查看更多>>摘要：The flatheaded root-borer Capnodis tenebrionis (Linne ') (Coleoptera: Buprestidae) causes serious damage to stone fruit trees in Mediterranean countries. The use of entomopathogenic nematodes (EPNs) is an eco-friendly tool that can efficiently control C. tenebrionis. In this study, the efficacy of five EPN isolates native to Morocco was assessed against different developmental stages of C. tenebrionis in laboratory and greenhouse experiments. In Bioassay 1, the susceptibility of neonate larvae of C. tenebrionis to EPNs was evaluated according to temperature (25 and 32 degrees C) and soil moisture (5 and 10%). The greatest mortality rates were observed for Heterorhabditis bacteriophora HB-MOR7 (97.5%) and Steinernema feltiae SF-MOR9 (95%) with the 10% soil moisture-25 degrees C combination. S. feltiae SF-MOR9 and Heterorhabditis sp. HJo-MOR14 induced moderate to high mortality regardless of the temperature-soil moisture combination. In Bioassay 2, Heterorhabditis sp. HJo-MOR14 performed better against adults of C. tenebrionis than the other isolates. In addition, no difference in susceptibility between females and males was recorded for each EPN isolate. In pot experiment, more live larvae of C. tenebrionis were found in roots and collar of almond trees for HJo-MOR14 (0.93) than HB-MOR7 (0.47) and SFMOR9 (0.43). Furthermore, treatments by SF-MOR9 and HB-MOR7 ensured low infestations of trees by larvae of C. tenebrionis than the treatment by HJo-MOR14 (36.7, 43.3 and 66.7% respectively). Our results show that Moroccan EPN isolates have potential as alternative methods for the control of C. tenebrionis.
查看更多>>摘要：Tripyrasulfone is an 4-hydroxyphenylpyruvate dioxygenase (HPPD)-inhibiting herbicide applied postemergence (POST) to control Echinochloa crus-galli (L.) P.Beauv. and other annual weeds in directly seeded and transplanted paddy fields in China. In this study, the baseline sensitivity to tripyrasulfone of E. crus-galli in paddy fields in China was established using dose-response assays between June and September 2020. The results showed that the sensitivity to tripyrasulfone varied among 58 populations collected from paddy fields in China. The tripyrasulfone dose causing a 50% growth reduction (GR50) in the 58 field populations ranged from 1.95 to 46.47 g a.i. ha-1, and no populations showed resistance to tripyrasulfone. At the same time, the GR50 values were not normally distributed (P < 0.0001) but distributed as a unimodal curve, and the baseline sensitivity (GR50b) to tripyrasulfone for E. crus-galli in paddy fields in China was 18.12 g a.i. ha-1. The SI50 value (the ratio between the GR50 values of the least and most sensitive populations) showed 23.8-fold variability in tripyrasulfone sensitivity among the 58 E. crus-galli field populations, while the variability declined from 23.8-fold to 2.6-fold when the SI50b value (the ratio between the GR50 values of the least sensitive population and the GR50b) was used. This study confirmed the effectiveness of tripyrasulfone against E. crus-galli in paddy fields in China and provided a reference for detecting time-dependent shifts in the tripyrasulfone sensitivity of E. crus-galli field populations.
Bag, SudeepBlythe, Eugene K.Toews, Michael D.Jacobson, Alana L....
9页
查看更多>>摘要：This is the first study to research management strategies for cotton leafroll dwarf virus (CLRDV) in the south-eastern U.S. The efficacy of aphid vector management to reduce final CLRDV incidence was investigated con-current with efforts to monitor aphid population dynamics and timing of CLRDV spread. Adjusting the planting date and insecticide applications did not reduce the final incidence of CLRDV, which was confirmed in 60-100% of plants per plot using RT-PCR. Aphid population density was reduced, but not eliminated with foliar insecticide applications. Aphis gossypii was the only species observed on cotton and was the dominant species collected in pan traps. Three distinct periods of virus spread were detected with sentinel plants including early, mid-and late-season. Most virus spread occurred during large aphid dispersal events.
