Project reference: 2009-04
Optimising Phytophthora Management in radiata pine seedlings
Project description:
A trial will be conducted in the same block at Te Ngae nursery as previous experiments associated with the control Phytophthora root rot in radiata pine seedlings. Metalaxyl–mancozeb and phosphorous acid will be applied individually and in combination during the root pruning period in order to establish whether there are potential additive benefits with regard to disease control (Table 1). Effects of frequency and timing on phosphorous acid activity will also be investigated. Disease assessments will be carried out during April–June and soil and root samples will be taken from the area to confirm the presence of the pathogen. Soil samples will also be taken at regular intervals from metalaxyl–mancozeb plots in order to determine the half–life of metalaxyl.
Background: Methods to control Phytophthora root rot in radiata pine seedlings were evaluated at Te Ngae nursery between 2006 and 2008. Disease symptoms commonly developed following root pruning suggesting a link between this activity and root infection. Metalaxyl–mancozeb provided moderate control (8% root rot) when applied one week after root pruning but was ineffective (21% root rot) when applied at seedling emergence. Poor control of the latter was attributed to dilution or degradation of metalaxyl during the period between application and root pruning. The most effective treatment was phosphorous acid which reduced root rot incidence to 0.14% when applied at fortnightly intervals commencing one month before root pruning (seven applications). This project will advance these studies by optimising treatment combinations during the root pruning period. The trial will be funded in part by FRST; however, FHRC funding will significantly contribute to field activities and will enable delivery of a comprehensive report to members of the collaborative.
Research Provider:
Forest Research
HortResearch
