Rain Splash Research Articles

Temporal Dynamics and Dispersal Patterns of the Primary Inoculum of Coniella diplodiella, the Causal Agent of Grape White Rot.

Grape white rot can cause considerable yield losses in viticulture areas worldwide and is principally caused by Coniella diplodiella. The fungus overwinters in berry mummies on the soil surface or on the trellis and produces pycnidia and conidia that serve as primary inoculum. However, little is known about the temporal dynamics and dispersal pattern of C. diplodiella conidia. In this study, we investigated the production and dispersal of C. diplodiella conidia from a primary inoculum source, namely, affected mummified berries that overwintered in two vineyards in northern Italy in 2021 and 2022. Conidia of C. diplodiella were repeatedly produced in berry mummies from the budburst of vines to harvesting, with approximately 50 and 75% of the total conidia in a season being produced before fruit set and véraison, respectively. The production dynamics of C. diplodiella conidia over time were described by a Weibull equation in which the thermal time is the independent variable, with a concordance correlation coefficient of ≥0.964. A rainfall cutoff of ≥0.2 mm provided an overall accuracy of ≥0.86 in predicting conidial dispersal through rain splashes from berry mummies on the soil surface, with the number of dispersed conidia increasing with the amount of rainfall. The dispersal of conidia from mummies on the trellis by washing with rain required at least 6.1 mm of rain. The proposed mathematical equations and rain cutoffs can be used to predict periods with a high dispersal risk of C. diplodiella.

SOIL PHYSICAL QUALITY INDICES OF MINING-INDUCED DISTURBANCES IN SOIL WITHIN THE LOESS REGION OF WESTERN CHINA

Soil sampling and in situ measurements were conducted at 24 locations at three time points from May 2015 to April 2016. The statistical analysis showed that the variabilities of soil water content and soil penetration were moderate, while particle size and soil saturated hydraulic conductivity varied considerably. Rainfall before measurements contributed positively to the mean soil water content and negatively to particle size. This was mainly due to the soil aggregates and large soil particles being broken into smaller particles from rain splash. The detached small-sized soil particles could coalesce into larger-sized ones and even soil aggregates. Stressors in zones differ, resulting in variations between soil physical quality indices. The point-to-point comparisons indicated that the mean measured soil water content and soil saturated hydraulic conductivity were similar, if the measurements for these two indices were conducted under similar weather conditions during the same period between years. The investigation on the relationships among soil physical quality indices showed a negative relationship between the measured soil water content and soil saturated hydraulic conductivity. A positive correlation was also found between soil particle size and soil saturated hydraulic conductivity. Lower soil strength resulted in higher soil saturated hydraulic conductivity.

Soil Burn Severities Evaluation Using Micromorphology and Morphometry Traits After a Prescribed Burn in a Managed Forest

Prescribed burn is a tool that must imply low soil burn severity (SBS) levels; however, a wide range of soil impacts have been demonstrated because of the influence of very variable factors. The effects on biological, physical, and chemical soil properties are well reported in numerous studies; nonetheless, there are still questions about the effect of prescribed burns on soils at the micro-scale. As a result, an analysis of the link between micromorphological features and SBS does not currently exist. Thus, the main aim of the present study is to perform a micro-scale evaluation for complementing the SBS visual examination after prescribed burning in a managed pine forest in western Mexico. Morphometry and micromorphology analyses of mineral soil revealed that at low SBS levels, only the soil structure in the first centimeter is affected by prescribed burns. While at high SBS, the prescribed burn affected the first 2 cm, showing soil structure disturbance, ash filling porous, and soil aggregates getting reddish. Therefore, immediate actions have to be made by land managers after applying prescribed burns before the first rain to prevent post-fire surface soil erosion, particularly in bare soil patches where the burned aggregates are more susceptible to rain splash and runoff.

