Field validation of a decision support system for the control of pests and diseases in cereals in denmark

The decision in 1986, on an action plan to reduce pesticide use in Denmark by 50% led to increased research on the potential of reducing dosages. A decision support system (PC-Plant Protection), developed by The Danish Institute for Plant and Soil Science, implements this research. It combines a detailed use of threshold values to support decisions on treatment need, choice of pesticides and the appropriate dosage for actual problems in cereals. The pest and disease module within the system has been available commercially since 1993 and up to the end of April 1995, 2000 licences have been issued for its use at agricultural schools and by advisers and farmers. The recommendation model for pest and disease control has been validated in field trials since 1990. The validation has shown that the model is able to provide recommendations for the control of pests and diseases to a satisfactory level, without affecting farmers' gross margins. The model was able to adjust pesticide use to large yearly variations and the average amount of pesticides in the plots treated according to the model was well below that in the reference plots and in the commonly used strategies in Denmark.     

Molecular characterization and pathogenicity of a grouper iridovirus (GIV) isolated from yellow grouper, Epinephelus awoara (Temminck & Schlegel)

Molecular characterization was carried out on an iridovirus isolated from yellow grouper, Epinephelus awoara . The major capsid protein (MCP) gene was located, sequenced and compared with homologous genes from other iridoviruses. The nucleotide sequence is 1392 bases long and contains a single open reading frame beginning at an ATG codon from the 5' end and terminating at a TAA codon at the 3' end. The open reading frame encodes a protein of 463 amino acids with a predicted molecular weight of 50 272 Da. Pairwise amino acid alignments detected a high degree of sequence identity between grouper iridovirus (GIV) MCP and the homologous genes of other iridoviruses. The MCP gene of GIV was most similar to the MCP gene from frog virus 3 (FV3) with 70% nucleotide and 73% amino acid sequence identity. The predicted molecular weight of the protein of this gene is comparable with the apparent weight obtained by SDS–PAGE. Pathogenicity of the GIV was investigated in yellow grouper by intraperitoneal injection of 10⁷ and 10⁴ TCID₅₀ virus. Cumulative mortalities reached 100% within 11 and 25 days post-infection, respectively, while no grouper died in the control group. The molecular studies demonstrated that GIV is a member of the genus Ranavirus .     

Carbon-based supercapacitors produced by activation of graphene

Supercapacitors, also called ultracapacitors or electrochemical capacitors, store electrical charge on high-surface-area conducting materials. Their widespread use is limited by their low energy storage density and relatively high effective series resistance. Using chemical activation of exfoliated graphite oxide, we synthesized a porous carbon with a Brunauer-Emmett-Teller surface area of up to 3100 square meters per gram, a high electrical conductivity, and a low oxygen and hydrogen content. This sp(2)-bonded carbon has a continuous three-dimensional network of highly curved, atom-thick walls that form primarily 0.6- to 5-nanometer-width pores. Two-electrode supercapacitor cells constructed with this carbon yielded high values of gravimetric capacitance and energy density with organic and ionic liquid electrolytes. The processes used to make this carbon are readily scalable to industrial levels.     

Diversity,plant growth-promoting traits,and biocontrol potential of fungal endophytes of Sorghum bicolor

The diversity of fungal endophytes in Sorghum bicolor was investigated in samples collected from 10 different geographical regions of Karnataka state, India. A total of 360 endophytes were isolated from leaf, stem, and root tissues and were assigned to 26 fungal species based on morphology and molecular characterization using ITS sequences. All the endophytes belonged to the phylum Ascomycota. The diversity (Shannon H, 2.57; Simpson_1-D, 0.92) and species richness (Margalef's, 4.68; Menhinick, 3.61) were found to be higher for the endophytes isolated from leaf tissues. The species evenness of the endophytic assemblage was strongly influenced by tissue type, followed by geographical location. The biocontrol potential of isolated endophytes was evaluated against economically destructive sorghum grain mould pathogens such as Fusarium thapsinum, Epicoccum sorghinum, Alternaria alternata, and Curvularia lunata using the dual culture method. Biocontrol potential was exhibited by 26 endophytic isolates, of which Trichoderma asperellum recorded broad-spectrum activity against target pathogens, followed by E. nigrum and A. longipes. Most (82%) endophytes showed plant growth-promoting traits. Biosynthesis of indole-3-acetic acid (IAA) was observed in 84% of isolates, and phosphate solubilization, siderophore production, and cellulase activity was observed in 69%, 23%, and 27% of isolates, respectively. Seeds treated with T. asperellum exhibited a significantly higher seed vigour index (2096), germination percentage (94%), and yield under greenhouse and field conditions. The results were substantiated by the confocal microscopy analysis, which clearly demonstrated the colonization of treated endophyte in root tissues. The present study reveals an ecofriendly approach to explore T. asperellum in sorghum disease management.     

