Gama, Andre B.Peres, Natalia A.Singerman, ArielDewdney, Megan M....
9页
查看更多>>摘要：Gama, A. B., Peres, N. A., Singerman, A., and Dewdney, M. M. 2021. Evaluation of disease alert systems for postbloom fruit drop of citrus in Florida and economic impact of adopting the Citrus Advisory System. Crop Protec. XX: xx-xx.Postbloom fruit drop of citrus (PFD) is caused by Colletotrichum abscissum in the Colletotrichum acutatum species complex. PFD does not occur annually but some growers tend to apply fungicides during flowering every year, wasting resources and negatively impacting the environment. Due to its sporadicity, the Fungicide Application Decision system (PFD-FAD) and the Citrus Advisory System (CAS) were developed in Florida and Brazil in 2001 and 2017, respectively, to aid in PFD management. Our objectives were to compare the recommendations from CAS and PFD-FAD, a weekly fungicide treatment schedule, and a nontreated control. We also aimed to assess the economic impact of adopting CAS over the other fungicide schedule treatments with low-and high-risk aversion profile scenarios. Weather conditions were not favorable to PFD in seven field trials. We performed one fungicide application based on CAS over four seasons. An average of approximately 2 and 3 fungicide applications per trial was performed based on PFD-FAD and the weekly treatments, respectively. Average cost to manage PFD following CAS, PFD-FAD, and the weekly treatments were, respectively, $17.52, $186.87, and $272.35. The reduction in management costs related to CAS also translates to reduced use of commercial fungicide formulations in small properties by 382 and 573 L compared to PFD-FAD and the weekly treatments, respectively. CAS recommendations greatly reduced production costs and fungicide usage without compromising disease control and citrus yield in years of low weather favorability for PFD in Florida.
Santana, Alisson da SilvaBaldin, Edson Luiz LopesLima, Ana Paula Santanados Santos, Thais Lohaine Braga...
7页
查看更多>>摘要：The introduction of Bemisia tabaci Mediterranean (MED) (Gennadius) (Hemiptera: Aleyrodidae) (Biotype Q) into Brazil has attracted the attention of farmers and the scientific community as this species has a high capacity for infestation and high tolerance to conventional insecticides. As an alternative to chemical control, botanical derivatives stand out as a valuable tool for integrated pest management (IPM). In this context, this work eval-uated for the first time the bioactivity of essential oils of Piper marginatum Jacq. (Piperaceae) (PM-EO) and Mansoa alliaceae (Lam.) A.ww H. Gentry (Bignoniaceae) (MA-EO) against B. tabaci MED. First, concentration-mortality bioassays were performed to estimate the lethal concentrations (LCs) on nymphs of B. tabaci MED. The LC(50)s and LC(90)s were tested in multi-choice assays (repellency and oviposition deterrence) and no-choice assays (ovicidal effects and infestation ability). Finally, assays were carried out in a greenhouse to check the efficiency of the essential oils under semifield conditions. The major compounds identified in PM-EO were (E)-methyl eugenol (34.7%) and (Z)-methyl eugenol (27.5%), while diallyl trisulfide (52.8%) and diallyl disulfide (33.9%) were the major compounds in MA-EO. The EOs were toxic against nymphs in the laboratory and greenhouse and showed ovicidal effect and repellent action. The EOs also reduced oviposition and inhibited the colonization by B. tabaci MED. Our results reveal two promising sources of botanical pesticides to control B. tabaci MED. These compounds can cause lethal and sublethal effects in all insect life stages, increasing the control efficiency.