Wind Tunnel Experiments on Volcaniclastic Dust Emission and Dispersion Initiated by Water Droplet Impact

AbstractIceland contains active dust regions within high‐latitude, cold‐climate environments. An abundant supply of particulates <10 μm in diameter (PM10) is available within its extensive glacial outwash plains and through widespread transport and deposition of volcanic ash with hydrophobic tendencies. The climate is notably wetter than dust regions located in hot deserts, so that additional processes governing dust emission must be considered, inclusive of rain splash. Field workers in Iceland report that dust emission events sometimes overlap with precipitation. This study used high‐speed photography in wind tunnel experiments to assess the influence of water droplet impact and wind shear on the detachment and suspension of particulates collected from several active dust source regions within Iceland. Concentrations of PM10 sampled downwind of a single water droplet impact reached values as high as 104 μg m−3 and were positively correlated with increasing wind speed, droplet impact velocity and angle. Our measurements demonstrate that wind shear in a turbulent flow is important for the dispersion of aerosols ejected via water droplet impact from the surface of dry sediment, and that these coincident mechanisms can be highly effective agents of erosion, especially in light winds that are normally incapable of dust entrainment. Foremost, this study provides further evidence of the complexity of dust emission in cold environments and the importance of examining this phenomenon over a wide range of temporal and spatial scale.

Runoff and soil loss in biocrusts and physical crusts from the Tabernas Desert (southeast Spain) according to rainfall intensity.

Biological soil crusts (biocrusts) influence hydrological and erosive processes in drylands, and their effects increase with hypothetic successional development. Runoff and raindrops, both dependent on rain intensity, are among the main causes of erosion in these areas. However, little is known about the existence of soil loss nonlinearity in relation to rain intensity and crust types; this nonlinearity could control biocrust succession and dynamics. The assumption of biocrust types as successional stages, which allow space-for-time sampling, makes it advisable to include all the successional stages when exploring possible nonlinearity. We considered seven types of crusts, three physical and four biological. We created four rainfall intensity levels in controlled laboratory conditions: 18, 60, 120, and 240 mm/h. In all but the last, we conducted the experiments at two levels of antecedent soil moisture. Generalized Lineal Models enabled us to test for differences. These analyses confirmed previous knowledge regarding the significant effect of rainfall intensity, crust type and antecedent soil moisture and their interactions on runoff and soil loss, despite the small sample size of the sample units. For example, runoff, and particularly soil loss, decreased along succession. Moreover, some results were novel: the runoff coefficient increased only up to 120 mm/h of rain intensity. A decoupling between runoff and soil loss occurred at high intensities. Soil loss increased as rainfall intensity increased only up to 60 mm/h, and then it decreased, mainly due to physical crusts, because of the formation of a water sheet on the surface due to the incoming rainwater exceeding the drainage capacity. Although soil loss was greater in the incipient cyanobacteria than in the most developed lichen biocrust (Lepraria community), the protection provided by any biocrust against soil loss was great compared to the physical crust, and almost as strong at all rain intensities. Soil loss increased with antecedent soil moisture only in physical crusts. Biocrusts resisted the rain splash even at a rainfall intensity of 240 mm/h.

Citrus Canker: A Persistent Threat to the Worldwide Citrus Industry—An Analysis

Citrus canker (CC), caused by one of the most destructive subfamilies of the bacterial phytopathogen Xanthomonas citri subsp. Citri (Xcc), poses a serious threat to the significantly important citrus fruit crop grown worldwide. This has been the subject of ongoing epidemiological and disease management research. Currently, five different forms have been identified of CC, in which Canker A (Xanthomonas citri subsp. citri) being the most harmful and infecting the majority of citrus cultivars. Severe infection symptoms include leaf loss, premature fruit drop, dieback, severe fruit blemishing or discoloration, and a decrease in fruit quality. The infection spreads rapidly through wind, rain splash, and warm and humid climates. The study of the chromosomal and plasmid DNA of bacterium has revealed the evolutionary pattern among the pathovars, and research on the Xcc genome has advanced our understanding of how the bacteria specifically recognize and infect plants, spread within the host, and propagates itself. Quarantine or exclusion programs, which prohibit the introduction of infected citrus plant material into existing stock, are still in use. Other measures include eliminating sources of inoculum, using resistant hosts, applying copper spray for protection, and implementing windbreak systems. The main focus of this study is to highlight the most recent developments in the fields of Xcc pathogenesis, epidemiology, symptoms, detection and identification, host range, spread, susceptibility, and management. Additionally, it presents an analysis of the economic impact of this disease on the citrus industry and suggests strategies to reduce its spread, including the need for international collaboration and research to reduce the impact of this disease on the global citrus industry.

