Disease rapidly infecting nearly all indoor and outdoor plants

Question: Almost all my indoor and outdoor plants are infected with some kind of fungal disease. I’m sending photos of a miniature garden in a whiskey barrel that are most severely infected. The plants are( in the order of pics): thymus ‘Elfin’, dianthus gratianopolitanus ‘Tiny Rubies’, miniature daisies (Bellium Minutum). At the end of last September, I noticed that underneath the thyme it was severely black but the top layer of thyme was green, flowery and healthy looking. I also noticed a sludge looking layer underneath the Tiny Rubies but again the top was flowering profusely and otherwise healthy looking. Now this fall it’s the same with otherwise healthy flowers on top but the layer of the plant above the dirt is black or sludge-like. I sprinkled sulfur powder on this layer hoping to kill the fungi Al disease but now I see orange, yellow and black spots on all my other plants. I’ve been praying all my plants with fungicide to stop the spread but the chemical burnt many of my succulents that were healthy and all the rest are infected. I cannot cut the top layer of all my plants off or it will kill them all and I’m talking about thousands of dollars of plants. Even my grass has brown circles and vines growing on my trees are severely black and orange and yellow. I feel like it’s everywhere. Please help! I can’t tell what disease it is as it appears different on every different plant.

responder: Answered by the Home and Garden Information Center (HGIC), University of Maryland Extension. For timely gardening information and tips, subscribe to our Maryland Grows blog and quarterly newsletter. Follow us on Facebook, Instagram, and YouTube. Replied May 16, 2023, 1:18 PM EDT
response: It's unlikely a single disease is affecting such a wide variety of plants (a few pathogens have a wide host plant range, but many don't), but we'd need to see the symptoms on the other plants in order to try to diagnose the issue. You can send additional photos in your replies, and if the system limits you to three image files per reply, just reply more than once in order to share additional photos.  For the plants pictured, this type of mushy, dark foliage layer underneath the uppermost stems is fairly typical. (Not ideal, granted, but common enough it's not an unexpected issue.) Low-growing plants that require excellent drainage (as these three species do) and air circulation, both of which might be affected by the barrel planting where its rim reduces air circulation and the large soil volume is slower to drain excess moisture. Depending on their ingredients, some potting mixes drain better than others, though adjustments can be made in some cases by adding drainage-boosting ingredients like perlite, horticultural charcoal, and small expanded slate stones (sold as vole-discouraging amendments, often). Watering should only be done when the soil around several inches down is becoming dry to the touch, as over-watering is a common cause of decline that looks like this. As these lower leaves become covered-up by younger growth it's normal for them (especially on flattened creeping/sprawling plants) to shed by dying and turning brown, and their degradation by soil microbes and such occurs more rapidly when they stay damp, as appears to be the case here. Root rot, which happens when roots don't have enough access to oxygen in the soil due to wetness and succumb to opportunistic infection, and crown rot, when similar decay occurs on stems at the soil surface, is not treatable.  The only preventative measures that work well are using very well-drained soil or potting mix, giving plants good air circulation by avoiding crowding, and (in some cases) trying a grit-like stone mulch around the plant's root zone so the branches lying on the soil surface aren't in direct contact with the ground. (This kind of setup is used in rock gardens, for instance, which is what many of these dainty mini-groundcover-type species are used for. They also are often best grown in climates cooler and drier than ours, thought not exclusively.)  Sulfur is sometimes an effective fungicide but in this case it's not a useful treatment approach and might (over time) also alter the soil acidity to a level too low for these plants to thrive. Very few chemical fungicides are labeled for use in suppressing root and crown rot, but they are more expensive than most other fungicides, require reapplication to continually suppress fungal growth, and cannot cure existing infection (which may have already taken hold before symptoms manifested). As such, and because fungicides sometimes risk harming other organisms, we generally do not recommend their use. If certain plant species tend to contract recurring problems like crown rot, other species more tolerant of the site conditions (usually wetter) should replace them.  Since they share similar conditions conducive to infection, and since the symptoms of each of these diseases look very much alike, here are several web pages that will overlap a bit regarding the types of root and crown rot typically seen:Root, Crown, and Stem Rots on FlowersRhizoctonia Web Blight on FlowersOvergrown GroundcoversRoot Rots of Indoor Plants For now, you can try to trim away or comb out with your fingers any mushy growth under the live ends of the stems. Otherwise, you can focus more on monitoring the plants for water to make sure they're only watered when necessary and, for the future, consider amending the potting mix for improved drainage if growing species with greater moisture sensitivity.  Regarding the black, orange, or yellow spots on other garden plants, lawn, houseplants, and vines that you mention, these could be any number of infections, insect activity, normal leaf shed depending on the specific plant type and where on the foliage it's appearing. Please share photos of these so we can attempt a diagnosis. Fungicides cannot cure existing infections but might be warranted in a few cases to protect healthy growth from becoming infected. Sometimes, though, the fungal damage is only an eyesore and doesn't threaten the health of the plant enough to warrant treatment. (Or the opportunity for treatment has passed by the time symptoms appear.) If you have information about how some of those other plants are cared for (for example, is the lawn or garden irrigated using an automatic sprinkler system?), that can help us narrow-down possible causes of damage.  Miri

