Turnip Weed Research Articles

Influence of chaff and chaff lines on weed seed survival and seedling emergence in Australian cropping systems

AbstractChaff lining and chaff tramlining are harvest weed seed control (HWSC) systems that involve the concentration of chaff material containing weed seed into narrow (20 to 30 cm) rows between or on the harvester wheel tracks during harvest. These lines of chaff are left intact in the fields through subsequent cropping seasons in the assumption that the chaff environment is unfavorable for weed seed survival. The chaff row environment effect on weed seed survival was examined in field studies, and chaff response studies determined the influence of increasing amounts of chaff on weed seedling emergence. The objectives of these studies were to determine the influences of (1) chaff lines on the summer–autumn seed survival of selected weed species and (2) chaff type and amount on rigid ryegrass seedling emergence. There was frequently no difference (P > 0.05) in seed survival of four weed species (rigid ryegrass, wild oat, annual sowthistle, and turnip weed) when seeds were placed beneath or beside chaff lines. In one instance, wild oat seed survival was increased (P < 0.05) when seed were placed beneath compared to beside a chaff line. The pot studies determined that increasing amounts of chaff consistently resulted in decreasing numbers of rigid ryegrass seedlings emerging through chaff material. The suppression of emergence broadly followed a linear relationship in which there was approximately a 2.0% reduction in emergence with every 1,000 kg ha–1 increase in chaff material. This relationship was consistent across wheat, barley, canola, and lupin chaff types, indicating that the physical presence of the chaff was more important than chaff type. These studies suggested that chaff lines may not affect the survival over summer–autumn of the contained weed seeds but that the subsequent emergence of weed seedlings will be restricted by high amounts of chaff (>40,000 kg ha–1).

Germination ecology of turnip weed (Rapistrum rugosum (L.) All.) in the northern regions of Australia.

In Australia, turnip weed has been rapidly emerging as one of the major weeds in conservation agricultural systems. Germination and emergence of turnip weed were examined for two populations collected from Gatton and St George regions of Australia; two locations with high and low rainfall, respectively. The seeds of turnip weed germinated at all the tested temperatures, but germination was the lowest at 15/5°C, intermediate at 20/10°C and highest at 25/15°C and 30/20°C. The results indicated a high adaptability of turnip weed to warm environmental conditions, although it is a major problem in the winter season. Germination was higher in dark than light/dark regimes except at 30/20°C. Three was a concomitant reduction in germination as the osmotic potential values decreased from 0 to -1.0 MPa. There was 2 and 4% germination at -0.8 MPa for Gatton and St George populations, respectively, and no germination occurred at an osmotic potential of -1.0 MPa. There was a reduction in germination when the sodium chloride (NaCl) concentration was increased from 0 to 150 mM, and no germination was observed at 200 and 250 mM of NaCl. Turnip weed germinated over a broad range of pH (4 to 10). Seedling emergence was higher at 1 cm depth compared to 0.5 cm or at the soil surface. There was 28 and 33% emergence at the surface for the Gatton and St George populations, respectively, compared to 48 and 56% emergence from 1 cm depth for the Gatton and St George populations, respectively and no emergence was observed from 6 cm depth. The results indicated that tillage leading to shallow burial would promote the emergence of turnip weed; on the contrary, tillage that could bury seeds deep into the soil profile might minimise the emergence. Under ideal conditions and lack of integrated weed management programmes, this weed will emerge, set seeds and enrich the soil seed bank and thereby continue to be a problem in the northern grain region of Australia.

Diaporthe novem isolated from sunflower (Helianthus annuus) and other crop and weed hosts in Australia

In 2011, patches of lodged plants of Helianthus annuus (commercial sunflower) with stem lesions were observed in a commercial crop at Kingsthorpe, Queensland, Australia. Several species of Diaporthe were consistently isolated from the lesions. Diaporthe novem was identified by DNA sequence analysis. In following surveys, Diaporthe novem was found to be associated with other crop species including Cicer arietinum (chickpea), Glycine max (soybean), Lupinus alba (lupin), Sorghum bicolor (sorghum) Vicia faba (faba bean) and Vigna radiata (mungbean), and with the weed species Datura stramonium (common thornapple), Helianthus annuus (wild-type sunflower), Malva parviflora (small flowered mallow), Rapistrum rugosum (turnip weed), Sambucus gaudichaudiana (wild elderberry), Sisymbrium orientale (indian hedge mustard), Sonchus oleraceus (sowthistle), Verbena sp., Vicia sativa (common vetch), and Xanthium strumarium (noogoora burr). In pathogenicity tests, isolates of D. novem from sunflower were highly virulent when re-inoculated on commercial sunflower varieties. This study has identified D. novem as a frequent cause of stem canker of sunflower in the eastern cropping areas of Australia, and extends the known host range of D. novem.

