Crop Disease Control Research Articles

Interspecies gene transfer provides soybean resistance to a fungal pathogen.

SummaryFungal pathogens pose a major challenge to global crop production. Crop varieties that resist disease present the best defence and offer an alternative to chemical fungicides. Exploiting durable nonhost resistance (NHR) for crop protection often requires identification and transfer of NHR‐linked genes to the target crop. Here, we identify genes associated with NHR of Arabidopsis thaliana to Phakopsora pachyrhizi, the causative agent of the devastating fungal disease called Asian soybean rust. We transfer selected Arabidopsis NHR‐linked genes to the soybean host and discover enhanced resistance to rust disease in some transgenic soybean lines in the greenhouse. Interspecies NHR gene transfer thus presents a promising strategy for genetically engineered control of crop diseases.

Effects of tobacco–rice rotation on rice planthoppers Sogatella furcifera (Horváth) and Nilaparvata lugens (Stål) (Homoptera: Delphacidae) in China

Background and aim Tobacco–rice rotation is a useful traditional practice for controlling crop diseases and pests. However, its effect on rice pests has not been studied. We aimed to clarify the ecological effect of tobacco–rice rotation on two destructive rice pests Nilaparvata lugens (Stal) and Sogatella furcifera (Horvath).

Changes in the soil quality attributes of continuous no-till farming systems following a strategic tillage

The adoption of no-till farming systems has greatly reduced energy and machinery inputs while significantly improving soil health and productivity. However, the control of crop weeds and diseases in no-till (NT) systems has become increasingly difficult for landholders in Australia’s northern grains regions, with occasional strategic tillage (ST) being considered as a potential management option. This study investigated the effects of occasional ST on physical, chemical and biological soil properties, productivity, and weed control on five long-term (7–44 years) NT-managed soils. The study area extended from Biloela (Vertosol, 666 mm annual rainfall), Condamine (Sodosol, 624 mm annual rainfall), Moonie (Dermosol, 636 mm annual rainfall) and Warwick (Vertosol, 675 mm annual rainfall) in Queensland to Wee Waa (Vertosol, 582 mm annual rainfall) in New South Wales. Tillage treatments included chisel, offset disc and prickle–disc chain with various timings and frequencies. Soil samples (0–0.3 m) obtained 3 and 12 months after occasional ST were analysed for total and particulate organic carbon (TOC, POC), available phosphorus (P), bulk density, soil water, and microbial enzymatic activity. In-crop weed density was also recorded. One-time tillage, with chisel tines, offset disc or chain harrows, in long-term NT helped to control winter weeds in the first year, with variable results in the second year. Grain yield overall showed no significant impact in either year, except on the Brown Sodosol (P = 0.08) in the first year. The initial impacts of strategic tillage on soil water were largely restricted to the 0–0.1 m depth range, with slight, non-significant decreases occurring. Available P, TOC, POC and total microbial enzymatic activity were not significantly impacted by either cultivation frequency or implement type. The use of an occasional ST for the purpose of weed control could be utilised as a viable management option for NT systems in the region without impacting on long-term productivity.

Smart and sustainable agriculture through weather and climate informatics and multi-scale modelling.

Abstract Most agricultural processes, from choice of crops to sowing schedule to harvest management, depend on a number of weather variables; shifts in the weather regimes due to climate change determine crop variability at regional levels. Thus, advance and accurate information on weather variables, and their quantitative relations to the crop processes (agro-weather informatics) as well as quantification of role of climate conditions in agricultural processes (agro-climate informatics) can play critical to enabling roles in sustainable and smart (optimal in terms of planning, resource utilization and adaptability) agriculture. In particular, agro-weather-climate informatics have scopes and challenges including but beyond those in agriculture or weather informatics in isolation. This review examines principles and the scope of applications of weather and climate informatics in some of the key areas of agriculture such as crop choice, irrigation, energy management and long-term sustainability. While a serious bottleneck in application of forecast-based agro-advisories is low reliability of the forecasts, methodology combining optimization of forecast model, assimilation of data, multi-scale modelling and design of evaluation strategy for specific farm advisories is possible, so that the forecasts are risk-free and yet useful in spite of their errors. We provide a brief overview of weather and climate forecasting at different scales and the general methodology used; this is followed by an overview of status of these applications at different timescales such as daily, seasonal and beyond for a variety of issues such as precision agriculture and pro-active control of crop diseases. The roles of high-performance computing and multi-platform observations, including remote sensing, are outlined. This is followed by our conclusions and perspectives.

