Selection and breeding for insect and disease resistance
As reported earlier, data on field applications of conventional breeding can be difficult to find, as these are typically not reported so often in the scientific literature. Also, pest and disease resistance breeding is a long-term undertaking, and as most work started in the 1970s, it is not surprising that only a few practical applications have been noted. However, there seems to be a small but steady increase in moving programmes from pure research into the early phases of development and use of resistance in forestry. Again, because of the great interest in the development of transgenic trees for pest and disease resistance, some publications are becoming available for resistance to leaf-eating pests, with the use of Bacillus thuringiensis (Bt)-transformed poplars. These have been deployed in China starting in 2002 (<500ha in 2002), however, China is a specific case in the sense that:
- large man-made forests, mainly composed of poplar, have been crippled by insect pests and diseases;
- offsite planting, a narrow genetic base and poor silvicultural practices are often combined with heavy public investments in forest biotechnology, and incentives for the private sector to invest in commercial plantations (fuelled by wood demand) drives a dynamic plantation sector;
- plantation forests in many parts of China follow an agricultural model (private sector; reliance on few fast-growing species or genera; narrow genetic base; rapid adoption of new technologies; willingness to use improved genetic materials, including genetically-modified trees).
- Monitoring developments in the use of transgenic trees in China would be very informative, as there is almost a decade now of experience.