Herbicides for post-emergence control of weeds in a radiata pine nursery.  G. Minko and L. A. Stephens.  August 1984.  8 pp. (unpubl.)

SUMMARY

Three experiments were carried out to examine the effectiveness of several herbicides for post-emergence use in a radiata pine (Pinus radiata D. Don) nursery at Benalla, North-eastern Victoria.

The most promising herbicide, of those tested, was hexazinone. When applied at 0.25 kg ha^-1 over nursery beds, this herbicide successfully controlled weeds just beyond the two-leaf stage of development and caused no injury to radiata pine seedlings. Similarly, the same herbicide applied experimentally at 0.78 kg ha^-1 to three-month-old weeds overtopping the seedling crop provided effective control and caused little injury to the seedlings.

But, when applied operationally by boom spray at 0.63 kg ha^-1, hexazinone caused high mortality of seedlings. This mortality was due to uneven distribution of spray, causing a higher application rate than that specified for the treatment. Until this problem is solved, use of hexazinone for control of dense mature weeds in the Benalla Nursery is not recommended.