Arable Crop Disease Control, Environmental Change and Food Security

Crop diseases cause yield losses, yet crop productivity needs to increase by > 70% over the next 35 years to accommodate population growth and changing dietary preferences1. Crop plants and pathogens interact in response to changes in environmental conditions. Recent predictions made by combining climate model data with an oilseed rape growth model and a phoma stem canker model suggest that yield will increase in the UK, especially in Scotland, whereas potential losses from phoma stem canker will be greatest in southern England2. Oilseed rape production in China is threatened by the possible arrival of Leptosphaeria maculans, a more virulent causal agent of phoma stem canker than the existing species Leptosphaeria biglobosa3. A strong correlation found between sulphur dioxide concentration and the ratio of Phaeosphaeria nodorum to Zymoseptoria graminicola in archived wheat samples at Rothamsted Research (1844 to date) suggests that subtle environmental changes can also cause changes in pathogen populations4. Ensuring future food security under environmental change is challenging and will require increased understanding of in planta disease processes. Effector-triggered defence (ETD) operates against extracellular fungal pathogens by R gene-encoded cell surface receptor-like proteins that trigger cell death only after a period of endophytic pathogen growth5. An example of this is resistance in oilseed rape against Pyrenopeziza brassicae that operates by preventing asexual sporulation. Exploiting such understanding and developing strategies to control biotic stressors are important to ensure adequate food supply for the future6.

Host-induced gene silencing inhibits the biotrophic pathogen causing downy mildew of lettuce.

Host-induced gene silencing (HIGS) is an RNA interference-based approach in which small interfering RNAs (siRNAs) are produced in the host plant and subsequently move into the pathogen to silence pathogen genes. As a proof-of-concept, we generated stable transgenic lettuce plants expressing siRNAs targeting potentially vital genes of Bremia lactucae, a biotrophic oomycete that causes downy mildew, the most important disease of lettuce worldwide. Transgenic plants, expressing inverted repeats of fragments of either the Highly Abundant Message #34 (HAM34) or Cellulose Synthase (CES1) genes of B.lactucae, specifically suppressed expression of these genes, resulting in greatly reduced growth and inhibition of sporulation of B.lactucae. This demonstrates that HIGS can provide effective control of B.lactucae in lettuce; such control does not rely on ephemeral resistance conferred by major resistance genes and therefore offers new opportunities for durable control of diverse diseases in numerous crops.

Can Crop Disease Control Cope with Climate Change?

Can Crop Disease Control Cope with Climate Change?

Formulation of Pseudomonas chlororaphis strains for improved shelf life

Formulations of Pseudomonas strains with long-term shelf life are needed for commercial use in biological disease control and growth promotion in crops. In the present work Pseudomonas chlororaphis (Pc) 63-28 formulated with coconut fiber [moisture content (MC) of 80%], talc (MC 8%) or peat (MC 40%), with or without the addition of carboxymethylcellulose or xanthan gum, and formulations of Pc 63-28 and P. chlororaphis TX-1 in coconut fiber with water contents (v:v) of 75%, 45%, and 25%, were evaluated in terms of shelf life and cell viability. The shelf life of Pc 63-28 was longer when formulated in coconut fibre with a MC was 80% than in the other formulations and longer at 3±1°C compared to 22±1°C. Densities of viable Pc 63-28 cells in coconut fiber stored at 3±1°C did not decline significantly during 224days when the MC was 80% and within 120days at 75% MC. Densities of Pc TX-1 in coconut fiber of 75% MC did not decline within 60days at 3±1°C. P. chlororaphis 63-28 survived longer in deionized water and buffer than in canola oil. Cells of Pc 63-28 cells formulated in coconut fibre of 80% MC after storage for 140days at 3±1°C in coconut fiber improved hydroponic growth of hydroponic lettuce and better than cells freshly recovered from culture. We conclude that coconut fiber is a carrier of superior performance in maintaining shelf life of Pseudomonas strains. The observed shelf life would be sufficient for practical use of Pseudomonas strains as tools for disease control and growth promotion in crops.