Evaluation of a multi-parent advanced generation inter-cross (MAGIC) introgressed line population for Verticillium wilt resistance in Upland cotton

Verticillium wilt (VW, caused by Verticillium dahliae Kleb) is a destructive fungal soil-borne disease in Upland cotton (Gossypium hirsutum L.). High levels of VW resistance can be transferred into Upland from Pima cotton (G. barbadense L.) through interspecific introgression breeding. In this greenhouse study, VW resistance was evaluated in a multi-parent advanced generation inter-cross (MAGIC) introgressed line (IL) population, derived from a random mated Barbadense Upland population with five generations of intermating (called RMBUP-C4) between three Upland cotton cultivars and 18 CS-B Upland lines each carrying a pair of G. barbadense chromosome or arm in the TM-1 background. The objectives of this study were to, (1) evaluate VW resistance of 530 MAGIC ILs in the greenhouse; and (2) to identify lines with VW resistance in the MAGIC population based on a total of three replicated greenhouse tests. Approximately 8 plants for each line in each replicate were grown and screened for VW resistance using three parameters i.e., disease leaf severity rating, percentage defoliated leaves, and percentage infected plants, with a total of ~?25,190 plants evaluated. A correlation analysis indicated that the three parameters were significantly and positively correlated with one another in each test. The disease leaf severity rating was the best parameter to assess VW resistance due to its relatively low coefficient of variation and its higher resolution to differentiate resistant genotypes from susceptible ones. Of the 530 genotypes, 5 showed resistance to VW, namely, NMIL348, NMIL518, NMIL405, NMIL290, NMIL307 and had higher levels of resistance to VW with mean disease leaf severity ratings, percentage of defoliated leaves, and percentage of infected plants across three tests ranging from 0.58–1.46, 9.46–26.74, and 25–95%, respectively. These lines can be used as parental lines to improve VW resistance in cotton breeding programs.     

Foliar fungal disease‐resistant introgression lines of groundnut (Arachis hypogaea L.) record higher pod and haulm yield in multilocation testing

Introgression lines (ILs) of groundnut with enhanced resistance to rust and late leaf spot (LLS) recorded increased pod and haulm yield in multilocation testing. Marker‐assisted backcrossing (MABC) approach was used to introgress a genomic region containing a major QTL that explains >80% of phenotypic variance (PV) for rust resistance and 67.98% PV for LLS resistance. ILs in the genetic background of TAG 24, ICGV 91114 and JL 24 were evaluated for two seasons to select 20 best ILs based on resistance, productivity parameters and maturity duration. Multilocation evaluation of the selected ILs was conducted in three locations including disease hot spots. Background genotype, environment and genotype × environment interactions are important for expression of resistance governed by the QTL region. Six best ILs namely ICGV 13192, ICGV 13193, ICGV 13200, ICGV 13206, ICGV 13228 and ICGV 13229 were selected with 39–79% higher mean pod yield and 25–89% higher mean haulm yield over their respective recurrent parents. Pod yield increase was contributed by increase in seed mass and number of pods per plant.     

Estimating the Risk of a Crop Epidemic From Coincident Spatio-temporal Processes

Fusarium Head Blight (FHB), or “scab,” is a very destructive disease that affects wheat crops. Recent research has resulted in accurate weather-driven models that estimate the probability of an FHB epidemic based on experiments. However, these predictions ignore two crucial aspects of FHB epidemics: (1) An epidemic is very unlikely to occur unless the plants are flowering, and (2) FHB spreads by its spores, resulting in spatial and temporal dependence in risk. We develop a new approach that combines existing weather-based probabilities with information on flowering dates from survey data, while simultaneously accounting for spatial and temporal dependence. Our model combines two space-time processes, one associated with pure weather-based FHB risks and the other associated with flowering date probabilities. To allow for scalability, we model spatiotemporal dependence via a process convolutions approach. Our sample-based approach produces a realistic assessment of areas that are persistently at high risk (where the probability of an epidemic is elevated for extended time periods), along with associated estimates of uncertainty. We conclude with the application of our approach to a case study from North Dakota.