Physically based numerical model for the landscape evolution of soil-mantled watersheds driven by rainfall and overland flow

Soil and gully erosion is a critical threat to sustainable agricultural land management and productivity. Soil erosion by rain splash, sheet runoff, and concentrated flow are complex problems conditioned by the combined interactions of soil physical properties, hydrology, human activity, landscape topography, and climate. Effective management of erosion processes driven by rainfall and surface runoff requires a combined effort of field observation, physical experimentation, and numerical simulation. A physically-based hydrodynamic numerical model, CCHE2D with updated raindrop erosion effects, is applied to simulate landscape evolution processes as a result of raindrop impact and overland flow. The numerical model simulates a thin layer of runoff and concentrated flow over complex terrains, and predicts sediment transport due to raindrop splash detachment, transport and soil surface erosions. Soil erosion and landform evolution simulations due to rainfall are presented for an experimental landscape and a tilled large scale agricultural field. Photogrammetric field data were collected using an unmanned aerial system (UAS) following planting and subsequent rainstorms. Numerical simulation results agreed well with the observed experimental soil surface topography, sediment yield, and drainage network developments. The simulated soil and gully erosion in the tilled field also agreed well with observations. This research successfully demonstrates how high resolution spatial and temporal topographic measurements in experimental and field landscapes can be simulated and interrogated by 2D physically-based hydrodynamic and morphodynamic models. The accurate predictions of tillage field and gully erosion process in agriculture watersheds with complex tillage conditions also indicated the usefulness of the model for studying soil and landscape degradation.

First report of Rhizoctonia solani AG 4 causing brown bean of lima bean in Delaware.

Lima bean production has been an economically valuable staple in Delaware agriculture for almost a century, with annual revenue approaching 8 million dollars (USDA-NASS, 2019; Evans et al. 2007). From 2019-2021, lima beans displaying symptoms of brown discoloration, referred to as "brown bean" were observed in the green baby lima variety 'Cypress' across multiple commercial and research fields. Symptoms were present in approximately 1-5% of beans and not visible until pods were opened for harvest. Thirty-seven symptomatic beans were collected and surface disinfested in 0.85% sodium hypochlorite for 30 s, rinsed in sterile deionized water for 30 s, sectioned into four pieces and plated onto potato dextrose agar (PDA) amended with 50 µg/ml penicillin G and streptomycin sulfate. Petri dishes were incubated at 23ºC and observed for colony morphology. Pure cultures were obtained with tan colonies that had mycelia with right angle branching and septations near the branch, consistent with the description of Rhizoctonia solani Kuhn (Sneh et al. 1991). DNA extraction and pathogen identification was confirmed by sequencing of the internal transcribed spacer (ITS) region of nuclear ribosomal DNA using primers ITS4/ITS5 (White et al. 1990) for thirty-seven isolates collected in 2019 and 2020. Isolates were identified as Rhizoctonia solani AG 4 (99.9% sequence identity with GenBank Accession [MN106359.1].) A representative isolate was selected to complete Koch's postulates and the sequence was deposited in GenBank as accession number MW560551. To observe colonization ability, 10 detached pods were sterilized in 75% EtOH for 60 s, then rinsed in Milli-Q water. The detached pods were divided among two 150 mm Petri dishes containing a single 150 mm filter paper saturated with Milli-Q water. Five 1 mm2 agar plugs colonized with the representative R. solani isolate were placed 0.5 cm apart along the length of the pod. Plates were sealed with parafilm and left at room temperature. Control pods were kept in identical conditions but inoculated using clean agar plugs. The trial was repeated and a second trial was conducted on 12 attached asymptomatic pods from C-Elite Select lima bean plants at the succulent seed stage to complete Koch's Postulates. Pods were surface disinfested with 70% ethanol. Three attached pods were wounded with the tip of a sterile scalpel blade where a colonized agar plug was placed and loosely wrapped with a thin parafilm layer to maintain contact. Three attached pods not wounded were also inoculated with a colonized agar plug and wrapped by parafilm. Three wounded and non-wounded pods received clean agar plug controls. Both attached and detached pods were kept at room temperature for one week until symptoms began to manifest on the pod surfaces, at which point the beans from infected pods were removed and placed on PDA, three to a plate. In the attached assay, all beans of both wounded and non-wounded pods developed symptoms. The plates were stored in identical conditions and monitored for 5 days until tan colonies were observed. Culture morphology was consistent with the original isolate in all beans. Sequencing of the ITS region confirmed identity as R. solani AG-4. No symptoms were observed on control pods or seeds. Rhizoctonia solani is most frequently associated with symptoms of root rot (Sharma-Poudyal et al. 2015), but no stem symptoms are associated with the late season "brown bean" that has been observed throughout production in recent years. To our knowledge, this is the first report of Rhizoctonia solani AG 4 causing symptoms of brown bean of lima bean in Delaware. In preliminary observations, symptoms seem to be worse in pods that could have had contact with the soil directly or via rain splash. This disease cannot be detected until pods are split open, which has potential to reduce lima bean quality at harvest. Further monitoring should be conducted to quantify yield impacts and develop appropriate preventative and curative techniques.