查看更多>>摘要：Faba bean is the most important food legume crop; however, its productivity is threatened by faba bean gall (FBG) disease. Faba bean gall is an emerging and destructive disease in the highlands of Ethiopia. Field experiments were conducted on farmers' field during the 2018 and 2019 cropping seasons in Bassona Worana district, Ethiopia under natural conditions to estimate yield losses on local cultivar and improved faba bean varieties and to determine fungicides spray schedules. The experiments consisted of two moderately tolerant (Degaga and Gora) faba bean varieties and one susceptible local cultivar, two fungicides [Bayleton 25 WP (Triadimefon 250 g kg( -1)) and Ridomil Gold MZ 68 WG (Metalaxyl 40 + Mancozeb 640 g kg( -1))] and two application schedules (10 and 15 days). The treatments were arranged in randomized complete block design with three replications in factorial combinations. The results showed that use of different faba bean genotypes and applications of fungicides significantly (P < 0.001) reduced FBG disease epidemics and minimized grain yield loss. Variety Gora sprayed with Bayleton at 10 days interval recorded low mean FBG disease severity (26.7 and 13.0%) and AUDPC of 1866.7 and 751.7%-days in 2018 and 2019, respectively. High mean grain yields of 3.7 t ha(- 1) (2018) and 5.0 t ha(- 1) (2019) were also obtained from variety Gora sprayed with Bayleton at 10 days interval. High grain yield losses of 62.5% (Degaga), 54.1% (local cultivar) and 50.0% (Gora) were obtained from unsprayed plots of each genotype. Conversely, faba bean genotypes obtained yield increases of 166.4% (Degaga), 100% (Gora) and 121.3% (local cultivar) when treated with Bayleton at 10 days interval in 2018. Similar trends were observed regarding 100-seed weight (HSW) loss and in 2019. Moreover, unsprayed plots of each genotype recorded the highest disease severity and AUDPC and the lowest grain yield in both cropping years. On the other hand, faba bean grain yield and yield components demonstrated an inverse relationship with disease severity. Hence, use of tolerant faba bean varieties like Gora and application Bayleton at a rate of 0.7 kg ha(- 1 )at 10 days interval is essential to manage FBG disease, thereby minimizing yield and HSW losses of faba bean in the study areas.
Justus, Claudia MariaPaula-Moraes, Silvana VieiraPasini, AmarildoHoback, W. Wyatt...
8页
查看更多>>摘要：Although defoliation economic thresholds (ETs) in soybean are well-established, there are concerns about Spodoptera spp. and Helicoverpa spp. damaging soybean pods and flowers. Moreover, S. eridania is the most common species of its genus feeding on soybean in Brazil. On this account, we quantified the feeding of S. eridania larvae on leaves, pods and flowers of BRS388RR and BRS1001IPRO cultivars in the laboratory. In the field, trials were conducted testing artificial injuries for 3 consecutive crop seasons. Results indicated that third-instar S. eridania can grow when feeding on pods (from plants at R3 stage). However, the larval stage is lengthened (27.4 days) compared with larvae feeding on leaves (19.9 days). Tests with older pods (stages R5.1 and R5.5) resulted in 100% mortality. For neonates, 100% mortality was observed for both pod and pod + flower feeding. Also, soybean tolerated all tested injuries in the field, including 25% perforated pods with 16.7% defoliation or 100% flower removal, without yield reduction. Overall, S. eridania is a leaf feeder. Older larvae (from 3rd instar) can feed on pods at an early plant reproductive stage (R3 stage). However, soybean tolerance to pod and flower injuries is high, even when occurring in combination with defoliation. Therefore, an ET of 25% of injured pods or a general defoliation ET of 15% at the reproductive stage is safe. Flower removal at R2 reproductive stage by S. eridania should not trigger management because no reduction in yield was observed even when 100% of flowers were removed.
