Uptake and metabolism of hexazinone in Rubus hispidus L. and Pyrus melanocarpa (Michx.) Willd

Rooted cuttings of Pyrus melanocarpa (Michx.) Willd. had a 3.5-fold greater tolerance to soil-applied hexazinone than those of Rubus hispidus L. in a greenhouse trial. R. hispidus accumulated four times more ¹⁴C-label in the foliage following root uptake of ¹⁴C-hexazinone than P. melano-carpa . Here, the greater uptake and susceptibility of R. hispidus was related to its greater root:fol-iage (weight) ratio compared to the tolerant P. melanocarpa . However, in whole plant metabolism studies employing younger plants there were no differences in ¹⁴C accumulation in the leaves. Here ¹⁴Chexazinone was converted to a number of hydroxylated and/or demethylated triazinone metabolites in both species following vacuum infiltration into leaf disks and root sections, or following root uptake in whole plants. A major difference in metabolism between the two species was the greater formation of the mono demethylated metabolite, B, [3-cyclohexyl-6-methylamino-l-methyl-l,3,5-triazine-2,4-dione] in P. melanocarpa which may also contribute to its greater tolerance. A loss of total ¹⁴Clabel from all plant parts with time may reflect cleavage of the ¹⁴C-ring-labelled herbicide.     

EFFECT OF 2,4-D AND PICLORAM ON TRANSLOCATION OF 14C-ASSIMILATES IN VITIS VINIEERA L.

Summary. High concentrations of 2,4-D and picloram interfered with the downward movement of ¹⁴c-assimilates infield-grown vines. The interference in translocation was appreciably greater with picloram than it was with 2,4-D, Although basipetal translocation was retarded, translocation within the treated shoots continued from the vegetative part to the clusters. Translocation of 2,4-D appeared to follow the same route as ¹⁴c-assimilatcs for the most part. Formative effects were absent on untreated grape shoots although the adjacent shoots treated with 2,4-D or picloram on the same cordons were killed; however, formative effects were evident on some of the stump sprouts which developed after the vines were harvested. The malformed leaves on the stump sprouts were twelve or more nodes from the base of the shoots, while ¹⁴c was in the more basal leaves.
Thompson Seedless (Sultanina) rootings treated with 20 000 ppm 2,4-D or picloram transported less ¹⁴C to the roots than did the controls. Treatment with either herbicide resulted in a marked increase in the labelling of the stems.
Effet du 2,4-D et du pichlorame sur la migration de métabolites marqués au ¹⁴C dans Vitis vinifera L.     

Uptake and translocation of imazethapyr in peas as affected by parasitism of Orobanche crenata and herbicide application methods

[¹⁴C]-Imazethapyr was applied as a seed treatment and at plant pre-emergence and post-emergence to peas ( Pisum sativum L.) parasitized by Orobanche crenata Forsk. Herbicide uptake increased with time regardless of the application method. Uptake reached about 98%, 89%, 81% and 94% of the total herbicide applied for the seed coating, seed soaking, pre-emergence and post-emergence treatments respectively. Herbicide translocation within the host plants consistently differed between O. crenata -infected and non-infected plants. High levels of ¹⁴C activity were accumulated by parasitic plants from the host. In non-infected pea plants, pods were stronger sinks for imazethapyr than the other parts of the plant, regardless of the application method. The herbicide distribution in the pea plant: O. crenata complex showed the same pattern regardless of the application methods. However, accumulation of radioactivity in the parasite was lower with pre-emergence and post-emergence application than with the seed treatments. In addition, radioactivity concentration in O. crenata plants was slightly higher when [¹⁴C]-imazethapyr was applied to pea seeds by coating than by soaking.     

TRANSLOCATION OF AMINOTRIAZOLE AND DALAPON IN AG ROPY RON REPENS (L.) BEAUV.

