Surveying for Plant Destroyers

Lab Note #9
Mar 31, 2015

What is citizen science? <-click here to see my previous lab note

The purpose of this lab note is to showcase some of the numerous ways the public of South Africa will be able to participate in our research. We hope to involve members of the public in as much of the research as we can, but there will be several levels of participation depending on how involved a citizen wants to be.

Initial opportunities for public participation will involve sampling the forests. We want to sample from plant foliage, water, and soils in the native forests. Citizen science initiatives can provide new approaches to investigating the distribution and abundance of organisms across space and time. By motivating public participation, we hope to sample a larger portion of the native forests and find a greater diversity of Phytophthora species than we would independently.

Phytophthora surveys generally focus on three levels within a forest: streams, soils, and canopies. Each component of these surveys will require a different level of participation. Many Phytophthora species are soilborne, spending most of their lifecylce in the soil. A good example is Phytophthora lateralis, the species that causes Port-Orford cedar root rot. Below is its lifecycle.

For species like Phytophthora lateralis, preventing the spread of soil is critical for preventing the spread of the organism.

Soil sampling opportunities

This can be done in a few different ways. The first way is by actually digging holes out in the forest.

Another way to sample the soil is to collect (wipe off) the soil from your boots after a hike. Below is a self produced example of a low-budget trail head collection station.

I envision spending time at trailheads to explain the purpose of the sample collections, but I hope the public will make sample deposits a habit. I would like to make rounds to different trailheads to collect samples regularly during the rainy season.

I would also like to work with mountain bikers, they could use a similar station to wipe the soil from their mountain bike tires.

This is my a shot of my bike in the McDonald Dunn Forest (Oregon State University owned) in Corvallis, Oregon.

Stream Sampling Opportunities

Many Phytophthora species can also be recovered from streams. To do this requires 'baiting' (think of it as fishing for Phytophthora—thanks Daniel!). The 'bait' in this case is susceptible foliage—in the US, we typically use rhododendron leaves because they are fairly universal hosts (food) for many Phytophthora species. The most common way to fish for Phytophthora is to dangle bags containing bait leaves in streams for up to two weeks.

Photo credit for both above photos: Chastagner group, WSU Puyallup.

The Chastagner group has conducted community based stream surveys (citizen science!) in Washington. Recently when I met with Gary Chastagner, he told me they were encouraging community members to choose the baits they wanted to use. In South Africa, we will likely do the same—perhaps it will increase the diversity of species recovered. Figuring out which plant species in the native forests of South Africa are the best 'baits' for Phytophthora sounds like a fun mini project that the public can help with.

Canopy Sampling Opportunities

Similar methods of baiting can also be used to capture the species of Phytopthora present on the leaves of trees in the canopy.

Indigenous Ironwood tree near Cape Town, Photo Credit: Abu Shawka, Public Domain.

In this case, the public can use bait buckets (hopefully we can provide the buckets).

Alternatively, we may be able to use a pole-pruner or simply reach into the canopy to collect samples. It looks like there are sick plants in the below photo! Maybe its because of Phytophthora?!

Indigenous trees of South Africa, Newlands Forest, Cape Town. Photo credit: S. Molteno, Public Domain.

Hopefully with a combination of the above sampling methods we will capture many Phytophthora species while keeping the public interested.

Whats next? What do we do with all of the samples? Coming soon... in another lab note.

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