Researches regarding weed control in winter wheat in the context of climate changes

The aim of the researches carried out in Tămădăul Mare village from Călăraşi county, during 2015-2018 was the weeds control in winter wheat crop. The segetal flora that infests wheat crops in Romania is varied both in species and especially as a species-related relationship, being subject to permanent changes, especially in the context of climatic changes. The changes occurred in the structure of the segetal flora represent the qualitative and quantitative expression of the influence of the soil seed stock dynamics, of the changes in the plant cultivation technology and of the weed control management, of the climatic variations and, last but not least, of the influences related to the economic and social factors. These changes involve and justify permanent monitoring of weed structure and dynamics in a certain territory in order to establish the most effective and rational methods of control, having the effect of reducing the yield losses. In wheat cultivated fields, aspects related to: the dynamics of the degree of weed infestation, the identification of the problematic weeds, the criteria for choosing the most effective herbicides and the optimal moments of application were studied. The best results in weed control of autumn wheat crops were obtained by integrating agrotechnical, phytotechnical and chemical measures, conclusion resulting also from this study

Selectivity and efficacy of thifensulfuron-methyl with adjuvant and without in control of broadleaf weeds in winter wheat

The research was conducted in 2020-2021, in 3 different locations (Constanța, Călărași and Teleorman) and aimed to evaluate the biological activity of the herbicide Thifensulfuron-methyl 75% WG with adjuvant and without in control of broadleaf weeds in winter wheat. The experiments were placed in randomized blocks, in 4 repetitions with a plot area of 100 m2 . The floristic composition of the winter wheat fields studied has been diversified, being present: Amaranthus retroflexus, Capsella bursa – pastoris, Centaurea cyanus, Chenopodium album, Erigeron annuus, Fumaria officinalis, Galium aparine, Lamium spp., Papaver rhoeas, Polygonum convolvulus, Sinapis arvensis, Stellaria media, Veronica spp., Viola arvensis etc. Herbicides were applied in post-emergence when weeds were in the early stages of growth and development. The herbicide Thifensulfuron-methyl 75% WG with adjuvant and without was applied at the doses of 20, 30 and 40 g/ha. The adjuvant (Trend 90 EC) was applied at 250 ml/ha. The assessments made at 10, 20 and 30 days after treatments focused the density of weeds, the percentage of soil cover, selectivity and the effectiveness compared to the untreated control. The results obtained showed that the efficacy depends on the dose applied, the type of weeds and their density on square meter. The Thifensulfuron-methyl 75% WG ensured a good efficacy in controlling of broadleaf weeds in winter wheat, the best results being obtained at the higher dose and when it was applied together with Trend 90 EC. Some weed species were insufficiently controlled at the dose of 20 g/ha: shepherd's purse, cleavers, blackbindweed, lamb's quarters etc

COVER CROPS FROM WINTER WHEAT, TRITICALE AND PEAS CULTIVATED IN PURE STANDS AND MIXTURES – SOIL AND WEED SUPPRESSION BENEFITS

Cover crops had shown a potential to improving carbon sequestration in soil and environmental quality, but these beneficial effects can be modulated by precipitation conditions. In this paper was evaluated the effectiveness of three cover crops on soil chemical properties and weed suppression. The experiments were performed on cambic chernozem soil from NARDI Fundulea Romania in two contrasting years regarding the amount of precipitation. Three cover crops were studied. The cover crop consisting of peas + triticale has increased more soil carbon content and infestation with weeds were lower as compared with cover crop consisting of peas or triticale. The differences concerning carbon sequestration, soil organic carbon, carbon to nitrogen ratio, weed suppression were influenced also by level of precipitations from experimental site. Cover crops were slow to impact C/N ratio of soil. In contrast, the floristic composition, and the degree of weed infestation were very significantly influenced by the composition of the cover crops. The use of cover crop mixtures offered an additional benefit to weed suppression that of individual cover crops

ENVIRONMENTAL RISK ASSESSMENT OF SOME COPPER BASED FUNGICIDES ACCORDING TO THE REQUIREMENTS OF GOOD LABORATORY PRACTICE

The paper presents data demonstrating the functionality of biological systems reconstituted with aquatic organisms developed under Good Laboratory Practice testing facility within Research - Development Institute for Plant Protection Bucharest for environmental risk assessment of four fungicides based on copper, according to Good Laboratory Practice requirements. For risk assessment, according to GLP were made the following steps: Good Laboratory Practice test facility was established, we have ensured adequate space for growth, acclimatization and testing for each test species, it was installed a complex water production instalation needed to perform tests, it was achieved control system for checking environmental conditions and have developed specific operating procedures that have been accredited according to Good Laboratory Practice.The results showed that biological systems model of the Good Laboratory Practice test facility in Research - Development Institute for Plant Protection meet the requirements of Organisation for Economic Co-operation and Development Guidelines regarding GLP, and after testing copper-based fungicides in terms of acute toxicity Cyprinus carpio and to Daphnia magna revealed that three of them (copper oxychloride, copper hydroxide and copper sulphate) showed ecological efficiency, ie low toxicity. Metallic copper based fungicides showed a higher toxicity, resulting in fish toxicity symptoms: sleep, sudden immersion, faded, weakness, swimming in spiral, lack of balance, breathing slow and cumbersome, spasms and mortality

