Absorption,translocation and metabolism of 14C-glyphosate in several weed species*

The pattern and extent of ¹⁴C-glyphosate [N-(phosphonomethyl)glycine] translocation from the treated leaf and metabolism of ¹⁴C-glyphosate were studied in field bindweed (Convolvulus arvensis L.), hedge bindweed (Convolvulus sepium L.). Canada thistle [Cirsium arvense (L.) Scop.] tall morning glory [lpomoea purpurea (L.) Roth.] and wild buckwheat (Polygonum convolvulus L.). ¹⁴C was translocated throughout the plants within 3 days with accumulation in the meristematic tips of the roots and shoots evident. Cross and longitudinal sections of stems and roots showed that the ¹⁴C was localized in the phloem. Field bindweed translocated 3–5% of the applied ¹⁴C from the treated leaf, hedge bindweed 21.6%, Canada thistle 7.8%, tall morningglory 6.5%, and wild buckwheat 5%. Field bindweed, Canada thistle, and tall morningglory metabolized the parent glyphosate to aminomethylphosphonic acid to a limited extent. This metabolite made up less than 15% of the total 14C. Of the total ¹⁴C applied to excised leaves, 50% had disappeared within 25 days.     

Pathogenicity of fungi collected in northern Ghana to Striga hermonthica

Thirteen fungal species were isolated from diseased plants of Striga hermonthica (Del.) Benth in northern Ghana. The pathogenicity of 12 isolates of the fungal species including Curvularia fallax Boed, Fusarium equiseti (Corda) Sacc., Fusarium equiseti var. bullatum (Sherb.) Wollenw., F. oxysporum Schlecht, F. solani (Mart) Sacc., Macrophonuina phasealina (Tassi) Goidan, and Sclerotium rolfsii (Sacc.) were evaluated against S. hermonthica under controlled environmental conditions. All isolates were pathogenic to S. hermonthica when propagated on wheat (Triticum aestivum L.) grains and incorporated pre-planting into the soil. However, their virulence differed. Two isolates of F. oxysporum and one isolate of F. solani reduced the emergence of S. hermonthica by 88%, 98%, and 76%, respectively. Sorghum (Sorghum bicolor (L.) Moench) yield was increased by 26% when S. hermonthica was controlled. In contrast, in the control treatment with S. hermonthica no yield could be obtained. The F. oxysporum isolates were not pathogenic on sorghum. Germination tests indicated that the F. oxysporum isolates were highly pathogenic to S. hermonthica seeds. Although the F. solani isolate reduced the emergence of S. hermonthica in the pot experiments, it did not influence germination. This indicates that pathogens may attack different stages in the life cycle of S. hermonthica.     

Comparison of commercial glyphosate formulations for control of prickly sida, purple nutsedge, morningglory and sicklepod

The efficacy of the commercial glyphosate [( N -phosphonomethyl) glycine] formulations Roundup Ultra, Touchdown and Engame were compared for the control of prickly sida ( Sida spinosa L.), morningglory ( Ipomeae hederacea var. integriuscula Gray), sicklepod ( Senna obtusifolia L.) and purple nutsedge ( Cyperus rotundus L.). Engame is a new formulation of glyphosate that contains glyphosate acid and 1-aminomethanamide dihydrogen tetraoxosulfate (AMADS), a proprietary mixture of sulfuric acid and urea, other than glyphosate salt and surfactants. Injury by Engame differed from Roundup Ultra and Touchdown in that necrotic lesions formed on leaves several hours after treatment. Leaves of very susceptible species, such as prickly sida, were rapidly, although incompletely, desiccated and then became chlorotic and died in a manner typical of other glyphosate formulations. Engame was 2–3 times more active to growth inhibition than either the Roundup Ultra or Touchdown formulations, based on GR₅₀ comparisons expressed on an acid equivalent basis. The GR₅₀ estimates did not change over the 3 week evaluation period for prickly sida and purple nutsedge, and after 2 weeks after treatment for morningglory. The GR₅₀ estimates for sicklepod decreased over the 3 week evaluation period indicating a slower response to glyphosate. The application of AMADS alone caused minute necrotic lesions on sicklepod and purple nutsedge, and lesions up to 3 mm in diameter on prickly sida and morningglory. Further injury from AMADS was not noted and plants resumed growth without apparent delay. At glyphosate rates above 1120 g ha⁻¹, greater than 80% control was achieved at 7 days after treatment. These results demonstrate that glyphosate efficacy can be further enhanced by formulations that apparently improve uptake and translocation.     

