Invasive and potentially invasive plant species in State Nature Biosphere Reserves of the Altai Republic (Russia)

In the Altaiskiy and Katunskiy State Nature Biosphere Reserves we registered 44 alien plant species, which were considered in Siberia as invasive and potentially invasive. Among them, there were 30 xenophytes and 14 ergasiophytes species. Rumex acetosella L., Impatiens glandulifera Royle, Galinsoga ciliata (Rafin.) Blake, and Strophiostoma sparsiflorum (Mikan ex Pohl) Turcz. are considered invasive in the Altaiskiy Reserve because they actively spread there in natural and seminatural plant communities and habitats. Most of the species had appeared in the territories of the reserves before their establishment as a result of agricultural activity or appeared after their establishment because of activity of the reserves themselves. Despite of a big amount of tourists in the reserves, the invasive and potentially invasive plants are absent on the ecological paths at present.

Nuevas arvenses hospederas de Begomovirus colectadas en cultivos de tomate (Solanum Lycopersicum l.) en Cundinamarca

Los begomovirus forman parte del grupo de virus emergentes que afectan cultivos de interés agrícola a nivel mundial. Las arvenses pueden constituirse fácilmente en hospederos alternos de estos virus y ser fuente de inóculo de los mismos. El objetivo de este trabajo fue detectar begomovirus presentes en arvenses asociadas al cultivo de tomate en Cundinamarca, Colombia. Se colectaron arvenses con y sin síntomas virales en cultivos de tomate localizados en los municipios de Pasca y Fusagasugá, Cundinamarca. Se purifico el DNA genómico total de cada arvenses y para evidenciar la presencia de begomovirus se realizó una reacción en cadena de la polimerasa con oligos específicos para detectar el componente genómico A viral. Se recolectaron 36 arvenses, de las cuales 22 especies fueron identificadas taxonómicamente. Stellaria media, Veronica persica, Galinsoga ciliata, Malva sylvestris y una especie de la familia Asteraceae resultaron positivas para begomovirus. Para las especies Stellaria media y Galinsoga ciliata, constituyen el primer reporte a nivel mundial como hospederos de begomovirus. La especie Veronica persica es identificada como reservorio de begomovirus por primera vez en América Latina. Finalmente, la especie Malva sylvestris y una especie de la familia Asteraceae se reportan por primera vez como hospederos de begomovirus para Colombia. El control efectivo de las arvenses identificadas como hospederos alternativos para begomovirus es una estrategia efectiva para disminuir el impacto de esta familia de virus en los cultivos de tomate.

The effect of achene heteromorphism on germination in the shaggy soldier [Galinsoga ciliata (Rafin) S.F. Blake]

Heteromorphic achenes are formed within each capitulum of <i>Galinsoga ciliata</i> (Rafin) S.F. Blake. We examined (1) the effects of the duration of dry storage on germination and (2) the effect of burial in soil on viability and germination of heteromorphic diaspores. Fresh harvested peripheral achenes remained dormant, while central achenes germinated at 60%. Both achene types became non-dormant after one month of dry storage. In successive months of dry storage, peripheral achenes demonstrated a higher germination percentage than central achenes. The peripheral and central achenes showed similar temperature requirements during dry storage. A similar germination pattern was observed in both achene types, with a germination peak in March (96% of peripheral achenes at 12, 26 and 34^oC; 90% of central achenes at 26 and 34^oC). The germination capacity deteriorated over time. After 19 months of dry storage, both achene morphs failed to germinate at 12oC. At a 26^o and 34^oC, the same group of achenes continued to germinate at a relatively high level. After six and seven months of soil storage, 90-95% of both achene types remained alive. Dimorphic achenes were characterized by similar germination percentage (89-99%) at all temperature intervals, whereas peripheral achenes exhumed in May were the fastest to germinate. After 18 months of storage in soil (successive growing season), most of the harvested achenes were dead. The studied achenes did not form a permanent seed bank.

The effect of Achene heteromorphism on progeny traits in the shaggy soldier [Galinsoga ciliata (Rafin) S. F. Blake]

The shaggy soldier [<i>Galinsoga ciliata</i> (Rafin) S. F. Blake], family Asteraceae] is an invasive species that poses a growing threat to crop production. This annual plant produces heteromorphic achenes in a capitulum type inflorescence. The objective of this study was to compare selected morphological and phenological parameters and the success of generative reproduction in plants developed from peripheral and central achenes of the capitulum. The somatic variability of <i>G. ciliata</i> diaspores contributed to differences in the growth rates, development and fertility of the resulting populations. The progeny of central diaspores developed at a slower rate than the individuals derived from peripheral achenes, but at the end of their life cycle, the offspring of dimorphic achenes formed homogenous groups as regards height values. On average, the initial phenophases of <i>G. ciliata</i> plants derived from central achenes began one day later, and they entered the flowering stage eight days later than the individuals developed from peripheral seeds. At the initial growth stage (experimental day 65 to 83), the progeny of central achenes produced fewer capitula. On day 133, the individual fertility of the plants derived from central diaspores was 10% higher on average in comparison with the offspring of peripheral achenes.

