Seed viability of common ragweed (Ambrosia artemisiifolia L.) is affected by seed origin and age, but also by testing method and laboratory

Common ragweed (Ambrosia artemisiifolia L.) is an annual Asteraceae species native to North America which is highly invasive across Europe and has harmful impacts, especially on human health and agriculture. Besides its wide ecological range, particularly its high reproductive power by seeds is promoting its spread to various habitats and regions. To prevent further spread and to control the plant, the European Commission funded projects and COST-Actions involving scientists from all over Europe. A joint trial was set up comprising eight different laboratories from Europe to study seed viability variation in different seed samples. Three different testing methods (viability test with 2,3,5-triphenyltetrazolium chloride (TTC), a germination test combined with a subsequent TTC test and a crush test) were tested within the EU-COST-Action SMARTER network to four different seed origins. The viability test results from different laboratories were compared for variation amongst tests and laboratories. The main aim was to optimise the reliability of testing procedures, but results revealed not only significant effects of seed origin and seed age on seed viability, but also considerable differences between the output of the individual testing methods and furthermore between laboratories. Due to these significant differences in the results of the testing labs, additionally a second test was set up. Twelve Austrian ragweed populations were used for TTC testing to obtain a precise adjustment of the testing method as well as a tight guideline for interpreting the results, particularly for the TTC state “intermediate” since a proper classification of TTC-intermediate coloured seeds is still a challenge when determining viability rates.

Fitness and mating consequences of variation in male allocation in a wind pollinated plant

In hermaphrodites, the allocation of resources to each sex function can influence fitness through reproductive success and mating success. In wind pollinated plants, sex allocation theory predicts that male fitness increases linearly with investment of resources into male function. However, there have been few empirical tests of this prediction. We experimentally manipulated allocation to male function in Ambrosia artemisiifolia (common ragweed) in a field experiment and measured mating success using genetic assays. We investigated the effects of various morphological traits and flowering phenology on male fitness, and on male and female mate diversity. Our results provide evidence for a linear relation between allocation to male function and fitness. We find earlier onset of male flowering time increases reproductive success, while later onset flowering time increases the probability of mating with diverse individuals. This research is among the first empirical studies testing the prediction of linear male fitness returns in wind pollinated plants. Our results provide insight into the large investment into male function by wind pollinated plants and temporal variation in sex allocation.

Changes in Habitat Conditions of Invaded Forest Communities in Podunajská Nížina and the Impact of Non-Native Species on Biodiversity (SW Slovakia)

With the phytocenological research of riparian mixed forests and pannonic woods in the Podunajská nížina in 2018 and 2019, we obtained 113 phytocenological relevés of invaded and non-invaded stands. Using the Modified Permutation Test, we derived modified Ellenberg indication values (EIVs) in order to determine statistically significant differences and correlation relationships between diversity indices and EIVs. We recorded 15 invasive species in the stands, for example, Ailanthus altissima, Ambrosia artemisiifolia, Asclepias syriaca, Aster lanceolatus, Helianthus tuberosus, Impatiens parviflora, Negundo aceroides, Solidago canadensis, S. gigantea and Robinia pseudoacacia. We also confirmed the occurrence of species important for conservation: Epipactis helleborine agg., E. voethii, Cephalanthera longifolia, Clematis integrifolia and the like. We tested the statistical significance of EIVs as explanatory variables by redundancy analysis and Monte Carlo permutation test (stepwise selection, number of permutations 499, p < 0.05). In addition to the EIV continentality, the contribution of light, moisture, nutrients, soil reaction and temperature was higher than random. The model explains 20.21% of the variability pursuant to the coefficient of determination (R 2), with its adjusted (more accurate) variant (R 2 adj) capturing 15.70% of the variability of the model. Using the Kruskal–Wallis test, we confirmed the statistically significant differences (p*) in mean values between count of species, Shannon–Wiener index, Simpson dominance index and taxonomic diversity of invaded and non-invaded vegetation. For EIVs, we found significant differences in the mean values for moisture and soil reaction factors. In our model, count of species, Shannon–Wiener index, Simpson dominance index and taxonomic diversity index were positively correlated with invaded stands. Non-invaded stands showed statistically significant negative correlation with the EIVs moisture, soil reaction and nutrients. Biotic indices are appropriate and sensitive metrics for assessing the rate of community invasion. Lowland riparian forests are dynamic ecosystems through the structure of their stands and the dynamics of the nutrient and energy cycle of the river landscape. After disturbance (fire, wind, logging), the high degree of invasibility makes them vulnerable to the infiltration and spread of non-native species, which is a problem, especially in protected areas.