Summary. Tracer studies using single drops of solutions containing 3–amino-1,2,4–triazole-5–¹⁴C (aminotriazole-¹⁴C) or 2,2–dichloropropionic acid-2–¹⁴C (datapon-¹⁴C) revealed that in couch plants (Agropyron repens (L.) Beauv.) growing under field conditions in the autumn and at the stage where the aerial shoots were 40–50 cm long, both compounds moved in both symplast and apoplast. Dalapon was less mobile in the symplast than aminotriazole and only negligible amounts of dalapon were translocated to the rhizomes. The nodes of the treated shoots appeared to act as barriers to translocation, a phenomenon more pronounced for dalapon than for aminotriazole.
Application to a basal green leaf led to a more uniform distribution of the compounds within plants and rhizomes than when the application was made to the youngest fully-expanded leaf.
In couch plants with aerial shoots 10–15 cm long treated in the stubble, the distribution of both aminotriazole and dalapon was mainly restricted to the treated shoots. Even 15 days after application only trace amounts of radioactivity could be found in the rhizomes and untreated shoots.     

A qualitative quick-test for detection of herbicide resistance to tribenuron-methyl in Papaver rhoeas

A qualitative seed-based method useful for the detection of resistance to the herbicide tribenuron-methyl in Papaver rhoeas L. is described. Seeds were germinated on 35 mL of a 1.3% agar medium containing 2 g KNO₃ L^–1 in 8.5 cm Petri dishes in a growth chamber under 20 μmol s^–1 m^–2 of fluorescent light. When 0.24 μM tribenuron-methyl or more was added, growth in susceptible plants stopped after the cotyledon stage and they turned chlorotic. The resistant plants continued developing new leaves. The same effect was achieved when 0.2 g gibberellin (GA₃) L^–1 and 7.68 μM tribenuron-methyl or 0.5 g GA₃ L^–1 and 61.44 μM tribenuron-methyl were added. Germination percentage rose with gibberellin in the presence or absence of the herbicide. Plants developed rapidly, with only about 14 d needed to finish the test but sometimes root growth was reduced because of the addition of gibberellin. In the absence of gibberellin but in the presence of the herbicide, plants grew more slowly and developed smaller leaves with a 17-d evaluation period requirement. The test was validated with pot experiments in a greenhouse and also with field trials. The best combination was found to be 0.2 g GA₃ L^–1 and 7.68 μM tribenuron-methyl, assuring homogenous germination and testing of dormant seeds but avoiding root inhibition associated with too much gibberellin.     

Effects of the safeners CGA 154281, oxabetrinil and fenclorim on uptake and degradation of metolachlor in corn (Zea mays L.) seedlings

Summary. The influence of three crop safeners on the uptake and degradation of ¹⁴C-metolachlor was investigated in two corn varieties. Following application of herbicide and safener together to seedling shoots the concentrations of non-metabolized ¹⁴C-metolachlor in the tissues was found to be lower in the tolerant variety LG 9 than in the susceptible variety 211A. The difference between varieties was due to differences in both uptake and degradation of ¹⁴C-metolachlor.
Following shoot application most of the radioactivity was retained in the coleoptile and the mesocotyl. Two hours after application 95% of the herbicide had been degraded in coleoptiles and mesocotyls, whereas approximately 20% of non-metabolized ¹⁴C-metolachlor was present in the enclosed developing shoot leaves. In both corn varieties the safener CGA 154281 caused a substantial lowering of tissue levels of parent ¹⁴C-metolachlor. This was primarily due to an enhanced degradation. Glutalhione- S -transfer-ase (GST) enzyme activity in shoot tissues was found to be enhanced in both varieties by CGA 154281. Oxabetrinil and fenclorim were less effective than CGA 154281 both in reducing tissue levels of non-metabolized ¹⁴C-metolachlor and in enhancing GST activity in either variety.     

Distribution of 14C-glyphosate in legumes parasitised by Orobanche crenata

Absorption and translocation of ¹⁴C-glyphosate was evaluated under controlled conditions in peas ( Pisum sativum L.) and broad beans ( Vicia faba L.) parasitised or not by crenate broomrape Orobanche crenata Forsk.). Absorption increased with time up to 12 days after treatment, and reached about 50% of the ¹⁴C-glyphosate applied. Three days after treatment 70–85% of the total herbicide absorbed had been translocated out of the treated leaflet. There was no consistent differ ence in absorption and translocation between infected and non-infected plants 12 days after treatment. The ¹⁴C-glyphosate concentration in the root system increased with time in broad beans. In peas it remained more or less constant from 3 days after treatment. Generally, pods were stronger sinks for glyphosate than other parts of the plant. Herbicide accumulation in broomrape increased with its growth stage, and the parasite was a much stronger sink for glyphosate than the legume root system.     

