly journals Physiological Basis for Metamifop Selectivity on Bermudagrass (Cynodon dactylon) and Goosegrass (Eleusine indica) in Cool-Season Turfgrasses

Weed Science ◽  
2016 ◽  
Vol 64 (1) ◽  
pp. 12-24 ◽  
Author(s):  
Patrick E. McCullough ◽  
Jialin Yu ◽  
Mark A. Czarnota ◽  
Paul L. Raymer
Keyword(s):  
Laboratory Experiments ◽  
Cynodon Dactylon ◽  
Retention Factor ◽  
Creeping Bentgrass ◽  
Kentucky Bluegrass ◽  
Shoot Biomass ◽  
Cool Season ◽  
Physiological Basis ◽  
Eleusine Indica ◽  
Treated Leaf

Bermudagrass and goosegrass are problematic weeds with limited herbicides available for POST control in creeping bentgrass. Metamifop effectively controls these weeds with greater selectivity in cool-season grasses than other ACCase inhibitors. The objectives of this research were to determine the physiological basis for metamifop selectivity in turfgrasses. In greenhouse experiments, metamifop rate required to reduce shoot biomass 50% from the nontreated (GR50) at 4 wk after treatment was > 6,400, 2,166, and 53 g ai ha−1for creeping bentgrass, Kentucky bluegrass, and goosegrass, respectively. The GR50for bermudagrass treated with diclofop-methyl or metamifop was 2,850 and 60 g ha−1, respectively. In laboratory experiments, peak absorption of14C-metamifop was reached at 48, 72, and 96 h after treatment (HAT) for goosegrass, creeping bentgrass and Kentucky bluegrass, respectively. Grasses translocated < 10% of the absorbed radioactivity out of the treated leaf at 96 HAT, but creeping bentgrass translocated three times more radioactivity than goosegrass and Kentucky bluegrass. Creeping bentgrass, Kentucky bluegrass, and goosegrass metabolized 16, 14, and 25% of14C-metamifop after 96 h, respectively. Goosegrass had around two times greater levels of a metabolite at retention factor 0.45 than creeping bentgrass and Kentucky bluegrass. The concentration of metamifop required to inhibit isolated ACCase enzymes 50% from the nontreated (I50) measured > 100, > 100, and 38 μM for creeping bentgrass, Kentucky bluegrass, and goosegrass, respectively. In other experiments, foliar absorption of14C-metamifop in bermudagrass was similar to14C-diclofop-methyl. Bermudagrass metabolized 23 and 60% of the absorbed14C-diclofop-methyl to diclofop acid and a polar conjugate after 96 h, respectively, but only 14% of14C-metamifop was metabolized. Isolated ACCase was equally susceptible to inhibition by diclofop acid and metamifop (I50= 0.7 μM), suggesting degradation rate is associated with bermudagrass tolerance levels to these herbicides. Overall, the physiological basis for metamifop selectivity in turfgrass is differential levels of target site inhibition.

Source - sink differences in genotypes and water regimes influencing sucrose accumulation in sugarcane stalks

2009 ◽  
Vol 60 (4) ◽  
pp. 316 ◽  
Author(s):  
N. G. Inman-Bamber ◽  
G. D. Bonnett ◽  
M. F. Spillman ◽  
M. L. Hewitt ◽  
Jingsheng Xu
Keyword(s):  
Dry Matter ◽  
Supply And Demand ◽  
Leaf Tissue ◽  
Biomass Accumulation ◽  
Net Photosynthesis ◽  
Extension Rate ◽  
Sucrose Content ◽  
Dry Matter Partitioning ◽  
Physiological Basis ◽  
High Sucrose

Relatively little is known about the physiological basis for variation in sucrose content among sugarcane clones despite substantial research at the molecular and biochemical levels. We used irrigation and continuous monitoring of photosynthesis and plant extension rate to modify dry matter partitioning in four clones differing widely in sucrose content. Three pot experiments were conducted on two low sucrose content clones, KQ97-2599 and KQ97-2835, and two high sucrose content clones, Q117 and KQ97-5080, in a temperature-controlled glasshouse. As expected, sucrose content on a dry mass basis of whole stalks was greater in high (55% maximum) than in low sucrose clones (40% maximum), but sucrose content in the two clones selected for low sucrose reached 55% in some internodes. Differences between clones in whole-plant net photosynthesis and aerial biomass accumulation were small. However, biomass was distributed over fewer stalks in the high sucrose clones (4–7 stalks per pot) than in the low sucrose clones (9–11 stalks per pot). The high sucrose clones also allocated a considerably greater proportion of dry matter to the stalk (70% maximum) than the low sucrose clones (60% maximum). It is suggested that the relatively large amount of new leaf tissue produced by the high tillering, low sucrose clones placed an additional demand for structural photo-assimilate in these clones and delayed the accumulation of sucrose in the stalk. The results indicated that there is little direct genetic control on the maximum amount of sucrose that can accumulate in stalk tissue and that genetic contrasts in sucrose content reside more in the morphology of the plant and responses to ripening stimuli such as mild water stress, and how these traits influence supply and demand for photo-assimilate.

