This report describes experiments carried out with the anionic, water-dispersable, polyethylene emulsion (APE), "Valcoat", which forms a thin, clear film when applied to seeds or seedlings of Pinus radiata D. Don (radiata pine). The effects of APE on seed germination and seedling growth were examined between 1976 and 1978.
The results showed that APE severely curtailed germination when used on seeds at a concentration of 20% polyethylene solids. When applied to seedlings at this concentration, the emulsion significantly retarded growth but did not cause mortality, dead topping, stunting or deformation.
At a concentration of 4% (w/v), applied as a spray to the aerial parts of seedlings about two months before lifting or immediately before planting, APE significantly increased the subsequent year’s height growth. When applied at the same concentration as a dip to roots and shoots, or to roots alone, immediately before storage of seedlings, the emulsion caused mortality or significantly retarded height and diameter increment of planted seedlings.
Results of this study suggest that when applied at a concentration of 20%, the emulsion may be successfully used in the nursery as a growth retardant for P. radiata seedlings. When applied at 4% concentration, about two months before lifting of seedlings or to tops of unstored seedlings shortly before planting, the emulsion may increase early growth of P. radiata.