TRANSLOCATION OF 14C-ASSIMILATES AND 3-AMINO-1,2,4-TRIAZOLE AND ITS METABOLITES IN AGROPYRON REPENS

Summary. Translocation of 3-amino-1,2,4-triazole-5-¹⁴C (¹⁴C-aminotriazole) was compared to that of ¹⁴C-assimilates in couch grass ( Agropyron repens (L.) Beauv.) at three different growth stages.
Assimilates of ¹⁴CO₂ were translocated from the treated shoot to other shoots and rhizomes at the 2–3-leaf and 3–4-leaf stages of development. Much less labelled material was translocated into untreated shoots at the 5-leaf stage. More ¹⁴C-assimilates were translocated to the roots than to untreated shoots at all developmental stages. The translocation patterns of ¹⁴C-aminotriazole and ¹⁴C-assimilates were similar.
Two metabolites, A and B, were formed from ¹⁴C-aminotriazole, which chromatographed identically to previously described metabolites in Cirsium arvense (L.) Scop. A was further metabolized into B. Labelled aminotriazole and its two metabolites were translocated throughout the plants. Metabolite A was phytotoxic when concentrated and re-applied to couch grass, but its properties were not those of Unknown II from Cirsium arvense. They were the same as those of Unknown III. Whether or not metabolite A and Unknown III are identical was not established.
Migration des substances assimilables marquées au ¹⁴ C, du 3 amino-1,2,4-triazole et de ses métabolites chez Agropyron repens     

Phytotoxic activity of root absorbed glyphosate in corn seedlings (Zea mays L.)

Growth chamber experiments were conducted in order to study the absorption, translocation and activity of glyphosate when applied to roots with aqueous solution avoiding any glyphosate–substrate interaction. Corn seedlings at the first leaf stage were set up in individual graduated cylinders containing different solutions of ¹⁴C-glyphosate (0–30 mg ae kg⁻¹). After 26 h of root exposure, plants were transferred to fresh nutrient solution and grown for the next 5 days. After harvest, plants were separated into seed, root, mesocotyle, coleoptile, cotyledon, first leaf and all new leaves (apex), and quantified ¹⁴C radioactivity contained in each part. Glyphosate uptake was only 11% of the theoretical mass flow into the plant. The amount of glyphosate translocated from roots was positively correlated with plant uptake ( P  < 0.01). Total plant fresh weight presented a logistic response to glyphosate amounts, including a growth stimulant effect (hormesis), when plants absorbed less than 0.6 µg. The treated plants presented a normal pattern of glyphosate allocation, with the apex the principal sink, accumulating more than 38% of mobilized glyphosate. When corn plants absorbed more than 0.6 µg they showed a decrease in growth. The relatively high glyphosate quantities allocated in the new leaves showed the relevance of the symplastic pathway in the translocation process for root absorbed glyphosate.     

TRANSLOCATION STUDIES WITH ENDOTHAL-14C IN POTAMOGETON NODOSUS POIR.

Summary. Plants of Potamogeton nodosus, a submersed aquatic, were treated with the di-sodium salt of 7-oxabicyclo(2,2,l)heptane-2,3-dicarboxylic acid-¹⁴C (endothal-¹⁴C). Gross radioautographs showed that the ¹⁴C label moved from mature photosynthesizing leaves and accumulated in the apices and developing secondary plants. Similar results were obtained with mid-leaf, stem (internode) and winter-bud applications. No move-ment of radioactivity occurred following root treatment. The results indicate symplastic translocation of endothal-¹⁴C when applied to the leaf, stem or winter bud. It is suggested that endothal can cause the death of plants by direct injury to root tissues subsequent to absorption.
Recherches sur la migration de l'endothal-¹⁴C dans le Potamogeton nodosus Poir.     

Selectivity of 2,4-D in Solanum ptycanthum Dun. and Lycopersicon esculentum Mill.

