Gardening is often about problem-solving, sometimes to the point of feeling like a detective story. We look for clues, find patterns in the evidence, and then identify a culprit so we can solve the problem. This summer, the Gardzen Test Gardens in southeastern North Carolina USA were the sight of a particularly strange mystery: some of our eggplant plants kept dropping all their leaves! Otherwise healthy plants would start to droop, then all the leaves would fall off. With attention and care, they’d grow back—but what was causing this pattern? Why are our eggplants wilting? Well, we tackled the mystery and we’ll share what we found. Let’s dig in and solve this together!
Gardzen Executive Summary
· Some of our eggplant plants started wilting and dropping leaves and blossoms unexpectedly.
· We reviewed the possible causes, including temperature, watering, soil issues, and pests or parasites.
· We compared the possible causes to the list of known symptoms and reached a conclusion.
· The culprit seems to have been an unusual hot and dry spring combined with inefficient watering.
· Deep watering of the individual plants combined with added nutrition solved the problem in most cases.
· Solving gardening mysteries is a great way to learn more about plants, plant care, and gardening as a whole.
Common Eggplant Symptoms
So, when we’re confronted with a gardening mystery, the first thing to do is outline what we know. In this case—what are the adverse symptoms shown by our eggplant? Where are the plants in question located in our garden and what varietals are they? What else might they have in common? So here’s what we knew:
· Otherwise healthy individual eggplants would wilt, drop their leaves, and then start to regrow if we watered them heavily.
· Most of the plants in our eggplant raised bed were unaffected.
· The varietals in question were Japanese White—which produces a small round white eggplant—and Ichiban, which produces a long purple eggplant. All seeds were purchased from a highly reputable supplier and started at home.
· The soil had been recently refreshed with good home-made compost.
· Soil testing via our local cooperative extension revealed no issues.
· The weather had been hot and dry for much of the season.
· We were watering carefully twice a day with a hose
So we had a starting point, albeit a limited one. We didn’t have a lot of clues to go on, but that was OK! On to Step Two, when we compare the clues we had to some of the common problems eggplant can face during the growing season.
Common Eggplant Problems and Pests
Prior to encountering this issue, we hadn’t fully appreciated how relatively hardy and issue-free eggplant plants could be. We’ve never really had an issue with them before; the leaves and seeds contain nicotine alkaloids that give them a bitter flavor and deter many garden critters from eating them. Our regular applications of neem oil and Bt kept most aphids and other pests away. So unlike our squash and tomatoes—which always seem to attract some hungry insects—eggplant had never really given us a problem before.
However, eggplants do have pests, predators, and various potential problems and we reviewed the list in search of something that might be causing our leaf drop problem:
· Temperature and Water Stress: We’ll start with the big one—sustained daytime temperatures above 90F/32C are stressful for eggplant, especially when combined with relatively high nighttime temperatures. Heat stress most commonly manifests as blossom drop, and we would have expected to see it in all our plants rather than a select view. Likewise, erratic watering can cause similar drooping, wilting, and leave/blossom drop issues—but we thought we had been watering regularly and deeply . . .
· Common Garden Pests: The next most likely source of our issues is the presence of one or more common garden pests. What constitutes a “common” pest depends on location, geography, and season, so it’s best to consult gardening guides tailored to a particular locale or the local cooperative extension for relevant details. For us, the most likely culprits were either aphids or spider mites. Both of these tiny insects feed on the fluids they extract from the plant’s stems and leaves, leaving scars, opening the plant infection, and weakening the plant overall. We checked our plants carefully and saw no sign of either bug, so . . .
· Less Common Garden Pests: Outlier cases happen, and again it’s a good idea to consult sources that have information relevant to our region when looking for clues. Flea beetles—a small jumping insect that feeds on a wide variety of garden plants—aren’t especially common in our part of the world but we checked carefully anyway and didn’t find any. Likewise, neither our eggplant nor our potatoes showed signs of the potato beetle. These large bugs LOVE to feed on potatoes but will also target eggplants, tomatoes, and peppers when the opportunity presents itself.
· Soil Composition and Nutrition: Another strong possibility was an issue in our soil. This is a broad, vague category; it could mean a lack of vital nutrients, a pest disturbing the roots of our eggplants, a contaminant or infection in the soil itself, or something else entirely. We had our soil tested via our local cooperative extension and the test revealed . . . nothing. Our soil was healthy and nutrient rich.
So, having reviewed the evidence and compared it to the list of potential suspects and causes, we still didn’t have a lot to go on. No obvious pests or infections, no testable soil issues, so we were back to watering, temperature, and sun exposure. Our part of the world had been in a drought for much of the season, with an abnormally hot spring to boot. So we planned around that and tried to be honest with ourselves: had we maybe missed watering these particular plants as deeply as we should have.
We proceeded with that in mind.
Solving the Mystery of Eggplant Leaf Drop
Our conclusion was pretty mundane, almost boring. The solution to the mystery seemed to be hand watering these particular plants using a watering can and water from our rain barrel. We made sure the water was at a safe temperature and then watered directly around the roots, slowly and deeply, two or three times a day. After about a week of this we top dressed with some good rich compost and added a light application of an organic liquid fertilizer.
It took a bit of time and care, but most of our eggplant started to recover. New growth started to appear, leaves grew back, and eventually blossoms and fruit returned. We probably won’t get quite the same yield from these plants as we might have, but that’s OK!
Garden Mysteries are Learning Opportunities
This was a gardening mystery, and one that we didn’t solve entirely. However, we learned a lot about eggplant care and eggplant pests and problems along the way, and we did find a solution that works and saved most of our plants.
Sometimes that’s what gardening is about. We explore, we learn, we solve the mysteries and issues as they arise and carry those experiences with us. We’re lucky enough to have this blog so we can share our experiences and knowledge with the rest of you and then learn from your responses and feedback. Speaking of which—Gardzen is all about community and we love to hear from you. If you have similar experiences or you can think of something we might have missed, let us know in the comments or via email!
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