Purple Nutsedge Plants Research Articles

Impact of PRE- and POST herbicide on purple nut sedge (Cyperus rotundus L.) control and plasticulture tomato yields

Purple nut sedge (Cyperus rotundus L.) is a problematic weed in plasticulture tomato (Solanum lycopersicum L.) production in Iran as it is difficult to control due to its ability to penetrate plastic mulch. Field trials were carried out at the experimental area of the state farm Safadasht, Shahriar region, Iran, over the fall of 2015 and spring of 2016 to investigate PRE- and POST herbicide programs (PRE transplanting, POST transplanting, and combination of PRE- and POST transplanting) to control purple nut sedge in plasticulture tomato production. PRE herbicide treatment metribuzin and (S)-metolachlor were not effective when applied alone, and did not reduce purple nut sedge plants compared to the weedy control. POST transplanting application of halosulfuron did not significantly affect purple nut sedge plants at 12 wk after application (WAA) in the fall 2015, but treatment favorably reduced density of purple nut sedge at 16 WAA in both seasons. PRE transplanting application of metribuzin or (S)-metolachlor plus POST halosulfuron exerted the greatest control, and purple nut sedge numbers were eventually diminished in both seasons. Experimental treatments did not negatively affect tomato height and yields. Based on our findings, multiple PRE and POST herbicide programs were effective in greater purple nut sedge suppression compared to the lone application of PRE and POST herbicides. The herbicides were selected due to routine use by tomato producers in the area. Using active ingredients from the various herbicide families with different modes of action could facilitate effective management of herbicide-resistant purple nut sedge in tomato fields.

The Role of Tillage, Allelopathy, Dormancy-Breaking Mechanisms and Wind in the Spread of Purple Nutsedge (Cyperus rotundus) in Zimbabwe

Purple nutsedge (Cyperus rotundus) is an invasive weed in tropical cultivated lands and propagates through tubers, rhizomes, seed and corms. Weedy invasive plants have unique functional traits that enable their invasiveness. The objectives of this study were to determine the drivers of the purple nutsedge invasion in the Zimbabwe’s agricultural systems among allelopathy, dispersal and dormancy-breaking mechanisms. Three experiments were carried out each in the laboratory, greenhouse and field. All the experiments were in completely randomised design replicated six times. Results showed that purple nutsedge leaf, stem and tuber extracts successfully (P < 0.001) inhibited germination and radical extension of Sorghum bicolor. Cutting the seed, which mimics the plough action on tubers gave the highest (P < 0.05) sprouting compared to exposure to freezing temperatures. There was a direct relationship between dispersal distance and wind speed (R2 = 0.907). The purple nutsedge plants attached to the plough were related (R2 = 0.515) to the number of plough passes. This study confirmed that allelopathy, easiness for dispersal and dormancy-breaking by the cutting action of the plough were the drivers of the weed’s invasiveness. Therefore, allelopathy, ploughing, dispersal by wind and plough contribute to invasiveness of the weed.

Interação de imazapic no sistema integrado palha de cana-de-açúcar, herbicida e vinhaça no crescimento inicial da tiririca