Elicitin‐like proteins Oli‐D1 and Oli‐D2 from Pythium oligandrum trigger hypersensitive response in Nicotiana benthamiana and induce resistance against Botrytis cinerea in tomato

The biocontrol agent Pythium oligandrum and its elicitin-like proteins oligandrins have been shown to induce disease resistance in a range of plants. In the present study, the ability of two oligandrins, Oli-D1 and Oli-D2, to induce an immune response and the possible molecular mechanism regulating the defence responses in Nicotiana benthamiana and tomato were investigated. Infiltration of recombinant Oli-D1 and Oli-D2 proteins induced a typical immune response in N. benthamiana including the induction of a hypersensitive response (HR), accumulation of reactive oxygen species and production of autofluorescence. Agrobacterium-mediated transient expression assays revealed that full-length Oli-D1 and Oli-D2 were required for full HR-inducing activity in N. benthamiana, and virus-induced gene silencing-mediated knockdown of some of the signalling regulatory genes demonstrated that NbSGT1 and NbNPR1 were required for Oli-D1 and Oli-D2 to induce HR in N. benthamiana. Subcellular localization analyses indicated that both Oli-D1 and Oli-D2 were targeted to the plasma membrane of N. benthamiana. When infiltrated or transiently expressed in leaves, Oli-D1 and Oli-D2 induced resistance against Botrytis cinerea in tomato and activated the expression of a set of genes involved in the jasmonic acid/ethylene (JA/ET)-mediated signalling pathway. Our results demonstrate that Oli-D1 and Oli-D2 are effective elicitors capable of inducing immune responses in plants, probably through the JA/ET-mediated signalling pathway, and that both Oli-D1 and Oli-D2 have potential for the development of bioactive formulae for crop disease control in practice.

The cytotoxic and genotoxic effects of metalaxy-M on earthworms (Eisenia fetida).

As the main optical isomer of metalaxyl, metalaxyl-M has been widely used worldwide in recent years because of its notable effect on the prevention and control of crop diseases. Together with the toxicity and degradation of metalaxyl-M, the chemical has attracted the attention of researchers. The present study examined the toxic effects of metalaxyl-M on earthworms at 0 mg kg(-1) , 0.1 mg kg(-1) , 1 mg kg(-1) , and 3 mg kg(-1) on days 7, 14, 21 and 28 after exposure. The results showed that metalaxyl-M could cause an obvious increase in the production of reactive oxygen species (ROS) when the concentration was higher than 0.1 mg kg(-1) , which led to lipid peroxidation in earthworms. Metalaxyl-M can induce DNA damage in earthworms, and the level of DNA damage markedly increased with increasing the concentration of metalaxyl-M. Metalaxyl-M also has a serious influence on the activities of antioxidant enzymes, which results in irreversible oxidative damage in cells. The changes of these indicators all indicated that metalaxyl-M may cause cytotoxic and genotoxic effects on earthworms.