PAINTING THE WALLS OF AL-IKHLAS MOSQUE IN KAMPUNG WARUNG RT.09 / RW.03, PANYIRAPAN VILLAGE, BAROS DISTRICT, SERANG REGENCY

Painting on walls is the final stage process after sprinkling and plastering on the walls. Painting on the walls functions as beauty in a building. In addition to functioning as an aesthetic beauty, painting on the wall can also be used as wall protection from rain splashes and direct sunlight that can shorten the life of the wall. First prepare the tools and materials used for painting the walls. Supervision is required so that the work or painting is in accordance with the Regulation of the Minister of Public Works on The Maintenance and Maintenance of Building Buildings No. 24/PRT/M/2008. After the painting process is complete, the painting results need to be evaluated/reviewed to ensure that all parts of the wall are painted neatly and cleanly. If a wall is found with uneven paint, it is necessary to repaint the section until the result is neat and even. Furthermore, if you are sure that all the walls are painted neatly and cleanly, then it is only a matter of time before the paint dries. The type and quality of wall paint used is prioritized for domestic production in accordance with the Joint Decree of the Minister of Trade and Cooperatives, Minister of Industry & Menpen. No. 472/Kop/XII/80, No. 813/Menpen/1980, No. 64/Menpen/1980, December 23, 1980. special methods before painting, one of which is the sanding process on the walls from the remaining cement from the results of sprinkling, so that during the painting process a smooth and even wall surface is obtained

Direct rain splash and downwearing of internal surfaces as an important erosion process in alluvial gully development

Rainfall and runoff are significant contributors to gully erosion, usually in the form of concentrated flow at the gully head. Yet differences in the erosion processes driving the development of alluvial gullies have yet to be adequately addressed. In considering the role of rainfall on gully development, downwearing of partly-eroded, internal surfaces by direct splash and wash erosion were investigated at 11 alluvial gullies in northeastern Australia. Rainwash processes are well described in the soil and agricultural erosion literature but are rarely considered important gully erosion processes. 293 erosion pins/plates were installed on internal buttress crests between 2019 and 2021. Over 70% of pins recorded erosion depths of 5–55 mm y−1 despite below-average rainfall in that period. Gully subsurface sediments had a rate of 24.5 mm y−1 (SD = 18.1), accounting for toppled pins, while adjacent surface materials had a rate of 1 mm y−1 (SD = 2). Downwearing volumes represent 50 – 80% of the sediment losses from measured gullies, with specific yields from downwearing alone of 162 ± 29–495 ± 62 ha−1 y−1. Soil chemistry results provide limited ability to understand the specific factors driving intra-site variability in erosion rates, but rates are related to strongly sodic and magnesic subsurface sediments that had strong dispersion and slaking properties. Total rainfall is a significant factor at the site scale, but no relationship was found with seasonal erosivity. From these results, we suggest that rainwash erosion on internal gully surfaces is an important and significant erosion process of large, alluvial gullies, with relevance to all open form gullies. Downwearing of internal surfaces and ongoing adjustment in gully depth results in a sustained growth phase over the medium-term compared with most hillslope gullies.

Mathematical Model for Rice Blast Disease Caused by Spore Dispersion Affected from Climate Factors

Rice blast disease, caused by the fungus Pyricularia oryzae, is one of the diseases that reduce rice yields in Thailand. The fungus’s dispersal influences this disease outbreak. This study aims to develop a mathematical model for spore dispersion, namely a non-local diffusion equation in terms of the dispersal kernel, by adding a factor that causes spore dispersion due to rain splash and adjusting the infection term based on weather conditions such as air temperature and relative humidity. The model assessed the existence and uniqueness of solutions by Banach’s fixed point theorem and used a finite difference method to solve them. The numerical simulation confirmed the existence and uniqueness part of the analysis. Because the climate data was used effectively for developing the disease, the rice blast disease pandemic was widespread in the study areas.