查看更多>>摘要：Obtaining derivatives with insecticidal properties from abundant plant biomass (waste) represents a good opportunity to transform environmental problems into innovative solutions for pest management programs. In the present study, we evaluated the toxicity of the aqueous emulsions of the ethanolic extract of Annona mucosa and Annona sylvatica (Annonaceae) seeds on the European pepper moth Duponchelia fovealis (Lepidoptera: Crambidae), a major pest of strawberry plants. In addition, we evaluated anti-feeding and developmental inhibitory effects, as well as macro and microscopic damage to the excretory and nervous systems of European pepper moth larvae. In the contact bioassay, the aqueous emulsion of A. mucosa extract provided the fastest action on larvae with LT50 of 6.10 h, followed by chlorfenapyr (Pirate (R)) (LT5(0) = 8.2 h) and the aqueous emulsion of the A. sylvatica extract (LT50 = 10.3 h). In contrast, the commercial bioinsecticide based on acetogenins (Anosom (R) 1 EC) had a higher LT50 (32.8 h). In addition to the lethal effects, the aqueous emulsions tested caused significant phagodeterrence (> 90%) and inhibited the development of D. fovealis. Macroscopic observation revealed the presence of edemas as well as the darkening on the surface of the larvae's cuticle. Histological analyses detected alterations. Our results suggest that aqueous emulsions produced from ethanolic extract of A. mucosa and A. sylvatica seeds, a residue in fruit processing industrial complexes (pulp factories), are alternatives for the management of D. fovealis, especially in organic and/or ecological strawberry production systems.
Akoijam, RomilaSingh, Y. SurajThokchom, SushantiNongtdu, Emekamwamut...
7页
查看更多>>摘要：Tree bean (Parkia timoriana), is an important multipurpose leguminous tropical deciduous tree species widely grown in the Northeastern states of India. The occurrence of the high incidence of damping-off (86.19%) disease was observed in tree bean nursery grown in Umiam, Meghalaya, a state in Northeastern India. Therefore, a systematic study was undertaken to record the symptoms and characterize the morphological features, the taxonomy of pathogen causing damping-off disease of P. timoriana and confirm it by pathogenicity assay. The infected seeds exhibited typical symptoms of covering with whitish mycelium and cotyledons were completely rotten in later stages of infection and emitted foul odour. Infected seedlings exhibited the symptoms of root rot followed by wilting, dried stem, and complete mortality of the seedlings. The pathogen isolated from the rotten seeds and wilted seedlings consistently showed the association of Fusarium oxysporum and its identity was confirmed based on morphological characteristics and sequences of ITS-rDNA and TEF genomic regions. Five representative isolates (TBSR 1 to 5) exhibited high similarity (> 98%) to the known authentic gene sequence of F. oxysporum. The pathogenicity test produced similar to natural symptoms of wilt at 30 days after inoculation, confirming the etiological association of Fusarium oxysporum. To the best of our knowledge, this is the first to report on F. oxysporum causing damping-off disease of P. timoriana in India and worldwide.
查看更多>>摘要：Neonicotinoid insecticide nitenpyram is widely used in controlling rice hoppers including Sogatella furcifera (Horv & aacute;th). At present, the effects of nitenpyram on the biological traits and metabolic enzymes of S. furcifera remain unclear. In this study, we applied an age-stage, two-sex life table to evaluate the sublethal effects of nitenpyram on S. furcifera under one-or multi-generation exposure. Fecundity of F-0 individuals was significantly decreased in the LC25 treatment group compared to the control. Additionally, in contrast to control, the preadult period, male adult longevity, female adult longevity, longevity, total preoviposition period (TPOP), oviposition days and fecundity were significantly decreased in the F-1 and F-6 generations, while the development time of the 1st, 3rd and 5th-instar in the F-6 generation were significantly shorter than the control and (or) the F-1 generation. Moreover, except for the mean generation time (T) that was significantly decreased in the F-1 and F-6 generations, other population parameters such as the intrinsic rate of increase (r(i)), finite rate of increase (lambda) and net reproductive rate (R-0) were not influenced by nitenpyram exposure. The P450 and EST were both significantly increased in the F-0 and F-6 individuals after nitenpyram (LC25) treatment, and the P450 showed a higher activity in the F-6 generation than F-0. The mRNA levels of four P450 genes (CYP4CE3, CYP417A4, CYP439A3 and CYP6FJ3) were induced by nitenpyram (LC25) treatment in both the F-0 and F-6 generation, and these four P450 genes were also significantly upregulated in the F-6 generation compared with F-0. Our findings are useful for developing rational application strategies for using pesticides and understanding the metabolic resistance of nitenpyram in S. furcifera.
