Clover Fields Research Articles

Leaf Spot Disease of Red Clover Caused by Leptosphaeria weimeri (=Longiseptatispora meliloti) in China

Leaf Spot Disease of Red Clover Caused by Leptosphaeria weimeri (=Longiseptatispora meliloti) in China

Improving pollen and nectar supply by identifying the red clover (Trifolium pratense) cultivars that attract most pollinators

Abstract Red clover (Trifolium pratense) is an important legume in agriculture for fodder and building soil fertility. Red clover flowers are also a valuable pollen and nectar source for pollinators during bloom. Farmers can choose among hundreds of commercially available red clover cultivars to plant, but the value of different cultivars for pollinators is not currently assessed or used as a recommendation criterion for farmers. Here, we compared the numbers of pollinators on 20 red clover accessions (12 cultivars and 8 breeding lines) grown under management typical for silage production in the UK in 2022 and 2023. Other potentially pollinator‐friendly traits (inflorescence density, florets per inflorescence, floret length and nectar sugar production) were also measured to help determine which would be desirable to integrate into red clover breeding programmes. Accessions varied greatly, 50‐fold, in numbers of pollinators attracted per plot and varied significantly in all other traits examined. Only inflorescence density was significantly positively related to insect abundance and species richness. These results suggest that breeding and using red clover cultivars that produce more inflorescences can increase the value of red clover to pollinators. We note that data on insect visitation can be gathered easily and could be provided to farmers to help improve the value of red clover fields to pollinators.

326 Effect of Curing Extent on Ruminal in Vitro Gas Production Kinetics of Red Clover Hay and Silage Across Storage Phases

Abstract This study evaluated the effects of insufficient (WET) or ample (CUR) curing on red clover silage (29.4 and 45.3% DM, respectively) and hay (65.1 and 89.1% DM, respectively) in vitro fermentation measures. Measurements were taken at the start of storage (STRT), after 14 d (MicA), and once storage processes had stabilized for hay and silage (50 and 78 d, respectively; LATE). The red clover field was divided into 5 blocks and each block was divided into 2 plots and then assigned randomly to silage and hay (storage methods). Hay was packed into mini-bales (~500 fresh g; ~232 kg DM/m3) and silage into mini-silos (19.5 L; ~214 kg DM/m3). Samples at each storage stage were analyzed for in vitro gas production (48 h). Gas kinetics were recorded using the Ankom RF Gas Production System. Data were analyzed as a randomized complete block design (5 blocks) with a 2 (curing extents) x 2 (storage methods) x 3 (storage phases) factorial. Differences were declared at P ≤ 0.05. The data was analyzed using the GLIMMIX procedure of SAS 9.4. At STRT, the Asymptotic maximal gas production (M) and fermentation rate (k) were not different between CUR and WET hay (x̅ = 240.5 ± 7.33 mL/g incubated DM and x̅ = 13.2 ± 0.56% of gas production/h, respectively). However, at MicA, CUR hay had a greater M and k than WET hay (232.7 vs. 192.6 and 13.9 vs. 9.33, respectively). The same was observed at LATE (237.6 vs. 197.6 and 13 vs. 8.36, respectively). At STRT, the CUR and WET silage was not different for M and k (x̅ = 233.4 ± 7.33 mL/g incubated DM and x̅ = 14.06 ± 0.56% of gas production/h, respectively). A similar trend was observed at MicA (x̅ = 220 and 13.6, respectively) and LATE (x̅ = 219.7 and 14.7). In conclusion, ample curing of red clover hay preserves the fermentation kinetics relative to insufficient curing, especially after 14 d of storage. In the case of red clover silage, the fermentation kinetics was not affected by the curing extent across the storage period.

PSIII-24 Effect of Curing Extent on Red Clover Hay and Silage in Situ Degradability Kinetics in Dairy Cattle

