PhytophthoraContamination in a Nursery and Its Potential Dispersal into the Natural Environment

Abstract

A detailed site investigation of a eucalypt nursery suffering disease losses revealed the causal agent to be Phytophthora boodjera. The pathogen was detected in vegetation surrounding the nursery production area, including the lawn, under the production benches during the growing season, and, most importantly, from plant debris in used trays. However, it was not found in the container substrate, water supplies, or production equipment or on the workers themselves. The sterilization methods used by the nursery were shown to be ineffective, indicating that a more rigorous method was required. Boiling trays for 15 min or steaming at 65°C for 60 min eradicated P. boodjera. This pathogen was more pathogenic to the eucalypts tested in their early seedling stage than P. cinnamomi. Tracing of out-planting to revegetation sites showed that P. boodjera was able to spread into the environment. Dispersal via out-planting to native vegetation may affect seedling recruitment and drive long-term shifts in native plant species. Inadequate nursery hygiene increases the risk of an outbreak and can limit the success of biosecurity efforts as well as damage conservation efforts.

Field survey, isolation, identification and pathogenicity of Phytophthora species associated with a Mediterranean‐type tree species

“…These containers were kept in a temperature‐controlled room (21–25°C). The leaves were inspected daily for 10 days, and any discoloured or necrotic areas of the leaf were excised and plated on NARH agar, a Phytophthora selective medium (Hüberli, Tommerup, & Hardy, ; Simamora et al., ). The plates were incubated in the dark at 21°C (±1°C).…”

Pathogenicity of 21 newly described Phytophthora species against seven Western Australian native plant species

“…Phytophthora boodjera killed E. marginata and one isolate caused significant reduction in shoot height in all species. It has previously been shown to be a pre‐ and post‐emergent pathogen for seedlings of several Eucalyptus species (Simamora et al ., , 2018). Phytophthora moyootj , for which there was no previous information on host range, caused significant shoot and/or root damage to all species except Lambertia and killed B. littoralis.…”

“…The inoculum was rinsed with deionized water to remove excess nutrients (Matheron & Mircetich, ) immediately before use. Colonization of the inoculum was confirmed by plating 3 g subsamples onto both NARH, a Phytophthora‐ selective medium (Simamora et al ., ), and a Petri dish containing deionized water. These were incubated at room temperature and checked to ensure the viability of the inocula.…”

Antimicrobials in Phytophthora isolation media and the growth of Phytophthora species

“…The isolation medium NARPH was developed two decades ago and is currently used, without PCNB, as a medium for isolation of Phytophthora species (Belhaj et al ., 2018; Simamora et al ., 2018; Khaliq et al ., 2019). Although growth of three of the 47 species tested in the current study, P. cactorum , P. parvispora , and P. sojae , was severely affected by the antimicrobials in NARH, overall sensitivity to the NARH antimicrobials does not appear to be the reason why many species detected using high‐throughput sequencing are not possible to isolate by baiting.…”

“…The mode of action of these compounds is shown in Table 1. The carcinogenic properties of PCNB (Thomas et al ., 1998; Clary and Ritz, 2003; EPA, 2006), which was a component of the original formulation, means that this compound should not be used, and it has been eliminated by many researchers (Simamora et al ., 2018).…”