Growth and photosynthesis of four invasive aquatic plant species in Europe

Crassula helmsii , Hydrocotyle ranunculoides , Ludwigia grandiflora and Myriophyllum aquaticum are four well known invasive aquatic plants in European waters. In this study, plant growth at different nutrient availabilities, regeneration capacity and photosynthesis were investigated. Results show high relative growth rates (RGR) of the species of up to 0.132 ± 0.008 g g⁻¹ dry weight (dw) day⁻¹ ( H. ranunculoides ) and a significant increase in RGR with increasing nutrient availability. All species show a high regeneration capacity and the ability to form new shoots from single nodes, even though it differs between the species. Ludwigia grandiflora and M. aquaticum also show regeneration from single leaves. Species differed in maximal amounts, and in temperature and light optima of net assimilation rates: H. ranunculoides leaves reach maximum photosynthetic rates of up to 3500 μmol CO₂ × h⁻¹ g⁻¹ dw, L. grandiflora (leaves) up to 2200 μmol CO₂ × h⁻¹ g⁻¹ dw, M. aquaticum (shoots) 400   μmol CO₂ × h⁻¹ g⁻¹ dw and C. helmsii (shoots) up to 200 μmol CO₂ × h⁻¹ g⁻¹ dw. Hydrocotyle ranunculoides , L. grandiflora and M. aquaticum preferred high light intensity and high temperatures, whilst C. helmsii was negatively affected by intense sunlight. Summarising, it can be assumed that at least H. ranunculoides , L. grandiflora and M. aquaticum can grow well under current and likely future central European climate conditions.     

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.     

Possible involvement of gibberellins and ethylene in Orobanche ramosa germination

Summary Six inhibitors acting at different stages of gibberellin biosynthesis, applied during conditioning of Orobanche ramosa seeds, reduced subsequent germination in the presence of GR₂₄ (a strigol analogue). Ethylene seems to be involved in the induction of germination of conditioned seeds by GR₂₄, as inhibitors of its synthesis or action, applied to conditioned seeds, also strongly reduced induction of germination by GR₂₄. Exogenous ethylene did not induce germination of conditioned seeds, but 2-chloroethylphosphonic acid was able to do so. When inhibitors of gibberellin biosynthesis were applied to conditioned seeds in the presence of GR₂₄, they inhibited germination. These same inhibitors also strongly inhibited germination of conditioned Striga hermonthica seeds in response to GR₂₄; this inhibitory effect was reversed by the addition of 2-chloroethylphosphonic acid. The effect of these inhibitors on S. hermonthica , in which ethylene is a necessary mediator of germination induction by GR₂₄, strongly suggests that ethylene synthesis is also required for the induction of O. ramosa seed germination by GR₂₄. These growth regulators, which inhibit the two steps of germination in O. ramosa , could be useful for the development of methods for early season control of this parasite.     

Antifungal activity of bergenin, a constituent of Flueggea microcarpa

The antifungal activity of bergenin against some plant pathogenic fungi, namely, Alternaria alternata , A. brassicae , A. carthami , Fusarium udum , F. oxysporum f.sp. ciceri , Curvularia lunata and Erysiphe pisi , was studied. Bergenin as its monosodium salt was effective against all the fungi and the effective dose for complete inhibition of spore germination varied from 15 μg mL⁻¹ for F. udum to 125 μg mL⁻¹ for E. pisi . Experiments on the effect of bergenin on powdery mildew development under glasshouse conditions revealed that it can control powdery mildew of pea at 2000 μg mL⁻¹ by postinoculation treatment, the results being comparable with those of carbendazim (1000 μg mL⁻¹) and wettable sulfur (2000 μg mL⁻¹). It affected hyphal elongation and the number of primary and secondary branches.     

