Study On The Spore Formation And Release Pattern Of Valsa Ceratosperma, And The Lesion Expansion Dynamics Of Apple Tree Canker

Apple tree canker caused by Valsa ceratosperma (Tode et Fr.) Marie is one of the most serious diseases on apple production in China. It occurred almost all the apple production area in China, and threats the sound development of apple production. Investigation on the lesion year-round expansion dynamics, condia producing and release patterns was conducted to illuminate the disease outbreak regularity for the aim to help making up control methods. In vitro test and in vivo experiments were conducted.. The main results are as follows.1. The canker lesion of apple tree can develop all around the year. The canker lesion developed very fast in spring and the lesion expansion proportion occupied 68.2% of the amount of whole year. The canker lesion developed moderately in autumn and summer and slow in winter, the expansion proportions were 13.4%, 12.1% and 6.3% respectively.2. In field condition, visible sporocarp usually appeared one month after inoculation. It needed 21 days to form in spring, 35 days in summer, 29 days in autumn and 63 days in winter. Mature sporocarp could be found in the field all around the year, and the mature rate ranged from 70 to 90 percent.3. Condia horn could be found in the field at different periods of the year. Precipitation and relative humidity were the key factors affecting the condia producting and release of V. ceratosperma. Tepmerature was not the key factor.4. Six cultural media were used to test the pycnidium producing of V. ceratosperma. Results showed that the pycnidium producing ability of varied on the tested cultural media. The pycnidium mature rate of V. ceratosperma on ABA was the highest one, followed by that on PDA. When cultured on ABA under UV light lamp, V. ceratosperma produced biggest pycnidium with high mature rate and large number of conidia within a short time,...