Improvement of crucifer IPM in the Changjiang River Valley, China: from research to practice

Crucifers comprise a major group of vegetable crops in the Changjiang River Valley, China. The control of insect pests on crucifer vegetable crops has largely relied on the heavy use of chemical insecticides in the last 30 years, resulting in serious consequences of insecticide resistance, increased costs of control and insecticide residues hazardous to human health. A group of Chinese and Australian scientists have undertaken a joint venture to develop practical and sustainable IPM strategies for crucifer vegetable crops in this region. The work consists of three overlapping and ongoing phases: problem definition, research and development, and implementation. Natural enemies were surveyed and evaluated. Biological and selective insecticides were screened through bioassays and field tests. Damage relationships by various insect pests were assessed by artificial defoliation and natural infestation of plants. It was found that cabbages could endure some defoliation without reduction of head weight, but that the level of compensation varied with the growth stages being attacked. Plants at the pre-heading or mid-late heading stages could endure substantial damage while plants at transplant or cupping to early heading stage were sensitive to damage. These findings on various components interrelated to IPM were used to develop management strategies at the crop system level, which were tested in the field. Field IPM trials across several seasons and localities showed that the new strategy could offer effective control of all insect pests. Compared with conventional methods, IPM practices could usually reduce insecticide input by as much as 30–70%, with little risk of crop loss. Implementation activities included grower involvement in field trials, field days and participatory workshops as well as frequent dissemination of fact sheets. Evidence shows that a substantial improvement in farmers’ knowledge, attitude and approaches towards IPM has been achieved in the project areas. The future challenges to and opportunities for improving crucifer IPM in China are discussed.