AscotraceR: An R Package Resource to Simulate the Spatiotemporal Spread of Ascochyta Blight in a Chickpea Field Over a Growing Season.

ascotraceR: An R Package Resource to Simulate the Spatiotemporal Spread of Ascochyta Blight in a Chickpea Field Over a Growing Season.

Aggregate stability and size distribution regulate rainsplash erosion: Evidence from a humid tropical soil under different land-use regimes

Soil erosion by water is a serious global ecological issue that leads to land degradation and threatens ecosystem sustainability. Splash erosion resulting from raindrop impact is the first stage of the erosion process and is mainly responsible for the detachment and migration of soil surface aggregates. In humid tropical regions, however, there has been little quantitative analysis of the relations between splash erosion and variable aggregate characteristics such as stability, particle size distribution and organic matter content. The objective of the current study was to determine how rain splash erosion is related to soil aggregate characteristics under land-use change, i.e., the conversion of tropical rainforest (TR) into rubber plantation (RP). Splash cups containing dry-sieved aggregate samples with eight size classes were exposed to natural rainfall to measure the splash erosion rate. The results showed that the initial aggregate organic carbon, water-stable aggregate index (WSA) and mean weight diameter (MWD) decreased by 31%, 9% and 48%, respectively, after 32 years of rubber cultivation. These degenerations in aggregate properties increased the susceptibility of soil aggregates to erosion and mutually contributed to a higher average splash erosion rate in RP (1.20 kg m−2) than in TR (1.09 kg m−2), regardless of aggregate size fractions. Splash erosion rates for all aggregate sizes were significantly positively correlated with rainfall kinetic energy, rainfall amount and intensity during the study period. The average splash erosion rate of aggregates first increased and then decreased with a decline in aggregate size in both TR and RP. The minimum and maximum splash rates were observed within 10–8 mm and 0.5–0.25 mm size fractions, respectively. In particular, the proportion of small-sized aggregates (i.e., 1–0.15 mm) with a relatively high splash erosion rate increased remarkably after land-use change. This exerted a negative impact on splash erosion control as well as on the sustainable development of rubber cultivation. Increasing the additional input of organic materials (e.g., intercropping cash crops with rubber trees) may help to enhance large aggregate formation and stabilization, which could minimize the risk of splash erosion at the aggregate scale for eroded rubber plantation ecosystems.

Analysis of watershed parameters controlling turbidity following the West Fork Complex fire

In this work we explore watershed characteristics associated with increased turbidity following the 2013 West Fork Complex Fire (WFC) in southwest Colorado, USA with the goal of understanding the hydrologic and geomorphic controls on turbidity. Turbidity, precipitation, and stream discharge were measured from May to September in 2015 and 2016 in seven watersheds, four burned and three unburned. Slope, slope aspect, soil type, vegetation, and burn severity—as well as precipitation and discharge—were characterized as independent variables for each of the seven watersheds. During snowmelt-driven runoff from May to June, no significant difference in turbidity between burned and unburned watersheds was found. However, in results from July to September of both 2015 and 2016, burned watersheds had larger spikes in turbidity following precipitation events than unburned watersheds. In the watersheds with higher burn severity and poor vegetation recovery, positive correlations between total storm volume and turbidity existed, though short-term trends in Enhanced Vegetation Index (EVI) were not consistently correlated with turbidity changes with precipitation, nor were watershed slope and aspect alone. These results indicate that other drivers of turbidity in these burned watersheds, for example erodible soils, were more susceptible to precipitation than snowmelt due in part to processes like rain splash. Results from this work provide insight on characteristics that influence stream turbidity after a wildfire and can help watershed managers predict future wildfire impacts on water quality, the health of aquatic organisms, and water treatment infrastructure.

Direct Rain Splash and Downwearing of Internal Surfaces as an Important Erosion Process in Alluvial Gully Development

Direct Rain Splash and Downwearing of Internal Surfaces as an Important Erosion Process in Alluvial Gully Development

Dissemination of esca-related pathogens in German vineyards: do arthropods play roles in vectoring spores?