Abstract This objective was to evaluate the effects of insufficient (WET) or ample (CUR) curing on red clover silage (29.4 and 45.3% DM, respectively) and hay (65.1 and 89.1% DM, respectively) ruminal degradation. The red clover field was divided into 5 blocks and each block was divided into 2 plots and then assigned randomly to silage and hay. Hay was packed into mini-bales (~500 fresh g; ~232 kg DM/m3) and silage into mini-silos (19.5 L; ~214 kg DM/m3). Measurements were taken once storage processes had stabilized for hay and silage (50 and 78 d, respectively). Samples were ground to pass 4-mm screen and weighed (5 g DM) into 10 x 20 cm ANKOM R1020 in situ bags. Bags were hooked to a rope, placed in the ventral sac of the rumen of 2 dairy cows for 0, 3, 6, 12, 24, 48, 72, and 96 h. All bags were removed simultaneously, washed, dried, and weighed. This procedure was conducted separately for each block. Data were analyzed as a randomized complete block design (5 blocks) with a 2 (curing extents) x 2 (storage methods) factorial. Differences were declared at P ≤ 0.05. Discrete lag times were higher for WET than CUR (0.23 vs. 0 ± 0.08 h, respectively). The potentially degradable fraction was greater in hay than in silage (50.2 vs. 45.1 ± 1.32% of DM, respectively). Moreover, WET had a greater potentially degradable fraction than CUR (49.6 vs. 45.7 ± 1.32% of DM, respectively). The degradation rate was less in hay than silage (5 vs. 8 ± 0.4%/h, respectively). The WET treatment had a decreased degradation rate than CUR (5 vs. 7, respectively). The undegradable fraction was not different between WET and CUR hay (x̅ = 23.3 ± 1.13% of DM). In contrast, WET silage had a decreased undegradable fraction than CUR silage (17.1 vs. 20, respectively). In conclusion, haymaking increased the potentially degradable fraction relative to ensiling but reduced the rate of digestion. For both storage methods, curing reduced the potentially degradable fraction but increased the rate of digestion.

Identifying a suitable revegetation method for soil organic carbon, nitrogen, and phosphorus sequestration: A 16‐year in situ experiment on abandoned farmland in a semiarid area of the Loess Plateau, China

AbstractLegume pasture species have been widely used to re‐establish vegetation cover and control soil erosion in semiarid degraded ecosystems. Nevertheless, the long‐term effects of revegetation on aboveground biomass (AB) and the soil properties under different topographies remain unclear. We conducted a 16‐year in situ experiment to evaluate soil properties and biomass dynamics under fallow, sweet clover (Melilotus officinalis L.) and alfalfa (Medicago sativa L.), in northeast‐facing, southeast‐facing, and horizontal landscapes from 2003 to 2018. After 16 years of revegetation, soil organic carbon (SOC), soil total nitrogen (TN), soil total phosphorus (TP) concentrations were higher in alfalfa fields in the northeast‐ and southeast‐facing landscapes and greater in sweet clover fields in the horizontal landscape alongside soil profiles. In the 0–20 cm, the SOC, TN, and TP concentrations in alfalfa fields increased at rates of 0.322, 0.034, and 0.010 g kg−1 yr−1 in the northeast‐facing landscape and at rates of 0.189, 0.022, and 0.011 g kg−1 yr−1 in the southeast‐facing landscape. The SOC, TN, and TP concentrations in sweet clover fields increased at rates of 0.129, 0.023, and 0.009 g kg−1 yr−1 in the horizontal. Alfalfa introduction is recommended for northeast‐facing landscapes whereas alfalfa and fallow are recommended in southeast‐facing landscapes, introduce sweet clover is recommended in a horizontal landscape to improve the soil nutrient concentrations at mid‐long time. These results suggest that topography influences vegetation restoration by affecting plant growth and soil nutrient and should be considered during the revegetation process to ensure revegetation success and sustainable land use.

The Wind & the Clover by Audrey Helen Weber

Reviewed by: The Wind & the Clover by Audrey Helen Weber Amanda Toledo Weber, Audrey Helen The Wind & the Clover; written and illus. by Audrey Helen Weber. Little, 2022 [40p] Trade ed. ISBN 9780316459914 $18.99 Reviewed from digital galleys R 3-6 yrs In a verdant clover field, ground bees scurry out of their burrowed homes to enjoy playful, sunlit days and return to safety for restful windy nights. One morning a ground bee wakes up and flies on a cardinal wind to somewhere new. The next morning, another bee; the following day, another. One bee remains and wakes to find the familiar clover field turned wondrous, full of bits of vegetation and wildlife brought on the wind from the other bees' travels. The gouache painting style, with its varying opacity and richness of colors, enhances the whimsical mood of the story. Most pages are visually packed without overwhelming the senses, and portrayals of different ecosystems invite children to spot and name various critters and flowers populating the new homes for the ground bees. Short sentences on each page, plenty of repetition, and an engaging author's note call readers to notice the little things around them, making this a great fit for storytime. Copyright © 2022 The Board of Trustees of the University of Illinois