In controlled environmental studies, a marked difference was observed between the growth pattern of tomato and eastern black nightshade plants that received doses of 2,4-D ranging from 28 to 952 g a.e. ha^?1. The highest dose of 2,4-D reduced the dry weight of eastern black nightshade and tomato by approximately 15 and 50%, respectively, when compared with controls. Although the height of both species was reduced by all doses of 2,4-D, eastern black nightshade plants produced secondary shoots, which compensated for any potential loss in dry weight that otherwise may have occurred. Tomato plants did not produce secondary shoots. After application of ¹⁴C-2,4-D to tomato and eastern black nightshade, the pattern of ¹⁴C absorption and translocation was similar in both plant species. However, there was significantly more radioactivity recovered in tomato (72%) than in eastern black nightshade (52%) plants, 72 h after treatment. Assay radioactivity in the nutrient solution of hydroponically grown plants indicated that 7·0 and 27·9% of the applied radioactivity was exuded from the roots of tomato and eastern black nightshade, respectively, within 72 h after treatment. Assay of plant extracts by thin layer chromatography revealed that the amount of radioactivity that remained as unaltered 2,4-D was 73 and 49% in tomato and eastern black nightshade, respectively, 72 h after treatment. Thus the greater tolerance of eastern black nightshade appeared to be due to greater rates of 2,4-D metabolism and/or greater rates of herbicide elimination by root exudation.     

Propanil activity, uptake and metabolism in resistant Echinochloa spp. biotypes

Field resistance of Echinochloa spp. to propanil has been previously reported in Costa Rica, Colombia and Arkansas (USA). In this study, the mechanism of resistance was investigated in three resistant (R) and three susceptible (S) biotypes. The shoot fresh weight reduction in pot-grown plants from a post-emergence spray of propanil at 2.44 kg a.i. ha⁻¹ on biotypes R/S from Costa Rica, Colombia and Arkansas was 35/98%, 25/79% and 20/82% respectively. In vitro chlorophyll fluorescence data from leaf tissue incubated in propanil showed that photosynthesis was inhibited in all biotypes, indicating that the propanil-binding site and enzyme were not altered. After transfer to herbicide-free solution, photosynthesis recovered only in resistant biotypes, indicating that the mechanism of resistance was caused by enhanced metabolism of the herbicide. Simultaneous treatment with fenitrothion, an aryl acylamidase inhibitor, prevented the recovery of photosynthesis in leaf tissue in two resistant biotypes. In contrast, the cytochrome P450 mono-oxygenase inhibitor, 1-aminobenzotriazole, did not prevent recovery from propanil in leaf tissue. Application of ¹⁴C-propanil to the second leaf of intact Echinochloa plants showed that c . 90% of the radioactivity remained in the treated leaf for up to 72 h after application. No major differences in translocation between R and S biotype plants were found. TLC analysis of tissue extracts from the treated leaves showed substantially less radioactivity associated with propanil, present after 72 h in rice or in the three R biotypes, compared with S biotypes.     

VERTICAL DISTRIBUTION OF HERBICIDES IN SOIL AND THEIR AVAILABILITY TO PLANTS: SHOOT COMPARED WITH ROOT UPTAKE

Summary. Turnip, lettuce and ryegrass seedlings showed toxicity symptoms following shoot exposure to atrazine, linuron and aziprotryne at soil concentrations less than would be obtained from normal field applications. Responses following shoot exposure to simazine and lenacil were much less. Root exposure to all five herbicides caused seedling death at concentrations lower than those required for 'shoot-zone' toxicity. Pronamide and chlorpropham were tested against ryegrass only and at the concentrations examined were toxic only when localized in the shoot zone. Root exposure suppressed root growth, but the shoots were able to grow normally if the soil was kept sufficiently moist. Shoots contained more ¹⁴C-atrazine at emergence after shoot exposure compared with root exposure, but there was little subsequent uptake from the shoot zone. There was extensive uptake from the root zone after emergence. In the shoot-zone treatments, concentrations in the plant were high at emergence but were rapidly diluted by plant growth, whereas with root exposure, they increased throughout the experiments. The possible significance of these results to herbicide bebaviour under field conditions is discussed.
La distribution verticale des herbicides dans le sol et leur disponibilité pour les plantes: absorption comparée par la partie aèrienne et par les radnes     

THE EFFECT OF SIMAZINE ON THE PHOTOFIXATION OF CO2 AND ON TRANSLOCATION OF ASSIMILATES IN NORWAY SPRUCE (PICEA ABIES)