responder: The Question Asker Replied May 16, 2023, 3:54 PM EDT
response: ﻿Thank you so m uh for the thorough response. In the barrel, I have lava stone, perilite, and a number of added measures to try and increase airflow but I’ll try and salvage what I can.   Here’s more pictures of elsewhere in the yard and inside the home. I’m really concerned about the pitch black stems in several of my plants. I’m pretty sure there’s mold in my grass (big white spots) then the trees are covered in vines and the vines have a ton of yellow, brown and black spots. Inside plants are also showing similar patterns (yellow spots that keep spreading). After I used fungicides I feel my plants look worse and now the healthy ones are covered in burns. I’ll add more pictures in next email.   Sent from my iPhone  On May 16, 2023, at 1:18 PM, Ask Extension <<personal data hidden>> wrote:    ﻿

responder: The Question Asker Replied May 16, 2023, 3:54 PM EDT
response: ﻿Thank you so m uh for the thorough response. In the barrel, I have lava stone, perilite, and a number of added measures to try and increase airflow but I’ll try and salvage what I can.   Here’s more pictures of elsewhere in the yard and inside the home. I’m really concerned about the pitch black stems in several of my plants. I’m pretty sure there’s mold in my grass (big white spots) then the trees are covered in vines and the vines have a ton of yellow, brown and black spots. Inside plants are also showing similar patterns (yellow spots that keep spreading). After I used fungicides I feel my plants look worse and now the healthy ones are covered in burns. I’ll add more pictures in next email.   Sent from my iPhone  On May 16, 2023, at 1:18 PM, Ask Extension <<personal data hidden>> wrote:    ﻿

responder: The Question Asker Replied May 16, 2023, 4:00 PM EDT
response: Sent from my iPad  On May 16, 2023, at 1:18 PM, Ask Extension <<personal data hidden>> wrote:    ﻿

responder: The Question Asker Replied May 16, 2023, 4:00 PM EDT
response: Here’s more pics with yellow or browning leaves.   Sent from my iPad  On May 16, 2023, at 1:18 PM, Ask Extension <<personal data hidden>> wrote:    ﻿

responder: The Question Asker Replied May 16, 2023, 4:00 PM EDT
response: Thank you so much for the thoughtful response. I am really concerned about the black stems. I am seeing and all the yellowing leaves. I could only attach three pictures so I sent three pictures of one barrel but all my plants inside and out have slightly different symptoms although it can’t be a coincidence that every plant is infected with some thing. The majority have brown or yellow leaves that keep dying. Sam have a really really Blackstone. I’m attaching some labeled pictures of black stems.   Sent from my iPad  On May 16, 2023, at 1:18 PM, Ask Extension <<personal data hidden>> wrote:    ﻿

responder: The Question Asker Replied May 16, 2023, 4:06 PM EDT
response: ﻿Here’s more pics with yellow or browning leaves.   Sent from my iPad  On May 16, 2023, at 1:18 PM, Ask Extension <<personal data hidden>> wrote:    ﻿

