Influence of cutting off distal ends of Quercus robur acorns on seedling growth and their infection by the fungus Erysiphe alphitoides in different light conditions
Quercus robur seedlings are very often infested by oak powdery mildew caused by Erysiphe alphitoides.
This disease attacks primary leaves with high insolation. In our experiment seedling growth in different light
conditions was observed. Seedlings were derived from intact seeds or from seeds where the distal ends of
acorns were cut off. Acorns were sown in pots at four light conditions (2%, 8% and 30% light transmittance
and in full sunlight). For half of the seedlings we reduced the influence of powdery mildew by using a fungicide.
Height of seedlings, shoot dry mass and the degree of damage caused by Erysiphe alphitoides were measured.
The highest damages were in full light conditions and the lowest in the 30% light treatment. The influence
of acorn reduction on powdery mildew infection was not significant (p=0.0763), however, in the full
light conditions the seedlings from cut acorns were ca. 30% less damaged. The cutting of acorns also alters
the height of seedlings and shoot mass. The tallest seedlings were from cut seeds growing in the 30% light
treatment. The influence of the fungicide was lowest in the 30% light treatment where the decrease in damage
was only ca. 10%. For nursery practice we can say that oak seedling production from cut off acorns under
30% light transmittance should give the best results of seedling growth even without the fungicide application