Sesbania Exaltata Research Articles

A new genus record for Türkiye: Sesbania Adanson (Fabaceae)

The genus Sesbania Adanson (Fabaceae) is recorded for the first time in the flora of Türkiye. Collected specimens of this genus from Tarsus/Mersin are described here as a new record, Sesbania herbacea (Mill.) McVaugh which is an alien weed. Its detailed morphological features, Turkish name and photographs in its natural habitat, and the finding location are given in this study

Prickly Sida (Sida spinosa L.), Hemp Sesbania [Sesbania herbacea (Mill.) McVaugh], and Pitted Morningglory (Ipomoea lacunose L.) Response to Selective and Non-Selective Herbicide in Mississippi, USA

Prickly sida (Sida spinosa), hemp sesbania (Sesbania herbacea), and pitted morningglory (Ipomoea lacunose) are becoming problematic weeds in many crops including corn and soybean. Two separate field experiments, under non-crop conditions, were conducted at the Mississippi State University Delta Research and Extension Center, in Stoneville, MS to evaluate the response of these weeds to eight corn selective herbicides and three non-selective herbicides alone or in combination. The herbicides used were Aatrex (atrazine), Clarity (dicamba), 2,4-D (2,4-D amine), Callisto (mesotrione), Enlist Duo (2,4-D choline + dicamba), Capreno (thiencarbazone + tembotrione), Corvus (thiencarbazone + isoxaflutole), Halex GT (mesotrione + S-metolachlor + glyphosate), Gramoxone (paraquat), Liberty (glufosinate), and Roundup (glyphosate). Halex GT provided only 86% prickly side control 4-wks after application (WAA). Aatrex + Capreno and Aatrex + Corvus were the only treatments provided 99.5% prickly sida control. Liberty, Callisto, Capreno, and Corvus provided 71, 66, and 51, and 46% control of prickly sida, respectively. Hemp sesbania control was 100% from all herbicide applications except Corvus and Roundup. Hemp sesbania control was not satisfactory from Roundup application since this treatment provided only 72% control. By 4 WAA, all herbicide treatments provided 97 to 100% on pitted morningglory control except Corvus and Capreno treatments (72 to 75%). The herbicide management program should be able to provide acceptable weed control (i.e., greater than 95%) but also to prevent weed seed deposition onto the soil seedbank. Consequently, delaying the evolution of weed herbicide resistance will result in herbicide technology preservation for as long as possible by achieving a long-term weed management program.

Fall-sown small grain cover crops for weed suppression and soil moisture management in an irrigated organic agroecosystem

Abstract Adoption of cover crops in arid agroecosystems has been slow due to concerns regarding limited water resources and possible soil moisture depletion. In irrigated organic systems, potential ecosystem services from cover crops also must be considered in light of the concerns for water conservation. A constructive balance could be achieved with fall-sown small grain cover crops; however, their impacts on irrigated organic systems are poorly understood. Our first objective was to determine the ability of fall-sown small grains [cereal rye (Secale cereale L), winter wheat (Triticum aestivum L.), barley (Hordeum vulgare L.) and oat (Avena sativa L.)] to suppress winter weeds in an irrigated, organic transition field in the southwestern USA. Small grains were planted following the legume sesbania (Sesbania exaltata (Raf.) Rydb. ex A.W. Hill) during Fall 2012 and Fall 2013. In Spring 2013 and 2014, weed densities and biomass were determined within each cover crop treatment and compared against unplanted controls. Results indicated that both barley and oat were effective in suppressing winter weeds. Our second objective was to compare weed suppression and soil moisture levels among seven barley varieties developed in the western United States. Barley varieties (‘Arivat’, ‘Hayes Beardless’, ‘P919’, ‘Robust’, ‘UC603’, ‘UC937’, ‘Washford Beardless’) were fall-sown in replicated strip plots in Fall 2016. Weed densities were measured in Spring 2017 and volumetric soil moisture near the soil surface (5.1 cm depth) was measured at time intervals beginning in December 2016 and ending in March 2017. With the exception of ‘UC937’, barley varieties caused marked reductions in weed density in comparison with the unplanted control. Soil moisture content for the unplanted control was consistently lower than soil moisture contents for barley plots. Barley variety did not influence volumetric soil moisture. During the 2017–2018 growing season, we re-examined three barley varieties considered most amenable to the cropping system requirements (‘Robust’, ‘UC603’, ‘P919’), and these varieties were again found to support few weeds (≤ 5.0 weeds m−2). We conclude that several organically certified barley varieties could fill the need for a ‘non-thirsty’ cover crop that suppresses winter weeds in irrigated organic systems in the southwestern United States.

