Uptake of soil‐applied thiamethoxam in orange and its effect against Asian citrus psyllid in different seasons

Abstract

BACKGROUND: Asian citrus psyllid (ACP), Diaphorina citri Kuwayama, is an important pest of citrus worldwide because it transmits the bacteria causing huanglongbing (HLB). We investigated the effects and persistence of two soil application rates of thiamethoxam on ACP populations in two flushing seasons in the field. Thiamethoxam and clothianidin residues in the fruit were detected to evaluate food safety.RESULTS: Soil application of 50% thiamethoxam water-dispersible granules at concentrations of 4 and 10 g tree −1 significantly decreased ACP populations, and there was a positive correlation between control efficacy and the persistence of thiamethoxam and clothianidin in leaves, providing longer-term protection for up to 90 days in the fall compared with 60 days in the spring. Higher thiamethoxam and clothianidin amounts were observed in new leaves than in old leaves. Thiamethoxam and clothianidin residues at a high rate in fruit were 0.012 and 0.010 mg kg −1 at harvest, respectively, and neither insecticides was detectable at low rates.CONCLUSIONS: These results demonstrate that soil-applied thiamethoxam plays a role in defending ACP, and provides an extended period of control efficacy. This knowledge could provide a reference for the control of ACP by soil application of thiamethoxam to reduce HLB spread.

Evaluation of flupyradifurone for the management of the Asian citrus psyllid Diaphorina citri via dripping irrigation systems

“…The peak concentration of flupyradifurone occurred within 40 days of application, and measurable levels began to decline steadily in subsequent days for all three applied dosages. ACP populations are inextricably related to the temperature and flushing cycles of citrus trees, which are most abundant during August in south China 4,28 . If flupyradifurone is applied to the soil in July, it can persist long enough to protect citrus trees from ACP, and the preharvest interval is sufficient to ensure food safety.…”

Teaching Design of Online Ideological and Political Course Based on Deep Learning Model Evaluation

“…In practical terms, teachers are supported to use more straightforward teaching methods, such as creating real-life contextual problems, to help students develop deep learning skills. In this paper, using Bayesian theory and Bayesian classifier research methods, a machine learning model was constructed using Python to establish the correspondence between online teaching of curriculum thinking and highlevel semantic features and to achieve the ability of computers to identify high-frequency knowledge points through text learning and instructional design evaluation research [8]. Based on the above analysis, this paper focuses on the design and application of questions in the teaching of ideology and politics to promote students' deep learning, with the title of "Research on the Design of Teaching Questions in High School Ideology and Politics Based on Deep Learning.…”

Effect of Adjuvants on Oxytetracycline Uptake upon Foliar Application in Citrus

“…However, as little as 0.4% of the applied insecticide may reach its target and the rest of the applied material is deposited in the environment [ 22 ]. Soil drenching is utilized as an alternative to spraying in order to minimize chemical loss [ 23 ]. In this method, chemicals are applied to the soil in excess amount around the tree in order to be taken up by the roots [ 23 ].…”

“…Soil drenching is utilized as an alternative to spraying in order to minimize chemical loss [ 23 ]. In this method, chemicals are applied to the soil in excess amount around the tree in order to be taken up by the roots [ 23 ]. Soil drenching is used for many insecticides including neonicotinoids, which are used to control D. citri [ 24 ].…”