O objetivo deste trabalho foi avaliar o efeito da interação palha de cana-de-açúcar, herbicida imazapic e diferentes meios de aplicação de vinhaça no crescimento inicial da tiririca. O experimento foi realizado em casa de vegetação e em vasos dispostos em blocos ao acaso com quatro repetições, sendo avaliados os tratamentos: controle; apenas palha; apenas vinhaça; apenas o herbicida imazapic; palha + vinhaça; palha + herbicida; herbicida + vinhaça aplicada antes do herbicida; herbicida + vinhaça aplicada depois do herbicida; herbicida + vinhaça aplicada junto com o herbicida em mistura; palha + herbicida + vinhaça aplicada antes do herbicida; palha + herbicida + vinhaça aplicada depois do herbicida; e palha + herbicida + vinhaça aplicada junto com o herbicida em mistura. O imazapic foi aplicado na dose de 122,5 g ha-1 e, no tratamento onde a vinhaça foi aplicada em mistura com o herbicida, este foi diluído com água até ¼ do volume necessário e completado com vinhaça. O imazapic foi eficiente no controle da tiririca quando comparado com a testemunha. A aplicação isolada da vinhaça ou a adição de apenas a palha ao solo estimularam o crescimento da tiririca embora tenha reduzido a viabilidade dos tubérculos. Nos tratamentos sem palha, não houve diferença no crescimento da tiririca, quando a aplicação de vinhaça foi realizada antes ou depois do imazapic, sendo observado controle da espécie. Entretanto, quando em mistura com a vinhaça, o produto não controlou a tiririca. A presença da palha no tratamento onde foi aplicada vinhaça antes do herbicida reduziu a ação do imazapic, em comparação com aquele sem palha. O número de brotações e a altura média de plantas de tiririca foram maiores nos tratamentos com palha quando foi aplicado imazapic depois ou mesmo junto com a vinhaça. Sob palha, a aplicação de vinhaça após o herbicida ou em mistura com imazapic aumentou apenas o número de brotações.

Efeitos da adubação fosfatada nas relações de interferência inicial entre plantas de milho (Zea mays) e de tiririca (Cyperus rotundus)

O objetivo deste trabalho foi avaliar os efeitos da adubação fosfatada nas relações de interferência inicial entre plantas de milho e de tiririca. Para isso, foi montado um experimento em vasos de 90 L, preenchidos com substrato constituído por areia, terra e substrato Plantmax®. Os tratamentos constaram de combinações de colonização dos vasos por milho e/ou por tiririca nas densidades iniciais de 25 e 50 tubérculos por vaso; essas situações de colonização foram estabelecidas em três condições de adubação fosfatada adicional: 0, 100 e 300 ppm de fósforo. No campo, os vasos foram dispostos no delineamento inteiramente casualizado, com quatro repetições. As relações de interferência entre plantas de milho e de tiririca foram alteradas pela fertilização fosfatada do solo. O milho teve excelente aproveitamento do enriquecimento do solo pelo fósforo e interferiu mais decisivamente sobre a tiririca nos vasos bem fertilizados com esse elemento. Nessas condições, o milho reduziu drasticamente a resposta da tiririca à fertilização fosfatada, em termos de crescimento da parte aérea. A interferência da tiririca reduziu a altura das plantas de milho, a expansão da área foliar e o acúmulo de matéria seca na parte aérea.

First Report of Yellow Nutsedge (Cyperus esculentus) and Purple Nutsedge (C. rotundus) in Georgia Naturally Infected with Impatiens necrotic spot virus.

