Robigalia Roundup LXXXII: Get your research in front of 10,000 plant pathologists

Hello {{first_name | Robigalia readers}},

This week I'm putting out a call for the next round of Plant Pathologist of the Week features, and I'd love for you to throw your name in.

Being featured puts your research in front of thousands of newsletter readers across more than 85 countries and over 10,000 plant pathologists on social media.

Beyond the reach, it's one of the more practical ways to grow your presence in the global plant pathology community. Past features have sparked conversations, connected researchers working on similar problems, and opened doors to collaborations and advice that wouldn't have happened otherwise.

The form is open to anyone in the Robigalia community, not just students or early-career researchers. Whether you're a postdoc, an independent researcher, or a lab head, I'd love to hear from you.

One request before you hit submit.

Please write your responses in your own words, particularly in the advice to other plant pathologists section. I have a substantial backlog of responses and many are reading as AI-generated, resulting in a lot of features saying more or less the same thing.

If you're not sure how to phrase something, jot down your thoughts as rough notes and I'll work with whatever you give me. I'd much rather have the real you in messy sentences than a polished response that could have come from anyone.

The features that resonate are the ones that sound like a real person talking about their work, what drives them, what they'd genuinely tell someone earlier in their career.

The features fills up quickly, and the sooner you're in, the sooner you're in front of that global community.

Now, onto this week’s edition:

Let’s dive in!

This week's paper is a couple of months old, but with my background in myrtle rust research I couldn't resist including it.

It's also been sitting in the back of my mind for another reason. The more I read about interactions like this one, the more I find myself thinking about the boundary between plant diseases and insects, and whether Robigalia should start to cross it.

More on that soon!

Dispersal is often the deciding factor in how far and how fast a plant pathogen spreads, and for most rust fungi, wind is assumed to do most of the work. A paper by Shin-Clayton et al., published in NeoBiota, investigates whether western honey bees (Apis mellifera) may also be acting as vectors of Austropuccinia psidii, the fungus responsible for myrtle rust.

Field observations had previously noted honey bees collecting A. psidii urediniospores from infected plants and storing them in their pollen baskets, visually indistinguishable from normal pollen foraging. To test whether this behaviour could meaningfully contribute to dispersal, the authors needed to establish two things: that spores remain viable after entering a hive, and that they provide nutritional benefit to the bees. They placed honey bee colonies at active myrtle rust outbreak sites in Queensland, then assessed spore viability over nine days and analysed the protein and essential amino acid content of A. psidii urediniospores against known pollen sources. They also reared honey bee larvae on spore-supplemented diets to test effects on development and survival.

Austropuccinia psidii spores were detected in 45% of pollen storage cells and on 48% of returning foragers sampled from hives placed at outbreak sites. Spores remained viable for at least nine days within colonies, a timeframe that overlaps with the three to seven days typically taken to transport commercial hives between agricultural sites. Nutritionally, A. psidii urediniospores contained 22.5% crude protein and all ten essential amino acids above the minimum thresholds required for honey bee health, comparable to willow pollen. Larvae reared on A. psidii spore diets developed at rates and achieved weights similar to those fed pollen, with a survival rate of 78.7%.

The findings suggest that spore foraging by honey bees may not be incidental but a viable foraging strategy, particularly when floral resources are scarce. This has direct implications for biosecurity, as neither the Australian Myrtle Rust Action Plan nor New Zealand's surveillance framework currently lists managed beehive movement as a dispersal pathway for A. psidii, despite commercial pollination services regularly transporting hives across large distances. Whether bee-vectored spores can successfully infect new hosts remains untested, but this paper demonstrates the biological plausibility is there.

When Erwin Frink Smith formally described a bacterial wilt pathogen ravaging tomato, potato, and eggplant crops across the American South in 1896, he could not have anticipated that the organism he named Bacillus solanacearum would eventually be recognised as one of the most destructive plant pathogens on Earth. Nor could he have guessed that it would spend the next century shedding names almost as often as it claims new hosts.

Ralstonia solanacearum is a Gram-negative, soil-borne betaproteobacterium belonging to the family Burkholderiaceae. Its remarkable taxonomic journey, from Bacillus to Pseudomonas to Burkholderia to Ralstonia, mirrors the growing scientific recognition that this is no ordinary pathogen but a species complex encompassing extraordinary genetic and ecological diversity.