Efficiency of herbicide ACRIS (dimethenamid-P + terbuthylazine) on sunflower

Trials with a herbicide Acris, SE (280 g/l of dimethenamid-P + 250 g/l of terbuthylazine) were carried out in the Astrakhan, Krasnodar and Altai regions. The aim of this work is studying biological and economic efficiency of pre-emergence treatment with the combined herbicide Acris, SE on sunflower. The treatment with the herbicide Acris, SE (2.0–3.0 l/ha) made it possible to prevent many annual dicotyledonous weeds: Chenopodium album, Amaranthus retroflexus, Fagopyrum tataricum, Abutilon theophrastii and Solanum nigrum. Ambrosia artemisiifolia, found in the Krasnodar region, is less sensitive to this herbicide. The herbicide Acris, SE was highly effective in suppressing annual monocotyledonous weeds: Echinochloa crusgalli and Panicum miliaceum. Efficiency of the herbicide ACRIS was at the level of the standard Gardo Gold, and at the maximum application rate (3.0 l/ha) exceeded the standard one. Pre-emergence soil treatment with the herbicide Acris, SE did not have a negative effect on the germination of sunflower. Significant increase of sunflower yield was noted in all regions of trials. The most significant values were observed on varieties Flagman and R 453 in the Krasnodar region (8.7–9.2 and 7.0–7.5 quintal/ha, respectively). The lowest yields of sunflower in untreated control (10.2 and 11.0 quintal/ha) were observed in the Altai region, but the relative increase in yield in variants with the herbicide Acris, SE application was maximum (from 29.1 to 67.6% in relation to yields in untreated control). In the Astrakhan region, application rates of the herbicide Acris, SE of 2.5 and 3.0 l/ha were characterized by statistical significance (increases up to 2.5 and 3.2 quintal/ha, respectively).

Allelopathic Properties of Hemp

Summary Allelopathic effects of different plant allelochemicals have become the focus of studies that aim to determine new pesticidal compounds. Plant extracts with different chemical compositions can be obtained using different methods of extraction, whereas studies dealing with allelopathic properties use biotests to obtain fast and precise results. Such studies were undertaken after noticing the allelopathic effects of industrial hemp (Cannabis sativa L.) on the surrounding crops. Trials that involve the application of hemp extracts obtained by different methods resulted in determining the hemp allelopathic effects on Stellaria media (L.)Scop., Beta vulgaris ssp. vulgaris var. vulgaris, Lupinus albus L., corn (Zea mays L.), Cyperus rotundus L., Matricaria recutita L., Lepidium sativum L., lettuce (Lactuca sativa L.), rapeseed (Brassica napus L.), wheat (Triticum aestivum L.), rye (Secale cereal M. Bieb.), Ambrosia artemisiifolia L., Chenopodium album L., and Sorghum halepense L..

Weed Response to Co-Application of Herbicides and Acephate in Cotton

Determining compatibility of pesticides is important in developing effective management practices and adjusting to outbreaks of pests in cotton (Gossypium hirsutism L.). Field experiments were conducted in 2013 and 2014 to determine the effect of chloroacetamide herbicides with residual activity only and acephate with foliar activity against thrips (Frankliniella spp.) on control of emerged weeds by glyphosate, glufosinate, and a mixture of these herbicides. The residual herbicides acetochlor and S-metolachlor as well as the insecticide acephate did not affect control of emerged common ragweed (Ambrosia artemisiifolia L.) and Palmer amaranth (Amaranthus palmeri Watts.). Results from these trials indicate that weed control will not be compromised with co-application of glufosinate, glyphosate, and glufosinate plus glyphosate with acetochlor or S-metolachlor applied alone or with acephate.

Аналіз фітосанітарного стану Херсонської області за поширенням карантинних бур’янів

Мета дослідження – аналіз фітосанітарного стануХерсонської області за поширенням карантинних бур’я-нів, зазначених у списку А–2 «Перелік регульованихшкідливих організмів» і визначення тенденцій зміни зас-мічених площ за окремими видами. Методи. Аналіз про-ведено у період з 01.01.2016 до 01.01.2021 рр. на основіданих Державної служби України з питань безпечностіхарчових продуктів та захисту споживачів за такимивидами обмежено поширених карантинних бур’янів:гірчак повзучий Acroptilon repens L., амброзія полино-листа Ambrosia artemisiifolia L., ценхрус довгоголковийCеnchrus longispinus Fernald, повитиця польова Cuscutacampestris Junk. та паслін колючий Solanum rostratum Dunal. Під час дослідження використовували загаль-нонаукові методи, застосовували варіаційний методматематичної статистики. Результати. Забур’яненаамброзією полинолистою площа станом на перше січня2016–2021 рр. зменшилася від 277011,3 до 275350,6 га.Площа, засмічена гірчаком повзучим, скоротилася від203162,4 до 199808,6 га і залишалася стабільною про-тягом останніх трьох років. Станом на 01.01.2016 р. цен-хрус довгоголковий зареєстровано на площі 21606,5 га,з 01.01.2017 р. площа його поширення зменшилася до20052,2 га та була незмінною останні п’ять років. Площа,забур’янена повитицею польовою, скоротилась у дослі-джуваний період від 6052,7 до 5242,0 га. Паслін колючийна території країни було виявлено тільки в Херсонськійобласті на площі 134,0 га. Аналіз структури площ, засмі-чених обмежено поширеними видами бур’янів, свідчитьпро те, що основну їхню частину в Херсонській областізареєстровано в господарствах усіх форм власності.Паслін колючий був поширений тільки в господарствах.Висновки. У період із 01.01.2016 до 01.01.2021 рр.у Херсонській області спостерігалася тенденція змен-шення площ, засмічених гірчаком повзучим, амброзієюполинолистою, ценхрусом довгоголковим та повити-цею польовою. Ступінь варіювання площ поширеннязазначених видів бур’янів за роками був незначним, щопідтверджується результатами статистичного аналізу.Незмінною в Херсонській області залишалася площапасльону колючого.