Crop Protection最新文献

The insecticides used on coffee plants can function as bioactivators for this species and be utilized to manage Leucoptera coffeella. Thus, the objectives were to verify the bioactivation action on the morphophysiology of the coffee plant and its toxicity to L. coffeella. The treatments were dinotefuran + flutriafol 450 SC, dinotefuran + pyriproxyfen (100 + 25) EW, imidacloprid 700 WG, flupyradifurone 200 SL, thiamethoxam 250 WG, thiamethoxam + cyproconazole 600 WG, and control (water). The physiology of coffee seedlings was evaluated at 10, 20, and 40 days after application (DAA) of the insecticides. Analyses of biometric variables for aerial and root development of seedlings and survival of L. coffeella larvae were conducted at 10, 20, 40, 60, and 80 DAA. The insecticides did not alter the physiological parameters evaluated in the seedlings at 10, 20, and 40 DAA. At 60 and 80 DAA, height and leaf area were lower in seedlings treated with imidacloprid. The dry matter of the stem in seedlings treated with imidacloprid was lower than in other treatments. The volume and area of the roots of the seedlings at 80 DAA were higher in those that received the insecticide thiamethoxam 250 WG. All insecticides were toxic to L. coffeella larvae at all evaluation dates. The insecticides did not have bioactivator properties for aerial development. Thiamethoxam 250 WG has a bioactivator effect on root volume and area. The insecticides protect seedlings from infestation up to 80 DAA.

Polygonatum cyrtonema, also known as Huangjing, belongs to the Liliaceae family and is a commonly used medicinal and edible plant in Asia. In recent years, P. cyrtonema root rot disease has frequently occurred in China, significantly impacting its yield and medicinal value. However, the pathogen of the disease has not yet been identified. In this study, we aimed to identify the pathogen causing the root rot disease of P. cyrtonema by applying morphological and molecular methods following Koch's postulates. Twelve fungal strains were isolated from nine diseased rhizomes of P. cyrtonema. Morphological analysis showed that the twelve isolates included eight colony types. Among that strain, HJ-5 has the typical characteristics of Fusarium oxysporum, including single-cell microconidia, chlamydospores, and sickle macroconidia. BLAST alignment and phylogenic tree based on the tef1, rpb2, β-tubulin, and ITS genes demonstrated that strain HJ-5 exhibits the highest similarity with Fusarium oxysporum. The strain HJ-5 is identified as F. oxysporum based on morphological and molecular characteristics. In addition, the pathogenicity test showed that among twelve isolates, only strain HJ-5 led to the rhizome softening and rotting on detached rhizomes and living plants of P. cyrtonema, consistent with symptoms observed in the field. To our knowledge, this is the first report on root rot disease in P. cyrtonema caused by F. oxysporum in China, which will provide a clear prevention and management target for the root rot disease of P. cyrtonema.

Formal systems supporting the delivery of high-quality cassava seed are being established in several key cassava producing countries in Africa. Questions remain, however, about the value of certified cassava seed when compared to seed which is recycled multiple times, which is standard farmer practice. A study was therefore conducted to compare fresh cassava root yields of high-quality seed (HQS) versus farmer-saved (recycled) seed (FSS) for three widely grown improved cassava varieties in Tanzania namely: Mkuranga1, Kiroba and Mkombozi. Field experiments were established in two sites in different agricultural zones: Mkuranga (Coast Zone) and Maruku (Lake Victoria Zone). Four HQS sources (pre-basic, basic, certified, quality-declared), collectively referred to as HQS, were compared with FSS with respect to cassava brown streak disease (CBSD) foliar and root incidences, fresh root yield, marketable fresh root yield, and usable fresh root yield for each variety in the two locations. Results showed that foliar CBSD incidence in FSS was significantly greater than it was for HQS in Mkuranga1 and Kiroba varieties but not for Mkombozi. CBSD root incidence was on average six times more in FSS than in HQS. When comparing FSS with the specific certified seed treatment (CS), 25.8% of the roots were unusable due to CBSD root necrosis for FSS, compared to only 3.7% for CS. CS gave an overall fresh root yield which was 7.5 t/ha more than FSS, representing an 80.6% increase. Yield benefits derived from planting HQS were similar for Kiroba (+80.7%), Mkombozi (+81.3%) and Mkuranga1 (+79.5%), as well as across each of the four HQS classes. When also considering losses arising from severe CBSD root necrosis, the overall yield benefit arising from using CS when compared to FSS was 135%. The average estimated income gain for this increase was US$ 2279/ha, which is many times the estimated cost of obtaining certified seed. These results highlight the value of high quality seed systems and the potential gains that farmers can realize from planting high quality certified seed rather than recycling existing crops.