responder: Answered by the Home and Garden Information Center (HGIC), University of Maryland Extension. For timely gardening information and tips, subscribe to our Maryland Grows blog and quarterly newsletter. Follow us on Facebook, Instagram, and YouTube. Replied May 17, 2023, 5:19 PM EDT
response: This is a lot of images so we'll try to address everything. It helps to have plant IDs to know what pests or diseases might be more likely, but in some cases it won't matter as much.  The photo that appears to be a Clivia indoors looks more like phytotoxicity than an infection. Phytotoxicity is simply plant tissue damage from chemical exposure, essentially like a chemical burn. It can occur with pesticides used as the label directs if conditions are just right, but more often it happens when the dosage is wrong, if the plant is treated when it's stressed (hot weather, wilting or under-watered, etc.), or when the chemical used is not a registered pesticide. For example, drifting mist from glass being cleaned with window cleaner, or a spray made from home ingredients as a pesticide substitute (household soaps or detergents, oils, rubbing alcohol, and others), can both cause "burns" or bleach-like symptoms on leaves and stems. These will not heal, but if the circumstances don't repeat themselves, it probably won't worsen and it won't spread like a disease can. Sometimes wounded tissues can become infected though, as they do with animals, so it's not impossible that phytotoxicity plus an infection are happening at the same time. If you were using a home remedy to spray plants, stop using that mixture and select a labeled official pesticide product instead, and follow its instructions carefully about when to apply, when to re-apply, and at what dosage (if it's not ready-to-use).  The third image might be a bacterial rot and the leaf with that mushy brown end should be cut off. Avoid trimming burnt and dried-out leaf tips for cosmetic reasons because this creates a wound that bacteria and fungi can infect, where they will then move down the leaf and kill more tissue. Perhaps you were not doing this, but we mention it because a lot of indoor gardeners do trim off brown leaf tips to make plants look better.  The begonia with brown, dried/curled leaf edges is a normal development for them if growing in lower humidity indoors. If the plant is outdoors (we can't tell from the photo), then it might be stressed from having moved from dimmer conditions indoors into more intense light outdoors and needs time to adjust. If moving indoor plants outside, always put them in shade for a week or so, gradually moving them into more direct sunlight. Even so, very few indoor plants need or want more than a few hours of direct light, if any, once outside. Succulents don't need full sun when summering outside, so a location with a mix of sun and shade is usually perfectly fine for them. The begonia doesn't need treatment and can just be cleaned by removing leaves with too much "burn." This does not look fungal but can also happen when plants are over- or under-watered or over-fertilized, or in soil that's years old and hasn't been refreshed by repotting every year or two.  The vine on the tree isn't easy to see clearly but it appears to be English Ivy, a commonly-grown but very invasive non-native plant. We recommend that it be completely removed if you can, though do not tug branches attached to the bark off as this might injure the tree's bark. Instead, cut all ivy stems near ground level to deny the foliage on the trunk moisture and nutrients, and eventually the ivy stuck to the trunk will die, dry out, and fall off on its own. Too much ivy growth on trees can kill them, and while ivy itself sometimes contracts a few leaf-spot diseases, they are not worth treating because the plant itself is too ecologically hazardous to be worth keeping. Any diseases infecting the ivy aren't likely to threaten unrelated plants in the garden so by itself is not a concern.  The dark lesion on the succulent stem could be from sudden exposure to outdoor conditions (if the pot was indoors but is now outside) or it's an opportunistic stem rot but not one which is expected to run rampant through other plants. Trim off the affected stem and the plant should be fine as long as they're not being overwatered. Succulent pots should become quite dry to the touch at least an inch or two down into the soil before they need water. Make sure the pots have at least one drain hole and that, if sitting atop a saucer for drips, that the saucer is emptied promptly after watering so the collected pool of water doesn't drown roots in the base of the pot since it will seep back into the soil.  The brown spots on the Staghorn Fern don't appear to be anything serious. The plant's roots might have become too wet or dry at some point. Here too, make sure it's allowed to become a bit dry between waterings so the soil doesn't stay damp. In the wild these ferns do not grow in soil in the ground so are accustomed to getting drenched in rain but then drying-out fairly quickly around the roots, all while experiencing high humidity given the jungle-type of habitat. They like bright light but not too high an intensity since they aren't exposed to full sun in the wild, having a few tree leaves above them to cast some dappled shade.  