Aerial spraying combats pine blight

Waimarino Bulletin, Volume 2, Issue 28, 10 December 1984, Page 14

Aerial spraying combats pine blight

Large areas of both State and private forests in the Karioi and lower King Country region have been sprayed against the pine-tree blight known as dothistroma. The disease only affects inland forest areas — it cannot thrive in the saltladen winds of coastal regions. To combat the disease locally a copper-based antiblight spray is applied by air as a routine operation. Aircraft from Wanganui Aero Work did the spraying of Winstones Afforestation blocks between Raetihi and

Pipiriki while a Feildingbased company applied the spray to 1300 hectares of Karioi State Forest 's 19,000 hectares after a survey had. pin-pointed the affected areas. The annual survey of all forestry blocks indicated that a build-up of the dothistroma blight had occurred because of favourable climatic conditions in the past year. When it was discovered last year that this pine-tree disease had caused cancer in animals the guidelines for mandatory spraying were

changed. Previously if 25% of the forest area had been affected by the blight, spraying became necessary. Now, under the changed guidelines only 15% of the forest needs to be affected before spraying becomes obligatory.

Forest Service workers are not allowed to work among trees with more than 10% dothistroma infection. The spraying programme was costing about $5 per hectare. Private forest owners paid the Forest Service for applying this anti-blight treatment.