The aphidicidal activity and efficacy of azadirachtin- and oxymatrine-based biopesticides on the cabbage aphid Brevicoryne brassicae (Linnaeus, 1758) (Hemiptera: Aphididae), and their impacts on the main insect predators of this aphid were assessed under laboratory, semi-field, or field conditions. Laboratory results showed that azadirachtin- and oxymatrine-based biopesticides provided high acute toxicity against B. brassicae nymphs and adult females, in a manner dependent on the concentration, developmental stage, and exposure time of insects to residues. Among the insect's developmental stages, B. brassicae nymphs were more susceptible to biopesticides than adult females. In addition to acute toxicity, the biopesticides reduced the number of offspring and the amount of honeydew excreted by B. brassicae adult females. Furthermore, the biopesticides induced a repellent effect on B. brassicae adult females. Despite their high toxicity, in semi-field conditions, the azadirachtin- and oxymatrine-based biopesticides showed low biological persistence [mortality >80% up to 3 and 1 day after spraying (DAS), respectively] in comparison to the synthetic insecticide flupyradifurone (mortality >80% up to 7 DAS), which was used as a positive control. However, in the field, the biopesticides demonstrated high efficacy in controlling the B. brassicae population, with no significant impact on the population levels of different species of lacewings, ladybugs, and syrphids, which are considered the main insect predators of the cabbage aphid in agroecosystems. Therefore, azadirachtin- and oxymatrine-based biopesticides constitute an important management measure for B. brassicae in agroecosystems, including those with an ecological basis where management tools are limited, and effective control tactics must be incorporated.

Maize production faces persistent threats from maize diseases and pests (MDPs) throughout its growth cycle, posing substantial risks to food security. However, understanding the spatio-temporal dynamics of MDPs occurrences on a regional scale has remained elusive due to a lack of continuous observation data. This study curated a comprehensive dataset spanning two decades, from 1999 to 2018, across six key maize planting regions in China [Spring sown area in Northern China (1-NC), Summer sown region in Huang-Huai-Hai Plain (2-HHP), Southwest Mountain Maize Region (3-SM), Southern Hilly Maize Region (4-SH), Northwest Irrigated Maize Region (5-NI), and Maize Region in Qinghai-Tibet Plateau (6-QTP)]. The average extent of MDP occurrence in 1-NC and 2-HHP exceeded that in other regions over the two-decade period. Furthermore, the occurrence of MDPs exhibited a substantial increase in 1-NC, 2-HHP, 3-SM, 4-SH, and 5-NI over the same period. Meanwhile, the average occurrence intensity of MDPs in 2-HHP surpassed that in other regions. Notably, maize leaf blight and the Asian maize borer emerged as predominant diseases and pests in 1-NC, 2-HHP, 3-SM, 4-SH, and 5-NI. A bivariate trend analyses highlighted a notable increase in the species count for both the extent and intensity of MDP occurrences, including double-spotted leaf beetle in 1-NC, and cotton bollworm in 2-HHP. This extensive, long-term analysis offers a foundation for devising comprehensive strategies for MDP control on a national scale, enabling the formulation of tailored forecasting and control measures across six planting regions.