EFFICACY OF POST-EMERGENCE HERBICIDE FLAZULFURON FOR WEED MANAGEMENT IN STONE FRUIT ORCHARDS

Due to their longevity and the long distance between rows, orchards are infested every years by annual and perennial monocotyledonous and dicotyledonous weeds species, some of them being very difficult to control. In Romania, in the integrated weed control management, herbicides play an important role together with the other control methods. This paper provides data on weed control in stone fruit orchards with herbicide Flazulfuron. Flazasulfuron is a new sulfonylurea herbicide which inhibits the acetolactase synthase enzyme in susceptible plants, to control a wide range of annual and perennial weeds. Trials were carried out in a drip – irrigated apricot and peach orchard at Agigea, Constanta county, Romania. Experimental plots were placed in randomized complete blocks design, in four repetitions on a vermi – calcic chernozem soil with a clay loam texture, in 2019. Flazasulfuron (250g/l active ingredient) was applied in post emergence at the doses of 0.04, 0.06 and 0.08 kg/ha. Standard reference (Glyphosate 360g/l) was applied at the dose of 4 l/ha. The major weed flora in the experimental fields included: Capsella bursa-pastoris, Lamium purpureum, Fumaria officinalis, Fallopia convolvulus, Matricaria sp., Chenopodium album, Xanthium sp., Malva sylvestris, Veronica sp., Papaver rhoeas, Setaria sp. The results demonstrated that the different rates of Flazasulfuron provide good efficacy on annual dicotyledonous and monocotyledonous weeds in stone fruit orchards, depending on weeds infestation and climatic conditions. The results of herbicide Flazasulfuron were similar to the standard reference

CONTROL OF POWDERY MILDEW IN VINEYARDS USING SEVERAL APPLICATIONS OF UNPOLLUTANT TREATMENTS OF SULPHUR FUNGICIDES IN ROMANIA

Powdery mildew is one of the most damaging and common diseases of the vine, being caused by the fungus Uncinula necator. In the years with favorable conditions for the disease infection, especially for the sensitive varieties, it may produce important damages in the vineyards, because it can manifest throughout the growing season. This disease can affect from the beginning of the vegetation the young leaves and shoots, flowers and grapes in a situation of severe infection. The wine – making process is also affected and the wines are of poor quality. Sulphur-based products are contact fungicides that provide good protection against powdery mildew without polluting the environment. The mechanism of action is a multi - site, with low risk of occurrence of the pathogen resistance phenomenon. This paper highlights the effectiveness of the two sulphur – based on products in controlling powdery mildew in three vineyards where no other fungicides have been applied. The products tested in the trials were: Polisulf (sulphur 18%, calcium hydroxide 10%), Sulfomat 80 PU (sulphur 80%) and Kumulus DF (sulphur 80% - standard reference). Data obtained demonstrated that the efficacy of Polisulf and Sulfomat 80 PU was equivalent to the efficacy of the reference product Kumulus DF against Uncinula necator in vines

RESEARCH ON THE EFFECTIVENESS OF FUNGICIDES MIXTURES IN CONTROL OF CEREAL DISEASES

Romania is one of the most important European cereal producing countries. Foliar and ear diseases are a permanent risk factor for the quantity and quality of crops. In order to obtain increasing harvests, the control of diseases is implemented since spring by preventive and curative methods, one of the most efficient being the controlled and optimal use of fungicides. Fungicide resistance has been recognized as a factor affecting the control of cereal diseases. In order to reduce the risk of resistance developing in the target pathogens FRAC (Fungicide Resistance Action Committee) recommends the use of fungicide mixtures. In this context, this study presents research on the efficacy in combating wheat and barley diseases of two mixtures of fungicides (Prothioconazole 16% + Spiroxamine 30% and Trifloxystrobin 15% + Prothiconazole 17.5%) applied at different doses and phenophases of plants and phytopathogens. The experimental plots were placed in 2 different locations (Dâlga-Călărași - non-irrigated and Agigea-Constanța - irrigated), in randomized blocks, in 4 repetitions with a plot area of 30 m2. The mixture of Prothioconazole 16% + Spiroxamine 30% EC was applied at a dose of 0.8, 1.0 and 1.25 l/ha and the mixture of Trifloxystrobin 15% + Prothiconazole 17.5% SC was applied at a dose of 0.5, 0.75 and 1.0 l/ha. The two treatments were applied between BBCH 30-61 from the end of the twinning phenophase to the beginning of flowering, with an interval of 14 days between treatments. The assessments were made before the application of treatments at 15 and 30 days after application and focused on efficacy in control and selectivity to crop plants. The obtained results demonstrated a good efficacy of the two mixtures of fungicides in controlling cereal crops against the complex of foliar and ear diseases (Fusarium, Septoria, Puccinia, Rhynchosporium, Helminthosporium)

