Crop Protection最新文献

Garden pea (Pisum sativum L.), is an important legume grown worldwide as a source of proteins and carbohydrates. Since pea crop is cultivated globally in cool temperate climatic conditions, increasing temperatures accompanied by high humidity favors fungal infections. A fungal infection causing leaf blight symptoms was frequently observed on the leaves of pea plants grown in greenhouse and field conditions. The blight symptoms showed a water-soaked and wilting appearance with curly leaf edges accompanied by greyish mycelial growth and chlorotic lesions. The disease incidence in field conditions ranged between 5 and 10 %, whereas in the controlled greenhouse conditions, it ranged from 40 to 45%. Two isolates of the fungus, Gp03 and Gp04 were isolated from Arkel pea leaves and purified from a single conidium each. According to Koch's postulates, the pathogenicity tests with these isolates using detached leaf assay and whole plant leaf assays confirmed the pathogen. Morphological and molecular analysis of nucleotide sequences of the D1-D2 region, translation elongation factor-1α (TEF) and actin (ACT) genes confirmed these isolates as members of the genus, Cladosporium. The phylogenetic relatedness of these isolates with other members of the Cladosporium genus revealed them as fungal strains of Cladosporium tenuissimum. Further, these isolates were also confirmed as C. tenuissimum by Microbial Type Culture Collection and Gene Bank (MTCC), Chandigarh in India, and provided the accession nos. MTCC 13581 and MTCC 13582 to the C. tenuissimum strains, Gp03 and Gp04 respectively. This is the first report of Cladosporium tenuissimum infecting garden pea in Telangana, India.

The broad mite, Polyphagotarsonemus latus (Banks) (Acari: Tarsonemidae) is a highly significant pest in tropical and subtropical regions, with a wide host range that encompasses over 60 plant families. In particular, it can be a major and economically damaging pest on pepper plants, causing significant losses to the crop. The life table parameters of P. latus were determined under laboratory conditions to evaluate the susceptible and resistant cultivars of greenhouse pepper among 14 pepper cultivars, including Selva, Clavesol, Kamus, Chidem, Sympathy, Sven, Kamro, Lumos, Caoba, Bellisa, Sunset, Atlantic D90, Atlantic G50, and Atlantic P5001. The total pre-adult period was significantly different on the pepper cultivars tested, in which the shortest and longest duration was recorded on Atlantic P5001 (5.02 days) and Atlantic G50 (5.94 days), respectively. Adult longevity and total life span had significant differences among pepper cultivars, in which the longest durations were observed on Kamus (21.02 and 26.36 days, respectively). The population growth parameters, including the gross reproductive rate (GRR), net reproductive rate (R₀), intrinsic rate of increase (r), finite rate of increase (λ), and mean generation time (T), as well as the fecundity of the broad mite exhibited significant differences among the cultivars tested. Specifically, the maximum and minimum values of the intrinsic rate of increase (r) were observed in Lomus (0.319 day⁻¹) and Sunset (0.242 day⁻¹), respectively. The gross reproductive rate (28.33 eggs/individual) and net reproductive rate (27.18 eggs/individual) in the Kamus cultivar were significantly higher than those in the other cultivars. Our results indicated that among the pepper cultivars, Sunset, Sympathy, Chidem, and Clavesol were more resistant to P. latus compared with the others.

The blueberry gall midge, Dasineura oxycoccana, is a major blueberry pest in Florida and North America, primarily controlled with insecticides. However, their efficacy on D. oxycoccana and impact on natural enemies are poorly documented. We compared the effects of seven reduced-risk insecticides with malathion on larval and adult D. oxycoccana in laboratory bioassays. Acetamiprid showed the highest larval mortality, similar to malathion. Imidacloprid was effective after 2 h, while spirotetramat was effective after 3 h. On adults, cyantraniliprole and acetamiprid were as effective as malathion. Flupyradifurone began showing comparable lethality at 3 h, while spirotetramat, imidacloprid, and tolfenpyrad began inducing comparable mortality 6 h post-application. The same insecticides were evaluated for their effects on D. oxycoccana and their key parasitoids in two southern highbush blueberry plantings in North-central and Central Florida. A wetter-spreader adjuvant was added to spirotetramat as a ninth treatment. Spirotetramat + adjuvant effectively reduced adults and larval densities by up to 100% in the first year and adults by 59% and larvae by 56% in the second year. Acetamiprid reduced adult densities by 65% in 2019. Spinetoram reduced adults by 77% and larvae by 100% in 2019, while flupyradifurone reduced adults by 77% and larvae by 37% in 2020. These insecticides had minimal adverse effects on Platygaster spp. and overall parasitoid densities for both years. Based on these findings, there is potential for incorporating spirotetramat + adjuvant, flupyradifurone, spinetoram, or acetamiprid into a strategic rotational program with minimal impacts on natural enemies of D. oxycoccana.