查看更多>>摘要：Lentil (Lablab purpureus) is cultivated worldwide for its high nutritional value and ability to grow in relatively poor conditions. Anthracnose, a disease caused by Colletotrichum spp. that cause leaf lesions and impair growth, is common in legumes including lentils. In August 2020 in Guizhou Province, southwest China, anthracnose symptoms were observed on lentil plants growing in an agricultural field. Based on morphological characters and phylogenetic analyses of the combined sequences of internal transcribed spacer region (ITS), chitin synthase 1 (CHS-1), glyceraldehyde-3-phosphate dehydrogenase (GAPDH), beta-tubulin (tub2) and actin (ACT), the isolated fungus of the disease was identified as Colletotrichum karsti. Koch's postulates were confirmed by a pathogenicity test and pathogen re-isolation and identification. To the best of our knowledge, this is the first ever report of anthracnose in lentil plants caused by C. karsti in the world.
查看更多>>摘要：Diaphorina citri Kuwayama (Hemiptera: Liviidae), is a key pest of citrus associated with the yet uncurable Huanglongbing (HLB) disease, that is threatening worldwide citrus production. Control of D. citri has hitherto relied on chemical insecticides and on the use of the parasitoid Tamarixia radiata (Waterston) (Hymenoptera: Eulophidae). However, use of insecticides is problematic due to environmental and social issues, especially where D. citri is mostly spread in residential areas, and use of T. radiata has resulted in mixed success. Therefore, there is an urgent need to find sustainable and complementary practices to control this pest. Generalist predators, including green lacewings and coccinellids, have been frequently associated to D. citri in field surveys, yet they have rarely been tested. We have tested the predation capability under laboratory, greenhouse and semi-field conditions, of five predators: the green lacewings Chrysoperla comanche (Banks) and C. rufilabris Burmeister (Neuroptera: Chrysopidae), the coccinellids Diomus pumilio Weise and Rhyzobius lophanthae (Blaisdell) (Coleoptera: Coccinellidae) and the brown lacewing Sympherobius barberi Banks (Neuroptera: Hemerobiidae). All of them were capable of feeding on D. citri and reduce its populations under laboratory conditions, but critical differences emerged in greenhouse and field cages, with some predators (the green lacewings and D. pumilio) being the most effective. We discuss possible ways of utilizing these predators as an additional biological control tool to address current limitations of D. citri control in commercial groves, in residential areas and at the urban agricultural interface.
查看更多>>摘要：Fungicides remain the most important tool to manage downy mildew on cucumber. The objective of this study was to estimate yield losses that might occur if fungicides to which Pseudoperonospora cubensis has demonstrated reduced efficacy were applied to slicing cucumber. A downy mildew-susceptible hybrid cultivar was grown in spring and fall 2020, sprayed weekly with one of four oomycete-specific fungicides (cymoxanil, fluopicolide, propamocarb, or oxathiapiprolin + chlorothalonil) applied in alternation with chlorothalonil. Control treatments were chlorothalonil applied biweekly and water. The fluopicolide-chlorothalonil treatment and the water control were repeated in spring 2021. Cucumbers were harvested 12 times, sorted by size, and weighed. Profits were calculated by subtracting production and fungicide application costs from the crop values, which were calculated with prices from terminal markets in the eastern United States during the harvest periods. Treatments performed the same in spring and fall 2020. Area under the disease progress curve (AUDPC) was significantly lower with fluopicolide, propamocarb, and oxathiapiprolin + chlorothalonil than cymoxanil and both controls (P = 0.01). AUDPC was lower with fluopicolide than with oxathiapiprolin + chlorothalonil. Mean marketable weights did not differ among the four fungicide treatments but were greater than in the two control treatments (P = 0.05). Profits also were greater for the four fungicide treatments than the controls, a mean of $8,829/ha versus $2,437/ ha, respectively. Results with fluopicolide-chlorothalonil in 2021 confirmed results in 2020. Fungicides with reduced efficacy, like cymoxanil, or fungicides for which resistance has been reported, like propamocarb hy-drochloride or fluopicolide, may still protect hybrid slicing cucumber from yield losses due to downy mildew.
NSTL
Elsevier