A study on the physical mechanism of resistance of main poplar strains againstCryptorrhynchus lapathi L. in North China

Abstract

The physical mechanism of resistance of poplar againstCryptorrhynchus lapathi L. is directly correlated with the morphological structure of bark, concerning the following 5 aspects: 1. It is correlated with whether surface bark of larva transvered tunnel crack or not, early or late. Those that do not crack or crack late are susceptible strains while those that crack early are resistant strains. 2. It is correlated with thickness of cork layer. Thick cork layer can increase resistance against pest while thin one is more susceptible to pest attack. 3. It is related with age of tree. Trees at the age of 1–2 possess immunity to the pest, at 3–4 are relatively resistant, at 5–8 are susceptible and over 9 are more resistant. 4. It is also correlated with the rate of trees healing round the holes of larva tunnels. Those healing faster arc resistant while those healing slower are susceptible. 5. It is related with the number of various scars on bark surface.

Keywords

Young Tree / Heilongjiang Province / Damage Rate / Susceptible Strain / Poplar Plantation

References

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