Multiple Mechanisms Increase Levels of Resistance in Rapistrum rugosum to ALS Herbicides.

Rapistrum rugosum (turnip weed) is a common weed of wheat fields in Iran, which is most often controlled by tribenuron-methyl (TM), a sulfonylurea (SU) belonging to the acetolactate synthase (ALS) inhibiting herbicides group. Several cases of unexplained control failure of R. rugosum by TM have been seen, especially in Golestan province-Iran. Hence, there is lack of research in evaluation of the level of resistance of the R. rugosum populations to TM, using whole plant dose-response and enzyme assays, then investigating some potential resistance mechanisms Results revealed that the resistance factor (RF) for resistant (R) populations was 2.5–6.6 fold higher than susceptible (S) plant. Neither foliar retention, nor 14C-TM absorption and translocation were the mechanisms responsible for resistance in turnip weed. Metabolism of TM was the second resistant mechanism in two populations (Ag-R5 and G-1), in which three metabolites were found. The concentration of TM for 50% inhibition of ALS enzyme activity in vitro showed a high level of resistance to the herbicide (RFs were from 28 to 38) and cross-resistance to sulfonyl-aminocarbonyl-triazolinone (SCT), pyrimidinyl-thiobenzoate (PTB) and triazolopyrimidine (TP), with no cross-resistance to imidazolinone (IMI). Substitution Pro 197 to Ser 197 provided resistance to four of five ALS-inhibiting herbicides including SU, TP, PTB, and SCT with no resistance to IMI. These results documented the first case of R. rugosum resistant population worldwide and demonstrated that both RST and NRST mechanisms are involved to the resistance level to TM.

A severe outbreak of chickpea viruses in northern New South Wales, Australia, during 2012

Chickpea crops in northern NSW during 2012 showed an unusual high incidence of severe virus symptoms, mainly related to infection by Beet western yellows virus (BWYV) with minor incidences of Alfalfa mosaic virus (AMV) and Cucumber mosaic virus (CMV). Canola and turnip weed close to surveyed chickpea paddocks showed high BWYV and Turnip mosaic virus (TuMV) incidences and have likely played an important role in the BWYV epidemic in chickpeas.

Two novel mastreviruses from chickpea (Cicer arietinum) in Australia

Two novel mastreviruses (genus Mastrevirus; family Geminiviridae), with proposed names chickpea chlorosis virus (CpCV) and chickpea redleaf virus, are described from chickpea (Cicer arietinum) from eastern Australia. The viruses have genomes of 2,582 and 2,605 nucleotides, respectively, and share similar features and organisation with typical dicot-infecting mastreviruses. Two distinct strains of CpCV were suggested by phylogenetic analysis. Additionally, a partial mastrevirus Rep sequence from turnip weed (Rapistrum rugosum) indicated the presence of a distinct strain of Tobacco yellow dwarf virus (TYDV). In phylogenetic analyses, isolates of Bean yellow dwarf virus, Chickpea chlorotic dwarf Pakistan virus and Chickpea chlorotic dwarf Sudan virus from southern and northern Africa and south-central and western Asia clustered separately from these three viruses from Australia. An Australian, eastern Asian, or south-eastern Asian origin for the novel mastreviruses and TYDV is discussed.

Mastreviruses in chickpea (Cicer arietinum) and other dicotyledonous crops and weeds in Queensland and northern New South Wales, Australia

Natural infection by mastreviruses was investigated in chickpea (Cicer arietinum) and other dicotyledonous crops and weeds in grain production areas of Queensland and northern New South Wales, Australia, from 2000 to 2005. Altogether, 33 639 plants comprising 31 species and 10 dicot families were screened for infection by a tissue-blot immunoassay that did not distinguish between mastrevirus strains or species. Nine plant species in three families were identified as natural hosts. Chickpea was infected throughout the region although infection incidence did not exceed 5%. Infection was rare in faba bean (Vicia faba), canola (Brassica napus), and mustard (B. juncea) and not detected in field pea (Pisum sativum). Infection of chickpea and turnip weed (Rapistrum rugosum) was confirmed by immunocapture polymerase chain reaction (IC-PCR) with primers generic for dicot-infecting mastreviruses, and also immunosorbent electron microscopy and graft transmission in the case of chickpea. Individual mastreviruses were identified by comparing their IC-PCR amplicons by a combination of methods. Among 42 isolates from 41 chickpea plants, one was typical Tobacco yellow dwarf virus (TYDV) and the others were three recently distinguished strains including two proposed novel species: 34 Chickpea chlorosis virus strain A, six Chickpea chlorosis virus strain B, and one Chickpea redleaf virus. All of 10 isolates from 10 turnip weed plants were TYDV-B, a strain distinct from typical TYDV. The symptoms associated with mastrevirus infection in chickpea included foliar chlorosis or reddening, stunting, and usually phloem browning. The potential for losses in winter and summer grown field crops is discussed.

