Beran, F. 1949 Weitere Untersuchungen über die Frostspritzung von Obstbäumen. [Additional studies about frost spraying of fruit trees.]. Pflanzenschutzberichte. Wien 3(11/12): 161-176.

Notes: Frost spraying tests show an enormous increase on the effects of tar oil and mineral oil emulsions against Quadraspidiotus perniciosus on apple, pear, apricot, peach, cherry and plum trees. No adverse effects are observed on buds.