Influence of Interannual Meteorological Variability on Yeast Content and Composition in Sangiovese Grapes

<h3>Abstract</h3> The use of rotations is an effective strategy to control crop diseases and improve plant health. The soil bacterial communities in the rhizosphere are highly important for maintaining soil productivity. However, the composition and structure of soil bacterial communities in the rotations of vegetable crops remain unclear. In this study, we explored the bacterial diversity and community structure of the tomato rhizosphere, including enzyme activities, yield, and fruit quality, under three different cropping systems: tomato-tomato continuous cropping (TY1), eggplant-tomato (<i>S. melongena</i>) rotation (TY2) and arrowhead-tomato (<i>Sagittaria trifolia-Solanum lycopersicum</i>) rotation (TY3). The composition and diversity of the rhizosphere bacterial communities differed significantly. The diversity was more in the TY2 and TY3 treatments than those in the TY1 treatment. <i>Chujaibacter</i> and <i>Rhodanobacter</i> were two predominant and unique strains detected only in TY1, while the relative abundances of <i>Curvibacter</i> and <i>Luteimonas</i> were the highest in TY2 and TY3, respectively. Moreover, <i>Lysobacterium</i> was a relatively abundant type of biocontrol bacterium found only in the TY3 treatment, which could contribute to alleviating the obstacle of tomato continuous cropping. Compared with the TY1 treatment, the activities of catalase were significantly higher in the TY2 and TY3 treatments. In addition, compared with TY1, the TY2 and TY3 plots increased the following parameters: tomato yields by 24–46%, total soluble solids by 37-93%, total organic acid by 10-15.7% and soluble protein by 10-21%, while the content of nitrate was significantly reduced by 23%. Altogether, compared with the tomato monoculture, the rotations of tomato with eggplant and arrowhead shifted the rhizosphere bacterial communities and improved the yield and quality of the vegetables. Moreover, a tomato rotation, particularly with arrowhead, was an effective way to alleviate the obstacles of continuous cropping.

Plant MicroRNAs Responsive to Fungal Infection

MicroRNAs (miRNAs) are endogenous small RNAs transcribed from non-coding DNA, which have the capacity to base pair with the target mRNAs (messenger RNAs) to repress their translation or resulted in cleavage. We have paid much attention on the DNA and its coded proteins, the discovery of miRNAs as gene negatively regulators has led to a fundamental change in understanding of post-transcriptional gene regulation in plants. Fungal pathogens infection is the main cause of most economic crops diseases. Unlike humans, plants don’t evolved to have a adaptive immune system, they protect themselves with a mechanism consists of activation and response. Recently, high throughput sequencing validated that miRNA play a crucial role in plant-fungus interaction. A better understanding of miRNA-mediated disease mechanism in fungi should clarify the strategy of crop disease control. MiRNA-based manipulations as gene suppressors, such as artificial miRNAs, may emerge as a new alternative approach for the improvement of crops and control of crop disease.

Advances in Automatic Insect Classification

Entomology has been deeply rooted in various cultures since prehistoric times for the purpose of agriculture. Nowadays, many scientists are interested in the field of biodiversity in order to maintain the diversity of species within our ecosystem. Out of 1.3 million known species on this earth, insects account for more than two thirds of these known species. Since 400 million years ago, there have been various kinds of interactions between humans and insects. There have been several attempts to create a method to perform insect identification accurately. Great knowledge and experience on entomology are required for accurate insect identification. Automation of insect identification is required because there is a shortage of skilled entomologists. This paper provides a review of the past literature in vision-based insect recognition and classifications. Over the past decades, automatic insect recognition and classification has been given extra attention especially in term of crop pest and disease control. This paper details advances in insect recognition, discussing representative works from different types of method and classifiers algorithm. Among the method used in the previous research includes color histogram, edge detection and feature extraction (SIFT vector). We provides discussion on the state-of-the-art and provides perspective on future research direction in insect recognition and classification problem.

Vision Based Entomology : A Survey

Entomology has been deeply rooted in various cultures since prehistoric times for the purpose of agriculture. Nowadays, many scientists are interested in the field of biodiversity in order to maintain the diversity of species within our ecosystem. Out of 1.3 million known species on this earth, insects account for more than two thirds of these known species. Since 400 million years ago, there have been various kinds of interactions between humans and insects. There have been several attempts to create a method to perform insect identification accurately. Great knowledge and experience on entomology are required for accurate insect identification. Automation of insect identification is required because there is a shortage of skilled entomologists. This paper provides a review of the past literature in vision-based insect recognition and classifications. Over the past decades, automatic insect recognition and classification has been given extra attention especially in term of crop pest and disease control. This paper details advances in insect recognition, discussing representative works from different types of method and classifiers algorithm. Among the method used in the previous research includes color histogram, edge detection and feature extraction (SIFT vector). We provides discussion on the state-of-the-art and provides perspective on future research direction in insect recognition and classification problem.