scholarly journals Survival, Dispersal, and Potential Soil-Mediated Suppression of Phytophthora ramorum in a California Redwood-Tanoak Forest

2009 ◽  
Vol 99 (5) ◽  
pp. 608-619 ◽  
Author(s):  
E. J. Fichtner ◽  
S. C. Lynch ◽  
D. M. Rizzo
Keyword(s):  
Leaf Litter ◽  
Leaf Tissue ◽  
Soil Surface ◽  
Phytophthora Ramorum ◽  
Infested Soil ◽  
Splash Dispersal ◽  
Pathogen Suppression ◽  
Rain Events ◽  
Leaf Disks

Because the role of soil inoculum of Phytophthora ramorum in the sudden oak death disease cycle is not well understood, this work addresses survival, chlamydospore production, pathogen suppression, and splash dispersal of the pathogen in infested forest soils. Colonized rhododendron and bay laurel leaf disks were placed in mesh sachets before transfer to the field in January 2005 and 2006. Sachets were placed under tanoak, bay laurel, and redwood at three vertical locations: leaf litter surface, litter–soil interface, and below the soil surface. Sachets were retrieved after 4, 8, 20, and 49 weeks. Pathogen survival was higher in rhododendron leaf tissue than in bay tissue, with >80% survival observed in rhododendron tissue after 49 weeks in the field. Chlamydospore production was determined by clearing infected tissue in KOH. Moist redwood-associated soils suppressed chlamydospore production. Rain events splashed inoculum as high as 30 cm from the soil surface, inciting aerial infection of bay laurel and tanoak. Leaf litter may provide an incomplete barrier to splash dispersal. This 2-year study illustrates annual P. ramorum survival in soil and the suppressive nature of redwood-associated soils to chlamydospore production. Infested soil may serve as primary inoculum for foliar infections by splash dispersal during rain events.

scholarly journals Cryoprotectants Influence Freezing Resistance of Grapevine Bud and Leaf Tissue

HortScience ◽  
1991 ◽  
Vol 26 (4) ◽  
pp. 406-407 ◽  
Author(s):  
David G. Himelrick ◽  
Robert M. Pool ◽  
Philip J. McInnis
Keyword(s):  
Ethylene Glycol ◽  
Leaf Tissue ◽  
The Other ◽  
Freezing Resistance ◽  
Freeze Resistance ◽  
Brij 35 ◽  
Vitis Labruscana ◽  
Dormant Bud ◽  
Grape Leaf ◽  
Leaf Disks

Several cryoprotectant chemicals were tested for their ability to increase the freeze resistance of grapevine (Vitis labruscana Bailey) leaf and dormant bud tissue. DuPont Surfactant WK, ethylene glycol, and BRIJ 35 were effective in lowering the low-temperature exotherm (LTE) in `Concord' grape buds below controls by 5.4, 5.1, and 3.9C, respectively, in March. Measurements taken in April showed BRIJ 35 and Surfactant WK to be notably superior to the other products, giving LTEs 14.1 and 12.2C below controls, respectively. Ethylene glycol, Frostguard, and Frost Free were less effective. LTEs were also significantly decreased in grape leaf disks 4.1C by BRIJ 35, 2.1C by Frostguard, and 0.4C by Frost Free treatments. Chemical name used: trimethylnonylpolyethoxyethanol (DuPont Surfactant WK).

Imazamox Absorption, Translocation, and Metabolism by Cereal Rye (Secale cereale) at Low Temperatures

Weed Science ◽  
2019 ◽  
Vol 67 (2) ◽  
pp. 189-194 ◽  
Author(s):  
Michael H. Ostlie ◽  
Dale Shaner ◽  
Melissa Bridges ◽  
Phillip Westra
Keyword(s):  
Secale Cereale ◽  
Phenotypic Diversity ◽  
Warm Temperature ◽  
Herbicide Application ◽  
Cold Temperatures ◽  
Cereal Rye ◽  
Plant Parts ◽  
Greenhouse Study ◽  
Herbicide Treatments ◽  
Treated Leaf

