Risk of disease in poplars

Press, Volume CXII, Issue 32971, 18 July 1972, Page 13

Risk of disease in poplars

Forest Service officers throughout New Zealand have been alerted to watch closely for the possible appearance of a North American poplar leaf rust, a serious disease which could be spread by wind from Australia. The Director-General of Forests (Mr A. P. Thomson) has appealed to those who have poplars, whether isolated trees or plantations, to be on the lookout for any suspicious leaf spotting, and to report it immediately to the nearest Forest Service office. The disease, discovered in New South Wales earlier this year, has spread quickly there. It could appear in New Zealand within the next 18 months. Mr Thomson said that Mr C. van Kraayenoord, of the National Material Centre, Palmerston North, who is an authority on poplar culture, visited Australia to study the disease. He had

already disseminated information widely on its identification, the susceptibility of the various poplars grown in New Zealand, and the available control measures.

Small orange-yellow blisters (“pustules”) develop on the under sides of infected leaves and can cover both sides, giving the tree a yellow sheen. Leaves then turn brown at the edges, wither, and fall prematurely. Infection spreads rapidly from the lower branches through the tree, causing it to loose almost all its leaves within three weeks. Repeated attacks cause loss of growth. Mr Thomson said that poplars were an important soilstabilising and shelter species, and the demand for the wood was likely to increase in the future.