The Detection of Phytophthora Taxon “Agathis” in the Second Round of Surveillance Sampling

The detection of Phytophthora Taxon “Agathis” in the second round of surveillance sampling - with discussion of the implications for kauri dieback management of all surveillance activity A J Beauchamp Shared Services Threats and Transformation Department of Conservation for Joint Agency Kauri Dieback Response 18 April 2013 Executive summary Kauri dieback caused by Phytophthora taxon “Agathis” (PTA) (Beever et al. 2009), has been the subject of a joint agency response since 2009. Surveillance 2 aimed at a more comprehensive assessment of the location of PTA and its movement (Beauchamp 2011a). It added to the information from Surveillance 1 and a targeted assessment at Waipoua (Beauchamp 2011b, 2011c, 2011d). It also added to the surveying of the Auckland region, done by Auckland Council using different methods of data collection and only one assessment laboratory at Plant and Food Research (Nick Waipara, pers comm.). Surveillance 2 sampled 89 sites and took 212 samples (Fig 1). Eighty five percent of the samples included Kauri from seedlings to iconic large trees. Sites lacking Kauri include other vegetated areas of native bush and plantations associated with kauri plantations in the Coromandel and farm sites. The overall picture that emerges from all surveillance and sampling is that four forested areas have parts that contain a lot of foci; Waipoua, Waitakere, Punaruku and Aotea/Great Barrier Island. There are also extensive areas of small patches and reserves in the predominantly rural area between Auckland and the Brynderwyns that are contaminated. Sites at Aotea/Great Barrier Island, Centennial Park (Waitakere) and Tomarata all showed signs of dieback in the late 1960s and early 1970s and sampling in Surveillance 2 suggests this was PTA. Tree rings from the site at Centennial Park, and the plantation evidence from Waipoua nursery from trees planted in 1955-56 (at least), suggests that PTA was active in at least Waipoua and Waitakere, and the Tomarata rural area in the 1950s. The spread on Great Barrier Island and within Punaruku could be the result of forest service activity which moved soil to and within these sites as seedlings or on machinery, and/or local movement that may include goats and pigs. PTA has not been detected in areas or the Northern forests outside of isolated plantations at Raetea and Omahuta, or in the Hunua Ranges or the Coromandel and Kaimai forests. It is present in the rural blocks on the Awhitu Peninsula in South Auckland. The conclusions that can be reached from this sampling are: The results of sampling and a lack of symptomology in Kauri over large areas suggest that PTA is absent at sites within contaminated forests, and is potentially absent or still restricted to plantations near some large Kauri forests. It is not too late to save many natural sites from contamination. 1 The symptomology that is considered to generally be characteristic of PTA in kauri is not ubiquitous and cannot be used in all cases to identify positive sites. Kauri at Glenbervie and Punaruku are living with PTA and are not currently showing the extent of classic symptomology that would be expected from such widespread contamination. The environmental and other likely reasons for this are worth investigating. Some Kauri that were planted at Glenbervie are probably from the same stock as plantations at Waipoua and Raetea, where classic symptomology and deaths are occurring. Sampling now suggests that the dispersal of PTA from Waipoua nursery was quite restricted and potentially occurred through only one cohort of seedlings planted in the 1955-56 period in Waipoua, Raetea, Glenbervie and Aotea/Great Barrier Island. Some sites in Waipoua and Great Barrier Island need further assessment. The full investigation of this dispersal route should be undertaken because it is the likely source of movement of material to other amenity plantings (Omahuta). Isolation of some planted forests (Raetea) and amenity plantations (Omahuta) by fencing could control or slow the spread of PTA to natural areas. Such areas can be useful to allow key science on oospore destruction and natural longevity to be established. There is no information to suggest that PTA was spread from Sweetwater or other NZFS nurseries. The positive sites at Raetea and Punaruku and Glenbervie may be the result of poor equipment hygiene when the forests were blanked1 or due to animal (human, goat, pig) movement from contaminated plantings. PTA is present on farmland and has the potential for being moved on and between farms by stock and farming activity. PTA is not present in all farmland and mechanisms should be investigated with the farming and transport sectors to reduce the risk of spread within farmland and especially to farmland in the areas north of the Brynderwyns, South Auckland and the Coromandel. PTA appears to be being spread by pigs, and maybe other animals. The spread of pigs from contaminated forest to uncontaminated ones represents a high risk. There is the potential for pig spread within existing contaminated regions: in the Waitakere Ranges; in the Brynderwyn Ranges; Waipu and through Mareretu; Waipoua and surrounding forests; Glenbervie and Punaruku to Rawhiti; and on Great Barrier Island. Pigs could also spread material from the small foci in other forests at Omahuta and Raetea. There are some existing sites that were not sampled in Surveillance 2 but could add to the current information. Ad-hoc sampling of potentially infected sites and follow-up of their potential vector routes should remain a focus of the programme. 