The influence of intercrop plants and the date of their ploughing-in on weed infestation of root chicory (Cichorium intybus L.) var. sativum (Bisch.) Janch.

The field experiment was carried out in 2006-2008 in the Felin Experimental Farm (University of Life Sciences in Lublin) on podzolic soil developed from dusty medium loam. Root chicory (<i>Cichorium intybus</i> L.) var. <i>sativum</i> (Bisch.) Janch. cv. Polanowicka was involved in the experiment. The experimental factors were 3 species of intercrop plants: common vetch (<i>Vicia sativa</i>), phacelia (<i>Phacelia tanacetifolia</i>), oat (<i>Avena sativa</i>) and 2 dates of ploughing-in: pre-winter and spring. In total, 26 taxons characteristic for vegetable plantations were identified in chicory weed infestation. Monocarpic species dominated, among which <i>Senecio vulgaris</i>, <i>Chenopodium album</i>, <i>Lamium amplexicaule</i>, <i>Galinsoga ciliata</i>, and <i>Capsella bursa-pastoris</i> were predominant. The date of ploughing-in did not significantly affect the status and size of weed infestation of chicory plots. Short-lived species occurred after pre-winter ploughing-in, while perennial - after spring ploughing-in. The application of intercrops significantly reduced chicory weed infestation as compared to the cultivation with no intercrop. The ploughing-in of <i>Avena sativa</i> biomass appeared to be the most efficient. The intercrop plants reduced the occurrence of <i>Senecio vulgaris</i> and <i>Capsella bursa-pastoris</i> which were the most numerous in the treatment without intercrops. Biomass of <i>Vicia sativa</i> favored the growth of <i>Chenopodium album</i> and <i>Lamium amplexicaule</i>. The secondary weed infestation did not depend on agrotechnical factors applied during the experiment.

Seed dormancy and germination of Shaggy soldier (Galinsoga ciliata Blake.) and Common lambsquarter (Chenopodium album L.)

Laboratory experiments were carried out with seeds of Galinsoga ciliata and Chenopodium album in 1998, 2000 and 2001. The study involved germination of non-dormant seeds in the light and the dark at 5&ndash;30&deg;C, the germination energy at 15, 24, and 33&deg;C, and the primary dormancy of seeds matured during the period from July to October. Both weeds germinated better in the light compared to the dark. Seeds of G. ciliata germinated at 10&ndash;33&deg;C. Germination exceeding 85% was recorded at 12&ndash;28&deg;C. Ch. album germinated in a&nbsp;wider temperature interval (5&ndash;33&deg;C). Maximum germination (75%) was obtained at 18&deg;C. A&nbsp;very high germination energy of G. ciliata seeds was found at 24&deg;C. At this temperature, 89% of seeds germinated during the second and third day of the germination test. Seeds of Ch. album had a&nbsp;low germination energy at 15 and 24&deg;C. The germination energy was high only at 33&deg;C, however, the total germination reached at this temperature was only 26.5%. Both G. ciliata and Ch. album formed primary dormant seeds during all three testing years. The length of primary dormancy varied from 10 to 100 days depending on the date of ripening and on the year. The longest primary dormancy was found with early ripened seeds (July and August).

Seasonal emergence of selected summer annual weed species in dependence on soil temperature

This study aimed to describe emergence cycles of selected weed species under Central European conditions in relation to cumulative soil temperatures from the start of the vegetation season. Emergence of Chenopodium album, Echinochloa crus-galli, Galinsoga ciliata, and Abutilon theophrasti was observed from March to October during the period 2001&ndash;2006 at two locations. The beginning of main field emergence was determined as the day when the sum of effective hour temperatures was achieved, and was detected from the second decade of April to early May for C. album, in the second decade of May for E. crus-galli, from late April to the beginning of May for G. ciliata, and from the end of April to mid-May for A. theophrasti. The relationship between cumulative soil surface layer temperature and weed mass field emergence at the beginning of the growing season is very direct (differences &plusmn;7 days) &ndash; but only when soil moisture is sufficient. In a drier spring, the beginning of mass field emergence occurs with 1&ndash;4 weeks of delay and field emergence is usually slower and protracted.