Concurrent weed growth suppression with essential oils and species-specific response to fractionated coconut oil

Plant-derived oils are phytotoxic and thus are potential non-synthetic herbicides. The present study investigated the effectiveness of three essential oils (red thyme, clove bud, cinnamon bark) and a vegetable oil, fractionated coconut oil (FCO), used alone or in 2-way essential/FCO mixes for controlling some troublesome weeds at seedling stage. The tested weeds were mugwort (Artemisia vulgaris L.), crown daisy (Glebionis coronaria (L.) Spach), milk thistle (Sylibum marianum (L.) Gaertn.), dense-flowered mullein (Verbascum densiflorum Bertol.), goosegrass (Eleusine indica L. (Gaertn.)), entireleaf morningglory (Ipomoea hederacea (L.) Jacq.), small-flower morningglory (Jacquemontia tamnifolia (L.) Griseb), large crabgrass (Digitaria sanguinalis (L.) Scop.), hemp sesbania (Sesbania exaltata (Raf.) Rydb. ex A.W. Hill).Greenhouse trials included a negative control (non-treated) and a positive control (glyphosate) and were conducted in Sassari (IT) and Auburn (USA). In both locations, all the essential oils used severely injured weeds by 5 days after treatment (DAT), with least or no recovery by plants, with no harvestable plant biomass 20 DAT. FCO provoked more diverse species-specific responses, reducing biomass of crown daisy, large crabgrass, entireleaf morningglory and hemp sesbania compared to the non-treated control while it stimulated the growth of mugwort, dense-flowered mullein, goosegrass, and small-flower morningglory. Milk thistle was the only plant not influenced by FCO compared to the non-treated control. The essential oils mixed with FCO confirmed high phytotoxic effects with a significant improved action when red thyme oil + FCO was applied to goosegrass. Our research confirms the potential herbicidal effect of some phytotoxic essential oils and the potential beneficial growth effect of FCO to some species.

Vegetative development and biomass production of Sesbania herbacea in a wet floodplain environment

ABSTRACT Green manure provides countless benefits to the chemical, physical and biological quality of soils. This study aimed to evaluate the Sesbania herbacea potential, regarding growth and biomass production parameters, as a green manure option in wet floodplain environments. A completely randomized experimental design was used, with measurements repeated over time and six replications. The parameters were evaluated every 20 days (20, 40, 60, 80, 100 and 120 days after emergence - DAE), namely: mean plant height, root and shoot fresh and dry matter biomass, and total plant matter biomass. The legume showed a good development in soil under waterlogged condition, which led to high amounts of phytomass accumulation (approximately 139 t ha-1 of total plant matter biomass and mean height of 4 m at 120 DAE).

Interactions and Effects on Cysteine Synthase Activity of Aminooxyacetate and Boc-Aminooxyacetate on the Bioherbicides <i>Colletotrichum truncatum</i> and <i>Alternaria cassia</i> and Their Weed Hosts