Towards the primary target of chloroacetamides –new findings pave the way

This review reports on research of the last ten years to find the primary target enzyme for chloroacetamides. As could be shown first with the green alga Scenedesmus, the formation of very‐long‐chain fatty acids (VLCFAs) is severely impaired. Subsequently, in short‐term experiments, labelled malonate or stearate could be incorporated into leaf discs of cucumber, barley or leek seedlings. While the formation of ‘normal’ long‐chain fatty acids (up to C18) was not influenced, phytotoxic chloroacetamides strongly inhibited the synthesis of VLCFAs of C20, 22 and 24, with I₅₀ values of 10–100 nM . Inhibition depends on the amide structure and on stereospecificity. Also cafenstrole or recently developed tetrazolinones and phosphosulfonates were found active to inhibit fatty‐acid elongation. Subsequently, a cell‐free elongase assay was developed using a microsomal preparation from leek seedlings (Allium porrum L), [¹⁴C]malonyl‐CoA and C18, 20, or C22 acyl‐CoA primer substrates. All elongation steps were strongly affected by those phytotoxic herbicides which were also active in vivo. The inhibitors form a tight‐binding complex with the condensing elongase enzyme system which develops with time and lowers the I₅₀ values markedly. Apparently, a nucleophilic attack of the inhibitor takes place at the specific target enzyme. Acyl‐CoA elongation inhibition is correlated with growth inhibition of the intact cell. Due to the low I₅₀ values and the specific inhibition, we assume that impaired VLCFA‐formation is the primary phytotoxic impact of chloroacetamides and functionally related structures. © 2000 Society of Chemical Industry     

Phytotoxic activity of Chinese violet (Asystasia gangetica (L.) T. Anderson) and two phytotoxic substances

Chinese violet (Asystasia gangetica (L.) T. Anderson) is a perennial invasive weed belonging to Acanthaceae. Leaves of this weed have been suggested to possess phytotoxic activity. However, phytotoxic substances in this weed have not yet been reported. Therefore, the present study investigated phytotoxic activity of Chinese violet extracts and phytotoxic substances. The extracts of Chinese violet leaves inhibited the root and shoot growth of cress, lettuce, alfalfa, barnyard grass, ryegrass, and timothy, where the level of inhibition increased with increasing extract concentrations. Bioassay‐guided separations of the extracts led to isolation of two phytotoxic substances, indole‐3‐carboxaldehyde and (6R,9S)‐3‐oxo‐α‐ionol. Indole‐3‐carboxaldehyde significantly inhibited the root and shoot growth of cress at concentrations ≥100 and 30 μmol L^?1, respectively, and concentrations of the substance required for 50% growth inhibition were 210 and 127 μmol L^?1 for cress roots and shoots, respectively. The other substance, (6R,9S)‐3‐oxo‐α‐ionol, was reported to have strongly inhibited cress roots and shoots. The present results suggest that Chinese violet contains two phytotoxic substances indole‐3‐carboxaldehyde and (6R,9S)‐3‐oxo‐α‐ionol, and those substances may play an important role in the phytotoxic activity of Chinese violet.     

Effects of Plant Defence Activators on Anthracnose Disease of Cashew

The plant defence activators acibenzolar-S-methyl (Benzo[1,2,3]thiadiazole-7-carbothioic acid-S-methyl ester, ASM), 2,6-dichloro-isonicotinic acid (DCINA), salicylic acid (SA), and dibasic potassium phosphate (K₂HPO₄) were tested for their ability to protect cashew (Anacardium occidentale) seeds and leaves from anthracnose disease caused by Colletotrichum gloeosporioides. No inhibition of the early stages of pathogen development was caused by concentrations equal to or lower than 1.1mM a.i. ASM, 1.2mM a.i. DCINA, 5mM SA and 50mM K₂HPO₄. Maximum reduction of the disease in detached leaves, without phytotoxic effects, was obtained with 0.07mM a.i. ASM and DCINA, 5mM SA, and 50mM K₂HPO₄, with a time interval of at least 72h between application of the activator and inoculation with the pathogen. On attached leaves, foliar sprays were slightly more efficient than soil drench treatments, with 5mM SA being the most effective treatment, while 50mM SA as well as 0.3mM a.i. ASM and DCINA caused phytotoxic effects. In field-grown plants, protection was conferred by a soil drench of concentrations as low as 12.6M a.i. ASM and DCINA and 2.6mM SA. These concentrations were not phytotoxic suggesting that plant defence activators have potential for control of anthracnose disease in the field.     