Vitamin A deficiency in sub-Saharan Africa is mainly being addressed through crop biofortification. Several high provitamin A (PVA) maize varieties have been released as part of these measures. However, these varieties are grown in areas where Aspergillus ear rot (AER) and Fusarium ear rot (FER) frequently occur, leading to contamination with mycotoxins, which in turn reduce the yield and grain quality. Chronic mycotoxin exposure leads to serious public health problems. Therefore, PVA maize varieties should be resistant to mycotoxin contamination. In a previous study, we generated 120 PVA hybrids by crossing 60 PVA inbreds and two testers with contrasting PVA content. Several inbreds resistant to aflatoxin were detected through laboratory-based kernel screening assays. In the current study, 21 PVA inbred lines with varying carotenoid content inoculated with toxigenic isolates of A. flavus and F. verticillioides were evaluated in field trials conducted at two locations in Nigeria for resistance to ear rots and mycotoxin production. Inbred lines resistant to AER, FER, aflatoxin and fumonisin contamination were identified. High PVA inbred lines were less susceptible to the ear rots, aflatoxin, and fumonisin than those with low PVA content. There were negative correlations between PVA content and each of AER (r = −0.28, P < 0.0001), FER (r = −0.37, P < 0.0001), aflatoxin (r = −0.15, P < 0.05), and fumonisin (r = −0.27, P < 0.0001). Three promising inbred lines were resistant to both aflatoxin and fumonisin. Moreover, the inbred TZI1715 combined resistance to AER, FER, aflatoxin, and fumonisin with desirable general combining ability for high β-carotene and total PVA content. These results suggest that the PVA biofortified maize developed to address vitamin A deficiency can also contribute to reduced exposure to aflatoxin and fumonisin.

Florpyrauxifen-benzyl (FPB) is a novel auxin mimic rice herbicide used to control selected grasses, sedges, and broadleaves. Field experiments were conducted in 2020–2022 to 1) characterize the effects of FPB on rice crop safety and weed control when applied alone or in a mixture, 2) determine the FPB application timing to optimize smallflower umbrella sedge (SMF) control, and 3) evaluate the effect of late season application on rice flower sterility. In the first study, FPB was applied alone at 15, 30, and 60 g ai ha⁻¹ and in mixture with bispyribac-sodium, penoxsulam, and propanil. FPB applied alone at 30 g ha⁻¹ at 4–5-leaf (LF) rice stage controlled more than 80% of watergrasses, ricefield bulrush, and SMF and more than 99% of all broadleaf weeds at 28 days after treatment (DAT). The mixture treatments of FPB plus bispyribac-sodium applied at maximum use rate had the greatest grass weed control whereas, FPB plus propanil at the maximum use rate provided the greatest sedge control. In the second study, FPB at 40 g ha⁻¹ was applied at 1-LF, 10-, 15-, 20-, and 25-cm tall SMF, where treatments controlled 95%, 86%, 89%, 87%, and 85% of SMF at 42 DAT, respectively. In the third study, FPB at 40 and 80 g ha⁻¹ rate was applied at rice panicle initiation (PI) and 50% flowering (FL) growth stages. While the weed control was more than 90% at 42 DAT for all applications, the FL stage application caused 26% and 35% rice panicle blanking at 40 and 80 g ha⁻¹ rate, respectively. This research suggests, the window of FPB application should be from 2-LF rice to rice PI stage to ensure crop safety and highest weed control.

Large-scale application of chemical pesticides and insecticides over the years have led to resistance to these chemicals, along with a reduction in crop yield, increase in production cost as well as adverse effects on the environment and human health. In this scenario, there is a need to implement some other techniques to prevent crop losses due to pests and other pathogens. Biological control seems to be a plausible approach to remedy this situation and practice sustainable agriculture through integrated pest management. A feasible way to control nematodes, insects and fungal pathogens can be through the use of chitinase-producing microorganisms. Chitin makes up the exoskeleton of insects, cell wall of fungi, and eggshells of nematodes. Chitinase-producing microorganisms can extensively damage and even kill the pathogens. Therefore, chitinolytic bacteria and fungi might be potential candidates for the biocontrol of numerous plant pathogens. In this review, we aim to discuss the available literature on chitin degrading microorganisms, chitinase enzymes and their importance in biological control. A meta-analysis has been performed with data from the last 2 decades to assess the efficacy of different microbial chitinases on biocontrol of pathogens and a forest plot was produced to conclude the variations among different studies performed so far.