Aminooxyacetate (AOA) is a pyridoxal phosphate antagonist that inhibits various plant enzymes (including transaminases) which require pyridoxal phosphate as a cofactor and it exhibits phytotoxic and herbicidal properties. We examined AOA and its analog, N-t-butoxycarbonyl-AOA (Boc-AOA) for phytotoxicity, interactions with weed pathogens (bioherbicides), and effects on an important pyridoxal requiring enzyme, cysteine synthase (CS, E.C. 4.2.99.8). Studies were performed on two weeds, i.e., hemp sesbania [Sesbania exaltata (Raf.) Rybd. Ex A.W. Hill] and sicklepod (Senna obtusifolia), and two pathogens, (Colletotrichum truncatum and Alternaria cassiae), that are bioherbicidal agents against hemp sesbania and sicklepod, respectively. Pathogenicity tests, and assays for extractable, and in vitro CS activities were utilized. Phytotoxicity bioassays indicated that the bulky t-butoxycarbonyl moiety substitution on the AOA molecule did not substantially hinder expression of biological activity of Boc-AOA in these tests. Generally, spray application of the compounds to young dark-grown seedlings caused little growth effects, but root-feeding of the chemicals reduced growth (stem elongation) in both weeds. Hemp sesbania was generally more tolerant than sicklepod to these compounds. The only apparent positive interaction of the chemicals with these pathogens was the Boc-AOA: C. truncatum combination treatment on hemp sesbania. Both compounds reduced extractable CS in the seedlings by 30%, 72 h after treatment. CS activity was reduced by 15% in hemp sesbania treated with C. truncatum but increased 20% above control levels after infection of sicklepod by A. cassiae. This latter effect suggests that CS may be involved in sicklepod defense mechanisms against this pathogen.

Biochemical and Anatomical Investigation of Sesbania herbacea (Mill.) McVaugh Nodules Grown under Flooded and Non-Flooded Conditions.

Sesbania herbacea, a native North American fast-growing legume, thrives in wet and waterlogged conditions. This legume enters into symbiotic association with rhizobia, resulting in the formation of nitrogen-fixing nodules on the roots. A flooding-induced anaerobic environment imposes a challenge for the survival of rhizobia and negatively impacts nodulation. Very little information is available on how S. herbacea is able to thrive and efficiently fix N2 in flooded conditions. In this study, we found that Sesbania plants grown under flooded conditions were significantly taller, produced more biomass, and formed more nodules when compared to plants grown on dry land. Transmission electron microscopy of Sesbania nodules revealed bacteroids from flooded nodules contained prominent polyhydroxybutyrate crystals, which were absent in non-flooded nodules. Gas and ion chromatography mass spectrometry analysis of nodule metabolites revealed a marked decrease in asparagine and an increase in the levels of gamma aminobutyric acid in flooded nodules. 2-D gel electrophoresis of nodule bacteroid proteins revealed flooding-induced changes in their protein profiles. Several of the bacteroid proteins that were prominent in flooded nodules were identified by mass spectrometry to be members of the ABC transporter family. The activities of several key enzymes involved in nitrogen metabolism was altered in Sesbania flooded nodules. Aspartate aminotransferase (AspAT), an enzyme with a vital role in the assimilation of reduced nitrogen, was dramatically elevated in flooded nodules. The results of our study highlight the potential of S. herbacea as a green manure and sheds light on the morphological, structural, and biochemical adaptations that enable S. herbacea to thrive and efficiently fix N2 in flooded conditions.

Influence of Soil Moisture on Absorption, Translocation, and Metabolism of Florpyrauxifen-benzyl

AbstractFlorpyrauxifen-benzyl is a new active ingredient that represents an additional tool in rice (Oryza sativaL.) weed control by providing an alternative mechanism of action. Studies were conducted to evaluate soil moisture influences on florpyrauxifen-benzyl absorption, translocation, and metabolism in three problematic weeds. In the absorption/translocation study, barnyardgrass [Echinochloa crus-galli(L.) P. Beauv.], hemp sesbania [Sesbania herbacea(Mill.) McVaugh], and yellow nutsedge (Cyperus esculentusL.) were treated with [14C]florpyrauxifen-benzyl under two soil moisture regimes (7.5% and 60% field capacity). Greater absorption occurred under moist conditions (60% soil moisture content). More translocation of the herbicide to the area above the treated leaf occurred under moist versus dry soil across all weed species.Sesbania herbaceatranslocated 25% of the absorbed herbicide above the treated leaf, a result greater than that of the other two weed species at 60% soil moisture. However, no differences in translocation occurred among the weed species at the 7.5% soil moisture regime. In the metabolism study, 95% of the herbicide recovered was in its acid form under the high soil moisture regime forS. herbacea, a species that shows extreme sensitivity to even low doses of this herbicide, and soil moisture influenced the amount of acid form found in all species. While these data provide a limited view into the physiological processes being affected, they do suggest that forE. crus-galli,S. herbacea, andC. esculentus, soil moisture content in the field will likely play a significant role in absorption, translocation, and metabolism of florpyrauxifen-benzyl.