Agroecosystem Ecology of Northern Deermice (Peromyscus maniculatus bairdii) and White-Footed Deermice (P. leucopus noveboracensis) in the Inner Bluegrass of Kentucky

Peromyscus leucopus (White-Footed Deermouse) and Peromyscus maniculatus (North American Deermouse) are 2 widespread rodent species in North America, with North American Deermice more ecologically diverse and widely distributed than White-footed Deermice. Commonly, White-Footed Deermice are ecological generalists, and North American Deermice are ecological specialists. In the Inner Bluegrass Region of Kentucky, these 2 species are sympatric in agroecosystems habitats, including the University of Kentucky North Farm. This farm was the most trapped location in central Kentucky from 1950 to 1968, with results indicating the White-Footed Deermoouse was the more common of these species. Trapping from 1995 to 2015 found that North American Deermice were caught rarely. Our study examined agroecosystems habitats at the UK North Farm, including all perennial and annual habitats, to determine the relative abundance and habitat use by both these species. In our study, North American Deermice was the most commonly captured species; it was trapped rarely in perennial habitats but much more frequently in annual crops. Perennial clover fields and Medicago sativa (Alfalfa) were the 2 exceptions; however, these are short crops with exposed soil between rows. Essentially, North American Deermice were observed in the agricultural equivalent of early successional habitat. In contrast, White-Footed Deermice were captured in both perennial and annual habitats, but more commonly in perennial habitats, the exception being annual Salvia hispanica (Chia) fields where dense, green plants produced a thick canopy. Overall, the best predictor of habitat for North American Deermice was bare, exposed soil, whereas the best predictor for White-Footed Deermice was dense growth and overhead cover.

The Effects of Different Undergrowth Vegetation on the Types and Densities of Functional Ground-Dwelling Arthropods in Citrus Orchards

<p>In agricultural lands, citrus orchards, pest feeding and weed seed predation by ground-dwelling arthropods are essential ecosystem services. This research aims to investigate the effects of different undergrowth vegetation, including weed area, bare land, rattail fescue and white clover fields, on the types and densities of functional ground-dwelling arthropods in citrus orchards, using pitfall traps. The captured organisms included carnivorous beetles (<em>Pheropsophus jessoensis</em>,<em> Chlaenius naeviger</em> and <em>Dolichus halensis</em>), wolf spiders (<em>Lycosidae</em> sp.), earwigs (<em>Anisolabididae</em> sp.), house centipedes (<em>Scutigeromorpha</em> sp.), herbivorous ground beetles (<em>Amara</em> sp., <em>Harpalinae</em> sp.), crickets and millipedes. Furthermore, the population of the functional ground-dwelling arthropods was significantly increased by the presence of a live mulch, where a higher number was seen in the rattail fescue or white clover compared to the weed or bare land fields. The cover crops also affected the types of arthropods identified, with the rattail fescue field including more <em>Pheropsophus jessoensis</em> while the white clover had an elevated number of wolf spiders, earwigs and <em>Amara sp. </em>(a weed seed predator). This discovery indicates that the type of undergrowth vegetation plays an important role in enhancing functional biodiversity. The kind of pests and weeds that these arthropods are effective against, as well as the extent to which their densities can be decreased, is also unknown. Therefore, further research on the feeding habit and predation of these arthropods should be conducted.</p>

2D LiDAR based object detection and tracking on a moving vehicle

Environment perception is an important capability for fully autonomous operation of agricultural machinery. High-precision work requires perception systems that are able to locate objects with high and specified accuracy. In this paper, we present an object detection and tracking system in a global coordinate frame based on 2D LiDAR data and RTK-GNSS positioning. The LiDARs and the RTK-GNSS device are installed on a tractor that is moving while the data is recorded. The final mapping result is compared to an RTK-GNSS based ground truth measurement of the object positions. For a test setup with four objects on a clover field, the average object positioning accuracy of the LiDAR system was determined to be 0.135 m (CEP50) and the worst case accuracy was 0.178m (CEP50). The preliminary results from this study can be used as a basis for determining requirements for safety margins when using this system for autonomous driving.

Crop Cycle and Tillage Role in the Outbreak of Late Wilt Disease of Maize Caused by Magnaporthiopsis maydis.

