Something is killing my plants!

soonergirl1968(7a OKC)June 28, 2009

I'll keep this as brief and "to the point" as possible. My back yard is mostly shade (38 oak trees) except along the driveway were it is mostly sun. This is only my second summer in this house and had to start from scratch as it sat vacant for 3 years before my arrival. I have been battling brown patch in my fescue but think I finally have it under control and will (no doubt) have to use a fungicide next year as a preventative measure. (I will reseed this fall with a more fungus resistant variety of grass, as well.)

My problem is now my other plants are dying - one by one. In the past week, I have lost a red-leaf hydrangea, wine & roses weigela, and have MANY other plants which seem to be under attack by the same "killer" including; roses, dead nettle, heuchera, daylilies, hostas, hardy geraniums, etc. I have sprayed with fungicide but it didn't seem to stop it - in fact it has been worse. It is quickly affecting more plants and I don't know what to do. I have checked for insects and cannot find any evidence of aphids, rolly-pollies, scale, etc.

I figured if it was powdery mildew or a fungus it would have been stopped with the fungicide. Anyone have an idea as to what this is? The leaves on each plant are turning brown and dying and it happens VERY quickly. There is a little evidence of a powdery mildew type fungus but don't know why the fungicide wouldn't stop it or if it even affects all these types of plants. It is basically going from bed to bed and making its way around the yard.

Wish I knew a true master gardner who could come look at it and tell me what to do. Just seems like a guessing game.

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Sounds terrible! Can you post some close up pics? Maybe someone here would be able to recognize the problem.

    Bookmark   June 28, 2009 at 11:05PM
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Okiedawn OK Zone 7


I have a couple of questions that might help us arrive at a diagnosis, but it is a complicated scenario and my "hunch" might not be correct.

So, here goes.

1. What kind of soil do you have? Sandy loam? Heavy clay? Pure sand? Caliche clay with rock?

2. To the best of your knowledge, was your land ever part of a farm? And, if so, do you have an idea if cotton was raised there or if cotton was raised in your county back in the day when cotton was a widely grown crop in Oklahoma?

3. On the plants that are dying, is it hit and one dies here and then one dies there, or does the illness move in a straight line moving from one plant to the next one beside it and then the next one beside that, etc. If it progresses in a linear method like that, then I think I know what it might be.

4. Can you tell if the plants are dying from the top down or from the bottom up, or just all at one day they look fine, and the next they look sick, and the third day they look dead. Is it progressing that quickly?

5. When you dig in the soil around the dead plants----and it would be in the root zone area and likely no lower, do you ever encounter dead stringy tissue that almost looks like the remains of an old rug or burlap or something, but which is organic (i.e. alive). Sometimes it just looks like a mass of dead stringy roots but it isn't connected to your plants that have is separate from them but close to them.

6. Does your soil drain very slowly, holding water for a long time? Does it drain very quickly?

7. Have you or your neighbors sprayed any sort of weedkillers or used a weed-and-feed product?

8. Before you planted, did you add anything to the soil in terms of organic matter like compost, cow manure, pine bark fines, compost, etc.

9. Did you have a soil test before you planted so you'd know that your soil had everything it needed in terms of nutrition. Do you know what your soil pH is? Finally, do you know (in inches) how much rainfall you've had this year?

I know I asked a lot of questions, but diagnosing a plant problem sight unseen is complicated, and the answer to each question can help eliminate certain possible causes or, conversely, cam help confirm a hunch about what it might be.


    Bookmark   June 29, 2009 at 12:07AM
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soonergirl1968(7a OKC)

First...thanks for your help. I would post pictures but don't know how! :)

1, 2 & 8) Here's a little background info on my yard. My house was built in 1936 and is surrounded by HUGE native oaks. I live in the middle of OKC but know my house was originally built on 40 acres of trees so highly doubtful it was ever used as farm land. When I purchased the house last May, it had been vacant for several years and the yard was a MESS! Hauled away trailer after trailer of debris (leaves, limbs, etc) and cleaned it down to the dirt. The flower beds I planted last year did very poorly because of the lousy sandy soil. So this spring, I hauled in 20 tons of "garden-ready" soil, created new beds, dug up and replanted all my plants and added many more plants. I did further amend the soil around some of the more finicky plants with miracle grow garden soil, peat and added bone meal.

3) The plants are not dying in linear fashion, but does seem to be hitting one area, then the next. Out of 9 beds in the back yard - 3 have been affected. Also, there are 2 lady-in-red hydrangeas planted next to each other and one has it and the other doesn't... YET!

4) Yes. It is progressing that quickly. Seems to affect the leaves from the tip moving inward. They will be brown on the tip and edges then it moves inward and they curl up & die.

5) I haven't noticed that at all. However, I haven't been digging around them either. I will have to check.