Assessing Quantitative Resistance against Leptosphaeria maculans (Phoma Stem Canker) in Brassica napus (Oilseed Rape) in Young Plants

Quantitative resistance against Leptosphaeria maculans in Brassica napus is difficult to assess in young plants due to the long period of symptomless growth of the pathogen from the appearance of leaf lesions to the appearance of canker symptoms on the stem. By using doubled haploid (DH) lines A30 (susceptible) and C119 (with quantitative resistance), quantitative resistance against L. maculans was assessed in young plants in controlled environments at two stages: stage 1, growth of the pathogen along leaf veins/petioles towards the stem by leaf lamina inoculation; stage 2, growth in stem tissues to produce stem canker symptoms by leaf petiole inoculation. Two types of inoculum (ascospores; conidia) and three assessment methods (extent of visible necrosis; symptomless pathogen growth visualised using the GFP reporter gene; amount of pathogen DNA quantified by PCR) were used. In stage 1 assessments, significant differences were observed between lines A30 and C119 in area of leaf lesions, distance grown along veins/petioles assessed by visible necrosis or by viewing GFP and amount of L. maculans DNA in leaf petioles. In stage 2 assessments, significant differences were observed between lines A30 and C119 in severity of stem canker and amount of L. maculans DNA in stem tissues. GFP-labelled L. maculans spread more quickly from the stem cortex to the stem pith in A30 than in C119. Stem canker symptoms were produced more rapidly by using ascospore inoculum than by using conidial inoculum. These results suggest that quantitative resistance against L. maculans in B. napus can be assessed in young plants in controlled conditions. Development of methods to phenotype quantitative resistance against plant pathogens in young plants in controlled environments will help identification of stable quantitative resistance for control of crop diseases.

Abiotic Stresses Affect Trichoderma harzianum T39-Induced Resistance to Downy Mildew in Grapevine

Enhancement of plant defense through the application of resistance inducers seems a promising alternative to chemical fungicides for controlling crop diseases but the efficacy can be affected by abiotic factors in the field. Plants respond to abiotic stresses with hormonal signals that may interfere with the mechanisms of induced systemic resistance (ISR) to pathogens. In this study, we exposed grapevines to heat, drought, or both to investigate the effects of abiotic stresses on grapevine resistance induced by Trichoderma harzianum T39 (T39) to downy mildew. Whereas the efficacy of T39-induced resistance was not affected by exposure to heat or drought, it was significantly reduced by combined abiotic stresses. Decrease of leaf water potential and upregulation of heat-stress markers confirmed that plants reacted to abiotic stresses. Basal expression of defense-related genes and their upregulation during T39-induced resistance were attenuated by abiotic stresses, in agreement with the reduced efficacy of T39. The evidence reported here suggests that exposure of crops to abiotic stress should be carefully considered to optimize the use of resistance inducers, especially in view of future global climate changes. Expression analysis of ISR marker genes could be helpful to identify when plants are responding to abiotic stresses, in order to optimize treatments with resistance inducers in field.

Operation Allelopathy: An Experiment Investigating an Alternative to Synthetic Agrochemicals

Synthetic herbicides represent a serious problem in modern agriculture because they are not biodegradable and can accumulate in the soil and in the groundwater, a situation that allows them to enter the trophic chain and ultimately leads to human exposure. Allelopathic chemicals offer an effective alternative to the synthetic compounds. The aim of this experiment is to highlight the differences between chemical and biological control of diseases in crops and to demonstrate the use of natural fungicides and herbicides as alternatives to synthetic chemicals. The experiment involves an evaluation by students of the potential of plant extracts as an alternative to synthetic agrochemicals to identify new ecological farming techniques that could be applied in agriculture. In an effort to encourage 1800 students in high school (14 to 16 years old) to have an interest in science, technology, and innovation, the third edition of the Summer Science Campus was organized by the Spanish Foundation for Science and Tech...