The destructive maize late wilt disease (LWD) has heavy economic implications in highly infected areas such as Israel, Egypt, and Spain. The disease outbreaks occur near the harvest, leading to total yield loss in severe cases. Crop rotation has long been known as an effective means to reduce plant diseases. Indeed, agricultural soil conservation practices that can promote beneficial soil and root fungi have become increasingly important. Such methods may have a bioprotective effect against Magnaporthiopsis maydis, the LWD causal agent. In this two-year study, we tested the role of crop rotation of maize with either wheat or clover and the influence of minimum tillage in restricting LWD. In the first experiment, wheat and clover were grown in pots with LWD infected soil in a greenhouse over a full winter growth period. These cultivations were harvested in the spring, and each pot’s group was split into two subgroups that underwent different land processing practices. The pots were sown with LWD-sensitive maize cultivar and tested over a whole growth period against control soils without crop rotation or soil with commercial mycorrhizal preparation. The maize crop rotation with wheat without tillage achieved prominent higher growth indices than the control and the clover crop cycle. Statistically significant improvement was measured in the non-tillage wheat soil pots in sprout height 22 days after sowing, in the healthy plants at the season’s end (day 77), and in shoot and cob wet weight (compared to the control). This growth promotion was accompanied by a 5.8-fold decrease in pathogen DNA in the plant stems. The tillage in the wheat-maize growth sequence resulted in similar results with improved shoot wet-weight throughout the season. In contrast, when maize was grown after clover, the tillage reduced this parameter. The addition of commercial mycorrhizal preparation to the soil resulted in higher growth measures than the control but was less efficient than the wheat crop cycle. These results were supported by a subsequent similar experiment that relied on soil taken from commercial wheat or clover fields. Here too, the wheat-maize growth cycle (without permanent effect for the tillage) achieved the best results and improved the plants’ growth parameters and immunity against LWD and lowered pathogen levels. In conclusion, the results of this study suggest that wheat and perhaps other crops yet to be inspected, together with the adjusted tillage system, may provide plants with better defense against the LWD pathogen.

Teachers’ experience of inquiry into socioscientific issues in the Irish lower secondary science curriculum

The Irish lower secondary science curriculum emphasises the development of scientific literacy through the use of inquiry teaching and learning approaches. The Science in Society Investigation assessment in this curriculum requires students to carry out inquiry into socioscientific issues (SSI). This research presents two case studies exploring how teachers used inquiry in the context of SSI for the development of students’ skills and knowledge. There were differences in the pedagogical approach adopted by the two teachers, including the level and type of inquiry and the SSI context chosen. In Clover Field School, the teacher facilitated open, experimental and discussion-based inquiry. The students developed skills of experimentation, with little focus on scientific knowledge in SSI contexts. In Daisy Park School, the teacher facilitated guided, research and discussion-based inquiry, placing a central focus on authentic SSI contexts. Students developed skills relating to research and critical evaluation of scientific evidence and scientific knowledge was demonstrated while considering societal implications. The two different pedagogical approaches led to the development of a range of skills and knowledge. Open and guided inquiry pedagogical approaches, experimental, discussion and research-based inquiry, were shown to complement each other in achieving the outcomes of the Irish lower secondary science curriculum.

Mass-flowering red clover crops have positive effects on bumblebee richness and diversity after bloom

Floral resource quantity in agricultural landscapes plays a key role in the persistence of wild pollinators. An equally important, but less investigated factor is how variation in floral resource availability over time, e.g. floral resource pulses, affects pollinator abundances and diversity. Despite the potential importance of late-season resource pulses for bumblebee reproduction, few studies have evaluated the effects of late-season mass-flowering crops on bumblebee abundances and diversity during and after crop bloom. We assessed how bumblebee abundances, diversity and traits associated with species rarity were affected by cultivation of late-season mass-flowering red clover grown for seed production. Bumblebees were surveyed in red clover fields and flower-rich field borders across 20 landscapes with or without a red clover field during and after crop bloom in southern Sweden. Bumblebee worker abundances were higher in clover fields compared to flower-rich borders in the surrounding landscape. There was no relationship between presence of clover fields and the abundance of males of social bumblebees, but more male cuckoo bumblebees were found in flower-rich borders in landscapes with clover following crop bloom. Mass-flowering red clover also had a positive effect on bumblebee species richness and diversity after crop bloom. Overall, clover had positive and lasting effects on less common bumblebees thereby sustaining higher bumblebee species richness after bloom. Cultivation of red clover has the potential, in combination with the management of flower-rich habitats, to benefit less common bumblebee species in temperate agroecosystems.