Plant sensitivity to atrazine and chlorsulfuron residues in a soil-free system

The sensitivity of 22 major crops, pastures and weeds from the north-east grain region of Australia to atrazine and chlorsulfuron residues was determined in a glasshouse using a soil-free bioassay system. A logistic equation was fitted to the seedling fresh weights as a function of the logarithm of herbicide concentration by non-linear regression and used to calculate the doses for 10%, 30% and 50% inhibition of seedling growth (ID₁₀, ID₃₀ and ID₅₀). The ID₅₀ for atrazine ranged from 0.03 to 0.04 mg a.i. L^–1 for Salvia reflexa Hornem. and barley to 1.47 mg a.i. L^–1 for sorghum. The ID₅₀ for chlorsulfuron ranged from 0.19 to 0.21 μg a.i. L^–1 for lucerne and snail medic to 102 μg a.i. L^–1 for wheat. Based on ID₅₀ values measured, the predicted responses of each species to a range of concentrations of atrazine and chlorsulfuron were classified into four categories ranging from no damage to severe damage. These sensitivity data will assist in planning cropping sequences in soils previously treated with atrazine or chlorsulfuron.     

Resistance of Raphanus raphanistrum to chlorsulfuron in the Republic of South Africa

Herbicide resistance poses a substantial threat to the agricultural industry throughout the world and during the past decade several reports regarding herbicide resistance have been published. Raphanus raphanistrum L., from two wheat farms located in the winter rainfall region of South Africa, showed indications of resistance to chlorsulfuron. Seeds from these suspected resistant biotypes as well as seeds from a susceptible biotype were collected and transported to the ARC-Small Grain Institute for herbicide resistance studies. Herbicides registered for R. raphanistrum control, i.e. chlorsulfuron, MCPA and bromoxynil, were used in this study. Significant differences in the degree of control were found between the susceptible and two resistant biotypes, when treated with chlorsulfuron. The LD₅₀ values for the resistant biotypes (WR 1 & WR 2) were 45 and 11.3 g a.i. ha^–1, respectively, whereas the LD₅₀ value for the susceptible biotype was 5.6 g a.i. ha^–1. The almost eightfold difference between the susceptible and resistant biotype (WR 1), indicated that resistance has developed to chlorsulfuron. Only twofold resistance was established between the other resistant biotype (WR 2) and the susceptible biotype. Significant differences between herbicide rates were also established with the MCPA and bromoxynil experiments. No significant difference could, however, be found between the susceptible and resistant biotypes when treated with MCPA and bromoxynil, indicating the importance of different modes of action of herbicide as a strategy to prevent herbicide resistance.     

Genetic characteristics of Fusarium verticillioides isolates from maize in Costa Rica

Thirty-nine isolates of Fusarium verticillioides from maize seeds from three regions of Costa Rica were classified on fertility, fumonisin production, vegetative compatibility and pathogenicity. The identity of the isolates was verified by sexual crosses with standard tester strains and by isozyme analysis. Twenty-three isolates (59%) were mating type A⁻ and 16 (41%) were A⁺; 29 (74%) were female fertile. The isolates produced high amounts of fumonisin B₁ when grown on sterilized maize grits, 32 isolates producing more than 1000 μg g⁻¹, as determined by TLC, and 7 less than 1000 μg g⁻¹. Vegetative compatibility tests by pairing nit mutants identified 34 vegetative compatibility groups (VCGs), of which 29 had one member and 5 had two members. Isolates belonging to the same VCG were obtained from the same seed sample. Two pathogenicity tests with different inoculation methods were performed: on toothpick inoculation of 7-week-old maize stalks, 71% of the isolates were pathogenic according to the length of the necrosis formed in the stalk, and on sand inoculation of maize seedlings all the isolates were pathogenic, according to shoot length and dry weight production. Differences in aggressiveness between some of the isolates were recorded. It is concluded that natural populations of F. verticillioides in Costa Rica consist of genetically diverse, highly fertile and pathogenic isolates that represent a potential risk for disease development and fumonisin accumulation in maize crops.     

Effect of 2,6-dichloroisonicotinic acid, its formulation materials and benzothiadiazole on systemic resistance to alternaria leaf spot in cotton