Rapeseed rotation, compost and biocontrol amendments reduce soilborne diseases and increase tuber yield in organic and conventional potato production systems

Aims Integrating multiple soil and disease manage- ment practices may improve crop productivity and disease control, but potential interactions and limita- tions need to be determined. Methods Three different potential disease-suppressive management practices, including a Brassica napus (rapeseed) green manure rotation crop, conifer-based compost amendment, and three biological control or- ganisms (Trichoderma virens, Bacillus subtilis, and Rhizoctonia solani hypovirulent isolate Rhs1A1) were evaluated alone and in combination at sites with both organic and conventional management histories for their effects on soilborne diseases and tuber yield. Results Rapeseed rotation reduced all observed soil- borne diseases (stem canker, black scurf, common scab, and silver scurf) by 10 to 52 % in at least one year at both sites. Compost amendment had variable effects on tuber diseases, but consistently increased yield (by 9 to 15 %) at both sites. Biocontrol effects on disease varied, though Rhs1A1 decreased black scurf at the conventional site and T. virens reduced multiple diseases at the organic site in at least one year. Combining rapeseed rotation with compost amend- ment both reduced disease and increased yield, where- as biocontrol additions produced only marginal addi- tive effects. Conclusions Use of these treatments alone, and in combination, can be effective at reducing disease and increasing yield under both conventional and organic production practices.

Identification of the antifungal compound, trans-cinnamic acid, produced by Photorhabdus luminescens, a potential biopesticide against pecan scab

Pecan scab (caused by Fusicladium effusum) limits the productivity of pecan in the southeastern USA. Alternatives to conventional fungicides should be biorational, of low environmental risk with a lower risk of fungicide resistance. Research showed that metabolites from the nematode symbiont Photorhabdus luminescens suppress pecan scab, but the bioactive molecules had not been identified. Extracts from P. luminescens were investigated using a bioactivity-directed fractionation approach to identify the constituent(s) responsible for the activity. High throughput antifungal bioautography assays against Colletotrichum gloeosporioides, C. fragariae, and C. acutatum were used to guide the fractionation. One of the metabolites was purified and identified as trans-cinnamic acid (TCA) using silica gel chromatography followed by semi-preparative high-performance liquid chromatography. In vitro tests confirmed toxicity of TCA to C. gloeosporioides, C. fragariae, and C. acutatum at 10 and 100 μg mL−1 using fungal bioautography inhibition screening plates. The antimycotic activity of TCA was tested in vitro against F. effusum. Zone of inhibition tests, and tests with TCA incorporated into agar showed TCA toxicity to F. effusum at concentration 148–200+ μg mL−1. Further tests incorporating TCA into liquid media demonstrated that TCA arrested all growth of F. effusum at a concentration even as low as 64 μg mL−1. Naturally occurring antimicrobial products might offer an alternative to disease control in crops, helping in minimizing the risk of fungicide resistance, while also minimizing any negative impact on the environment. Additional research is warranted to determine the potential to use TCA as a suppressive agent for pecan scab and other diseases.

Study and Simulation on Fuzzy Control Model for Crop Disease

In order to solve the precision medicine problem of crop diseases control, the conventional fuzzy model which applies to crop diseases control was established. Subordinate function, reasoning pattern and domain of discourse of fuzzy model were select. The computational process of the weight of five drug need fuzzy control sub model was mainly introduced and AHP and Neural Networks were adopted. Self-learning fuzzy control model for crop disease control was proposed to make control rules study and better adapt the on-site work environment. The result of MATLAB showed an expected effect of controlling the spray rate of the system. The study provided a new control strategy and method to realize intelligent control of precision spraying for crop.