Estimating cover crop biomass nitrogen credits with Sentinel‐2 imagery and sites covariates

AbstractCover crops can positively impact productivity and the environment. While improved estimates of cover crop N benefits could help promote their adoption, little information is currently available at the broad scale. We conducted a multi‐site study to determine whether use of satellite images and site factors could fill this gap. Six spectral indices were extracted from Sentinel‐2 satellite imagery and used with modeling covariates to estimate cover crop properties and biomass N credits (biomass × N contents). The partial least squares regression (PLSR) models were calibrated and validated with samples from 42 cover crop fields located in the midwestern and northeastern United States collected in 2017–2018. Remote sensing (RS)‐derived spectral indices strongly correlated (r > .7) with red clover (Trifolium pratense L.) but not with rye (Secale cereale L.) biomass. Growing degree days (GDDs), cover height, ground cover percentage, and temperature often had high importance (variable importance in projection >1) in PLSR models. Model predictive power was limited for estimates of biomass N credits when data from all validation sites and cover types were used (adjusted [adj] R2 = .52). However, models for both biomass (adj R2 = .81) and biomass N credits (adj R2 = .89) were successful for red clover fields. This suggests N benefits could be more effectively modeled for specific cover crop types. We also found RS‐based estimation of C/N ratios performed moderately well when applied to the complete dataset (adj R2 = .54), suggesting a way to differentiate grass and legume cover crops that can potentially inform biogeochemical models.

БАЛАНС ЭЛЕМЕНТОВ ПИТАНИЯ В СЕВООБОРОТАХ В УСЛОВИЯХ БИОЛОГИЗИРОВАННОГО АДАПТИВНО-ЛАНДШАФТНОГО ЗЕМЛЕДЕЛИЯ

In the light of recent developments, the use of biological techniques in crop cultivation technologies needs to be expanded. The role of crop rotations with a high proportion of legume grasses, green manure crops and intermediate crops is increasing. The purpose of the research is to study soil fertility dynamics in terms of the main nutritional elements and determine their balance for the development of the adaptive landscape farming system in the North-Eastern region of the European part of Russia. Experiments were carried out on the experimental plots of the FARC of the North-East in 2002–2009. Soil – sod-podzolic middle loamy. We analyzed data of a long-term stationary experiment in four grain-fallow-grass field crop rotations. Meteorological conditions during the years of research were close to the average long-term values and favorable for crop cultivation. The introduction of low doses of fertilizers (N45P45K45 as mineral, 11.5–22.5 t/ha as green manure) increased the content of mobile phosphorus in the soil by 11–14 mg/kg (LSD05 = 9.5) in crop rotations with occupied and green manure fallows. An increase in exchangeable potassium by 15 mg/kg (LSD05 = 14.1) was noted in crop rotation with two clover fields for green manure. A positive balance of nitrogen and phosphorus was obtained in crop rotation with occupied and green manure fallows. The nitrogen balance was with a higher intake of +157.8 – +483.5 kg/ha and balance intensity – 115–140 %. The balance of phosphorus has developed at +6.0…+49.6 kg/ha. The positive balance of potassium was only in crop rotations with the introduction of green manure fertilizers and intermediate crop (+69.9…+175.8 kg/ha). The intensity of the balance of these elements was 101–118 %. In the control crop rotation with bare fallow at a minimum intake of nutrients, the negative balance of nitrogen, phosphorus and potassium was obtained; the intensity was below 100 %. Productivity of crop rotation was at the level of 4.90–5.41 thousand fodder units. According to the optimal combination of productivity and the balance of nutritional elements, crop rotation with two clover fields for green manure and an intermediate crop stood out.

The Effectiveness of The Application of Comprehensive Measures To Combat Erosion Using Irrigation In A Market Economy In Azerbaijan (On The Example Of The Kur-Araks Plain)