Grapevine Trunk Diseases (GTDs) such as esca challenge viticulture. The main fungal agents of Petri disease or young esca, Phaeomoniella chlamydospora (Pch), diverse Phaeoacremonium species (Pm spp.) and Cadophora luteo-olivacea (Clo), are transmitted to pruning wounds of vines by rain splashes and air currents. Arthropod-mediated dispersal is another possibility for the pathogens to reach pruning wounds. The present study was the first to evaluate possible involvement of arthropods in the dissemination process of esca-related pathogens in German vineyards. Diversity of arthropods on grapevine trunks was determined in 2019 and 2020, using cardboard traps mounted on vine trunks. Captured arthropods were surveyed for the presence of esca-related pathogens on their exoskeletons by using a nested multiplex PCR. In total, 2099 arthropods were examined, of which 35% were positive for Phaeomoniella chlamydospora (Pch), 21% for Phaeoacremonium spp. (Pm), and 7% for Cadophora luteo-olivacea (Clo). Earwigs and spiders were the most prevalent trapped arthropods; Pch was detected on 27% of earwigs and 38% of spiders, Pm spp. on 17 and 19%, and Clo on 3 and 8% of these arthropods. In both years, arthropods carrying the pathogens were already present in April, and therefore within the presumed susceptibility phase of pruned vines. These results indicate involvement of arthropods in the dispersal of esca-related pathogens in German vineyards. Further research, particularly to determine the infection potential of insect-borne fungi, is needed to confirm transmission risk. These results underline the importance of protecting vine pruning wounds to prevent host invasion by GTD pathogens.

Blowin’ in the Wind: Wind Dispersal Ability of Phytopathogenic Fusarium in a Wind Tunnel Experiment

Dispersal processes play an essential role in cereal diseases caused by phytopathogenic Fusarium. However, most empirical studies of Fusarium spore dispersal have focused on vertical transport by rain splash, while wind dispersal has been mostly neglected. Our objective was to determine the ability of Fusarium conidiospores to disperse via wind under controlled conditions in a wind tunnel study. Ten Fusarium species with diverse spore varieties were studied by placing them in the wind stream at wind velocities of 5 and 8 m s−1 and collecting them after 6 m and a period of 1 h using a newly developed air sampling box. Although spore concentrations were high in the releasing Petri Dishes, the tested isolates were recaptured in only 18 of 78 runs. F. equiseti and F. cerealis were the most frequently recovered species. Changing abiotic conditions, wind speed, and spore shapes had no significant effect on Fusarium spore recapture rates. Another experiment showed that conidiospores were rarely released from the grown mycelium. Therefore, the importance of wind alone as a dispersal medium for Fusarium conidiospores may have been overestimated so far. Further studies should investigate the importance of carrier media or mobile linkers combined with the wind dispersal of spores.

Prediction of Land Erosion Events in the Down Stream Kreung Meureubo Watershed West Aceh District

This study aims to predict the occurrence of erosion in the downstream Krueng Meureubo watershed, West Aceh Regency. Erosion is the loss of topsoil due to rain splash which is analyzed as a factor of rain erosivity, but the occurrence of erosion is not necessarily calculated by the occurrence of rain alone, but many other factors, such as soil erodibility, slope and length of land, land cover and the presence or absence of land conservation efforts. the. The Krueng Meurebo watershed shows a large sediment transport, with an indication that the river is getting shallower caused by sediment deposition at the riverbed, this sediment comes from sediment carried through the process of soil erosion. The method used in analyzing the occurrence of soil erosion in this study is the USLE method and uses a Geographic Information System (GIS). The results obtained are the distribution of erosion rate values in 228 polygons, with the largest erosion rate value occurring in polygon 1 with an erosion rate of 8495.308 tons/ha/year. The smallest erosion rate occurs in polygons 30, 34, 35, 179, and 180, with an erosion rate of 0 meaning that there is no land erosion event, which occurs in organosol and glehumus and regosol soil types, land cover is settlements and water bodies. It is concluded that the occurrence of erosion in a land is very dependent on the type of soil and the type of land cover. It is recommended for land with large erosion events to take serious land conservation actions so that erosion events can be minimized and do not occur continuously which of course can cause the watershed to become critical. Conservation efforts can be carried out in various ways, one of which is by vegetative means using plants that can reduce the rate of soil erosion.

First report of Colletotrichum tropicale causing anthracnose on Passiflora edulis in Brazil.