Impatiens necrotic spot virus (INSV), family Bunyaviridae, genus Tospovirus, is an emerging virus found mostly in ornamentals under greenhouse production. INSV has been detected in peanut (Arachis hypogaea L.) in Georgia and Texas (3) and recently in tobacco (Nicotiana tabacum L.) in the southeastern United States (2) but little is known about INSV distribution and impact on these crops. Noncrop plant hosts are likely to contribute to disease spread by serving as reservoirs for the virus and reproductive hosts for thrips (Frankliniella occidentalis Pergande), which transmit the virus. Yellow nutsedge, a native of North America, and purple nutsedge introduced from Eurasia, are considered serious weed problems in the southeastern United States. To date, there are no reports of natural INSV infections in these weeds. A survey was conducted at two research farms in Tift County, Georgia to determine if yellow and purple nutsedge plants were naturally infected with Tomato spotted wilt virus (TSWV) and INSV. The first field at the Black Shank Farm had been planted with flue-cured tobacco K-326 earlier in the year and fallow at the time of sampling. The second field at the Ponder Farm was planted at the time of sampling with yellow squash (Cucurbita pepo L.) and cabbage (Brassica oleracea L.). In early October 2002, 90 nutsedge plants were taken at random from each site. Leaf and root tissues of each of the nutsedge plants were tested for TSWV and INSV using double-antibody sandwich enzyme-linked immunosorbent assay (DAS-ELISA) alkaline phosphatase antisera kits (Agdia Inc., Elkhart, IN). No visible symptoms of INSV or TSWV were observed. Samples from the field at the Black Shank Farm resulted in 2 of 26 positive for INSV in purple nutsedge plants and 6 of 64 in yellow nutsedge plants. At the Ponder Farm, 3 of 12 were positive for INSV in purple nutsedge plants and 14 of 78 in yellow nutsedge plants. None of the samples in either site tested positive for TSWV. The DAS-ELISA positive samples were verified for INSV using reverse transcription-polymerase chain reaction (RT-PCR) as previously described by Dewey et al. (1). Total RNA extracts were obtained from the DAS-ELISA positive nutsedge samples using RNeasy extraction kits (Qiagen Inc., Valencia, CA). The RT-PCR was carried out with primer 1F: 5'-TCAAG(C/T) CTTC(G/T)GAA(A/G)GTGAT 3' (1) and primer 2R: 5'-ATGAACAAAGCAAAGATTACC 3' specific to the 3' end of the INSV N gene open reading frame (GenBank Accession No. NC003624). DAS-ELISA negative tissues of Cyperus esculentus L. and Emilia sonchifolia (L.) DC and an E. sonchifolia DAS-ELISA positive for INSV were included in the reactions as controls. All of the DAS-ELISA positive nutsedge samples yielded an amplification product with the expected size of 298 bp when PCR products were resolved by agarose (0.7%) gel electrophoresis. The relatively high occurrence of INSV found in the sampled fields may explain the recent increase in incidence of INSV in susceptible field crops. Although yellow nutsedge is more common than purple nutsedge in North America, the potential for dispersal of INSV in both species could be significant because of the nature of nutsedge tuber survival and spreading capabilities.

Efficacy of Methyl Bromide Alternatives on Purple Nutsedge (Cyperus rotundus) Control in Tomato and Pepper

Field trials were conducted to compare the effect of various soil fumigants along with in-bed pebulate and row-middle metribuzin applications on purple nutsedge control and on tomato and bell pepper growth and yield. Treatments consisted of combinations of soil fumigants, pebulate, and metribuzin. Fumigants levels were (1) untreated control, (2) methyl bromide (MBr) + chloropicrin (Pic) (67 + 33%, respectively), (3) Pic, (4) metham, (5) dazomet, and (6) 1,3-dichloropropene (1,3-D) + Pic (83 + 17%, respectively). Pebulate levels were either applied in-bed or not applied. Row middles were either sprayed with metribuzin or untreated. In both crops, purple nutsedge populations were independently influenced by fumigants and pebulate applications, with the highest number of purple nutsedge plants in the untreated control. The addition of pebulate reduced purple nutsedge populations in all treatments. In tomato trials, the yield was affected by fumigants, with the highest losses (53 and 50% reductions in fruit number and weight) observed in the nonfumigated control. In pepper trials, fruit number and weight were individually influenced by fumigants and metribuzin sprayings. Application of metribuzin to row middles increased yields 10% relative to nontreated plots.

Dactylaria higginsii, a Fungal Bioherbicide Agent for Purple Nutsedge (Cyperus rotundus)

Ten different fungi recovered from diseased purple nutsedge and yellow nutsedge plants collected in several locations in Florida and southeastern United States were screened for pathogenicity to purple nutsedge (Cyperus rotundus) plants. Only Dactylaria higginsii, recovered from diseased purple nutsedge plants collected in Gainesville, caused disease in greenhouse trials. Based on the results of pathogenicity and host-range tests conducted in a greenhouse, D. higginsii was determined to have potential as a bioherbicide agent for purple nutsedge. It was highly pathogenic to purple nutsedge, yellow nutsedge (C. esculentus), annual sedge (C. compressus), globe sedge (C. globulosus), rice flatsedge (C. iria), and green kyllinga (Kyllinga brevifolia [=Cyperus brevifolius]). Initial symptoms on inoculated plants consisted of moist, dark-brown leaf spots that appeared 4 days after inoculation. The spots later coalesced into larger lesions and blotches, killing the leaves and sometimes the entire aerial parts. The fungus sporulated on the infected leaves and caused secondary infections on the emerging leaves and shoots within 20 to 28 days after inoculation. Inoculation with conidial suspensions of D. higginsii resulted in significant reductions in shoot numbers (72%), shoot dry weight (73%), and tuber dry weight (67%) of greenhouse-grown purple nutsedge plants 45 days after inoculation. The fungus did not infect any of the crop plants or weedy grasses (Poaceae) tested.