Seasonal activity of EPTC for Cyperus rotundus L. control in a tropical climate*

Four experiments were conducted at six week intervals to determine the seasonal activity and persistence of soil-incorporated EPTC (5-ethyl N,N-dipropyl(thiocarbamate)) for Cyperus rotundus L. control and tolerance of okra (Hibiscus esculentus L.), cucumber (Cucumis sativus L.), lettuce (Lactuca sativa L.), red beet (Beta vulgaris L.) and carrot (Daucus carota L.) during the dry and wet seasons in Viçosa, Brazil. Satisfactory control of C. rotundus was obtained at 2 kg/ha EPTC during the dry season and 4 kg/ha or more during the wet season. Only red beet and carrot tolerated these doses of EPTC when the crops were planted five days after application. However, selective control of C. rotundus was obtained when the planting date of lettuce was delayed for three or six weeks after EPTC application. EPTC controlled C. rotundus at half the dose that was required to control three species of annual grass that germinated near the soil surface. EPTC persisted longer when applied to air dry soil and incorporated with a rototiller than when incorporated into moist or wet soil.     

Isolation and identification of two phytotoxic compounds from the medicinal plant Cassia alata L.

Cassia alata (Caesalpiniaceae), an ornamental shrub, has many biological properties such as antifungal and antibacterial activities. Several bioactive and phytotoxic compounds have already been isolated from C. alata. Phytotoxic substances from plants have drawn attention as an alternative biological approach to control weeds. Thus, we conducted this research to explore other phytotoxic compounds in C. alata leaves. Aqueous methanol extracts of C. alata leaves strongly inhibited the seedling growth of broccoli, cabbage, cress, radish and rapeseed, in which the level of inhibition correlated with concentration. Two active compounds were isolated through chromatographies and identified using spectral data as (S)‐4‐(3‐hydroxybutyl)phenol [(+)‐rhododendrol] and (E)‐4‐((1R,4R)‐4‐hydroxy‐2,6,6‐trimethylcyclohex‐2‐en‐1‐yl)but‐3‐en‐2‐one [3‐hydroxy‐α‐ionone]. These two active compounds inhibited the growth of cress seedlings in a concentration‐dependent manner. The required concentrations for 50% growth inhibition (I₅₀ value) of cress seedlings were 192.0–296.1 μM for (+)‐rhododendrol and 132.4–195.3 μM for 3‐hydroxy‐α‐ionone. These results indicate that the two phytotoxic compounds play a part in the phytotoxic activity of C. alata leaves.     

Differential metabolic response of barley genotypes,varying in resistance,to trichothecene‐producing and ‐nonproducing (tri5−) isolates of Fusarium graminearum

Resistance of barley to Fusarium graminearum was studied using a pair each of resistant and susceptible black and yellow barley lines. The spikelets were inoculated with a trichothecene‐producing isolate, a trichothecene‐nonproducing isolate (tri5^?), or a mock solution. Spikelets were collected 72 h after inoculation and metabolites were analysed using a LC‐hybrid MS system. Metabolite abundances were used to identify the constitutive (RRC) and induced resistance‐related metabolites (RRI). The pathogen virulence factor, DON, and its plant detoxification product, DON‐3‐O‐glucoside (D3G), were also identified and designated as resistance‐indicator (RI) metabolites. The RRC, RRI and RI metabolites were putatively identified. Jasmonic acid was significantly induced in barley following inoculation with a trichothecene‐producing isolate, but not with a tri5^? isolate. The former isolate reduced the induction of both the number and amount of RR metabolites. The metabolites cinnamic acid, sinapoyl alcohol, coniferin, catechin and naringin were identified only in response to the inoculation with a tri5^? mutant. The abundances of p‐coumaric acid, coniferaldehyde and sinapaldehyde increased more in response to the tri5^? mutant than to the trichothecene‐producing isolate. The total amount of DON synthesized and its conversion to D3G varied greatly between the resistant and susceptible black barley, but not in yellow barley. Interestingly, an increase in the amount of total DON produced was associated with a decrease in the conversion of DON to D3G. The roles of RRC, RRI and RI metabolites in plant defence and their further use as potential biomarkers in screening are discussed.     