A wettable powder (WP) formulation providing 5–25 μg mL⁻¹ of 2,6-dichloroisonicotinic acid (INA) and 15–75 μg mL⁻¹ of WP applied to cotton cotyledons significantly increased the resistance of the next two leaves to challenge inoculation by Alternaria macrospora . The wettable powder alone at 15–75 μg mL⁻¹ had a lesser effect. A wettable granule (WG) formulation supplying 35 μg mL⁻¹ of benzo-(1,2,3)-thiadiazole-7-carbothioic acid S-methyl ester (BTH) and 35 μg mL⁻¹ of WG, applied as a cotyledonary treatment, significantly reduced the formation of lesions on the subsequent two leaves when challenged with A. macrospora . The WG control had no effect. Each treatment except for the WG control also raised the activities of β-1,3-glucanase in unchallenged leaf and stem tissue. Each of the components of the wettable powder without INA applied to cotyledons raised enzyme activities in the next leaves. Individual components, as suspensions of silicic acid and kaolin and solutions of the detergent Attisol II, the wetting agent Ultravon W300 and pure INA, applied to cotyledons increased the resistance of the next leaves to A. macrospora . The responsiveness of cotton to BTH and to each of the components of formulated INA is discussed in relation to knowledge of the effects of BTH and INA on other plants and to possible ways in which the other components of the wettable powder may affect the process of signalling for systemic resistance to disease.     

Susceptibilities of some aquatic ferns to paddy herbicide bensulfuron methyl

Paddy herbicides have the potential to cause adverse effects on non-target plants. Susceptibilities of some aquatic ferns ( Azolla japonica Franch. et Savat., Isoetes japonica A. Braun, Marsilea quadrifolia L. and Salvinia natans All.) and duckweeds ( Lemna minor L. and Spirodela polyrhiza Schleid.) to paddy herbicide bensulfuron methyl (BSM) were evaluated with a 20 day exposure experiment using 200 cm² pots. The BSM concentrations in the surface water of monitoring pots with no plants dissipated exponentially with half lives of 3.5 and 3.9 days at application rates of 15 and 150 g ha⁻¹, respectively. The BSM concentrations in the surface water 1 day after application in the culture pots were comparable among plant species, and were lower than those in the monitoring pots. Bensulfuron methyl reduced the plant growth in all species. I . japonica showed the lowest intrinsic relative growth rate (RGR) and the lowest susceptibility with an effective dose resulting in 50% growth inhibition (ED₅₀) of 21 g ha⁻¹. Except for I . japonica , the RGR of the duckweeds was similar to the ferns, and ED₅₀ for the duckweeds was higher than the ferns. ED₅₀ for Sa . natans , A . japonica and M . quadrifolia were 1.1, 1.8 and 1.2 g ha⁻¹, respectively, which were smaller than 1/20 of the recommended field dose (51–75 g ha⁻¹) and ranged from 1/2 to 1/6 of ED₅₀ for L . minor and Sp . polyrhiza (6.5 and 3.2 g ha⁻¹, respectively). These results suggest that BSM application in paddy fields and its runoff in some localities is expected to have adverse effects on the growth of Sa . natans , A . japonica and M . quadrifolia .     

Control of soilborne clubroot disease of cruciferous plants by epoxydon from Phoma glomerata

Culture broth from an isolate of Phoma glomerata (no. 324, = JCM 9972) from the leaves of Viola sp., controlled the soilborne pathogen Plasmodiophora brassicae which causes clubroot disease of cruciferous plants. This effect was caused by epoxydon (5-hydroxy-3-(hydroxymethyl)-7-oxabicyclo[4.1.0]hept-3-en-2-one). Although this substance was known to have antitumour activity, phytotoxicity and antiauxin activity, no plant disease reduction had been reported previously. Epoxydon possessed neither strong antimicrobial activity nor did it induce acquired resistance. It protected crucifers from clubroot disease at 250  μ g mL⁻¹ following addition to the soil. Several antiauxins were tested for similar properties resulting in the suppression of clubroot disease and one, 2,3,5-triiodobenzoic acid, was effective at 10  μ g mL⁻¹. Clubroot reduction by epoxydon may result from antiauxin activity. This opens opportunities for a new group of agrochemicals.     

Influence of straw management, nitrogen fertilization and dosage rates on the dissipation of five sulfonylureas in soil

The dissipation behaviour of metsulfuron-methyl, tribenuron-methyl, thifensulfuron-methyl, triasulfuron and amidosulfuron were studied in soil following post-emergence spring applications to cereal crops. Incorporation or removal of straw and different fertilizer applications had no influence on the disappearance time (DT₅₀) of the herbicides. However, in laboratory trials dissipation of metsulfuron-methyl, triasulfuron and amidosulfuron at higher application rates was accelerated after incorporation of straw into the soil. The addition of straw decreases soil pH thereby causing faster hydrolysis of the compounds. Addition of nitrogen fertilizer increased the half-lives (t_1/2) of the herbicides. Combination of both straw and N fertilizer, however, had no effect. Neither straw nor N influenced the degradation of tribenuron-methyl and thifensulfuron-methyl.
The DT₅₀ of all herbicides investigated varied from 6 to 17 days in the field trials. Except for amidosulfuron, herbicides could not be detected 38–68 days after application. In the laboratory, t_1/2 values were higher than those in the field at 75 days (amidosulfuron), 63 days (metsulfuron-methyl), 35 days (triasulfuron) and 13 days (tribenuron-methyl). Only the t_1/2 of thifensulfuron-methyl was at 29 h faster under laboratory conditions. T_1/2 values of all herbicides were influenced by their initial concentration. The t_1/2 values of amidosulfuron and tribenuron-methyl at 1 mg a.i. kg⁻¹ soil were 2–2.5 times higher than at the recommended field application rate of 42 μg a.i. kg⁻¹ soil.     

A note on the chemical composition, intake and digestion of Striga hermonthica herbage by sheep

Striga hermonthica causes serious crop yield losses in West Africa. Hand pulling, an effective method for the reduction of light infestations, might be encouraged if farmers could use this weed as livestock feed. This study evaluated the chemical composition and the voluntary intake and digestion of S. hermonthica herbage by sheep. Crude protein (g kg⁻¹ dry matter (d.m.)) was 184 in the whole plant, 230 in the leaf and 87 in the stem. Ash content varied from 183 to 253 g kg d.m.⁻¹. The concentration of neutral and acid detergent fibre and lignin in whole pot-grown plants was 364, 278 and 127 g kg d.m.⁻¹ respectively. The digestibility of dry and organic (o.m.) matter was 493 and 657 g kg⁻¹, respectively, and intake of digestible o.m. was 27.1 g kg W^−0.75. The relatively high N and P levels in S. hermonthica warrant further evaluation in terms of its potential use as a source of protein or for compost. Its use as a feed appears to be limited by the high ash content and possibly by anti-nutritional effects on animals. These effects should be further investigated before recommending its use for this purpose.     

Genetic variation in Danish populations of Erysiphe graminis f.sp. hordei: estimation of gene diversity and effective population size using RFLP data

Genetic variation of the barley powdery mildew fungus ( Erysiphe graminis f.sp. hordei ) was estimated in three Danish local populations. Genetic variation was estimated from the variation amongst clones of Egh , and was therefore an estimate of the maximum genetic variation in the local populations. The average gene diversity, Ĥ , was estimated as 0.84. The effective population size was estimated as: log₁₀ ( N^ _e ) = 0.64 − log₁₀(μ), or 4.4 × 10⁹, assuming a nucleotide mutation rate ( μ) of 10⁻⁹ per base per generation. There was no significant genetic differentiation between locations.     

Cutting weeds with a CO2 laser

Stems of Chenopodium album . and Sinapis arvensis . and leaves of Lolium perenne . were cut with a CO₂ laser or with a pair of scissors. Treatments were carried out on greenhouse-grown pot plants at three different growth stages and at two heights. Plant dry matter was measured 2 to 5 weeks after treatment. The relationship between dry weight and laser energy was analysed using a non-linear dose–response regression model. The regression parameters differed significantly between the weed species. At all growth stages and heights S. arvensis was more difficult to cut with a CO₂ laser than C. album . When stems were cut below the meristems, 0.9 and 2.3 J mm⁻¹ of CO₂ laser energy dose was sufficient to reduce by 90% the biomass of C. album and S. arvensis respectively. Regrowth appeared when dicotyledonous plant stems were cut above meristems, indicating that it is important to cut close to the soil surface to obtain a significant effect. When cutting L. perenne plants with 2-true leaves at a height of 2 cm from the soil surface with a laser, the biomass decreased significantly compared with plants cut by scissors, indicating a delay in regrowth. This delay was not observed for the dicotyledonous plants nor for the other growth stages of L. perenne .     

