水稻多病虫害协同防控技术初探

为了将水稻防治适期窗口叠加或相近的病虫害进行整合,集成水稻多病虫害协同防控技术,以减少施药次数、施药量和防治成本的目的,选择常规防治水稻主要病虫害的化学药剂,开展多药剂兼施田间药效试验。结果表明,浸种期可协同防控水稻干尖线虫、青立枯病和恶苗病,移栽前苗期可协同防控1代二化螟、稻水象甲和稻潜叶蝇,孕穗末期可协同防控稻瘟病、稻曲病和2代二化螟,齐穗期可协同防控稻瘟病、稻曲病和稻飞虱。该技术的研究,有效地降低了施药频次与施药量,提高对病虫害防治的及时和有效性,节本增效效果显著。

广东柑橘化肥农药减量增效技术模式

广东是我国柑橘重要产区,柑橘产业受黄龙病影响严重,在柑橘生产中,果农高度依赖化肥、农药的投入。近些年随着品种改良和产业结构优化调整,广东柑橘生产水平逐年提高,但仍存在施肥过量、施肥方式不合理、管理粗放、农药滥用、肥药利用率低等问题,并由此带来了生态环境污染及柑橘果品质量安全等问题。目前,广东柑橘产区化肥、农药用量高,施用方式不合理,具有较大的减施和改进潜力。为改善广东产区柑橘施肥施药现状,按照“科学用量、替代减量、协同增量”的橘园科学用量的思路,通过多年田间关键技术筛选、集成与示范,优化整合相关配套措施,构建了广东产区柑橘化肥农药减量增效技术模式。该技术模式明确了水肥一体化、有机肥替代化肥、病虫害精准测报、同适期多病虫害协同防治、合理配施增效助剂、地面覆盖除草等技术要点,已经在广东柑橘产区应用推广,有效地减少了橘园化肥、农药的用量,并且在主要病虫害防控、产量及品质上取得效果良好,为广东产区柑橘的健康可持续生产提供了科学技术支撑。

Active changes of lignification-related enzymes in pepper response to Glomus intraradices and/or Phytophthora capsici

The activities of enzymes responsible for lignification in pepper, pre-inoculation with arbuscular mycorrhizal (AM) fungus of Glomus intraradices and/or infection with pathogenic strain of Phytophthora capsici, and the biological control effect of G. intraradices on Phytophthora blight in pepper were investigated. The experiment was carried out with four treatments: (1) plants pre-inoculated with G. intraradices (Gi), (2) plants pre-inoculated with G. intraradices and then infected with P. capsici (Gi+Pc), (3) plants infected with P. capsici (Pc), and (4) plants without any of the two microorganisms (C). Mycorrhizal coloni-zation rate was reduced by about 10% in pathogen challenged plants. Root mortality caused by infection of P. capsici was com-pletely eliminated by pre-inoculation with antagonistic G. intraradices. On the ninth day after pathogen infection, Peroxidase (POD) activity increased by 116.9% in Pc-treated roots but by only 21.2% in Gi+Pc-treated roots, compared with the control, respectively. Polyphenol oxidase (PPO) and Phenylalanine ammonia-lyase (PAL) activities gradually increased during the first 3 d and dramatically decreased in Pc-treated roots but slightly decreased in Gi+Pc-treated roots, respectively. On the ninth day after pathogen infection, PPO and PAL decreased by 62.8% and 73.9% in Pc-treated roots but by only 19.8% and 19.5% in Gi+Pc-treated roots, compared with the control, respectively. Three major POD isozymes (45 000, 53 000 and 114 000) were present in Pc-treated roots, while two major bands (53 000 and 114 000) and one minor band (45 000) were present in spectra of Gi+Pc-treated roots, the 45 000 POD isozyme was significantly suppressed by G. intraradices, suggesting that the 45 000 POD isozyme was induced by the pathogen infection but not induced by the antagonistic G. intraradices. A 60 000 PPO isozyme was induced in Pc-treated roots but not induced in Gi+Pc-treated roots. All these results showed the inoculation of antagonistic G. intraradices alleviates root mortality, activates changes of lignification-related enzymes and induces some of the isozymes in pepper plants infected by P. capsici. The results suggested that G. intraradices is a potentially effective protection agent against P. capsici.

Interdependence between Natural Habitats and Ricefields for Rice Pest Management in the Agusan Marsh Floodplain

This paper describes how aquatic insect diversity in major natural habitats of Agusan marsh relates with nearby ricefields to determine the interdependence between them for sustainable rice production through natural pest control and for conservation of aquatic fauna in the marsh. Sampling for one year including two cropping seasons of rice production was conducted in various natural habitats of the marsh and in the adjoining rice fields. Both the natural habitats and rice fields were characterized in relation to determining habitat suitability for aquatic insects. The sedge-dominated swamp had the highest diversity among the natural habitats, while the fern-dominated swamp had the lowest. In the adjacent ricefields, diversity was similarly highest in the site near the sedge-dominated swamp, while the lowest was in the ricefields adjoining the Sago forest. Species composition of aquatic insects among the habitats differed between the wet and dry seasons. However, similarity patterns exist between natural habitats and rice fields. The closer similarity in species composition between natural habitats and ricefields indicates habitat connectivity which is an important consideration in planning and effective pest management and ecologically sound rice farming in the marsh.

The Potential of Subculture Helicoverpa armigera Nuclear Polyhedrosis Virus as an Alternate Synthetic Insecticides to Control Insect Pests in Cabbages Plantation （Brassica oleracea var. capitata L.）

Subculture Helicoverpa armigera nuclear polyhedrosis virus （HaNPV） is an entomopathogenic virus isolated from cadaver of Helicoverpa armigera larvae, and is successfully produced in Spodoptera litura larvae as an alternate host. These viral agents have been used to control the population of three species insect pests Spodoptera litura, Crocidolomia pavonana and Plutella xyllostella, which were infested in cabbages plantation. The concentration of virus of 4 × 10^7 polyhedra/mL was sprayed in cabbage leaves 24 h before infested of larva and every four days after. The research used randomized design which consisted of one factor （three species of second instar larvae, S. litura, C. pavonana, P. xyllostella） and eight replications. The result showed that the three species of larvae were sensitive against subculture HaNPV infection. The mortality of each larval species （S. litura, C. pavonana and P. xyllostella） was 100%, 97.5% and 98.7%, respectively. Subculture HaNPV can be utilized to control the population of three species of insect pests in cabbage plantation.