Purple Nutsedge (Cyperus rotundus) and Sicklepod (Senna obtusifolia) Response to Glyphosate Mixtures with ALS-Inhibiting Herbicides

Greenhouse studies were conducted to evaluate potential interactions among glyphosate mixtures with five acetolactate synthase (ALS)-inhibiting herbicides (chlorimuron, imazamox, imazaquin, MON 12,000, or pyrithiobac) for the control of purple nutsedge and sicklepod at two growth stages. Herbicides were tested alone at 0.5X and 1X rates (1X being suggested use rate for these herbicides) and in combination with glyphosate at 560 (0.5X) and 1,120 (1X) g ai/ha on 3-wk-old plants and at 1,120 g/ha on 6-wk-old plants. Glyphosate alone at 1,120 g/ha gave complete control of purple nutsedge and at least 78% control of sicklepod regardless of growth stage. In 3-wk-old purple nutsedge plants, three of the 20 herbicide combinations were antagonistic and 17 combinations were additive, whereas all five combinations were additive in 6-wk-old plants. In sicklepod, eight combinations were antagonistic and 12 combinations were additive in 3-wk-old plants, and all five combinations were antagonistic in 6-wk-old plants. In 3-wk-old plants, the glyphosate (0.5X) plus imazaquin (0.5X) combination resulted in highest antagonism in purple nutsedge control (79%), and the combination of glyphosate (0.5X) plus imazamox (0.5X) resulted in highest antagonism in sicklepod control (54%). These results indicate that mixing chlorimuron, imazamox, imazaquin, MON 12,000, or pyrithiobac with glyphosate does not increase glyphosate efficacy on purple nutsedge or sicklepod.

Incident photosynthetically active radiation as a basis for integrated management of purple nutsedge (Cyperus rotundus)

Artificial shading studies indicated that competition for photosynthetically active radiation (PAR) will limit tuber production in purple nutsedge. There were no data available to test whether there is a relationship between incident PAR underneath crop canopies and tuber production of this weed. In this study, the effect of crop competition on net reproductive rates of purple nutsedge tubers was measured under field conditions. Purple nutsedge plants were grown in association with bush beans, maize, maize and beans intercropped, sweet potato, pole beans, and bell pepper in a 2-yr field study in Costa Rica. Measurements were taken on the number of tubers produced during the growing season of each crop, and PAR transmittance was monitored weekly for the duration of the respective cropping cycles. Data on transmittance and incident solar radiation were used to calculate the daily average amount of PAR, available 15 cm above the soil surface. Regressions indicated that average incident PAR accounted for 95% of the variation in net reproductive rates. Average incident PAR also allowed a more precise competitive ranking of crops than either average or minimum transmittance. Bush beans had consistently the lowest average incident PAR values and therefore ranked as the most competitive crop in both years. Our data suggest that no net increase in tuber populations occurs if average incident PAR is below 2.7 MJ m−2d−1. Differences in the duration of the cropping cycle accounted only for a small proportion of the overall variation in net reproductive rates of purple nutsedge tubers. Information on the competitive ranking of different crops can be used to design crop rotations that could reduce reliance on herbicides on small farms in Costa Rica.

Genetic Diversity in Purple Nutsedge (Cyperus rotundusL.) and Yellow Nutsedge (Cyperus esculentusL.)