Today, strains are grouped into four phylotypes reflecting distinct geographic origins: Asia (I), the Americas (II), Africa (III), and the Indonesian archipelago (IV). Recent genomic work has further split the complex into three distinct species, with R. solanacearum sensu stricto, Ralstonia pseudosolanacearum, and Ralstonia syzygii each occupying different phylogenetic and ecological space.

Ralstonia solanacearum infects more than 450 plant species across more than 50 families, an astonishing breadth that takes in tomato, potato, tobacco, banana, pepper, eggplant, and ginger, among many others.

The bacterium enters through root wounds or the points where secondary roots emerge, colonises the root cortex, and advances into the xylem, where it multiplies rapidly and produces copious exopolysaccharide. It is this EPS that is lethal: the slime physically occludes the vascular system, reducing sap flow until leaves wilt suddenly and catastrophically. Unlike many wilting diseases, infected plants rarely yellow first. The collapse is abrupt, often appearing when bacterial populations in the xylem are already enormous.

The pathogen is distributed across tropical, subtropical, and warm temperate regions on every inhabited continent, and is considered a quarantine organism across much of Europe, where the cold-adapted Race 3 Biovar 2 strains periodically emerge via infected seed potato or ornamental imports.

Yield losses span an enormous range depending on host, cultivar, climate, and strain, from 33 to 90% in potato and up to 100% in banana under severe pressure. Rising global temperatures are expected to expand its geographic range into cooler regions that currently offer some natural reprieve.

Management remains deeply challenging. Ralstonia solanacearum can persist in soil and irrigation water for years, often entering a viable but non-culturable state under cold or nutrient-stressed conditions before resuscitating when conditions improve. No fully resistant commercial cultivars exist for most hosts, though grafting susceptible scions onto resistant rootstocks offers partial protection in tomato and some solanaceous crops. Crop rotation with non-hosts for five to seven years can reduce inoculum, but this is impractical for many smallholder systems. Biological control through soil microbiome manipulation and bacteriophage-based approaches are active areas of development, but no silver bullet has emerged.

Keep reading to meet Pooja Vilas Raut, this week's featured plant pathologist who previously investigated the pathogen.

This week, we meet Pooja Vilas Raut, a plant pathologist completing her doctorate at Vasantrao Naik Marathwada Krishi Vidyapeeth (VNMKV) in Parbhani, Maharashtra, where her research sits squarely at the practical end of biological disease control.

Early in her Master's program at the College of Agriculture, Nagpur (Dr. PDKV, Akola), Pooja's supervisor suggested she work on Ralstonia solanacearum, a bacterial wilt pathogen of regional significance but limited prior study at the time, with the understanding that if isolation proved impossible they would reconsider. Pooja was new to research and accepted anyway, read the literature methodically, and had the bacterium in hand within twenty days. The experience confirmed not just her technical ability but her appetite for problems that don't come with guaranteed answers.

Now in her PhD at VNMKV, Pooja's research focuses on Pseudomonas fluorescens and its potential as a biocontrol agent against major soil-borne diseases of safflower. The work spans molecular characterisation of the bacterium alongside evaluation of its disease-suppressive properties, a combination that reflects both the diagnostic rigour and the applied ambitions that have defined her training. Safflower is an important oilseed crop in Maharashtra and across semi-arid India, and soil-borne pathogens remain a persistent constraint on its productivity, making the question Pooja is asking one with direct relevance to the region.

Beyond the laboratory, Pooja has been writing about plant pathology and agriculture on Medium, a commitment to public-facing science communication that sits alongside her research work.

Her advice to fellow plant pathologists is characteristically grounded: resist the pull of metrics and awards, and concentrate instead on building real practical skills and genuine knowledge. That philosophy, and the quiet determination it reflects, has guided her own journey from a first uncertain isolation to the threshold of a completed doctorate.

You can connect with Pooja on LinkedIn or follow her writing on Medium.

Have a job, scholarship, or event to advertise? List it in Robigalia. I’ll help promote your opportunity or event to a global network of over 10,000 plant pathologists for free.

See you next Monday!

P.S. Why Robigalia? The name originates from the Ancient Roman festival dedicated to crop protection. You can read all about the history here: