Controlled‐release granules for the delivery of pymetrozine to roots of transplanted rice seedlings with decreased phytotoxicity and enhanced control efficacy against paddy planthoppers

BACKGROUND Seedling transplanting is widely used in rice cultivation. Systemic insecticides can be delivered to seedling roots by application through rice seedling boxes before transplanting. The most challenging aspect is to provide long‐term control of rice pests and overcome transplanting shock....

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Bibliographic Details
Published in:Pest management science 2022-02, Vol.78 (2), p.812-820
Main Authors: Hao, Fengjiao, Liu, Xiaohui, Yuan, Huizhu, Yan, Xiaojing, Yang, Daibin
Format: Article
Language:English
Subjects:
Animals
Aquatic plants
Biodegradability
Biodegradation
controlled‐release granule
Cultivation
Delayed-Action Preparations
Diffusion rate
Fluorescence
Formulations
Fulgoroidea
Grain cultivation
Granular materials
Hemiptera
Insecticide resistance
Insecticides
Insecticides - administration & dosage
Kaolin
Neonicotinoid insecticides
Oryza
Pest control
Pests
Phytotoxicity
pymetrozine
rice planthopper
Roots
Seedlings
Spraying
Survival
transplanting shock
Triazines - administration & dosage
Water uptake
Xanthan
Xanthan gum
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Summary:BACKGROUND Seedling transplanting is widely used in rice cultivation. Systemic insecticides can be delivered to seedling roots by application through rice seedling boxes before transplanting. The most challenging aspect is to provide long‐term control of rice pests and overcome transplanting shock. Precise control of the release rate of insecticide can meet these requirements. Pymetrozine is a promising insecticide used for the control of rice planthoppers resistant to neonicotinoid insecticides. RESULTS In this study, four controlled‐release granular formulations of pymetrozine were prepared based on a mixture of cost‐effective and biodegradable kaolin and xanthan gum or a mixture of calcined kaolin and xanthan gum. Fluorescence images showed that different 3D networks were formed in the four granular formulations. The four granular formulations showed different water uptake rates and release rates of pymetrozine in water. Pymetrozine release rate was positively correlated with the water uptake capacity, rather than the water uptake rate of granules. Diffusion was the dominant mechanism for the release of pymetrozine from granules. Pymetrozine was found to reduce the survival of transplanted rice seedlings suffering from transplanting shock. Incorporating pymetrozine in controlled‐release granules alleviated this phytotoxicity. The survival rate of rice seedlings in granular pymetrozine treatments ranged 68.8–85.0%, whereas the survival rate was
ISSN:1526-498X
1526-4998
DOI:10.1002/ps.6696