Differential susceptibility of nutsedge biotypes ( Cyperus sp.) to Puccinia canaliculata, a rust fungus registered as a bioherbicide, exists. In an attempt to understand the possible genetic basis of this difference, RAPD (random amplified polymorphic DNA) analysis was used to study genetic variation within collections of purple nutsedge ( Cyperus rotundus ) and yellow nutsedge ( Cyperus esculentus ) samples obtained from different geographical locations. Expectedly, purple nutsedge genotypes differed significantly from yellow nutsedge genotypes. Purple nutsedge samples, however, showed very limited intraspecific variation, with most showing no differences. In contrast, yellow nutsedge samples showed a wide range of variation. The RAPD technique revealed a far greater level of variation in nine Californian samples than was previously shown by isozyme analysis, raising questions about the method of dispersal of this species. The uniformity of RAPD patterns in most purple nutsedge samples suggests that purple nutsedge plants may form large regional clones that are most likely propagated by asexual means. In contrast, however, the extensive variation exhibited by the yellow nutsedge samples may be attributable to dispersal by seeds produced as a consequence of sexual reproduction. These results have implications for biological control of these weed species.

Influence of native endomycorrhiza, soil flooding and nurse plant on mycorrhizal status and growth of purple nutsedge ( Cyperus rotundus L.)

A study was made to investigate the effects of native endomycorrhizal fungi, soil flooding and nurse plant (onion) on the mycorrhizal status, growth and phosphorus (P) uptake of purple nutsedge ( Cyperus rotundus L.). Above ground (AG) and below ground (BG) dry weight of mycorrhizal purple nutsedge plants were significantly lower than the non-mycorrhizal plants, but ratios of BG:AG dry weight were the same except when grown with onion. Mycorrhizal infection was characterized by vesicles and hyphae, both intraradical and extramatrical, but lacked arbuscules. Percentage root colonization of purple nutsedge and onion was significantly higher when the two grew together, but plants growing alone had less infection. Flooding of soil inhibited mycorrhizal formation in purple nutsedge, and mycorrhizal infected plants produced smaller tubers than uninfected plants. AG tissue P concentration was lower in mycorrhizal purple nutsedge but BG P concentration had no significant variations between infected and uninfected plants. P utilization efficiency (PUE) was similar for mycorrhizal and non-mycorrhizal purple nutsedge. Plants in flooded soil had the maximum AG and BG dry weights, tuber dry weight and P content, but had lower AG:BG dry weight ratio and PUE.

Evaluation of herbicide-coated larvae ofBactra verutana [Lep.: Tortricidae] to control nutsedges [Cyperus rotundus L. andC. Esculentus L.

Feeding by 10-day old mid-instar larvae of the native moth,Bactra verutana Zeller, coated with solutions of bentazon [3-isopropyl-1 H-3-benzothiadiazin-4(3H)-one 2,2-dioxide] or glyphosate [N-(phosphonomethyl) glycine], reduced the dry weight of purple (Cyperus rotundus L.) or yellow nutsedge (C. esculentus L.) an average 25% more than did uncoated larvae. The herbicide-coated larvae reduced dry weight by 71% for 4-week yellow nutsedge and by 80% for 2-week purple nutsedge plants within 15 days after release. This integrated approach was apparently not pratical, however, because larvae randomly damaged the non-target crops, cotton (Gossypium hirsutum L.) and turnip (Brassica rapa L.). The more mature larvae killed about 3% of the cotton and 14% of the turnip plants. Newly-emerged larvae were highly sensitive to the herbicides. Mature larvae are less host-specific than are newly-emerged larvae. Therefore, the use of repeated broadcasts of newly-emergedB. verutana larvae is still the best method known for using insects to control nutsedge.

Effect of intervals between application and tillage on glyphosate control of Cyperus rotundus L.*

Summary:Research conducted in El Salvador, Central America, demonstrated that an interval of 3 days between application of glyphosate and tillage was sufficient to cause 90% reduction in purple nutsedge (Cyperus rotundus L.) plants, while delays of 11–23 days generally gave slightly less reduction. à second application to the same plots 35 days following tillage resulted in more than 90% reduction with all intervals. Approximately 3 months after the initial treatment, tuber numbers had been reduced to half the original population. Germination of the remaining tubers was reduced by more than 50%.Glyphosate applied during the dry season caused an average of 79% reduction in plant numbers compared with 88% in the rainy season. However, in the dry season, the remaining plants had no competition from other weeds and after 5 months there was only à 40% reduction in nutsedge population. During the rainy season, 1, 2 and 3 kg/ha were equally effective, but 1 kg/ha was not sufficient in the dry season.

