Pilosella officinarum

The main method of control at present is to improve pasture land by application of fertilizer and oversowing with pasture species. However, species of Hieracium / Pilosella remain a problem on areas of limited potential economic development, abandoned land, reserves and national parks (Grundy, 1989). Timely oversowing and top dressing combined with intensive grazing show promise for control (Robertson, 1979). Makepeace et al. (1985) found that of all the plant species investigated, clover is the best competitor. Where perennial grasses, legumes, and other beneficial forbs are present in the plant community, fertilizers can help control Hieracium / Pilosella species by increasing the competitive ability of more desirable species.
Mechanical Control
Due to its low, mat-forming growth, mowing is not effective. Mechanical control is ineffective since small fragments of plants can root and form new populations. In addition, plants or plant parts can be accidentally transported by machinery and establish elsewhere.
Chemical Control
Species of Hieracium/Pilosella have proved resistant to most herbicides, so that chemical control of the weed does not appear practical (Grundy, 1989). P. officinarum can be controlled with 2,4-D amine or ester, and a mecoprop + MCPA + dicamba formulation, although results have been variable. This variability in effectiveness was thought to be related to the time of application. The 2,4-D ester usually yielded better results than the amine formulation (Meeklah, 1980). However, total kill is unlikely and follow up with fertilizer and top dressing is considered essential (Grundy, 1989). A problem with chemical control is that the chemicals have as much, or more, impact on many desirable pasture species than they do on P. officinarum (Grundy, 1989). In many areas in New Zealand chemical control is uneconomic and thus not considered on a large scale (Grundy, 1989).