Static Battles
02.16.15
Steam diffused from the tilled soil into the biting morning air as I examined the guava-laden trees for sickly green leaves and traces of what looked like corrosion crawling up the bodies of the chartreuse fruits. The night before, as lightning crackled and rain thundered down for the third time that week, my host family told me of the havoc they anticipated in their small orchard every monsoon season from the “red rust.”
It comes with the rains and chews through the lowest foliage of the orchard, floating with the humid breeze to find its next victim; just one touch from the red rust can trigger weaving networks of prickling filamentous growth across dispersed fruit trees. Some years were certainly worse than others, they said, but the rust arrived annually almost without fail — and as the summers grew increasingly warm, the family worried that the infections would worsen.
Cephaleuros virescens — that was the scientific name of the parasitic algae I’d first stumbled on in a market a few weeks prior (see attached journal entry below). Though it typically just grazes cells off the plant’s surface, the microscopic algae can leech the life out of guavas, coconuts, mangoes, and more. I wonder how I never noticed the leaf spots on any of the fruit trees around my grandparents’ apartment complex in India, especially considering that many of our family visits were during the warm, damp monsoon season.
Algae is a staple of both fresh and saltwater environments, but I hadn’t anticipated that just the presence of heavy rains had let it make its way all the way to fruit orchards, as well. I thought back to the round spore capsules that I saw under the microscope, ready to release their contents. C. virescens spores float along with the wind, settling in stagnant heat and growing on new plants along the way.
The family dug angled trenches throughout the orchard to direct excess rainwater away from the trees in hopes it would dry out the soil enough to ward away the parasite. Sometimes, though, the red rust would still emerge. Most of the time, the family would just separate their harvest of spotted fruits from the pristine ones; the fruits were usually still edible, so they’d slice or juice them at home. I thought back to the woman I met at the fruit stand weeks ago, about how her family also pulled the lesioned fruit out of their to-be-sold pile, and about how my cousin and I skinned the spotted guava back at our hostel to eat it anyway.
The morning ticked on, the air hung motionless, and I counted upwards of fifty infected guavas. While the older trees seemed undisturbed by a contaminated fruits, the younger, thinner trees bore most of the sallow fruit, their emerald leaves decimated by beige splotches — in some cases, there were more leaves scattered around the base of the tree trunk than there were on the developing branches. The red rust overwhelms the leaves’ vibrant green photosynthetic pigments, which diminishes the host plants’ ability to harness energy from the sun; the parasite competes with the tree’s fundamental means of survival.
I pried off a few ripe, infected fruits and nearby leaves and dropped them into my tote to probe later in the afternoon. I needed a microscope to help the family-run farm figure out the exact culprit behind the fruit attacks. C. virescens is just one of many microscopic destroyers, alongside its sister species C. parasiticus, which often brings a much more severe torrent of damage upon guava orchards.
Back at the house, I carefully sliced the fruit into thin slivers, preserving large sheets of its skin as much as possible. I brought out a handheld microscope — courtesy of an old research mentor — and inspected the red rust.
While the blotches looked two-dimensional to my human eyes, the magnification revealed protruding, thin strands with several round enclosures at the tips (see sketch). The microscope light refracted through green and amber splotches that reminded me of stained glass. The inside of the fruit was completely unharmed.
I swapped the fruit skin out for a leaf and saw similar prismatic filaments intertwined in a mat across its cuticle. When I flipped the leaf, the underside was clear of any spore capsules. I was definitely looking at C. virescens. I had taken a guess pre-magnification based on the scarring being only surface-level on the leaf — a hallmark of this species of algae — but the microscope confirmed my diagnosis.
For my host family, customers’ perception of this algae is arguably more destructive than the algae itself. That evening, they told me about the business hits they inevitably took every year not because their trees wouldn’t fruit, but because the fruit wouldn’t sell. The algae typically didn’t eat through the fruit’s flesh, but ugly guavas are never really a popular choice.
My host family did what they could to avoid scarred fruit. Besides caring for the soil and removing infected portions, they relied on the trees’ own immune systems to fend off the algae. The standstill trees and a wind-dispersed parasite — two organisms locked in a silent, gradual battle — somehow, the seemingly static systems fight an ongoing combat.
01.23.15
Gleaming vermillion peppers, crimson carrots, and lychees that looked ready to burst with nectar overflowed from wooden baskets as customers browsed the bustling alley’s produce stands. On the third day of our travels to the southern coast of Thailand, my cousin had sent me on a mission to track down more guavas. We grew up eating the soft, rosy fruits that our parents bought at our local Indian markets and we’d quickly wormed our way through the bag of crisp, white-fleshed Thai guavas we’d picked up on our first day — now, we were in need of more.
Soon, I came across heaps of the fresh, yellow-green fruit in plastic crates. Some of them still bore leaves, reminding me that they were brought to the stand straight from the tree. A few inches from the central fruit pile lay a single guava that had a spattering of coffee-colored indents dancing up one edge of the fruit and onto the leaves. It looked like mud scattered by squealing tire trucks, but unlike the results of a roadside misfortune, the leaf spots were rimmed by lemon-yellow rings. The leaves were a slightly darker shade of green than the fruit itself, but the rotund maroon spots obscured much of the emerald coloration.
I turned away from the speckled guava to pick out a few other fruits but kept glancing back. None of the other guavas looked like it; somehow, this one had slipped by. I’d seen bruised, rotting, and bug-bitten fruits, but this didn’t look like any of those. The spots looked more like a secondary growth, especially across the leaves — a steadily increasing film of life bleeding across the plant.
I slid four guavas into a brown paper bag and gently placed the speckled guava at the top of my small pile. When the stand owner saw my fruit choices, I was met with a mildly puzzled look.
“You don’t want to pick a better one?” she asked as she weighed the bag and tapped at the price number that popped up. I fished around for bills and passed them over.
“I’m just curious about the spots,” I told her. She sighed and gave me a small smile. “Spotted fruits are much harder to sell. Usually when the red rust reaches the orchard, we scrap them.”
The red rust. I thanked her and made my way back to the hostel, guavas in hand.
Additional field notes will be updated in the appendix.
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