1 Blanking is the process of planting into areas of a plantation where tree death has occurred. 2 1.0 Background The second round of surveillance sampling was designed to add to the information that has been collected on kauri dieback at other sites, and to complete a more comprehensive coverage of the sites with Kauri (Beauchamp 2011a). It follows some follow-up of surveillance 1 sites and resolution of issues related to temperature monitoring during sample transport (Beauchamp 2012). The sampling aimed at investigating further some of the track and road issues investigated in Surveillance 1 and other issues including: presence in iconic trees and stands the potential for animal/farmland transport of PTA misidentification at sites where past science has taken place, presence on islands lacking large animal (non-human) vectors spread by New Zealand Forest Service (NZFS) activities and nurseries including looking at sites where planting was a complete failure presence in natural sites within the full range of kauri, including those important to hapu. It was initially considered that sampling would include both soil and cork cambial sampling but no final method has been developed for cork cambial sampling. The results comprise soil sampling alone. The leadership team of the joint agency wanted the soils sampling process to be an open tender, and requested that the sampling area be divided into three so that tangata whenua could bid for the work. The successful contractors were Wildlands Ltd., who sampled the areas south of Whangarei, and the operations group of Te Roroa, who sampled the area north of Whangarei. Both of these contractors had handled previous soil sampling contracts for the Joint Agency, so no further training was required ( Beauchamp et al. 2012). There had been some difficulty with the interpretation of Surveillance 1 results, and there was suspicion that samples had been temperature compromised during transport. This was resolved in the Waipoua sampling (Beauchamp 2011c). This report is not intended to be an environmental assessment of the drivers of Kauri dieback. It includes an assessment of some data collected during sampling but not the detection probabilities of the sampling (Beauchamp 2011b, 2012). 3 2.0 Methods Field sampling was undertaken between 24 Oct 2012 and 14 Dec 2012 by two teams of two samplers using the sampling protocol (Beauchamp et al. 2012). Sites were chosen to target specific aspects of vectoring or areas of interest (see section 3). The reasoning behind each site chosen was not made obvious to the sample collectors, but they were encouraged to phone if the sites had no kauri present. Some forestry sites were known (Athenree) and likely (Punaruku, Riverhead, Tairua) to lack plantation kauri but could have kauri seedlings and rickers present. The full range of samples at some other sites were not taken as I had instructed the samplers that due to the reduction in allocated budget to the labs that only 80 sites worth (three trees per site) could be sampled. Most of the reduction was in areas found to be lacking kauri and in kauri sites on positive farm sites, where we were assessing the non-kauri associated distribution of oospores. I was not aware of the location of sites on the ground in the Coromandel and relied on stock maps to define the location of specific sites. Mistakes were made in the positioning of sites aimed at plantations in Puketi, Tairua and Kauaeranga Valley. Samples taken at these sites should have been interpreted as control sites ((samples 61-66 and samples 180-187) and in the Tairua plantation (samples 207-210) in the Coromandel). These results are discussed in this report in relation to expectation of spread and detection of PTA. The laboratory procedures were those used in the first surveillance and the Waipoua sampling, however, the number of labs we required to test each sample was reduced from three to two2. Landcare received all samples and downloaded temperature probe information for all sample movement to and between labs. All samples were allocated by Stan Bellgard (Landcare Research) to two of the three labs (Landcare, Plant and Food, SCION) and Landcare Research compiled the results (Bellgard 2013). The minimum field data was loaded by the contractors (DOCDM-1141591 (northern) and DOCDM-1141600 (southern) and the results from the labs were loaded (Appendix 1), after checking the interim report from the contractors and the labs (DOCDM-1145165; Bellgard et al.

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