Brazil is the world's largest producer and consumer of yellow passion fruit (Passiflora edulis f. flavicarpa), mainly for the manufacture of concentrate and frozen juice as well as for fresh consumption (Faleiro et al. 2005). Between June and July 2018, passion fruit plants with symptoms of anthracnose were observed in commercial planting in the municipality of Coruripe (20 ha), northeastern state of Alagoas, Brazil. Approximately 70% of the plants showed leaves with relatively large, watery, circular spots that affected 30% of the leaf surface. Small fragments taken from the transition region of symptomatic tissue were superficially disinfected in 70% ethanol for 30 s and in 1% NaClO for 1 min, rinsed in sterile distilled water (SDW), dried on filter paper, plated on potato dextrose agar (PDA-Kasvi) incubated at 25°C under white light and 12 h photoperiod, for 3 days. Two isolates were obtained and deposited in the Collection of Phytopathogens at the Universidade Federal de Alagoas (COUFAL0281 and COUFAL0282). To identify the isolates, partial sequences of the glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and β-tubulin (TUB2) genes and of the rDNA-ITS (ITS) region were amplified by PCR. The partial sequences were deposited at GenBank (MT299339, MT334694, MT310553, MT299340, MT334695 and MT310554). Based on the BLASTn analysis, sequences of the PCR products showed high nucleotide similarity with sequences of the species C. tropicale (CBS 124949/ex-type and ICMP 18672), for GAPDH (98.94% and 100%), TUB2 (99 and 100%) genes and ITS (100%). This result was also confirmed in the phylogenetic tree of Bayesian Inference assembled with concatenated data (GAPDH, TUB2 and ITS). The colonies of the isolates were white with a white reverse, with dense mycelium, and mean growth rate of 7.54 mm/day, after 7 days on PDA medium at 25° C. Conidia were subcylindrical with rounded ends, hyaline, smooth walls and measured 13.63-20.59μm (= 17.54μm; n= 50) in length and 4.40-7.93 μm (= 5.88 μm; n= 50) in width. Appressoria were melanized, subglobose, irregular and measured 7.44 - 18.57 μm (= 10.04 μm; n= 50) in length and 5.49-10.16 μm (= 7.66 μm; n= 50) in width. These morphological characteristics were consistent with those described for Colletotrichum tropicale E.I. Rojas, S.A. Rehner & Samuels (Rojas et al. 2010). To confirm pathogenicity, 30 µL of a 106 conidia/mL sterile distilled water (SDW) conidia suspension, together with a drop of 20% Tween were deposited on the adaxial surface of passion fruit leaves wounded with a sterile needle, with four repetitions. The control consisted of leaves inoculated only with SDW. The leaves were placed in a plastic Gerbox box with sterilized filter paper moistened with SDW and maintained in a Biochemistry Oxygen Demand (BOD) incubator stove at 25 ºC and photoperiod of 12 h. After 7 days, typical anthracnose symptoms were observed on inoculated leaves. The pathogen was re-isolated and confirmed by morphological characterization, according to Koch's postulates. No symptoms were observed in the negative control. The occurrence of this species has been frequently reported in several other crops grown in northeastern Brazil (Silva et al. 2017; Veloso et al. 2018; Vieira et al. 2018; Costa et al. 2019). Additionally, many of these crops are grown in close proximity to the passion fruit orchards, thus favoring pathogen movement between hosts, probably, due to the anthropic influence, circulation of animals and insects, as well as wind driven rain splashes. However, this is first report of C. tropicale in Passiflora edulis in the world.

Synergistic dispersal of plant pathogen spores by jumping-droplet condensation and wind

Plant pathogens are responsible for the annual yield loss of crops worldwide and pose a significant threat to global food security. A necessary prelude to many plant disease epidemics is the short-range dispersal of spores, which may generate several disease foci within a field. New information is needed on the mechanisms of plant pathogen spread within and among susceptible plants. Here, we show that self-propelled jumping dew droplets, working synergistically with low wind flow, can propel spores of a fungal plant pathogen (wheat leaf rust) beyond the quiescent boundary layer and disperse them onto neighboring leaves downwind. An array of horizontal water-sensitive papers was used to mimic healthy wheat leaves and showed that up to 25 spores/h may be deposited on a single leaf downwind of the infected leaf during a single dew cycle. These findings reveal that a single dew cycle can disperse copious numbers of fungal spores to other wheat plants, even in the absence of rain splash or strong gusts of wind.