EVALUATION OF CARBOHYDRATE CONTENT IN THREE MEDICINAL PLANTS OF GENUS SESBANIA IN MAHARASHTRA

The genus Sesbania belongs to the family Leguminoceae. Sesbania are known for exceptionally fast growth rates as well as a high affinity for association with several nitrogen fixing rhizobia in the soil that cause formation of numerous and large nodules in the plant roots. The member of this genus also have several potential uses including forage, poles for light construction, fuel wood, medicines, shade trees for other crops and gums. The seasonal variation of starch , total sugar and total carbohydrates content have been investigated from leaves, wood and bark of Sesbania rostrata , Sesbania exaltata and Sesbania sesban are the medicinal plants in Maharashtra. Comparative account of starch content of leaves, wood and bark of Sesbania rostrata showed higher level (range 7.49 to 8.54 mg/g dry wt.) than Sesbania exaltata (range 7.16 to 7.52 mg/g dry/wt.) and Sesbania sesban (range 6.07 to 6.72 mg/g dry wt.). Comparative account of total sugar content of leaves, wood and bark of Sesbania rostrata showed higher level (range 2.62 to 3.13 mg/g dry wt.) than Sesbania exaltata (range 2.34 to 2.87 mg/g dry wt.) and Sesbania sesban (range 1.81 to 2.35 mg/g dry wt.). Comparative account of total carbohydrate content of leaves, wood and bark of Sesbania rostrata showed higher level (range 10.11 to 11.67 mg/g dry wt.) than Sesbania exaltata (range 9.50 to 10.40 mg/g dry wt.) and Sesbania sesban (range 7.88 to 9.07 mg/g dry wt.). Keywords : Starch , Total sugar , Total carbohydrate , Medicinal plant , Sesbania

BIOCHEMICAL EVALUATION OF THREE MEDICINAL TAXA OF GENUS SESBANIA IN MAHARASHTRA

The genus Sesbania belongs to the family Leguminosae and its subfamily is Papilionoideae.There are four subgenera of which Sesbania and Agati are of agriculture value. The seasonal variation of proteins and amino  acids have been investigated in leaf , bark and wood of Sesbania rostrata , Sesbania exaltata and Sesbania sesban are the medicinal plants in Maharashtra. Comparative account of protein content of leaves of three tree species revealed that Sesbania exaltata were rich in protein( range from 3.34 to 3.81 mg / g dry wt .) than Sesbania rostrata ( range from 3.60 to 3.72 mg / g dry wt .) and Sesbania sesban ( range from 2.31 to 2.55 mg / g dry wt .) . Amino acids content of leaves of three tree species revealed that Sesbania exaltata were rich in amino acid ( range from 2.47 to 2.67 mg / g dry wt .) than Sesbania rostrata ( range from 2.29 to 2.46 mg / g dry wt .) and Sesbania sesban ( range from 1.74 to 1.89 mg / g dry wt .). Key words: Protein , amino acid , endangered medicinal taxa