查看更多>>摘要：In recent years, new fungal diseases in kiwifruits have emerged worldwide. This study is the first report of a postharvest kiwifruit rot in South Korea caused by Diaporthe eres and related fungal pathogens. After single spore isolation of Diaporthe-like fungi isolated from rotten kiwifruits, isolates were identified based on the multi-locus phylogeny using the nuclear rDNA internal transcribed spacer and three nuclear protein-coding loci. Among the 41 single-spore isolates, a majority of the isolates (75%) were identified as D. eres, followed by D. unshiuensis, D. phaseolorum, D. cf. pseudomangiferae and D. caryae. We evaluated fungicide resistance of the 41 isolates and confirmed that a significant fraction of the isolates (15%) was resistant to thiophanate-methyl, raising a concern on overuse of this type of fungicide in kiwi orchards. By sequencing a region of beta-tubulin gene, we identified two point mutations altering amino acid sequences correlated with the observed resistance. For effective diagnosis of incidence of the fungicide resistance in the fields, we developed allele-specific PCR analyses detecting the point mutations that confer reduced sensitivity to thiophanate-methyl. Genetic structure of the 41 isolates suggested that there were at least five independent mutational events for acquiring the fungicide resistance. Unexpectedly, there was no clear distinction in the genetic structure between the 41 kiwifruit isolates and Chinese isolates that caused grapevine dieback disease, suggesting these Diaporthe species are non-host-selective pathogens that could damage different horticultural crops of economic importance. This study will help develop a discerned protection program to cope with the ongoing and upcoming threats of these genetically diverse kiwifruit rot pathogens.
查看更多>>摘要：Crop health is acknowledged as a key component to secure global food security. Pisum sativum L. (pea) cultivation is questioned by different biotic, and abiotic stresses. Among them, pea root rot complex (PRRC) is the most prevalent disease caused by soil-borne fungi, and it is usually considered the limiting factor in pea yield (30-57% reduction in yield). PRRC has a diverse spectrum of hosts and may be found all around the globe. The condition stands complex, and numerous approaches such as cultural, physical, biological, and pharmaceutical have failed miserably to control PRRC pathogens. In light of the many tactics and their success, host-plant resistance represents just one realistic choice for controlling the disease in pea agriculture for the long run. It's a strong, lowcost, long-lasting, and environmentally sustainable phenomenon. Plant breeding strategies along with advanced molecular approaches viz., SNP genotyping, gene(s), QTLs mapping, marker assisted selection (MAS), have been led to rise of host-plant-resistance against PRRC. Partial resistance to Fusarium spp. is more common in pea genotypes with coloured flowers and seed coatings. MAS can speed up the breeding process by assisting in the genetic selection of targeted traits in early generations. QTLs for resistance to PRRC can be validated using NILs/ RILs generated by MAS. In the present manuscript, we review the recent results and breeding strategies for PRRC.
Arthur, Aston L.Kirkland, LisaChirgwin, Evattvan Rooyen, Anthony...
7页
查看更多>>摘要：The green peach aphid, Myzus persicae (Sulzer) is a significant global pest of a broad range of horticultural and grain crops. Control of M. persicae is primarily dependent on insecticides, however, this species has a high propensity to evolve insecticide resistance and has evolved resistance to over 80 insecticides from various chemical groups worldwide. In Australia, widespread resistance to carbamates, organophosphates, pyrethroids and neonicotinoids in M. persicae populations is commonplace. Given the ability of M. persicae to establish resistance to new chemistries quickly, programs are needed to monitor susceptibility to new insecticides before their widespread use. In this study, we used leaf-dip bioassays to generate sensitivity data and investigate potential cross-resistance in multiple field-collected populations of Australian M. persicae to two recently registered insecticides, flonicamid and afidopyropen. After 144 and 168 h exposure, we found little variation in the susceptibility of M. persicae populations to either flonicamid or afidopyropen, and no evidence of sensitivity shifts in the field. Additionally, there was no evidence of cross-resistance between flonicamid or afidopyropen and multiple known resistance mechanisms for carbamate, pyrethroid, organophosphate and neonicotinoid insecticides. The sensitivity data generated in this study prior to the evolution of field resistance provides a useful starting point for future resistance monitoring, and allows for the development and implementation of insecticide resistance management strategies which should prolong the long-term efficacy of flonicamid and afidopyropen against M. persicae.
Bibiano, Camila SilvaAlves, Dejane SantosFreire, Brenda CarolineBertolucci, Suzan Kelly Vilela...
10页
查看更多>>摘要：The fall armyworm (FAW) Spodoptera frugiperda is a key pest of countless cultures of economic importance. FAW control is still mostly achieved by using synthetic chemicals and genetically modified plants, which can cause adverse effects on nontarget organisms. In this sense, secondary metabolites are an inexhaustible source of bioactive substances. Thus, this study investigated the insecticidal activity of essential oils (EOs) of plants of the Lamiaceae family against FAW. The EOs from Hyptis marrubioides (LD50 = 18.49 mu g/larvae) and Ocimum basilicum (LD50 = 38.21 mu g/larvae) were toxic to FAW in topical bioassays. The majority of compounds of H. marrubioides were identified as beta-thujone (41.50%) and alpha-thujone (15.82%), while for O. basilicum, linalool (35.68%) and 1,8cineole (16.03%) were the major substances. The pure compounds linalool (survival probability = 28.1%), alpha-thujone (survival probability = 24.5%) and 1,8-cineole (survival probability = 40.4%) were employed in a new bioassay; although all substances were toxic to FAW, the toxicity was less than that observed for EOs from H. marrubioides (survival probability = 9.5%) and O. basilicum (survival probability = 2.1%). These results suggest that there is more than one active substance in the EOs or else, there is synergism and/or an additive effect between the substances. With regard to the experiment conducted with the parasitoid Trichogramma pretiosum, the EOs from H. marrubioides and O. basilicum were classified as harmless according to the IOBC criteria, so they are safe for this parasitoid and have potential to be used in programs of integrated FAW pest management the natural enemy T. pretiosum.