Movement and Activity of Glyphosate in Purple Nutsedge

Tubers from purple nutsedge (Cyperus rotundusL.) plants grown in the greenhouse for 2 to 10 weeks did not germinate after foliar applications of 4 kg/ha glyphosate (N-(phosphonomethyl)glycine). Some tubers from 12- and 24-week-old purple nutsedge plants survived glyphosate application. Translocation of14C-glyphosate from treated purple nutsedge leaves to other plant parts increased from 5% of the amount applied at 1 day to 19% at 4 days after application. Specific activity of14C in tubers was greater than in leaves of plants 2- to 6-week-old. With increasing plant age, specific activity decreased in both tubers and leaves. As purple nutsedge grew older, total14C translocated increased in tubers, and decreased slightly in leaves. Thin layer chromatography showed no evidence of glyphosate metabolism in purple nutsedge.

Biologically Active Substances in Subterranean Parts of Purple Nutsedge

The growth of barley (Hordeum distichum L., var. Esperanza) seedlings in nutrient solution was reduced by purple nutsedge (Cyperus rotundus L.) plants growing in connected vials and by addition of ethanolic extract of purple nutsedge. Aqueous and ethanolic extracts from subterranean parts of purple nutsedge reduced the germination and root elongation of barley; stimulations of barley root elongation were obtained with diluted aqueous extract. The germination of barley, mustard (Brassica nigra L., var. Alsace), and cotton (Gossypium hirsutum L., var. Acala 1517) was reduced in soil which had been infested previously with purple nutsedge. Radicle elongation of barley was inhibited by ethanolic extract of soil previously infested. Chromatographic studies indicated that the inhibitors are phenolic substances.

The Effects of Dichlobenil on Assimilate Transport in Purple Nutsedge

Assimilate transport in purple nutsedge (Cyperus rotundusL.) was studied using autoradiographic technique. Results show the basic pattern of assimilate distribution was from areas of synthesis to areas of use or accumulation. The initial underground centers of high metabolic activity were replaced as these organs matured, by new centers of actively growing rhizomes, tubers, and roots. The planted tuber did not accumulate assimilates. Treatment of purple nutsedge plants with 2,6-dichlorobenzonitrile (dichlobenil) resulted in accumulation of assimilates in the tubers rather than in young underground tissues. Leaves of treated plants also accumulated labeled assimilate in excess of control plants. Assimilate accumulation in leaves of dichlobenil-treated plants resulted from the destruction of the phloem in the basal portions of the leaf-sheaths. An increase in tuber respiration accompanied an increase in accumulation of assimilates in dichlobenil treated tubers.

Effect of AMA on Synthesis and Utilization of Food Reserves in Purple Nutsedge

Chemical analyses for carbohydrates, fats, and protein and C14O2 tracer techniques were employed to study the influence of repeated applications of amine methylarsonate (hereinafter referred to as AMA) on food reserves in purple nutsedge (Cyperus rotundus L.). Purple nutsedge plants were grown under greenhouse conditions and treated at 3-week intervals with an aqueous solution of AMA. Chemical analyses suggested that repeated applications of AMA accelerated starch hydrolysis in tubers but had little effect on the fat and protein content. The disappearance of starch was correlated with an increase in the arsenic (hereinafter referred to as As) content of tubers following repeated applications. In leaf tissue, applications of AMA significantly reduced the sugar content and increased the protein content. Tracer studies on the rate of C14O2 fixation and evolution suggested that, in general, AMA-treated plants had a higher rate of utilization of the products of photosynthesis than untreated plants. Apparently, the carbohydrate fraction of food reserves was utilized in preference to fats and protein.