Red Needle Cast – What we now know

In:
2017 FGR Annual Conference
Report No:
AC2017-03
Report Date:
October 18, 2017
Author(s):
Nari Williams, Lindsay Bulman, Grant Pearse: Scion

Red needle cast and other needle diseases of radiata pine

Conference presenter: Dr Nari Williams, Scion

Presentation:  Red Needle Cast Overview

Red Needle Cast (RNC) is the latest in a suite of needle diseases that cause concern to radiata pine growers. It is caused by a Phytophthora, Phytophthora pluvialis. P.pluvialis is water-borne, and the wet winter and spring of 2017 meant the geographical extent and severity of RNC was greater than ever before.

Key research findings

  • RNC has a very rapid infection cycle. Trees are infected through the stomata on their needles. The disease does not penetrate vascular tissue. It sporulates on the needle surface, which means it is susceptible to environmental and chemical control.
  • RNC is not fatal to trees: repeated defoliation year-after-year is rare. Volume growth loss is severe in the first year of an outbreak, but then quickly recovers – for example:
    • 40% growth loss in Year 1
    • 15% in Year 2
    • 0% in Year 3 (if no further defoliation occurs).

  • pluvialis does not survive on logs, so there is no risk to the overseas log trade.
  • pluvialis does infect Douglas-fir, so Douglas-fir is not a risk-free alternative in areas prone to RNC.

Combatting Red Needle Cast

1. Chemical control

  • Copper has been identified by Scion as the most promising alternative. Copper is cheap, has low environmental impact, and is familiar to the industry thanks to its use in Dothistroma control.
  • Scion anticipates being able to provide RNC spray recommendations in 2018; these will include information on the economic threshold of infection beyond which spraying is recommended, and the optimum timing of spray applications.

2. Breeding for resistance

  • Work is well-underway to identify resistant genotypes from current radiata pine breeding populations.
  • Scion will work with the Radiata Pine Breeding Company to produce new, RNC-resistant lines of stock which will be made available to nurseries and hence to forest growers within a relatively short time-frame.

Website: https:/healthytrees.co.nz

Document:
Red Needle Cast Overview (1.98 Mb)
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