Summary. A method of exposing seedlings of Norway spruce (Picea abies (L.) Karst.) to ¹⁴CO₂ is described. Within the 1st hr alter ¹⁴CO₂ exposure, no translocation of the ¹⁴C out of the treated branch could be observed. After a 24-hr period, however, the ¹⁴C in dormant seedlings had been translocated basipetally to part of the root system only, with no lateral diffusion of the ¹⁴C-compounds in the stem. About a week after exposure, both symplastic and apoplastic patterns of translocation had caused a more uniform distribution of ¹⁴C. In seedlings at active internode elongation, the translocation patterns were fundamentally identical to those in dormant seedlings, but the active shoot growth had led to a more uniform distribution of the ¹⁴C.
Simazine at 20 ppm had apparently stimulated both the photofixation of ¹⁴CO₂ and the rate of translocation of the ¹⁴C-assimilates. At 30 ppm, however, simazine had blocked the translocation of nutrients to the roots. On the other hand, the ¹⁴CO₂ uptake was not influenced. The simazine incubation had apparently no influence on the synthesis of cationic photosynthate.     

Contamination and subsequent multiplication of soft rot erwinias on healthy potato leaves and debris after haulm destruction

Small plots of potatoes were inoculated with a mixture of Erwinia carotovora (E. c.) subsp. carotovora and E. carotovora subsp, atroseptica strains resistant to rifampicin. Subsequently the population off, c. subsp, carotovora and E. c. subsp, atroseptica (rifampicin-resistant and wild types) present as epiphytes on the surface of potato leaves was assessed using three methods, qualitative, semi-quantitative and quantitative, during 1986 and 1987. The population was generally low (< 10² colony forming units (> 10⁴cfu/g leaves) but reached higher levels (> 10⁴ cfu/g) on occasions later in the growing season, Rifampicin-resistant erwinias were reisolated only infrequently throughout this study. Different methods of haulm destruction (herbicide, pulverization, sulphuric acid treatment and natural senescence) greatly influenced the number of erwinias present in the resulting plant debris. Pulverization resulted in the highest population (10⁶-10⁷ wild-type cfu/g) in both seasons. In 1987. the wettest of the two seasons of this study, herbicide treatment resulted in similarly high populations. The results suggest that the high numbers of erwinias found in the haulm debris were probably derived from the generally low populations of epiphytic bacteria previously present on healthy leaves, E. c. subsp, carotovora was the most frequent subspecies in the rotting plant debris; E. c. subsp, atroseptica was more commonly found on healthy leaves. The implications of the results are discussed in relation to the production of seed potatoes with a low risk of blackleg.     

THE EFFECT OF MCPA ON THE AMINO ACID AND SUGAR COMPOSITION OF VICIA FABA LEAVES

Summary. The effect of spraying Vicia faba leaves with 5000 ppm MCPA is described. Three to 4 days after spraying, a marked increase (× 5 approx.) was found in the concentrations of leucine iso -leucine and valine in the leaves. No significant changes were detected in the other amino acids. Treatment with MGPA also caused a significant increase (× 4 approx.) in the glucose and fructose content of the leaves. Detached leaves (sprayed and unsprayed), when kept in a moist atmosphere for 3–4 days, exhibited very similar increases in amino acids and sugars to sprayed intact plants. Experiments using ¹⁴CO₂ revealed that in short term photosynthesis (30 min) of sprayed and unsprayed plants, 80–90% of the radioactivity was incorporated in sucrose, with about 5% in each of glucose and fructose. Over photosynthelic periods of 4 days, glucose and fructose were found to be almost as heavily labelled as sucrose in sprayed plants, but in the controls the distribution of radioactivity was similar to that in short term photosynthesis. It is suggested that the build up of amino acids and sugars in plants treated with MCPA is due to an interruption of the translocatory flow from the leaves, and that this build up of metabolites may be a contributory factor in the toxic action of this herbicide.
Effet du MCPA sur la composition en amino-acides et en sucre des feuilles de Vicia faba     

