Plant diseases and insect pests are the arch-enemies faced by growing paulownia. They might affect the normal growth of paulownia or even cause death of the whole plant. In order to cultivate fast-growing and high-yield paulownia forests, especially the pure forests of paulownia with larger density and higher output, preventing diseases and insect pests in time is a most essential technical measure for paulownia afforestation, which will throughout the whole process of paulownia afforestation.
Primary pests of paulownia
- Root pest
The underground soil is where the root pests live. They will eat the root and stem of the sapling. They are the most harmful pests for paulownia saplings. There are more than 10 kinds of insects jeopardizing root of paulownia of which Gryllotalpidae, Agrotis and Holotricha trichophor Fairmaire are the most common ones.
- Foliar pest
Paulownia leaves are fat and large providing abundant food materials for foliar pests. There many species of pests that harm leaves of paulownia. According to investigation and documents of the paulownia production region in north of China, there are about 80 kinds of such pests of which about 10 kinds could cause disaster.
- Branch pest
The damage characteristic of such pests is relatively complex. The targets harmed by such pests are the branch and trunk of paulownia. At present, we have found 7 kinds of such pests.
Primary diseases of paulownia
- Diseases of paulownia are commonly caused by fungus (pl. fungi), virus, nematode, sunburn or flooding damage, mainly harming to root, stem and leaf of paulownia.
Ecological prevention and control for plant diseases and insect pests of paulownia
- In the natural state without human intervention, group planted paulownia will be seriously harmed by plant diseases and insect pests which will not only bring concentrated damage but also occur in the rapid speed. Especially for paulownia pure forest, forecast for diseases and insect pests is a piece of professional work which is hard for forest growers to deal with, once diseases and insect pests outbreak, the optimum opportunity for prevention and control will be missed due to the areas are too large to be prevented and controlled artificially. Moreover, the higher of the intensive degree, the faster of occurring speed and the deeper of hazard degree will be. Therefore, preparing control program for diseases and insect pests before afforestation takes on great significance.
In the process of prevention and treatment for diseases and insect pests of paulownia, besides selecting fine species with strong resistance (such as Shan Tong) and integrated control measures combining artificial method with chemical method, ecological control is economic, simple and easy to be actualized which is an effective way to prevent diseases and insect pests of paulownia occurring in large areas.
Through many years of researching and testing, we have selected a tree species --- Guangzhong Melia azedarach which could effectively resist diseases and insect pests of paulownia. Planting a small amount of such trees around or in the pure forests of paulownia will build a natural blockade for pest control of paulownia by which effectively inhibit diseases and insect pests of paulownia. Compared with those forests without Guangzhong Melia azedarach, forests with such trees will not be damaged by diseases and insect pests if their occurrence degree is slight， and will suffer from slight degree of diseases and insect pests with a slower occurring speed if their occurrence degree is serious, which wins valuable time for artificial and chemical control.