Modelling light interception and distribution in mixed canopies of wild oat (Avena ludoviciana) and turnip weed (Rapistrum rugosum) in competition with wheat

Modelling light interception and distribution in mixed canopies of wild oat (Avena ludoviciana) and turnip weed (Rapistrum rugosum) in competition with wheat

The effect of row spacing and weed density on yield loss of chickpea

The adoption of no-till farming and the desire to maintain stubble cover when sowing legumes in northern New South Wales and southern Queensland have resulted in an increase in commercial row spacing for chickpea (Cicer arietinum L.). This paper examines the effects of increasing crop row widths on weed competition in chickpea crops. Weed densities of 0, 2, 4, 8, 16, and 32 plants/m2 of wild oats (Avena sterilis ssp. ludoviciana ) and turnip weed (Rapistrum rugosum) were established with chickpea crops planted with either 32�or 64�cm row configurations in northern New South Wales during 1996 and 1997. A rectangular hyperbolic model adequately represented the loss in chickpea yield with increasing density of either weed. Even low densities of <10 plants/m2 caused large (approx. 50%) reductions in yield, particularly with turnip weed. In these experiments, weed-free yields were higher when chickpea was sown in 32�cm rows compared with 64�cm rows, but weeds caused no greater loss in crop yield with the wider row spacing. The results of this work show that the use of wide rows has minimal impact on weed competion in northern chickpea crops.

Changes in fallow weed species in continuous wheat in northern New South Wales 1981-1990

Four experiments in northern New South Wales comparing fallow management treatments of no-tillage, cultivated with the stubble retained, and cultivated with the stubble burned, from 1981 to 1990, were sampled for weeds between wheat harvest and seeding on a number of occasions during this period. Eighty weed species were identified, 23 of which were found at all 4 sites but only 13 were recorded in the samples taken. These were dwarf amaranth, wild turnip, spear thistle, Australian bindweed, fleabane, bladder ketmia, prickly lettuce, turnip weed, variegated thistle, common sowthistle, dandelion, wild oats and native millet. The density of weeds during the fallow period decreased by 97% from 1981 to 1990 with some species eliminated, probably because of the herbicides used, particularly glyphosate and chlorsulfuron. These included Boggabri and redroot amaranth, button grass, caustic weed, dense crassula, fat hen, legumes, common peppercress, hedge mustard, London rocket, shepherd’s purse, wild mustard, sorghum-almum, paradoxa grass, wild zinnia, and wireweed. Twenty-four weed species were classified as a problem or a potential problem in the future at 1 or more sites. Seventeen weed species, including perennial grasses, often were tolerant to glyphosate at the rates used. The densities of common sowthistle and wild oat were reduced after 10 years, but still remained at all 4 sites. Plant density of species with wind-blown seeds was greater in no-tillage plots than stubble-retained or stubble-burned plots. Weeds whose seeds are dispersed by wind and weeds tolerant to glyphosate were the most troublesome. The perennial grass native millet increased at all 4 sites.

Significance of mite prey in the diet of the onion thrips Thrips tabaci Lindeman (Thysanoptera: Thripidae)

Second‐instar larvae of the phytophagous thrips, Thrips tabaci, consumed significantly more spider mite (Tetranychus urticae Koch) eggs than did any other T.tabaci life stage. We supplemented two plant diets with mite eggs to assess whether the inclusion of prey could make up completely for dietary deficiencies in the host plant. Therefore, turnip weed (Rapistrumrugosum L.) floral tissue (a major breeding host of T.tabaci) and cotton vegetative tissue (a host on which T.tabaci populations dwindle) were compared. In both cases, prey in the diet reduced the developmental time from egg to adult and increased fecundity over that achieved on a host‐plant diet alone, but had no effect on immature mortality or adult life span. Females on turnip weed plus mite eggs produced more eggs than those on cotton cotyledons plus mite eggs. We discuss the role of facultative predation (or opportunism) in the ecology of T. tabaci.