Studies in the article have shown that productivity increases with improved structure. This is explained by the fact that in soils with 0.25 mm diameter water-resistant aggregates of 14%, grain yield is 22.2 cents / ha, while water-resistant aggregates are 8%. In soils, this figure decreased to 18.4 cents / ha (3.8 cents / ha). It is also known that alfalfa plays a key role in improving the water-physical properties of the soil, as well as its agrochemical composition. The author's research shows that the amount of water-resistant aggregates under the clover is much higher than in the cotton fields. This can be clearly seen from the following comparison. Thus, the amount of water-resistant aggregates in 0-10 cm of soil in the cotton field is 4.0-18.5; While 0.5 cm is 6.5-11.2 and 20-30 cm is 4.5-18.2, in clover crops this indicator is 35.0; Increased to 24.7 and 27.0. In addition, it revealed the accumulation of more organic and mineral substances under alfalfa cultivation. They proved this by the analysis of soil samples taken from the one year and two-year plots. It was found that 1.66% humus and 0.112% total nitrogen were accumulated in the topsoil of the annual alfalfa field, while the amount of humus accumulated in the topsoil in the biennial clover field was 1.70% and the total nitrogen content was 0.150%. It should be noted. That the development of irrigation erosion in irrigated arable lands depends on the fact that the surface of the area is covered with a large cover. This was clearly shown by the observations. It was found that both relatively weak (0.4 mm / min) and very (1.4 mm / min) heavy rains protect clover soil from further washing. Thus, 0.4 mm / min. In heavy rains, the depth of the furrow under alfalfa is 14.4 mm, 31 mm at 1.4 mm / min, 50.9 and 64.2 mm between rows of cotton, respectively, and 78.6 and 113 mm along the row. 6 mm.

Efficiency of Application of Integrated Measures To Combat Erosion With The Use of Irrigation Systems In Azerbaijan

Studies in the article have shown that productivity increases with improved structure. This is explained by the fact that in soils with 0.25 mm diameter water-resistant aggregates of 14%, grain yield is 22.2 cents / ha, while water-resistant aggregates are 8%. In soils, this figure decreased to 18.4 cents / ha (3.8 cents / ha). It is also known that alfalfa plays a key role in improving the water-physical properties of the soil, as well as its agrochemical composition. The author's research shows that the amount of water-resistant aggregates under the clover is much higher than in the cotton fields. This can be clearly seen from the following comparison. Thus, the amount of water-resistant aggregates in 0-10 cm of soil in the cotton field is 4.0-18.5; While 0.5 cm is 6.5-11.2 and 20-30 cm is 4.5-18.2, in clover crops this indicator is 35.0; Increased to 24.7 and 27.0. In addition, it revealed the accumulation of more organic and mineral substances under alfalfa cultivation. They proved this by the analysis of soil samples taken from the one year and two-year plots. It was found that 1.66% humus and 0.112% total nitrogen were accumulated in the topsoil of the annual alfalfa field, while the amount of humus accumulated in the topsoil in the biennial clover field was 1.70% and the total nitrogen content was 0.150%. It should be noted. that the development of irrigation erosion in irrigated arable lands depends on the fact that the surface of the area is covered with a large cover. This was clearly shown by the observations. It was found that both relatively weak (0.4 mm / min) and very (1.4 mm / min) heavy rains protect clover soil from further washing. Thus, 0.4 mm / min. In heavy rains, the depth of the furrow under alfalfa is 14.4 mm, 31 mm at 1.4 mm / min, 50.9 and 64.2 mm between rows of cotton, respectively, and 78.6 and 113 mm along the row. 6 mm.

THE EFFECTIVENESS OF THE APPLICATION OF COMPREHENSIVE MEASURES TO COMBAT EROSION USING IRRIGATION IN A MARKET ECONOMY IN AZERBAIJAN (ON THE EXAMPLE OF THE KUR-ARAKS PLAIN)

Studies in the article have shown that productivity increases with improved structure. This is explained by the fact that in soils with 0.25 mm diameter water-resistant aggregates of 14%, grain yield is 22.2 cents / ha, while water-resistant aggregates are 8%. In soils, this figure decreased to 18.4 cents / ha (3.8 cents / ha). It is also known that alfalfa plays a key role in improving the water-physical properties of the soil, as well as its agrochemical composition. The author's research shows that the amount of water-resistant aggregates under the clover is much higher than in the cotton fields. This can be clearly seen from the following comparison. Thus, the amount of water-resistant aggregates in 0-10 cm of soil in the cotton field is 4.0-18.5; While 0.5 cm is 6.5-11.2 and 20-30 cm is 4.5-18.2, in clover crops this indicator is 35.0; Increased to 24.7 and 27.0. In addition, it revealed the accumulation of more organic and mineral substances under alfalfa cultivation. They proved this by the analysis of soil samples taken from the one-year and two-year plots. It was found that 1.66% humus and 0.112% total nitrogen were accumulated in the topsoil of the annual alfalfa field, while the amount of humus accumulated in the topsoil in the biennial clover field was 1.70% and the total nitrogen content was 0.150%. It should be noted. that the development of irrigation erosion in irrigated arable lands depends on the fact that the surface of the area is covered with a large cover. This was clearly shown by the observations. It was found that both relatively weak (0.4 mm / min) and very (1.4 mm / min) heavy rains protect clover soil from further washing. Thus, 0.4 mm / min. In heavy rains, the depth of the furrow under alfalfa is 14.4 mm, 31 mm at 1.4 mm / min, 50.9 and 64.2 mm between rows of cotton, respectively, and 78.6 and 113 mm along the row. 6 mm