Phytotoxic potential of Chrysopogon aciculatus (Retz.) Trin. (Poaceae)

The creeping weed, Chrysopogon aciculatus (Retz.) Trin., is widely known for its use as folk medicine, while its phytotoxic potential has not been examined. Therefore, we carried out an investigation into the phytotoxic potential of C. aciculatus to identify phytotoxic substances. C. aciculatus extracts showed inhibitory effects on shoot and root growth of cress, lettuce, rapeseed, and Italian ryegrass. Inhibition was both species‐dependent and concentration‐dependent. Two substances, (9S,10E,12Z)‐9‐hydroxyoctadeca‐10,12‐dienoic acid (9‐HO‐ODDEA) and rhizopycnin A, were isolated using chromatographies and characterized by spectral analysis. 9‐HO‐ODDEA retarded shoot and root growth of cress at concentrations higher than 1.0 and 0.3 mM, respectively, while on cress seedling by rhizopycnin A, the inhibition began from 1.0 mM. The concentrations needed for 50% inhibition of the shoot and root growth of test plants ranged from 1.71–2.31, and 0.71–0.72 mM for 9‐HO‐ODDEA and rhizopycnin A, respectively. These results indicate that these substances may contribute, to a certain extent, to the phytotoxic activity of C. aciculatus.     

Biocontrol ofRhizoctonia damping-off of cucumber by non-pathogenic binucleateRhizoctonia

Three isolates of binucleateRhizoctonia (BNR) were tested for biological control of damping-off of cucumber seedlings caused byRhizoctonia solani AG 2-2 and AG 4. BNR isolates L2 (AG Ba) and W1 and W7 (AG A) provided protection of 58 to 71% against virulent isolate C4 of AG 4 and 64 to 75% protection against virulent isolate RH 65 of AG 2-2. Varying protection was provided to the seedlings by the BNR isolates against the virulentR. solani from the two AGs depending on their combination. The BNR isolates did not vary in providing protection to the seedling when tested against virulent C4 when both isolates were inoculated using three different methods,viz. in water agar, combination of water agar and soil and using soil alone. Protection of 58 to 71 % was provided by the isolates when inoculation was done on the hypocotyl using water agar, 62.8 to 75% using the combination of water agar and soil, and 75 to 85% when inoculation of both isolates was done in soil. Pre-incubation of BNR W7 or delayed inoculation of C4 (from 0.5 day to longer duration) using the different methods provided an increased protection to the seedlings to give complete inhibition of damping-off disease. Simultaneous inoculation of both BNR W7 and C4 using the three methods failed to provide protection to the seedlings. Among the BNR isolates, BNR W7 showed plant growth promotion in terms of significant increase in plant height (P=0.01) and fresh weight (P=0.05).     

New and little-known lepidopteran (Lepidoptera) phytophages on the poplars (Populus spp.) in Bulgaria

