Control of Dothistroma using aerial application of copper oxychloride

Summary

Copper fungicides are used routinely in New Zealand to help manage Dothistroma needle blight in their pine plantations. In the summer of 2013 Forest Research set up an aerial spraying trial in an area of Scots pine near Monaughty in Moray and Aberdeenshire. The fungicide, copper oxychloride, was applied once via a Micronair system mounted on a helicopter.

Research Objectives

This initial, 5 hectare trial was carried out to identify what environmental impacts may be associated with the aerial application of copper oxychloride to pine crops in Britain. 

We investigated: 

  • The persistence of copper on pine foliage
  • Persistence of copper in the soil
  • Impacts on ground flora and fauna

Results so far 

Copper oxychloride persisted for at least 13 weeks on pine foliage following aerial application. Soil and needle litter in the sprayed stand also had higher copper content at 13 weeks than before application. Copper concentrations were higher in water traps situated in the sprayed plot than the unsprayed plot, but considerably lower than concentrations in local tap-water.

Background

Dothistroma septosporum, the causal agent of Dothistroma needle blight (DNB) in the UK, has become a significant tree health issue within Great Britain’s commercial pine plantations and forest tree nurseries Infection causes premature defoliation, and in some cases tree mortality. Pine species vary in susceptibility and, although Corsican and lodgepole pine are very susceptible, there is increasing infection within Scots pine. Scots pine, particularly in Caledonian pine forests, is very important ecologically and culturally and so its protection is a high priority for the forest industry. 

Current methods of control involve clear-felling to reduce inoculum loads, changing thinning regimes within infected stands to open up the crop and decrease humidity, taking statutory action in tree nurseries to remove infected stock, and re-planting in the forest with less susceptible species where possible. In New Zealand however, aerial application of copper compounds is routinely carried out to manage the disease. 

Copper is effective against Dothistroma septosporum as:

  • copper deposits are slowly distributed over the needle surface and spores coming into contact with the copper ions are killed and fail to germinate
  • copper stops fruiting bodies producing and releasing spores.

Status

This experiment was set up in the summer of 2013 and the plot will be monitored for 3 years post application. There are plans to repeat the aerial application of copper oxychloride to a larger (c. 20ha) area of Scots pine in 2014.

Contact

Dr. Kath Tubby