Triclosan inhibits arbuscular mycorrhizal colonization in three wetland plants

In terrestrial ecosystems, plant growth, plant community structure, and ultimately the ecosystem services provided by plants are dependent on the presence and composition of below ground arbuscular mycorrhizal (AM) fungal communities. AM fungi form obligate symbioses with plants providing nutrients to their host plants in exchange for photosynthates. While AM have been found in most wetland ecosystems, the effects of urban contaminants on AM associations are largely unknown. Triclosan (5-chloro-2-[2,4-dichlorophenoxy]phenol; TCS) is a widespread contaminant found in surface waters throughout North America and in addition to antimicrobial properties is purported to have antifungal properties. To determine the effects of TCS on arbuscular mycorrhizal associations, we exposed AM inoculated wetland plant species (Eclipta prostrata, Hibiscus laevis, and Sesbania herbacea) to TCS at concentrations of 0.0, 0.4 and 4.0μg/L in a continuous flow-through exposure system. TCS exposure caused significant reductions in hyphal and arbuscular colonization while no significant effect was detected for vesicular colonization. Across all species, hyphal colonization was significantly higher in controls (18.58±1.84%) compared to 0.4 and 4.0μg/L (10.20±1.34% and 9.86±1.32% respectively) TCS treatments. Similarly, arbuscular colonization was significantly higher in the controls (4.58±0.75%) compared to 0.4μg/L (2.20±0.38%) and 4.0μg/L (1.22±0.24%) TCS exposures. Since our lowest effect concentration, 0.4μg/L, lies within the range of concentrations found in North American streams it is plausible that AM colonization has been impacted in streams receiving WWTP effluent. Further studies are required to understand the mechanism of TCS inhibition of mycorrhizal colonization in wetland plant species as well as the potential ecological consequences that a decline in the AM colonization levels may represent.

Effects of Lead on Plant Growth, Lead Accumulation and Phytochelatin Contents of Hydroponically-Grown <i>Sesbania </i><i>E</i><i>xaltata</i>

Phytoremediation is the use of living plants for the removal of contaminants from soil, water, sediments, and air. Soil contamination by heavy metals (HMs) is an important environmental concern. The success of phytoextraction, a subset of phytoremediation, as an environment clean-up technology depends on several factors including the extent of soil contamination and the bioavailability of the metal. The aim of phytoextraction research is to identify metal-tolerant plants that are capable of uptake and efficient translocation of HMs to harvestable above-ground organs. The main objective of this study was to assess the metal tolerance of coffeeweed (<i>Sesbania exaltata </i>Raf.) after exposure to lead (Pb) solutions. <i>Sesbania</i> plants were grown for 30 days at the Jackson State University greenhouse prior to exposure to different concentrations (0, 0.1, 1.0, 5.0, 10.0, 20.0 μM Pb) of lead nitrate. Four 30-day old seedlings were grown hydroponically in each designated 15-mL cup containing the Pb treatments. Plants were harvested after various exposure periods (0, 2, 5, 8, 12, 15 days). Morphological characteristics were evaluated, and lead contents were quantified by Inductively Coupled Plasma - Optical Emission Spectrometry (ICP-OES). Phytochelatin synthesis was determined indirectly by quantifying the acid - thiol contents of roots and shoots. Our results indicated that lead tissue uptake increased with increasing concentrations of lead (i.e. 20.0 μM versus 1.0 μM). However, plant roots and shoots displayed symptoms of toxicity as evidenced by their decreased biomass with increasing concentrations of lead. Also, plants exposed to higher Pb concentrations exhibited mild chlorosis. Overall, <i>Se</i><i>s</i><i>bania</i> was relatively tolerant to lead. Although acid - soluble thiol contents appeared to correlate with Pb uptake especially at higher concentrations of Pb treatments, phytochelatin synthesis as a metal-tolerance mechanism in <i>Sesbania</i> is inconclusive at this time. Further experiments are warranted to elucidate whether such tolerance mechanism exists in <i>Sesbania.</i>

Interaction between saflufenacil and imazethapyr in red rice (Oryza ssp.) and hemp sesbania (Sesbania exaltata) as affected by light intensity

Saflufenacil is a broadleaf herbicide for preplant burndown and pre-emergence applications in various crops. This study was established to evaluate the absorption and translocation of saflufenacil in hemp sesbania and imazethapyr in red rice as a function of their post-emergence interaction and light intensity. Imazethapyr plus saflufenacil provided a greater uptake (30%) and translocation (35%) of (14) C-imazethapyr than imazethapyr alone. In the section above treated leaf (ATL), a higher percentage of the absorbed imazethapyr (23%) was quantified in the imazethapyr plus saflufenacil treatment after 168 h. Faster basipetal movement of imazethapyr was identified under higher light availability. Absorption of (14) C-saflufenacil ranged from approximately 40 to 60% among herbicide and light intensity treatments. At 12 and 24 h after treatment (HAT) a greater percentage (15-20%) of the absorbed saflufenacil was quantified above the treated leaf at the two lower light intensities. Similar trends were observed for basipetal movement of saflufenacil. Saflufenacil enhanced absorption, overall translocation and acropetal movement of imazethapyr in the TX4 red rice. Basipetal movement of imazethapyr was faster under higher light intensities. Overall, imazethapyr improved absorption of saflufenacil in hemp sesbania plants. Reduction in light intensity resulted in greater translocation of saflufenacil, promoting acropetal and basipetal distribution at the two lower light intensity treatments.