Investigations were carried out during the period 1997-1999 on lepidopteran entomofauna deleterious to poplars (Populus spp.) in Bulgaria. The phytophages were collected in larval and pupal stage and were reared under laboratory con-ditions to the adult stage. In two regions of Bulgaria, Sofia and Montana, 18 new and little-known phytophages in seven families were established on the trees in Populus genus: Limenitis populi (L.) (Nymphalidae); Anacampsis populefia (Cl.), Gelechia turpella (Den. & Schiff.) (Gelechiidae); Synanthedon melliniformis (Lasp.) (Sesiidae); Euproctis similis (Fuessl.) (Lymantriidae); Drymonia velitaris (Hufn.), Notodonta tritophus (Den. & Schiff.) (Notodontidae); Amphipyra pyramidea (L.), Catocala nupta (L.), Cosmia trapezina (L.), Enargia paleacea (Esp.), Eupsilia transversa (Hufn.), Ipomorpha subtusa (Den. & Schiff.), Parastichtis ypsilon (Den. & Schiff.), Scoliopteryx libatrix (L.) (Noctuidae); Gastropacha quercifolia (L.), Phyllodesma tremulifolia (Hb.) and Poecilocampa populi (L.) (Lasiocampidae). G. turpella and S. melliniformis are new records for Bulgaria and D. velitaris was found for the first time in Northern Bulgaria. Thirteen species (L. populi, E. similis, D. velltaris, N. tritophus, A. pyramidea, C. nupta, C. trapezina, E. transversa, I. subtusa, P. ypsilon, G. quercifolia, P. tremulifolia and P. populi) were established for the first time in Bulgaria to have a trophic relationship with poplars. G. turpella and L subtusa were occurred in the highest population densities – up to 1.6 larvae/m and up to 1.1 larvae/m respectively. The remaining species occurred in low population densities in the studied habitats and were not considered to be pests on the poplars.     

New and little-known lepidopteran (Lepidoptera) phytophages on the poplars (Populus spp.) in Bulgaria

Investigations were carried out during the period 1997-1999 on lepidopteran entomofauna deleterious to poplars (Populus spp.) in Bulgaria. The phytophages were collected in larval and pupal stage and were reared under laboratory con-ditions to the adult stage. In two regions of Bulgaria, Sofia and Montana, 18 new and little-known phytophages in seven families were established on the trees in Populus genus: Limenitis populi (L.) (Nymphalidae); Anacampsis populefia (Cl.), Gelechia turpella (Den. & Schiff.) (Gelechiidae); Synanthedon melliniformis (Lasp.) (Sesiidae); Euproctis similis (Fuessl.) (Lymantriidae); Drymonia velitaris (Hufn.), Notodonta tritophus (Den. & Schiff.) (Notodontidae); Amphipyra pyramidea (L.), Catocala nupta (L.), Cosmia trapezina (L.), Enargia paleacea (Esp.), Eupsilia transversa (Hufn.), Ipomorpha subtusa (Den. & Schiff.), Parastichtis ypsilon (Den. & Schiff.), Scoliopteryx libatrix (L.) (Noctuidae); Gastropacha quercifolia (L.), Phyllodesma tremulifolia (Hb.) and Poecilocampa populi (L.) (Lasiocampidae). G. turpella and S. melliniformis are new records for Bulgaria and D. velitaris was found for the first time in Northern Bulgaria. Thirteen species (L. populi, E. similis, D. velltaris, N. tritophus, A. pyramidea, C. nupta, C. trapezina, E. transversa, I. subtusa, P. ypsilon, G. quercifolia, P. tremulifolia and P. populi) were established for the first time in Bulgaria to have a trophic relationship with poplars. G. turpella and L subtusa were occurred in the highest population densities – up to 1.6 larvae/m and up to 1.1 larvae/m respectively. The remaining species occurred in low population densities in the studied habitats and were not considered to be pests on the poplars.     

Characterization of Alternaria species associated with potato foliar diseases in China

The population structure of Alternaria species associated with potato foliar diseases in China has not been previously examined thoroughly. Between 2010 and 2013, a total of 511 Alternaria isolates were obtained from diseased potato leaves sampled in 16 provinces, autonomous regions or municipalities of China. Based on morphological traits and molecular characteristics, all the isolates were identified as Alternaria tenuissima, A. alternata or A. solani. Of the three species, A. tenuissima was the most prevalent (75·5%), followed by A. alternata (18·6%) and A. solani (5·9%). Phylogenetic analysis based on sequences of the internal transcribed spacer (ITS) region of ribosomal DNA (rDNA) of representative Alternaria isolates showed that A. solani was distinct from the two small‐spored Alternaria species. Phylogenetic analysis of the partial coding sequence of the histone 3 gene divided the same collection of isolates into three main clades representing A. tenuissima, A. alternata and A. solani, respectively. The pathogenicity of the isolates on detached leaves of potato cv. Favorite did not differ significantly between the three species or between isolates from different geographical origins. The results indicate that the population structure of Alternaria species associated with potato foliar diseases differs from that reported previously in China. This is the first report of A. tenuissima causing potato foliar diseases in China.     