Assessing chemical control options and their effects on the lesser clover leaf weevil (Hypera nigrirostris) and red clover pollinators in Western Canada

Single-cut red clover (Trifolium pratense L.) is an important forage seed crop in Western Canada due to its winter hardiness and economical value. However, infestation of lesser clover leaf weevil (Hypera nigrirostris F.) can lead to drastic yield losses (over 50%). The aim of this research was to evaluate the effectiveness of insecticides deltamethrin (Decis) and cyantraniliprole (Exirel) in controlling H. nigrirostris in red clover in both field and laboratory conditions and their impacts on the pollinator community. Pest pressure data in red clover fields was tracked during the 2018 and 2019 growing season in six locations. Under the field conditions both deltamethrin and cyantraniliprole were effective at controlling H. nigrirostris numbers. However, only deltamethrin provided rapid pest suppression in 24 h after treatment application. Rearing H. nigrirostris larvae on treated plants in laboratory conditions showed similar results where both insecticides significantly reduced H. nigrirostris numbers in 10–12 days after treatment. The abundances of H. nigrirostris was always negatively related to seed yield regardless of treatment and initial weevil pressure. Seed yield was significantly lower in untreated controls whereas no differences were found between deltamethrin and cyantraniliprole. In contrast, no yield response was found when H. nigrirostris abundance was lower than 4 larvae per 10 shoots. Unexpectedly, densities of bees were not affected by either treatment and were not related to seed yield. Overall, results indicate that both insecticides can provide sufficient H. nigrirostris control, and that pollinator densities are not limiting seed yield, whereas lack of H. nigrirostris management can cause substantial yield losses.

First report of Leaf Spot Associated with Boeremia exigua on White Clover in China.

White clover (Trifolium repens L.) is an important perennial legume forage widely cultivated in China (Zhang et al. 2016). In April 2018, severe necrotic lesions on leaves were observed in a cultivated white clover field in Chongqing, China. Approximately 90% of plants in the field were affected. Leaf spots were amphigenous, dark-brown, elliptic to subcircular, with diameter ranging between 1 to 12 mm, well defined by brown margins and yellow halos. Severely infected leaves became withered and abscised. Stems and flowers were not affected by the disease. Symptomatic leaves were surface sterilized with 70% ethanol for 30 s followed by 0.1% HgCl2 treatment for 3 min, and rinsed in sterile water three times. Thereafter, tissue samples from margins of individual lesions were placed on potato dextrose agar (PDA) amended with 50 mg/L of chloramphenicol and incubated at 25℃ in the dark. An olivaceous gray fungal colony was consistently isolated (90.5% isolation frequency). After 15 days of incubation, subglobose, black pycnidia developed in the cultural medium. Conidia were hyaline, ellipsoid to oblong, nonseptate(n = 50), ranging from 4.0 to 7.5 μm long (5.6 ± 2.3µm) × 2.0 to 3.8 μm wide(2.8 ± 1.0 µm). On the basis of its morphological characteristics, the fungus was identified as Boeremia sp. (Aveskamp et al. 2010). To confirm the identity, the internal transcribed spacer region (ITS), large subunit ribosomal RNA (LSU), partial actin (ACT), RNA polymerase II second largest subunit (rpb2) and beta-tubulin (tub2) genes were amplified with primers ITS1/ITS4, LR0R/LR7, ACT-512F/ACT-783R, RPB2-5F2/fRPB2-7cR, and Btub2Fd/Btub4Rd, respectively, in eight representative isolates and sequenced(Aveskamp et al. 2009; Chen et al. 2015). BLAST results showed 100% identity of the ITS (506/506 nucleotides), LSU (966/966 nucleotides), ACT (244/244 nucleotides) and tub2 (297/297 nucleotides) sequences with those of B. exigua (KY419536, MK398746, EU880878, and MK514090) and 99.83% identity of those of the rpb2 (593/594 nucleotides) sequence with B. exigua (KT389572).Based on morphology and DNA sequence analysis, the associated fungus was identified as B. exigua. Representative sequences of one isolate (BT2-1) were deposited in GenBank (MN826339, MN836592, MT265217, MT265218 and MT265219). In a pathogenicity test, ten 2-month-old potted white clover plants were spray-inoculated with a spore and mycelial suspension (approximately 105 CFU/mL) and the control plants were inoculated with sterile distilled water. Plants were incubated in a greenhouse at 20 to 24°C under natural light and enclosed in plastic bags for the first 3 days to maintain high humidity. After 10 days, typical dark-brown lesions similar to those seen in naturally infected leaves developed on the inoculated leaves and not on the control plants. B. exigua was reisolated from the lesions, thus completing Koch's postulates. There is some evidence that B exigua is capable of invading seedling root tissue of white clover and causing necrotic lesions on roots (Skipp and Christensen,1982). However, to our knowledge, this is the first report of leaf spot on T. repens caused by B. exigua. This disease severely reduces forage quality and yield. Proper identification of the causal organism is essential in formulating management strategies.