AN AUTORADIOGRAPHIC STUDY OF THE MOVEMENT OF 14C-LABELLED ASSIMILATES IN THE DEVELOPING WHEAT PLANT

Summary. ¹⁴CO₂ together with autoradiographic techniques was used to stuy the movement of labelled carbon within wheat plants at different stages in their development. Movement of ¹⁴C about the plain was found to be extensive in the early stages, gradually bccoming more localized until at a stage after ear emergence there was little transference of labelled carbon between tillers within a 24-hour period.
In the early stages of development ¹⁴C from leaves on the main shoot was transported throughout the plant but accumulated in greatest amounts in the meristematic regions. Assimilates produced by the leaves of newly formed tillers were distributed mainly to the meristematic regions of those tillers although labelled carbon was moved in into the rest of the plant. In the later stages of development of each tiller the labelled assimilate was restricted to the tiller itself and to any very young tillers associated with it. After car emergence the pattern of distribution of the labelled carbon from the youngest and second youngest leaves was found to differ. Movement was predominantly towards the ear from the flag leaf and towards the root system from the leaf below the flag.
It was noticed that mature leaves accumulated some labelled material and the possibility that this occurred via the transpiration stream following migration from phloem to xylem, as is the case with some of the case with some of the translocated herbicides, was investigated, but no indication of xylem transference was obtained.
The possible application of these studies to investigations into the relationship between the movement natural assimilates and of translocated herbicides is discussed.     

THE MOVEMENT OF PARAQUAT IN PLANTS

Summary. A qualitative study of the movement of the herbicide paraquat from droplets applied to leaves of tomato plants, using ¹⁴C-methyl-labelled and ¹⁴C-ring-labelled paraquat dichloride and di(methylsulphate), has shown that it moves in the xylem with the transpiration stream. The chemical is as well transported from young leaves as from mature ones, and will move through a steam-ringed petiole. The enhancement of the amount of paraquat transported from the treated leaves which occurs when treated plants are kept in darkness for a period following treatment and then exposed to light, is probably due to the greater movement into the xylem through undamaged tissue which can occur in the dark. Once the chemical has been absorbed into treated leaves, light-induced damage is required for significant movement through the rest of the plant to take place, but the damage then inhibits further entry of paraquat into the xylem. The movement of paraquat in broad bean and maize is essentially similar, though the enhancement of movement by a period of darkness after application is much less marked.
La migration du paraquat dans les plantes     

Effect of take-all root infections on nitrate uptake in winter wheat

The effect of take-all root lesions on nitrate uptake of wheat was investigated in two experiments under controlled conditions. Plants were supplied with a nutrient solution labelled with ¹⁵N during stem elongation and flowering to assess the distribution of the isotopic tracer in the different plant organs, and particularly in root segments located on both sides of take-all lesions. The ¹⁵N atom percentage excess measured in root segments located below lesions longer than 1 cm was reduced on average by half compared with that in healthy roots and root segments above lesions, reflecting a reduction in nitrogen uptake by these root segments. This reduction probably resulted from the invasion and breakdown of phloem vessels by the fungus hyphae, interrupting energy supply and thus the uptake process. Severely infected plants showed an increase in the uptake rate per unit of efficient root, which appeared to be a compensatory response to reduction of efficient root biomass in order to satisfy shoot nitrogen demand. However, this compensatory response was insufficient to ensure nitrogen accumulation equivalent to that of healthy plants, as reductions in nitrogen accumulated in roots and aerial parts at flowering were up to 56 and 49%, respectively, for plants with more than 50% of the root system below lesions longer than 1 cm.     

STUDIES ON THE TRANSLOCATION IN AGROPYRON REPENS OF 14C-LABELLED 2,2-DICHLOROPROPIONIC ACID

Summary. Previous findings suggested that the translocation in Agropyron repens of 2,2-dichloropropionic acid (dalapon) may be considerably affected by the transpiration rate. This relationship has been studied further in the present investigation using ¹⁴C-labelled material and autoradiography.
It was found that when dalapon was applied to the leaves and the treated plants were placed in darkness a reduction in the transpiration rate of ca. 90% was associated with a marked increase in the amount of dalapon translocation into the roots and tillers. The evidence provided by the autoradiographs was confirmed by a quantitative assay of the ¹⁴C present in the roots. It was also found, however, that translocation was not appreciably affected either by a 50% reduction in the light intensity or when the transpiration rate was reduced by placing the plaints under conditions of high humidity in the light or by the application of white petroleum jelly to the leaves. An alternative hypothesis, namely that the effect of darkness on the movement of the herbicide might be due to changes induced in the normal pattern of assimilate translocation was also investigated but was not supported by the results obtained. Further experimentss, in which various parts of the treated shoot were placed in the dark, suggested that the effect of darkness on the translocation of dalapon is exerted primarily on the treated leaf itself.
Etudes sur to migration dans Agropyron repens de l'acide 2,2-dichloropropionique marqué avec ¹⁴C