Effects of Spring-sown Cover Crops on Establishment and Growth of Hairy Galinsoga (Galinsoga ciliata) and Four Vegetable Crops

Hairy galinsoga [Galinsoga ciliata (Raf.) Blake] has become a troublesome weed in vegetable crops. Field studies were conducted in 2006 and 2007 in central New York to determine the effects of: 1) spring-sown cover crops on hairy galinsoga growth and seed production during cover crop growth grown before subsequent short duration vegetable crops; and 2) cover crop residues on establishment of hairy galinsoga and four short-duration vegetable crops planted after cover crop incorporation. The cover crops [buckwheat (Fagopyrum esculentum Moench), brown mustard (Brassica juncea L.), yellow mustard (Sinapis alba L.), and oats (Avena sativa L.)] were planted in May and incorporated in early July. Lettuce (Lactuca sativa L.) and Swiss chard [Beta vulgaris var. cicla (L.) K. Koch] were transplanted and pea (Pisum sativum L.) and snap bean (Phaseolus vulgaris L.) were sown directly into freshly incorporated residues. Aboveground dry biomass produced by the cover crops was 4.2, 6.4, 6.8, and 9.7 mg·ha−1 for buckwheat, brown mustard, yellow mustard, and oats, respectively. Cover crops alone reduced the dry weight (90% to 99%) and seed production of hairy galinsoga (98%) during the cover crop-growing season compared with weedy controls. In 2006, only yellow mustard residue suppressed hairy galinsoga emergence (53%). However, in 2007, all cover crop residues reduced hairy galinsoga emergence (38% to 62%) and biomass production (25% to 60%) compared with bare soil, with yellow mustard providing the greatest suppression. Cover crop residues did not affect snap bean emergence, but reduced pea emergence 25% to 75%. All vegetable crops were suppressed by all cover crop residues with crops ranked as: pea > Swiss chard ≥ lettuce > snap bean in terms of sensitivity. The C:N ratios were 8.5, 18.3, 22.9, and 24.8 for buckwheat, brown mustard, yellow mustard, and oat residues, respectively. Decomposition rate and nitrogen release of brown mustard and buckwheat residues was rapid; it was slow for oats and yellow mustard residues. Spring-sown cover crops can contribute to weed management by reducing seed production, emergence, and growth of hairy galinsoga in subsequent crops, but crop emergence and growth may be compromised. Yellow mustard and buckwheat sown before late-planted snap beans deserve further testing as part of an integrated strategy for managing weeds while building soil health.

Experimental Transmission of Pospiviroid Populations to Weed Species Characteristic of Potato and Hop Fields

ABSTRACT Weed plants characteristic for potato and hop fields have not been considered in the past as potential hosts that could transmit and lead to spreading of potato spindle tuber (PSTVd) and hop stunt (HSVd) viroids, respectively. To gain insight into this problem, we biolistically inoculated these weed plants with viroid populations either as RNA or as cDNA. New potential viroid host species, collected in central Europe, were discovered. From 12 weed species characteristic for potato fields, high viroid levels, detectable by molecular hybridization, were maintained after both RNA and DNA transfers in Chamomilla reculita and Anthemis arvensis. Low viroid levels, detectable by reverse transcription-PCR (RT-PCR) only, were maintained after plant inoculations with cDNA in Veronica argensis and Amaranthus retroflexus. In these two species PSTVd concentrations were 105 and 103 times, respectively, lower than in tomato as estimated by real-time PCR. From 14 weeds characteristic for hop fields, high HSVd levels were detected in Galinsoga ciliata after both RNA and DNA transfers. HSVd was found, however, not to be transmissible by seeds of this weed species. Traces of HSVd were detectable by RT-PCR in HSVd-cDNA-inoculated Amaranthus retroflexus. Characteristic monomeric (+)-circular and linear viroid RNAs were present in extracts from weed species propagating viroids to high levels, indicating regular replication, processing, and circularization of viroid RNA in these weed species. Sequence analyses of PSTVd progenies propagated in C. reculita and A. arvensis showed a wide spectrum of variants related to various strains, from mild to lethal variants; the sequence variants isolated from A. retroflexus and V. argensis exhibited similarity or identity to the superlethal AS1 viroid variant. All HSVd clones from G. ciliata corresponded to a HSVdg variant, which is strongly pathogenic for European hops.