BIOLOGICAL EFFICACY AND SELECTIVITY OF FLUROXYPYR AND FLORASULAM IN CONTROL OF BROADLEAF WEEDS IN WINTER BARLEY

During 2021-2022 two fields trial with the winter barley variety “Lucian” was conducted. The studys was conducted in 2 different locations (Constanța and Călărași) and aimed to evaluate the biological activity of two herbicides based Fluroxypyr and Florasulam in control of broadleaf weeds in winter barley crops. The experiments were placed in randomized blocks, in 4 repetitions with a plot area of 100 m2. Efficacy and selectivity of the herbicides Flurostar Super SE (100 g/l fluroxypyr +1 g/l florasulam) and Tomigan XL 102.5 SE (100 g/l fluroxypyr + 2.5 g/l florasulam), applied at registered and higher rates, was evaluated. The herbicide application was done at the phenophase of the crop – 1st – 2nd stem node (ВВСН 30-32). The efficacy of the products by the 10 score scale of EWRS was recorded. The results were compared with untreated controls. The herbicide selectivity for the winter barley by the 9 score scale for phytotoxicity of EWRS was reported. The results obtained showed that the efficacy depends on the dose applied, the type of weeds and their density on square meter. The herbicide based floroxypyr and florasulam ensured a good efficacy in controlling of broadleaf weeds in winter barley, the best results being obtained at the higher dose. For both herbicides (Flurostar Super and Tomigan XL) at all evaluated rates signs of phytotoxicity for the crop were not observed

RESEARCH REGARDING PROBLEM WEEDS IN POTATO CROP IN SOUTHERN ROMANIA

Potato (Solanum tuberosum L.) is considered to be one of the most competed crop by weeds. They may cause great losses, reducing the yield by 20-35%, consume large amounts of water and nutrients, decrease the effectiveness of treatments against diseases and pests and mechanized harvesting becomes difficult or impossible. The observations and assessments carried out aimed at deciding the problem weeds in the potato crop against which prevention and control measures must be effectively applied. The research targeted the monitoring and mapping of weeds in potato crops in Dâmbovița, Prahova and Călărași counties, in Romania. 30 determinations per hectare were conducted during 2020-2021, using the metric frame and the observations focused on density (number of plants/m2), participation (% in which each species is involved in the whole weed infestation), frequency (% in which each species was found in the observation points), class (pteridophytes, monocotyledonous, dicotyledonous) and the life span of each species (ephemeral, annual, biennial, weeds that can overwinter, perennials). The results obtained marked that the problem weeds in potato crops are usually perennial species difficult to control. Thus, among the dicotyledonous weeds, the species of Cirsium arvense, Sonchus arvensis and Convolvulus arvensis were identified as problem weeds, and among the monocotyledonous weeds, Sorghum halepense and Agropyron repens. Also in Lungulețu, due to the monoculture, the species Equisetum arvense, Ambrosia artemisiifolia and Symphitum officinalis created special problems for control, in Călărași county at Dâlga Cannabis ruderalis and in Prahova, Polygonum convolvulus and the Xanthium species. Even annual species, when they find favorable conditions for growth and development, are causing troubles: Chenopodium album, Polygonum aviculare, Echinochloa crus-galli. It has also been noted the increasing presence of invasive species: Ambrosia, Erigeron, Veronica, Xanthium

PROBLEM WEEDS CONTROL IN STRAWBERRY CROPS IN DIFFERENT GROWING SYSTEMS IN ROMANIA

Irrespective of the growing system practiced, strawberry plants are very susceptible to weed competition, especially in the beginning stage after planting, when they are small and frequent irrigations provide perfect conditions for the weed seeds germination. Weeds emerged inside the cannopies, in perennial crops, negatively influence the longevity of the plantations by weakening the plants or even suffocating them, consuming water and nutrients, favoring the infection with diseases and pests, negatively influencing the ripening of the fruits. The research aimed the identification of problem weeds and measures to combat them in 3 different systems of perennial strawberry crops grown under field conditions. The research and assessments were carried out in Giurgiu County at Hotarele in the strawberry crop cultivated with plastic film in rows and straws substrate between the rows, in the village of Oinacu in the strawberry crop with plastic film in rows and in the experimental field at RDIPP - Bucharest where the strawberry was grown without film and without straws substrate between the rows. Two determinations were made on each row of strawberries in the period 2021-2022, using a metric frame and the observations concerned the density (number of plants/m2), the participation (% in which each species participates in the general weeding), the frequency (% where each species was noticed at the observation points), family, class (monocotyledonous, dicotyledonous) and living period of each species. The growing system with plastic film on rows and with a layer of straws between rows ensured the best protection of the strawberry crop against the weeds competition, on condition that after harvesting the weeds that sprout through the holes of the film, on the interval between rows and around the strawberry field, to be destroyed