Characterization of reactive oxygen species-involved oxidative damage in Hapalosiphon species crude extract-treated wheat and onion roots

Crude extract-induced oxidative damage using the cyanobacterium, Hapalosiphon sp., was investigated in wheat seedlings ( Triticum aestivum L. cv. Norin 61) and onion seedlings ( Allium cepa L. cv. Raputa II). The analysis of root cell viability or cell death using Evans blue uptake showed that the root-tip cells of wheat and onion lost viability after 24 h and 48 h treatment with 3 g dry weight (DW) L⁻¹ of the crude extract, respectively. Lipid peroxidation was induced in the roots of both species and the shoots of onion, whereas no increase in lipid peroxide formation was observed in the wheat shoots. In onion, the degree of random DNA fragmentation increased with the increasing concentration of the extract and laddering of the DNA was observed with 6 g DW L⁻¹ of the extract, but no apparent DNA ladder formation occurred in the wheat. Pretreatment for 1 h with the NADPH oxidase inhibitors, diphenyleneidonium or imidazole, reduced the crude extract-induced root cell death in both species. From the results, we suggest that the Hapalosiphon sp. crude extract might enhance reactive oxygen species (ROS) production, which causes membrane lipid damage and fragmentation of the DNA of plant cells, resulting in cell death and growth inhibition. The crude extract-mediated phytotoxic damage might be caused by ROS, triggered by NADPH oxidase.     

Reduced sensitivity of Cercospora beticola isolates to sterol-demethylation-inhibiting fungicides

In a survey conducted during October 1995, single-lesion isolates of the sugar beet leaf-spot fungus, Cercospora beticola , were tested for sensitivity to the sterol demethylation inhibiting fungicides (DMIs) flutriafol and bitertanol. The isolates were collected from fields in three different areas of northern Greece. Fields at Serres and Imathia had been sprayed with DMIs for about 15 years to control sugar beet leaf-spot. At the third site, Amyndeon, DMI fungicides had not been used. From each area 150 isolates were tested. ED₅₀ values were calculated for individual isolates by regressing the relative inhibition of colony growth against the natural logarithm of the fungicide concentration. The mean ED₅₀ values for flutriafol for the Serres, Imathia and Amyndeon populations were 1·07, 0·73 and 0·5 µg mL⁻¹, respectively (significantly different at P  = 0·05). For bitertanol the mean ED₅₀ values for the Serres and Imathia populations were 0·72 and 0·81 µg mL⁻¹, respectively, which were not significantly different at P  = 0·05. The mean ED₅₀ value of the Amyndeon population was 0·48 µg mL⁻¹, which was significantly lower than those of the other two populations ( P  < 0·05). A cross-resistance relationship was found to exist between the two triazole fungicides tested when log transformed ED₅₀ values of 60 isolates were subjected to a linear regression analysis ( r  = 0·81).     

Proper adjuvant selection to enhance the activity of triclopyr combined with metsulfuron on the control of Hedyotis verticillata

A study was conducted to evaluate the combined activity of a tank mixture of triclopyr plus metsulfuron with non-ionic surfactant (NIS), crop oil concentrate (COC), and organosilicon (OS) adjuvants on the control of Hedyotis verticillata under glasshouse and field conditions. The results of both the glasshouse and field experiments showed that 160 g ai ha⁻¹ triclopyr plus 0.2 g ai ha⁻¹ metsulfuron and 320 g ai ha⁻¹ triclopyr plus 0.4 g ai ha⁻¹ metsulfuron, with the addition of 0.25% NIS, 0.05% COC, or 0.05% OS, were effective in controlling H. verticillata . A comparison of the cost revealed that the most cost-effective combination for controlling H. verticillata is 160 g ai ha⁻¹ triclopyr plus 0.2 g ai ha⁻¹ metsulfuron combined with 0.25% NIS.     