Medicago truncatula as a model host for studying legume infecting Rhizoctonia solani and identification of a locus affecting resistance to root canker

The broad‐host‐range necrotizing fungal pathogen Rhizoctonia solani is responsible for economically significant diseases to crops as diverse as wheat, maize, barley, canola, sugar beet, potato, soyabean, bean, lupin and alfalfa. Germplasm screens in many of the crop hosts have not identified strong genetic resistance which, together with the lack of effective control, mean the pathogen remains a substantial problem for agriculture in many parts of the world. Following the establishment of a robust inoculation assay, a germplasm collection of the model legume Medicago truncatula was screened with various legume‐infecting isolates of R. solani. While some significant differences in susceptibility/resistance were detected between some lines, in the majority of cases M. truncatula was susceptible to R. solani. Comparison of a legume‐ and cereal‐infecting AG8 isolate with a legume‐specific AG11 isolate revealed no difference in pathogenicity between the two isolates when infecting M. truncatula. The most significant differences in susceptibility occurred with an AG6 isolate, which caused root canker. This included significant differences between the moderate resistance of the M. truncatula reference genotype A17 and the high susceptibility of line A20. The analysis of a recombinant inbred line population derived from A17 and A20 revealed a single locus contributing to the resistance in A17. Interestingly, the locus only affected the development of post‐emergent (late) symptoms, such as necrosis of cotyledons at 11 days after inoculation and root‐ and above‐ground‐weights, but not pre‐emergent seedling damping off. These findings pave the way for further studies to dissect the genetic and molecular mechanisms of resistance.     

Real-time weed detection, decision making and patch spraying in maize, sugarbeet, winter wheat and winter barley

Information on temporal and spatial variation in weed seedling populations within agricultural fields is very important for weed population assessment and management. Most of all, it allows a potential reduction in herbicide use, when post‐emergence herbicides are only applied to field sections with weed infestation levels higher than the economic weed threshold; a review of such work is provided. This paper presents a system for site‐specific weed control in sugarbeet (Beta vulgaris L.), maize (Zea mays L.), winter wheat (Triticum aestivum L.) and winter barley (Hordeum vulgare L.), including online weed detection using digital image analysis, computer‐based decision making and global positioning systems (GPS)‐controlled patch spraying. In a 4‐year study, herbicide use with this map‐based approach was reduced in winter cereals by 60% for herbicides against broad‐leaved weeds and 90% for grass weed herbicides. In sugarbeet and maize, average savings for grass weed herbicides were 78% in maize and 36% in sugarbeet. For herbicides against broad‐leaved weeds, 11% were saved in maize and 41% in sugarbeet.     

Differences in flowering phenology and seed production of four morning glory (Ipomoea) species in Japan

The spread of morning glory (Ipomoea spp.) in soybean fields in Japan has severely decreased soybean yield. Yet, current control measures do not control the proliferation of Ipomoea spp. As little is known about the flowering period and seed production among the different invading Ipomoea spp., it is challenging to create targeted control measures based on ecological characteristics. This study aimed to reveal the characteristics of the flowering phenology and seed production of four morning glory species, namely, Ipomoea coccinea L. (red morning glory), Ipomoea lacunosa L. (pitted morning glory), Ipomoea hederacea L. Jacq. var. integriuscula A. Gray (entireleaf morning glory), and Ipomoea triloba L. (three-lobe morning glory). Between 2017 and 2019, the four selected study species were grown under similar conditions of soil quality, irrigation, and environmental influences and their flowering phenology and seed data were recorded. The flowering period ranged from 36 to 40 days, and the initial flowering of I. triloba was approximately 2 weeks later than the others. I. coccinea had the highest flowering number and seed production, followed by I. lacunosa, I. triloba, and I. hederacea var. integriuscula. The fruit setting rate of I. triloba decreased later in the reproductive stage but tended to increase as the daily mean temperature increased on each flowering day. Thus, we report that the flowering phenology and seed production differed greatly among the Ipomoea spp. These findings can provide crucial insights into designing targeted species-specific control measures against the spread of Ipomoea spp. in Japan.     