Hemp sesbania (Sesbania exaltata) control in rice (Oryza sativa) with the bioherbicidal fungus Colletotrichum gloeosporioides f. sp. aeschynomene formulated in an invert emulsion

In greenhouse and field experiments, an invert emulsion (MSG 8.25) was tested with dried, formulated spores of the bioherbicidal fungus Colletotrichum gloeosporioides f. sp. aeschynomene, a highly virulent pathogen of the leguminous weed Aeschynomene virginica (northern jointvetch), but considered ‘immune’ against another more serious leguminous weed, Sesbania exaltata (hemp sesbania). A 1:1 (v/v) fungus/invert emulsion mixture resulted in 100% infection and mortality of inoculated hemp sesbania seedlings over a 21-day period under greenhouse conditions. In replicated field tests of the fungus/invert formulation conducted in Stuttgart, AR, and Stoneville, MS, hemp sesbania was controlled 85 and 90%, respectively. These results suggest that this invert emulsion expands the host range of C. gloeosporioides f. sp. aeschynomene, with a concomitant improvement of the bioherbicidal potential of this pathogen.

Aminomethylphosphonic Acid Accumulation in Plant Species Treated with Glyphosate

Aminomethylphosphonic acid (AMPA) is the most frequently detected metabolite of glyphosate in plants. The objective of this study was to determine if there is any correlation of metabolism of glyphosate to AMPA in different plant species and their natural level of resistance to glyphosate. Greenhouse studies were conducted to determine the glyphosate I 50 values (rate required to cause a 50% reduction in plant growth) and to quantify AMPA and shikimate concentrations in selected leguminous and nonleguminous species treated with glyphosate at respective I 50 rates. Coffee senna [ Cassia occidentalis (L.) Link] was the most sensitive ( I 50 = 75 g/ha) and hemp sesbania [ Sesbania herbacea (P.Mill.) McVaugh] was the most resistant ( I 50 = 456 g/ha) to glyphosate. Hemp sesbania was 6-fold and Illinois bundleflower [ Desmanthus illinoensis (Michx.) MacM. ex B.L.Robins. & Fern.] was 4-fold more resistant to glyphosate than coffee senna. Glyphosate was present in all plant species, and its concentration ranged from 0.308 to 38.7 microg/g of tissue. AMPA was present in all leguminous species studied except hemp sesbania. AMPA concentration ranged from 0.119 to 4.77 microg/g of tissue. Shikimate was present in all plant species treated with glyphosate, and levels ranged from 0.053 to 16.5 mg/g of tissue. Non-glyphosate-resistant (non-GR) soybean accumulated much higher shikimate than glyphosate-resistant (GR) soybean. Although some leguminous species were found to be more resistant to glyphosate than others, and there was considerable variation between species in the glyphosate to AMPA levels found, metabolism of glyphosate to AMPA did not appear to be a common factor in explaining natural resistance levels.

Biocontrol efficacy of Colletotrichum truncatum for hemp sesbania (Sesbania exaltata) is enhanced with unrefined corn oil and surfactant

In greenhouse and field experiments, an oil‐in‐water emulsion of unrefined corn oil and Silwet L‐77 increased the biological weed control efficacy of Colletotrichum truncatum (Schw.) Andrus et Moore for control of the weed, hemp sesbania (Sesbania exaltata[Raf.] Rydb. ex A.W. Hill). The surfactant – corn oil emulsion stimulated germination and appressoria formation in vivo and in vitro and delayed the need for dew. We hypothesize that the corn oil protected the conidia from desiccation during the dew‐free period and the surfactant stimulated spore germination and appressoria formation. In field experiments conducted over 3 years, a single application of a 50% (v/v) unrefined corn oil tank mixture containing 0.2% (v/v) Silwet L‐77 surfactant controlled hemp sesbania in soybeans an average of 95%. Aqueous fungal suspensions or adjuvants alone did not visually affect or control hemp sesbania. The soybean yields were significantly higher in the plots where weeds were effectively controlled. These results suggest that formulating C. truncatum in unrefined corn oil and surfactant greatly increases its infectivity and the biocontrol potential of this pathogen.