Quinoa (Chenopodium quinoa) is a pseudocereal crop, and has been widely cultivated in China with excellent sources of nutrients, amino acids, and vitamins. During the inflorescence emergence stage to the grain-filling stage, Neocamarosporium betae leaf spot and stem necrosis of quinoa (NLSQ) as a new emerging disease was observed in Shanxi Province of China. NLSQ usually infected the leaves and then gradually spread towards to the stems. Typical symptoms included tan to brown lesions and with many black pycnidia, leading to lodging, leaf abscission, and grain unfilling. Based on morphological characteristics, phylogenetic analyses, and pathogenicity tests, the pathogen was identified as N. betae. The morphological characterizations of N. betae from quinoa were pycnidial conidiomata, hyaline conidiogenous cell, and smooth hyaline aseptate conidia. At 2–6 days postinoculation, the typical symptoms induced by inoculations of N. betae on leaves and stems of quinoa. To our knowledge, this study firstly reported that N. betae was the pathogen of NLSQ in China. The findings of this current study will contribute to developing the disease diagnosis and management.

This investigation assessed the impact of calcium chloride (CaCl₂) seed priming on the direct and indirect defense mechanisms of rice (Oryza sativa L.) against the brown planthopper (BPH), Nilaparvata lugens (Stål). Our findings revealed that seeds primed with CaCl₂ significantly curtailed the survival and developmental rates of BPH nymphs and diminished the honeydew secretion by adult females. The feeding behaviour of BPH on CaCl₂-pretreated rice showed an extended non-proboscis handling (np) duration, while the phloem ingestion time (N4-b) and xylem ingestion time (N5) were reduced. Additionally, BPH nymphs exhibited a marked preference for H₂O-pretreated plants over CaCl₂-primed ones for both feeding and oviposition. Conversely, the natural enemy Cytorhinus lividipennis displayed a heightened preference for preying on BPH nymphs and eggs on CaCl₂-primed rice. The treatment with calcium led to an increased release of a diverse range of volatile compounds following BPH infestation, compared to H₂O pretreatment. Notably, the volatiles Methyl salicylate and 1-octen-3-ol were identified as the most effective deterrents for BPH and attractants for C. lividipennis, respectively, highlighting their potential role in mediating plant-insect interactions.

Drosophila suzukii is an invasive, polyphagous pest of soft-skinned fruits, causing widespread economic damage in orchards and vineyards worldwide, including Germany. Decision support systems (DSS) are necessary to control D. suzukii prior to the occurrence of considerable yield loss in terms of quantity and quality. In this study, we introduce the newly developed DSS SIMKEF, simulating and predicting the daily infestation probability of D. suzukii during the fruit ripening phase of different host crops, using hourly air temperature data. The model validation of daily infestation probability of D. suzukii resulted in correct simulations of 75% in blackberry, 54% in sweet cherry, 54% in grapevine ’Dornfelder’, 40% in sour cherry, 27% in grapevine ‘Portugieser’, and 25% in raspberry. Therefore, the current prototype of SIMKEF needs to be further improved to achieve higher accuracies of the simulation results in the future.

The soilborne pathogen Spongospora subterranea f. sp., which is subterranean and responsible for powdery scab, poses a serious threat to potato production in China. Single applications of fluazinam, cyazofamid and bupirimate via furrow application or seed dressing during the sowing period and combined application with root irrigation during the tuber initiation stage were assessed for their ability to control powdery scab under field conditions. Three field trials revealed that fluazinam or cyazofamid furrow application at 1500 g a.i. ha⁻¹ during the sowing period combined with root irrigation at 1500 g a.i. ha⁻¹ during the tuber initiation stage significantly reduced the disease incidence and disease index of potato powdery scab, with good control efficacy (58.1–79.4% and 53.1–78.5%, respectively), and provided high potato yields (3.37–5.08 kg m⁻² and 3.26–4.88 kg m⁻², respectively) and gross revenue for growers. However, due to the low price of potato and high control cost, the two selected promising chemical treatments have few advantages in terms of economic benefits. Overall, considering their control efficacy and economic benefits, fluazinam or cyazofamid furrow application combined with root irrigation treatment could be recommended for integrated powdery scab management, especially for high-value seed potato production in China.