查看更多>>摘要：Tetranychus urticae Koch (Acari: Tetranychidae) is one of the key pests causing economic losses in vegetable fields. Phytoseiulus persimilis Athias-Henriot (Acari: Phytoseiidae) is used effectively in the biological control of this mite on many vegetable crops. The present study determined how different crops such as pepper, eggplant, cucumber and tomato affected the biological control of T. urticae when using P. persimilis in the field-grown vegetables in the canakkale of northwestern part of Turkey in 2016 and 2017. Predatory and prey mites were released at a ratio of 1:10 predator:prey on host plants and their numbers on leaves were counted weekly for a period of 8 weeks. The highest number of T. urticae and P. persimilis were counted on cucumber with 108.70 +/- 8.14 and 81.00 +/- 6.00 mites per leaf in 2016, and with 113.30 +/- 10.95 and 24.00 +/- 4.58 mites per leaf in 2017, respectively. Also, there was a significant difference for both the populations of T. urticae and P. persimilis on the crops on all weeks in both years. It was revealed that P. persimilis markedly suppressed T. urticae on eggplant and tomato compared to pepper and cucumber in both years. It is clear that the host crops is a key factor on the success of P. persimilis on the biological control of T. urticae on field-grown vegetables. Consequently, it is thought that these results should be taken into account in the biological control strategies of mite pests by using the predatory mites on field-grown vegetables.
查看更多>>摘要：Tomato gray mold (TGM), a worldwide destructive disease, is caused by Botrytis cinerea, and fungicide treatments are effective for its control. Pydiflumetofen is a new fungicide of succinate dehydrogenase inhibitors. In this research, 153 B. cinerea isolates were collected from eight different cities in Hebei Province from 2015 to 2017. The sensitivity of these 153 isolates to pydiflumetofen was determined by spore germination assays and mycelial growth rate assays. The results indicated that for these tested isolates, the EC50 values of pydiflumetofen ranged from 0.0036 to 0.0822 mg/L (on conidia germination), and 0.0287-1.2659 mg/L (on mycelial growth rate), with average EC50 values of 0.0327 & nbsp;+/- 0.0213 mg/L and 0.3717 +/-& nbsp;0.2744 mg/L, respectively. The frequency distribution of the sensitivity of these 153 isolates to pydiflumetofen was a continuous single-peak curve, and could be used as the baseline for testing the sensitivity of B. cinerea to pydiflumetofen. No cross-resistance existed between pydiflumetofen and the other six botryticides such as diethofencarb, pyrimethanil, iprodione, pyrisoxazole, and fludioxonil, apart from fluopyram. The control efficacy of pydiflumetofen against TGM was determined using detached leaves and in field trials. Pydiflumetofen exhibited good control efficacy against TGM and the preventive effect was better than the curative effect. In the field trials, the control efficacy of pydiflumetofen against TGM was higher than 80%, both on leaves and fruits, at doses of 120, 160 and 200 g a.i./ha. It was significantly better than pyrimethanil. This study showed that pydiflumetofen had high activity and could effectively control the prevalence of TGM, but it should be administered carefully.
查看更多>>摘要：Soybean is emerging as an important legume and oil crop in Ethiopia. However, the crop has been facing serious threats from Asian Soybean Rust (ASR), causing significant damage to the crop and not allowing it to realize its potential. This study aimed to determine the interaction of three varieties with various fungicide treatments across two seasons and two locations to manage ASR. The experiment was laid out in a RCBD in a factorial [three soybean varieties (V) and six fungicides (F)] treatment combination at two locations (L) for two years (Y) with three replications. The analysis of variance across seasons revealed highly significant V x F x Y interactions for grain yield, and F x Y interactions for severity (%) and AUDPC; while efficacy was significant (P = 0.05). The V x Y interaction showed highly significant differences for AUDPC. Across locations, there were highly significant differences for V x F x L for grain yield and V x L for AUDPC. It was only AUDPC that showed significant (P = 0.05) for the V x F interaction. There were two rates (0.75 and 1 l ha-1) of the fungicide Opera Max that provided the best protection against ASR across locations, varieties, and seasons. The yield loss on the unsprayed control treatment ranged between 29 and 65%. The evidence generated from this study clearly demonstrates the importance of identifying the right variety, rates and types of fungicides for the control of ASR for higher production and productivity of soybean in Ethiopia.
NSTL
Elsevier