Healthy poplars ready to plant

Press, Volume CXIV, Issue 33601, 1 August 1974, Page 9

Healthy poplars ready to plant

More than 20,000 poplar cuttings — four times the usual output — are being dispatched all over New Zealand this winter by the National Plant Materials Centre to counteract poplar rust disease. The large number of cuttings of the rust-resistant variety are available mainly through the efforts of the scientist m charge of the plant materials centre near Palmerston North, Mr C W. S. Van Kraayenoord. The centre is run by the Ministry’ of Works and Development. It was Mr Van Kraaynoord who first predicted that the rust would enter New Zealand about two years ago, and threaten the survival of millions of poplars, which are vital ini soil conservation. 18 MONTH SPREAD It has taken the rust a httle more than 18 months

to spread all over New Zea- ! land. It shows up as small ( yellow-orange spores on the leaves of poplars and can cause premature leaf-drop. Repeated attacks reduce growth, generally weaken the tree and in the long term may kill it. ’ While posing a serious problem, the effects of the rust have been counteracted by making available rustresistant replacement seedlings as quickly as possible. Records of the disease’s spread and characteristics have been maintained. The degree of susceptibility of the various poplar varieties has been established, trials] have been conducted on methods of containing the disease, and special efforts made to produce additional supplies of rust-resistant 1 vaneties. The increased number of rust-resistant cuttings available this winter will play an important part in counteracting the rust’s effects.