The citrus brown mite Eutetranychus orientalis (Klein), is known as one of the most significant pests in citrus growing areas worldwide. It has recently caused outbreaks in the Mediterranean region of Türkiye. This study aimed to determine the resistance levels of E. orientalis populations between 2020 and 2021 collected from 9 commercial citrus orchards in Adana province against 5 different acaricides, in order to determine whether the observed population outbreak was due to acaricide resistance. The resistance ratios were changed between 1.67 and 2.50, 1.00–2.53, 1.85–3.68, 1.30–2.65, and 1.93–3.13-fold for abamectin, etoxazole, fenbutatin oxide, pyridaben, and spirodiclofen, respectively. The enzyme activity levels of carboxylesterase, glutathione S-transferase, and cytochrome P450 monooxygenase ranged between 1.00 and 1.13, 1.02–1.52, and 0.94–1.72-fold, respectively. As a result of the resistance study carried out for the first time on this species in Türkiye, the resistance ratios were determined to be low for E. orientalis against acaricides. Although the current resistance rates were low, certain populations exhibited a noteworthy surge in enzyme activities when compared to the susceptible population. Based on these findings, it was concluded that by implementing an appropriate resistance management strategy using acaricides with different modes of action, it is possible to prevent potential resistance development and use these acaricides effectively on this spider mite species for many years through rotation.

Pea aphids, Acyrthosiphon pisum, are one of the major insect pests of faba bean (Vicia faba). Infestations of pea aphids on faba bean can occur at any plant growth stage and result in drastic yield losses (up to 100%). There was no established guideline to determine when to manage pea aphids on faba bean in Saskatchewan. We conducted a field study to develop an economic threshold for pea aphids on faba bean at six sites in the Saskatoon area in 2019 and 2020. No choice experiments were performed to determine pea aphid growth rate on tannin and low tannin faba bean. Under field conditions, the population of pea aphids on faba bean doubled in approximately 5.25 ± 0.19 days. The average economic threshold (ET) was 34–50 aphids per main stem of a plant. This ET provides a 7-day lead time before aphid populations are expected to exceed the economic injury level (EIL) of 680–984 cumulative aphid days or 96 to 142 aphids per faba bean main stem. All ETs were estimated based on the cost of registered insecticides and the average of three benchmark prices (high, medium and low) of faba bean from January 2018 to July 2021. Laboratory no-choice bioassays demonstrated no significant effect of faba bean tannins on pea aphid growth. Therefore, economic thresholds established in this study are applicable to both tannin and low tannin varieties of faba bean.

The effective wetting and deposition of pesticide droplets on the leaf surface significantly affect the control of pests and diseases, and its mainly affected by the leaf surface properties and pesticide formulation properties. This article aims to investigate the wettability regulation mechanism and dynamic wetting properties of banana leaves, in order to intelligently design appropriate pesticide formulations. The micro-morphology of the banana leaves exhibits a micro-nano dual-scale structure with different microstructures and roughness on the adaxial side and abaxial side. Correspondingly, the wettability on the adaxial side of the banana leaf with higher roughness (R_q = 71.1 nm) is always better than that on the abaxial side (R_q = 42.5 nm). The droplet contact performance of droplets exhibits a strong concentration dependence of surfactants, which regulate the inter-species differences in the wettability of different pesticide formulations on both sides. Besides, the dynamic wetting process of pesticide droplets exhibits strong time dependence, by using a time series method to establish an AR(2) model, precise simulation and prediction of the contact angle changes on the adaxial side (R² = 0.9560) and abaxial side (R² = 0.8903) during the dynamic wetting process were achieved. The dynamic wetting model provides new insights into the spreading and deposition processes of droplets on leaves. This work provides a favorable reference for the study of the dynamic balance between wetting and adhesion properties of pesticide spray on leaf surfaces.