Effects of alternative winter cover cropping systems on weed suppression in organically grown tomato (<Emphasis Type="Italic">Solanum lycopersicum</Emphasis>)

Weed control is a major concern for organic farmers around the world and non-chemical weed control methods are now the subject of many investigations. Field studies were conducted in tomato (Solanum lycopersicum L.) from 2004 to 2006 at the Black Sea Agricultural Research Institute experiment field to determine the weed suppressive effects of winter cover crops. Treatments consisted of ryegrass (Lolium multiflorum L.), oat (Avena sativa L.), rye (Secale cereale L.), wheat (Triticum aestivum L.), gelemen clover (Trifolium meneghinianum Clem.), Egyptian clover (Trifolium alexandrinum L.), common vetch (Vicia sativa L.), hairy vetch (Vicia villosa Roth.) and a control with no cover crop. Treatments were arranged in a randomized complete block design with four replications. To determine the weed suppressive effects of the cover crops, weed density and total weed dry biomass were assessed at 14, 28, and 56 days after termination (DAT) of the cover crops from all plots using a 50 × 50 cm quadrat placed randomly in each plot. After cover crop kill and incorporation into soil, tomato seedlings variety ‘H2274’ were transplanted. Broadleaved weed species were the most prominent species in both years. Total weed biomass measured just prior to cover crop incorporation into the soil was significantly lower in S. cereale plots than in the others. The number of weed species was lowest at 14 DAT and later increased at 28 and 56 DAT, and subsequently remained constant during harvest. This research indicates that cover crops such as L. multiflorum, S. cereale, V. sativa and V. villosa could be used in integrated weed management programs to manage some weeds in the early growth stages of organic tomato.     

Species composition,toxigenic potential and pathogenicity of Fusarium graminearum species complex isolates from southern Brazilian rice

This study aimed to assess the extent and distribution of Fusarium graminearum species complex (FGSC) diversity in rice seeds produced in southern Brazil. Four species and two trichothecene genotypes were detected among 89 FGSC isolates, based on a multilocus genotyping assay: F. asiaticum (69·6%) with the nivalenol (NIV) genotype, F. graminearum (14·6%) with the 15‐acetyldeoxynivalenol (ADON) genotype, and F. cortaderiae (14·6%) and F. meridionale (1·1%), both with the NIV genotype. Seven selected F. asiaticum isolates from rice produced NIV in rice‐based substrate in vitro, at levels ranging from 4·7 to 84·1 μg g^?1. Similarly, two F. graminearum isolates from rice produced mainly 15‐ADON (c. 15–41 μg g^?1) and a smaller amount of 3‐ADON (c. 6–12 μg g^?1). One F. meridionale and two F. cortaderiae isolates did not produce detectable levels of trichothecenes. Two F. asiaticum isolates from rice and two from wheat (from a previous study), and one F. graminearum isolate from wheat, were pathogenic to both crops at various levels of aggressiveness based on measures of disease severity in wheat spikes and rice kernel infection in a greenhouse assay. Fusarium asiaticum and the reference F. graminearum isolate from wheat produced NIV, and deoxynivalenol and acetylates, respectively, in the kernels of inoculated wheat heads. No trichothecene was produced in kernels from inoculated rice panicles by any of the isolates. These findings constitute the first report of FGSC composition in rice outside Asia, and confirm the dominance of F. asiaticum in rice agroecosystems.     

Tachinidae parasitoids of<Emphasis Type="Italic">Traumatocampa ispartaensis</Emphasis> from Turkey

Tachinid parasitoids ofTraumatocampa ispartaensis Doğanlar & Avcı (Lepidoptera, Thaumetopoeidae), which was found to be a new species, were collected from the cedar forests around Isparta-Kapıdağ. The species found wereBlondelia nigripes (Fall.),Compsilura concinnata (Meig.),Pales processioneae (Ratz.),Phryxe caudata (Rond.),Exorista segregata (Rond.) andCarcelia iliaca (Ratz.). Within the six species of Tachinidae,B. nigripes was the most common one, parasitizing up to 4.6% ofT. ispartaensis pupae. http://www.phytoparasitica.org