AbstractCereal rye (Secale cerealeL.) control in wheat (Triticum aestivumL.) can be difficult with existing selective herbicides. High phenotypic diversity within populations coupled with suboptimal herbicide application conditions leads to varying degrees of control with herbicide treatments. The following research focused on the consequence of low temperature on imazamox fate inS. cereale. A greenhouse study was conducted to determine the number of warm-temperature days required for imazamox to controlS. cereale. Absorption, translocation, and metabolism of imazamox was evaluated under warm (22/18C) and cold (4/4C) temperatures to identify changes to the fate of imazamox under different environmental conditions. In greenhouse conditions, more than 5 d of warm temperature following herbicide application was required to achieve 80%S. cerealemortality. Absorption of imazamox was reduced 20% whenS. cerealewas subjected to cold compared with warm temperatures. Only 10% of applied imazamox was moved from the treated leaf in continuous cool temperatures compared with greater than 60% in warm conditions. In cold conditions, imazamox content increased in all tested plant parts evaluated for the duration of the study, whereas in warm conditions, imazamox concentrations decreased in root and crown tissues after 3 d. Imazamox behavior was affected more by temperature thanS. cerealegrowth stage.Secale cerealemetabolism of imazamox was reduced, but not stopped in cold temperatures. After 6 d, only a 10% difference in intact imazamox remained between temperature treatments. In cold temperatures, reduced absorption and translocation, coupled with continued metabolism, allow plants to recover from an otherwise lethal imazamox treatment.

Host Plant Influence on Activity of Bacillus thuringiensisBerliner Against Lepidopterous Pests of Crops

2004 ◽  
Vol 39 (3) ◽  
pp. 311-317 ◽  
Author(s):  
M. Ibrahim Ali ◽  
S. Y. Young ◽  
R. C. McNew
Keyword(s):  
Helicoverpa Zea ◽  
Spodoptera Exigua ◽  
Leaf Tissue ◽  
Pest Species ◽  
Speed Of Kill ◽  
Median Lethal Concentration ◽  
Percent Survival ◽  
Treated Leaf ◽  
The Mean ◽  
Laboratory Bioassays

Mortality of second-instar Helicoverpa zea (Boddie), Spodoptera exigua (Hübner) and Pseudoplusia includens (Walker) fed Bacillus thuringiensis Berliner (Bt), Dipel ES®-sprayed leaves of field grown cotton, soybean and tomato were compared in laboratory bioassays. The median lethal concentration (LC50) for larvae of all species fed Bt-treated leaf tissue was higher for cotton than for soybean or tomato. The LC50 for larvae fed Bt-treated soybean and tomato leaves did not differ significantly for any species of insects. When the mean number of days until death was plotted against percent survival at that rate, the mean number of days until death increased with an increase in percent survival. Survival time of the three insect species exposed to Bt increased most rapidly when fed cotton leaves. Results show that foliarly-applied Bt on field-grown cotton leaves is less effective against larvae of these pest species in terms of mortality and speed of kill.

RESPONSES OF LARVAL CHORISTONEURA ROSACEANA (HARRIS) (LEPIDOPTERA: TORTRICIDAE) TO A FEEDING STIMULANT

1997 ◽  
Vol 129 (2) ◽  
pp. 363-369 ◽  
Author(s):  
S.Y. Li ◽  
S.M. Fitzpatrick
Keyword(s):  
Bacillus Thuringiensis ◽  
Filter Paper ◽  
Leaf Tissue ◽  
Choice Experiments ◽  
Choristoneura Rosaceana ◽  
Leaf Discs ◽  
Feeding Stimulant ◽  
Treated Leaf

AbstractThe commercial feeding stimulant Pheast® was tested in the laboratory to determine its attractive and phagostimulatory effects on larval Choristoneura rosaceana (Harris). In choice experiments, larvae were attracted initially to filter paper discs treated with Pheast, but did not remain on or near treated discs. Larvae were not attracted initially to raspberry leaf discs treated with Pheast, but were more likely to stay near treated leaf discs than water-dipped ones. Larvae were neither attracted to nor arrested on whole raspberry leaves treated with Pheast. In no-choice experiments, larvae fed Pheast-treated leaves consumed more leaf tissue than, and grew almost twice as quickly as, larvae fed leaves dipped in water. When larvae were fed leaves treated with Dipel WP (Bacillus thuringiensis var. kurstaki) plus 5% Pheast, the mortality was 93% greater than that of larvae fed leaves treated with Dipel WP alone. These results suggest that Pheast has potential to enhance efficacy of B. thuringiensis against C. rosaceana on raspberries in the field.

Starch associated particles in D-glucosamine-treated leaf tissue

PROTOPLASMA ◽  
1975 ◽  
Vol 85 (2-4) ◽  
pp. 261-270 ◽  
Author(s):  
Cathryn J. Mittelheuser ◽  
R. F. M. van Steveninck
Keyword(s):  
Leaf Tissue ◽  
Treated Leaf
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