Sesbania exaltata biocontrol with Colletotrichum truncatum microsclerotia formulated in ‘Pesta’ granules

The weed Sesbania exaltata (Raf.) Rydb. ex A.W. Hill (hemp sesbania) was effectively controlled in soybean (Glycine max (L.) Merr.) field test plots over a 2-year testing period (1995-1996) with microsclerotia of the bioherbicidal fungus, Colletotrichum truncatum, formulated in wheat gluten-kaolin granules called 'Pesta'. Weed control averaged 84% and 88%, respectively, in plots treated pre-plant incorporated (PPI) at 'Pesta' rates of 168 or 336 kg ha )1 , and 71% and 78%, respectively, in plots treated pre-emergence (PE) at 'Pesta' rates of 168 or 336 kg ha )1 over the testing period. Post-emergence (POE) control averaged 30% and 50%, respectively, for the 168 and 336 kg ha )1 treatments, and was significantly less effective than either PE or PPI treatments. Although pathogenesis and mortality occurred in hemp sesbania tissues, satisfactory weed control was not achieved in plots treated at rates of 17 or 84 kg ha )1 with any of the application methods. Soybean yields were significantly greater in test plots treated PPI or PE, as compared to yields from test plots treated either POE, with inert 'Pesta' granules, or from untreated controls. Microsclerotia formulated in 'Pesta' granules exhibited excellent shelf-life, retaining high viability after storage for 10 years at 4 C. These results suggest that microsclerotia of C. truncatum formulated in 'Pesta' granules offers an effective method for controlling this important weed and preserving the activity of this bioherbicide.

Feeding and Maturation by Soybean Looper (Lepidoptera: Noctuidae) Larvae on Soybean Affected by Weed, Fungus, and Nematode Pests

Feeding and maturation by the soybean looper, Pseudoplusia includens (Walker) (Lepidoptera: Noctuidae), were investigated in a 2-yr study on 'Davis' soybean, Glycine max (L.) Merr., grown alone and combined with the weed hemp sesbania, Sesbania exaltata (Raf.) Rybd. ex. A. W. Hill, the root-knot nematode, Meloidogyne incognita (Kofoid & White) Chitwood, and the charcoal rot fungus, Macrophomina phaseolina (Tassi) Goid. Of the three pests, hemp sesbania had the greatest effects on plant growth and insect feeding and maturation. When fed foliage from soybean stressed by hemp sesbania, soybean looper larvae remained longer in feeding stages, consumed more foliage, and showed altered weight gain compared with larvae fed control foliage. Results suggest that nutrient (s) critical for proper development of larvae may have been limited in weed-stressed soybean foliage. Less dramatic results were observed when larvae fed on foliage from soybean with roots colonized by the charcoal rot fungus. Such larvae consumed more foliage, weighed more, and showed a slight increase in larval feeding period, but only in 1 yr of the study. Colonization of soybean roots by the root-knot nematode had no consistent effects on either the soybean host or insect.

Weed Control and Species Shift in Bromoxynil- and Glyphosate-Resistant Cotton (Gossypium hirsutum) Rotation Systems1