Reduced rates of tank mixtures for red sprangletop (Leptochloa chinensis [L.] Nees) and greater club-rush (Scirpus grossus [L.] f.) control in rice

A study on the efficacy of tank-mix combinations on the growth of Leptochloa chinensis (L.) Nees and Scirpus grossus (L.) f. at the 3–4-leaf stage was conducted under glasshouse conditions. Sethoxydim plus cyhalofop-butyl at 8 + 25, 16 + 25, 32 + 25, 32 + 12.5, and 32 + 6.25 g ai ha⁻¹ provided good control of L. chinensis , ranging from 89–95%. However, a comparison of the costs of herbicide mixtures revealed that sethoxydim at 32 g ai ha⁻¹ plus cyhalofop-butyl at 6.25 g ai ha⁻¹ were the most cost-effective among the combinations. For Scirpus grossus , bensulfuron plus 2,4-D dimethylamine at 2.5 + 18, 5.0 + 18, 1.25 + 36, 2.5 + 36, and 5.0 + 36 g ai ha⁻¹ gave good control that ranged from 88–93%. Tank-mixing bensulfuron with 2,4-D at 1.25 + 36 g ai ha⁻¹ was, however, the most cost-effective mixture compared to the other mixtures. None of the tank mixtures tested in this study caused injury to the rice seedlings. However, further field studies need to be undertaken to verify these findings.     

Occurrence of Corynespora cassiicola isolates resistant to boscalid on cucumber in Ibaraki Prefecture, Japan

A total of 651 isolates of cucumber corynespora leaf spot fungus ( Corynespora cassiicola ) collected from cucumber in Japan, either with (438 isolates) or without (213 isolates) a prior history of boscalid use, were tested for their sensitivity to boscalid by using a mycelial growth inhibition method on YBA agar medium. Additionally, seven isolates of C. cassiicola obtained from tomato, soybean, eggplant (aubergine) and cowpea in different locations in Japan were tested before boscalid registration. Minimum inhibitory concentration (MIC) and 50% effective concentration (EC₅₀) values for 220 isolates from crops without a prior history of boscalid use ranged from 0·5 to 7·5 μg mL⁻¹ and from 0·04 to 0·59 μg mL⁻¹, respectively. Two hundred and fourteen out of 438 isolates collected from ten cucumber greenhouses in Ibaraki Prefecture, Japan, which received boscalid spray applications showed boscalid resistance, with MIC values higher than 30 μg mL⁻¹. Moreover, resistant isolates were divided into two groups: a moderately resistant (MR) group consisting of 189 isolates with EC₅₀ values ranging from 1·1 to 6·3 μg mL⁻¹, and a very highly resistant (VHR) group consisting of 25 isolates with EC₅₀ values higher than 24·8 μg mL⁻¹. MR isolates were detected from all ten greenhouses, but VHR isolates were detected from only three. As a result of fungus inoculation tests which used potted cucumber plants, control failures of boscalid were observed against resistant isolates. Efficacy of boscalid was remarkably low against VHR isolates in particular. This is the first known report on boscalid resistance in Japan.     

Tolerance of black, cranberry, kidney, and white bean to cloransulam-methyl

The level of tolerance of various market classes of dry bean to cloransulam-methyl is not known. Three field studies were conducted in Ontario, Canada during 2007 and 2008 to determine the level of tolerance of black, cranberry, kidney, and white bean to the pre-emergence (PRE) and postemergence (POST) application of cloransulam-methyl at 17.5, 35, and 70 g ai ha⁻¹. Cloransulam-methyl applied at 17.5, 35, and 70 g ha⁻¹ caused between 13 and 23% injury in black, cranberry, kidney, and white bean, respectively. Cloransulam-methyl applied at 17.5, 35, and 70 g ha⁻¹ reduced the shoot dry weight by between 16 and 28% compared to the untreated control. Cloransulam-methyl applied PRE reduced the height of black bean by 27% and the height of cranberry bean by 25% at 70 g ha⁻¹ and reduced the height of white bean by 19% at 35 g ha⁻¹ and by 37% at 70 g ha⁻¹. Cloransulam-methyl applied PRE reduced the yield of black bean by 29% at 35 g ha⁻¹ and by 43% at 70 g ha⁻¹, reduced the yield of cranberry bean by 43% at 70 g ha⁻¹, and reduced the yield of white bean by 36% at 35 g ha⁻¹ and by 54% at 70 g ha⁻¹. Based on these results, there is not an adequate margin of crop safety for the PRE and POST application of cloransulam-methyl in black, cranberry, kidney, and white bean at the rates evaluated.