Host species and plant part specificity of the polyphagous onion thrips, Thrips tabaci Lindeman (Thysanoptera: Thripidae), in an Australian cotton‐growing area

We determined the pattern of host plant use of Thrips tabaci by surveying wheat and five weed species growing near cotton crops in the area centred on the Namoi Valley, northern New South Wales. Highest densities of T. tabaci females and larvae were found on inflorescences and vegetative parts of turnip weed, Rapistrum rugosum, and lowest on wheat, Triticum aestivum. The other plant species (Paterson’s curse, Echium plantagineum, curled dock, Rumex crispus, Mayne’s pest, Verbena tenuisecta and sowthistle, Sonchus oleraceus) hosted intermediate densities of T. tabaci. The presence of high densities of reproductive T. tabaci on flowering and vegetative parts of turnip weed suggests that this species is a primary host of T. tabaci in the study area.

Host species and plant part specificity of the polyphagous onion thrips, Thrips tabaci Lindeman (Thysanoptera: Thripidae), in an Australian cottongrowing area

AbstractWe determined the pattern of host plant use of Thrips tabaci by surveying wheat and five weed species growing near cotton crops in the area centred on the Namoi Valley, northern New South Wales. Highest densities of T. tabaci females and larvae were found on inflorescences and vegetative parts of turnip weed, Rapistrum rugosum, and lowest on wheat, Triticum aestivum. the other plant species (Paterson's curse, Echium plantagineum, curled dock, Rumex crispus, Mayne's pest, Verbena tenuisecta and sowthistle, Sonchus oleraceus) hosted intermediate densities of T. tabaci. the presence of high densities of reproductive T. tabaci on flowering and vegetative parts of turnip weed suggests that this species is a primary host of T. tabaci in the study area.

Weed control with atrazine and chlorsulfuron is determined by herbicide availability and persistence in soils

Effectiveness and length of weed control with atrazine and chlorsulfuron can be variable in the field. While some of this may be due to climatic variations, differences in soil properties may also be important. We tested this by recording changes in control of mintweed (Salvia reflexa Hornem.) and turnip weed (Rapistrum rugosum L.) with time in different soils, and comparing these results with the measured changes in plant-available herbicide in the soils. Length of weed control with the same herbicide rate varied from 0 to >15 weeks. Mintweed and turnip weed were controlled (85-100%) only when the soils had ¸ 0·1µ#9839;g available atrazine/g and 0·8 ng available chlorsulfuron/g, respectively. This agreed with the sensitivity data for these weeds when grown in a soil-free system. The herbicides were initially more available in grey clays than in black earths, and soil pH accounted for most of the variations in the persistence of the available residues. Thus, the efficacy of these herbicides in different soils could be estimated if the available residues in the root-zone could be predicted and the sensitivity of different weeds was known.

Development, Longevity and Fecundity of the False Wireworms Pterohelaeus Darlingensis and P. Alternatus (Coleoptera: Tenebrionidae). Ii. Effect of Food Type.

Pterohelaeus darlingensis Carter and P. alternatus Pasc. were reared under constant temperatures on 10 different foods in the laboratory in Australia. In P. darlingensis, wheat, barley and sorghum resulted in the shortest larval development periods, longest pupal periods and lowest pre-imaginal mortality. Egg-laying rates were highest on wheat, barley and maize and lowest on oats and soyabean. No females were produced after feeding on wheat straw, and no eggs were laid after feeding on linseed and turnip weed. Only wheat, barley, maize and sorghum (in descending order) allowed an increase in population. In P. alternatus, wheat, sorghum and barley resulted in the shortest pre-imaginal development with the least mortality. Egg-laying rates were highest on wheat, maize and sorghum and lowest on barley and oats. No eggs were laid by females fed on linseed. Wheat, sorghum, maize, sunflower, barley and soyabean allowed a positive population growth. These results are discussed in relation to control of the tenebrionids by crop rotation.

Studies on Endemic Goitre III an Investigation of the Antithyroid Aotivities of Isothiocyanates and Derivatives With Observations on Fractions of Milk From Goitrous Areas

Certain isothiocyanates and thioureas, in particular 3-methylsulphonylpropyl isothiocyanate (cheirolin) and dicheirolin thiourea, were tested for their antithyroid activity by an acute 1311 test and by chronic administration to rats. Cheirolin proved more active in the acute test than n-propyl isothiocyanate, but dicheirolin thiourea, the major product resulting from the incubation of cheirolin with rumen liquor, was without activity, whereas di-n-propylthiourea had a marked effect. Dicheirolin thiourea was also inactive when tested in the human. The response to cheirolin when chronically administered, either as such or in the form of its thioglucoside present in turnip weed fruit, appeared to be less than in the acute test. Its possible mode of action is discussed.