Occurrence of Leaf Spot Associated with Alternaria alternata on White Clover in China

White clover (Trifolium repens L.) is a perennial legume widely cultivated as forage, lawn grass, a green manure crop, and soil conservation plant worldwide (Zhang et al. 2016). In March 2018, necrotic leaf lesions were observed in several white clover fields in Chongqing, southwest China. The disease incidence varied from 10 to 65% between fields. Infected leaves had small, brown, circular spots that became elliptic to irregular. The spots were 1 to 15 mm in diameter with dark brown margins, yellow halos, and sometimes concentric rings. As the disease progressed, lesions gradually coalesced, forming large necrotic patches. In advanced infections, severe disease led to defoliation. Symptomatic leaves were collected from eight different fields in the Rongchang and Qianjiang districts of Chongqing, surface sterilized with 70% ethanol for 30 s followed by 0.1% HgCl₂ treatment for 3 min, and rinsed in sterile water three times. Thereafter, tissue samples (2 × 2 mm) from margins of individual lesions were placed on potato dextrose agar (PDA) amended with 50 mg/liter of chloramphenicol and incubated at 25°C in the dark. Fungal colonies consistently isolated on PDA were initially white and then turned grayish black (93.75% isolation frequency). Conidia were light to dark brown, ovoid to long ellipsoid, with one to four transverse and zero to two longitudinal septa, slightly constricted near some septa, and approximately 12 to 29 × 6 to 17 µm in size. Conidiophores were straight or flexuous, brown, and 11 to 60 × 3 to 8 µm. Morphological characteristics matched the descriptions of Alternaria alternata (Woudenberg et al. 2013). To confirm the identity, the internal transcribed spacer region (ITS), partial sequencing of 28S large subunit ribosomal RNA (LSU), major allergen Alt a 1 (Alt), and glyceraldehyde-3-phosphate dehydrogenase (GPD) genes of eight representative isolates were amplified with primers ITS1/4, LSU1Fd/LR5, Alt-for/rev, and gpd1/2, respectively, and were sequenced (Woudenberg et al. 2015). BLAST results showed 100% identity of the ITS, LSU, and Alt sequences and 99.83% identity of the GPD sequences with those of A. alternata strain CBS 104.26 (KP124299, KP124450, KP123848, and KP124156). Based on morphology and DNA sequence analysis, the associated fungus was identified as A. alternata. Representative sequences of one isolate (ATH1-2) were deposited in GenBank (MK894882, MK903026, MK903027, and MK903028). Pathogenicity tests were carried out on potted white clover, cultivar Gede. Ten healthy plants were sprayed with a conidial suspension (approximately 10⁵ conidia/ml), and the control plants were inoculated with sterile distilled water. Plants were incubated in a greenhouse at 20 to 24°C under natural light and enclosed in plastic bags for the first 2 days to maintain high humidity. After 7 days, characteristic dark brown spots were observed on the inoculated leaves and not on the control plants. A. alternata was reisolated from inoculated symptomatic leaves, thus completing Koch’s postulates. To our knowledge, this is the first report of leaf spot on white clover caused by A. alternata in China. This disease not only seriously affects lawn appearance and quality but also greatly reduces forage quality and yield, resulting in economic losses to animal husbandry.