Both Tradescantia plants are not showing symptoms of concern. Lower leaf browning or yellowing is perfectly normal on most plants because older leaves deteriorate with age and plants shed them as they produce new growth. A tiny amount of browning on a leaf edge is often due to low indoor humidity, soil with too much fertilizer residue, or inconsistent watering. Poor air circulation can contribute to leaf infections but such infections are not always catastrophic or at risk of spreading far if you remove the symptomatic leaves.  Outdoor plants also routinely shed their lowest leaves as they grow, which will often turn yellow before falling. This is normal and can be ignored. You can remove the leaves that are yellowing if it bothers you, but they contain some resources the plant is going to otherwise recycle by re-absorbing before the leaf falls, so it's best to just let them shed in their own time.  We can't tell what kind of shrub has the section of leafless branches but those stems are dead and can be pruned out. This is not easy to diagnose because it likely happened weeks or months ago and could have been due to too much or too little soil moisture, storm breakage, or (less likely) infection. No treatment is needed and the rest of its foliage looks fine.  Stems becoming dark are not always dying; sometimes, they just darken with age or environmental conditions. Leaves that blacken and mush as they die and deteriorate are typical of those shed by plants that either have too little air circulation, are shaded by younger upper growth, or are being kept too wet. It's also normal for some growth on succulents and a few other plants to "bronze" (turn kind of orange-brown) when exposed to full sun, especially if they were used to lower light. Some plant stems, including among groundcovers, naturally shed older leaves as they creep and thus have bare stems and leafy tips. This is normal and nothing needs to be done, and as the plants mature more this will probably fill-in from nearby growing tips that cover-up the gaps. Using a light mulch over the bare soil surface can help avoid issues with wet soil contact promoting leaf rot. If you irrigate the yard on a schedule, stop and instead feel the soil a few inches deep near the plants you want to check for water, since automatic or too-frequent watering can also encourage stem or leaf rot or infections.  Fungicides do not cure existing infection. At best, when they work well (which is not always), they can help prevent infection for leaves which are still healthy. However, several re-applications of these chemicals are often needed to keep suppressing spores that land on the leaves, and keeping the leaves dry when watering will help avoid infection in general. You can't change the weather of course, but by growing plants sensitive to root rot in a very well-drained soil or potting mix, you will reduce the risk of root rot even if we have a rainy season. Many herbs like rosemary (we think this is one of your photos, but couldn't tell), lavender, thyme, oregano, marjoram, and others are sensitive to being over-watered and prefer to dry out some between waterings. Succulents as well are sensitive to over-watering and must have a well-drained soil and a container with good drainage in order to thrive.  Although we were cautioning against over-fertilizing, if you haven't fertilized the indoor plants in at least a year, or since last summer, you may want to give them a dose now, according to the package directions for the fertilizer of your choice. (Although there are fertilizer blends marketed towards specific plant groups, usually any general-purpose formulation for foliage or flowering plants will be perfectly fine.)  For plants that haven't been repotted in a couple years or more, consider repotting them with fresh potting mix since old mix tends to hold more water than it used to and risks stressing or rotting roots. This freshening of the soil will also reduce the risk that old fertilizer or tap water mineral buildup over time will also stress or injure the roots.  For the future, it would be helpful to us if you can submit questions about particular symptoms on different plants in separate questions, since looking through a large collection of photos can make it easier for us to miss something and review what you were saying about each one. For example, all concerns with ivy can be sent in one question, concerns with the succulents in another, the herbs another, and so on. We realize in this case you were suspecting that a single problem was affecting lots of different plants, but that is rarely what happens and often the commonality instead lies with growing conditions than a single pest or pathogen spreading around an indoor or outdoor garden. This is good news in a way, because it means the solution will be easier to implement since it tends to involve changing plant care rather than having to treat lots of plants with a pesticide.  Miri

responder: The Question Asker Replied May 17, 2023, 6:25 PM EDT
response: Thank you so much Miri! This is great information! I still feel like something has to be causing nearly all my healthy plants to turn brown, black or yellow and black stems on some plants are spreading. I’m going to send some samples into a lab. You gave great advice and I wish I would’ve contact3d you first before resorting to fungicides as you were so right about them and they caused probably more damage, especially to all my healthy plants. I hope they heal. Thank you again!  Sent from my iPad  On May 17, 2023, at 5:19 PM, Ask Extension <<personal data hidden>> wrote:    ﻿