A field study was conducted from 1999 through 2001 at Stoneville, MS, to determine the effects of bromoxynil-resistant (BR) and glyphosate-resistant (GR) cotton rotation systems under ultranarrow- (25-cm spacing) and wide- (102-cm spacing) row planting on weed control, weed density and shift, and cotton yield. The four rotations during 3 yr included BR–BR–BR, GR–GR–GR, BR–GR–BR, and GR–BR–GR, all with bromoxynil or glyphosate postemergence (POST) only or following fluometuron plus pendimethalin preemergence (PRE). Control of hemp sesbania, pitted morningglory, prickly sida, and hyssop spurge was ≥97% regardless of row width, rotation, and herbicide program. Control of common purslane, sicklepod, and smooth pigweed was higher with glyphosate POST in GR cotton than with bromoxynil POST in BR cotton. Broadleaf and yellow nutsedge weed biomass were higher with bromoxynil POST in BR cotton than with glyphosate POST in GR cotton. Continuous BR cotton system resulted in higher densities of common purslane, sicklepod, and yellow nutsedge (15.3, 1.5, and 373 plants/m2, respectively) compared with continuous GR cotton (0.7, 0.1, and 1.0 plant/m2, respectively). Seed cotton yield was consistently higher in wide- than in ultranarrow-row cotton. Seed cotton yield was lower in continuous BR cotton than in the other three rotation systems, and yields greatly improved when BR cotton was rotated with GR cotton. During a 3-yr period, seed cotton yields with glyphosate POST only (4,000 to 4,890 kg/ha) or after PRE herbicides (4,480 to 4,860 kg/ha) were similar in GR cotton, whereas in BR cotton, bromoxynil POST only (1,390 to 4,280 kg/ha) resulted in lower yield than did bromoxynil POST after PRE herbicides (2,550 to 4,480 kg/ha). The results indicated that the shift in spectrum of weeds toward more tolerant species and yield decline in continuous BR cotton can be prevented by rotating BR with GR cotton.Nomenclature: Bromoxynil; fluometuron; glyphosate; pendimethalin; common purslane, Portulaca oleracea L. #3 POROL; hemp sesbania, Sesbania exaltata (Raf.) Rydb. ex A.W. Hill # SEBEX; hyssop spurge, Euphorbia hyssopifolia L. # EPHHS; pitted morningglory, Ipomoea lacunosa L. # IPOLA; prickly sida, Sida spinosa L. # SIDSP; sicklepod, Senna obtusifolia (L.) Irwin & Barneby # CASOB; smooth pigweed, Amaranthus hybridus L. # AMACH; yellow nutsedge, Cyperus esculentus L. # CYPES; cotton, Gossypium hirsutum L. ‘BXN 47’, ‘DP 436 RR’.Additional index words: Bromoxynil, fluometuron, glyphosate, pendimethalin, rotation, transgenic cotton, weed density, weed shift.Abbreviations: BR, bromoxynil resistant; GR, glyphosate resistant; POST, postemergence; PRE, preemergence; WAA, weeks after second POST application.

Use of Common Weeds of Rice as Hosts for the Rice Water Weevil (Coleoptera: Curculionidae)

The rice water weevil, Lissorhoptrus oryzophilus Kuschel, is the most important insect pest in rice, Oryza sativa L., in the United States. Prior research indicates that rice water weevils feed primarily on monocotyledonous plants. Many monocot weeds occur in rice fields, but little is known about rice water weevil-weed interactions in rice. Host utilization of the rice water weevil was evaluated on rice, cultivar ‘Cocodrie’, and seven weeds commonly found in rice fields in preference and life cycle compatibility tests in the greenhouse. Barnyardgrass, Echinochloa crus-galli Beauv., yellow nutsedge, Cyperus esculentus L., broadleaf signalgrass, Brachiaria platyphylla Nash., and fall panicum, Panicum dichotomiflorum Michx., were more preferred for oviposition than rice. More neonate larvae eclosed on barnyardgrass and yellow nutsedge than eclosed on rice. Densities of late instars feeding on roots of yellow nutsedge and broadleaf signalgrass were significantly lower than densities on rice. Barnyardgrass was also more preferred for adult feeding than rice and all other weeds. Rice water weevils were able to complete their life cycle on all plants examined except hemp sesbania, Sesbania exaltata (Rafin.) Cory, the only dicotyledonous plant species tested in the greenhouse. Several new hosts can be added to an existing list of host plants for the rice water weevil. Field surveys confirmed larvae infested roots of all weed species sampled in the greenhouse, as well as several other weed species. Many of the plants infested with larvae were dicotyledonous plants, suggesting that the host range of rice water weevil is much broader than previously reported.