6) My "natural" soil is like a sand box and drains incredibly fast. The beds seem to hold water better because of the imported soil - but certainly drain much better than say red clay. They are moist but not wet.

7) No weed-killer spray that I know of. My lot is about 3/4 of an acre so the neighbors are pretty far away.

9) I don't know how much rainfall we've had this year. We had a wet April & May but has been fairly dry since. It has been over 100 degrees for the past week or so - when this all started!

I took some samples to Horn's Seed this morning and they told me I was just watering too much - which I probably am. However, I checked when I got home and several of the plants affected are planted in the sun and the soil was completely dry. I also found some tiny little reddish colored spots on the leaves of one of my climbing roses which stain your fingers when you rub them. I also found some white web-like material on some of my "knockout" roses. I have 30+ "knockout" roses and probably 6 have been affected in the past week!

My tendency right now is to remove all affected leaves and branches, spray with malathion for the bugs and continue to treat with a fungicide as a preventative measure. I have reset the sprinklers to water 3X week. I should probably only do 2X a week but I can't bring myself to do it in this heat. I don't know what else to do. I have worked too hard and spent too much to watch everything die - just makes me sick :(

    Bookmark   June 29, 2009 at 2:58PM
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Okiedawn OK Zone 7

From your initial description of the issues your plants are facing, I was leaning towards thinking your plants were having a root rot issue. I still sort of lean that way, but not as much as I was in the beginning.

Root rot is very common on heavy, slow-draining clay and you have fast-draining sandy soil where it is much less common.

The specific root rot I had in mind often progresses in a linear manner. For example, if it hits a row of shrubs, you'll see it move from one to another in a linear manner. However, in field crops it also progresses in a circular manner. However, you're in OKC and it is more common in the southern OK counties, and not so much in OKC, I think. If you did find the stringy growth I described in the root zones of dead plants, or observed a white spore mat on the soil surface near those plants, though, I'd go back to my original feeling that it sounds a lot like cotton root rot, which I just happen to have battled here in our heavy red clay.

One question that would help rule out cotton root rot is this: when the leaves die, do they cling to the plant or do they drop? Cotton root rot can affect plants very suddenly, it affects over 2000 known species, it is very fast-acting (i.e. quick to kill plants), it moves in a linear or, in crops, in a circular fashion, and it is common in clay soil. So, it might not be your problem, but a similar root rot might be.

Keep in mind, there's the disease type of root rot caused by specific fungal diseaes and there's the physiological kind of root rot caused by plants standing in water/wet soil until their roots literally rot and die. The folks at Horn's seemed to lean towards the physiological form of root rot when they expressed their opinion that your plants are being overwatered. You're the one who has to decide if they are right. I still think it is very hard for fast-draining sandy soil to stay wet enough to root rots.

One way to figure out if the plants are dying because they are too wet is to dig up a dead plant and look at the roots. Do they look healthy and alive or dead?

Since you have sandy soil, I think root knot nematodes could be an issue, but I don't have a lot of experience with them. If you have root knot nematodes, you'll see knots, galls or swellings on the roots of an affected plant that has died. You can google and find a photo of roots with root knot nematode damage.

I am inclined to think you need to take a three-pronged approach.

1.) Feed your plants if they haven't been fed in the last couple of weeks. Fast-draining sandy soil that is being heavily watered may not be providing the plants with enough nutrition, and plants that are "hungry" or underfed are more vulnerable to diseases and to heat stress.

2.) Spray with a fungicide on a regular schedule as the fungicide labels direct. Watch to see if your plants improve.

3.) Treat for insects in whatever way you're comfortable using, but I am not convinced they are the issue.

And then there is the watering issue. You want your plants to be in moist soil, and you want it to be as uniformly moist as possible. It is better to keep it somewhat moist at all times than to alternate between very dry and very wet because both those extremes stress plants.

And, if it were the heavy April/early May rains that were the issue, I would have thought the plants would have showed symptoms long before the heat wave arrived last week.

As long as you water with a sprinkler system, your plants are going to be more vulnerable to fungal diseases, so a regular preventative spraying program of fungicide during the growing system probably would be a good idea.

You didn't mention if your beds are mulched, but if they aren't, they need to be. Mulching helps keep fungal spores in the soil from being carried up onto the plants by water splashing up when the sprinkler system is in use.

I am a little worried about the roses. Look at the undersides of the leaves. Do you see spider mites? Both the fine webbing and the discolored leaves sound like spider mite damage. Look at the photos in the link below and see if they resemble your roses. The ones in the linked photos may be further along with the mites than yours are, but your plants still ought to look similar if it is mites.

I don't really know what the answer is as far as plant death. I think it is still likely to be a fungal disease, but without seeing the plants can't rule root knot nematodes in or out, or anything else for that matter.


Here is a link that might be useful: Spider Mites on Roses

    Bookmark   June 29, 2009 at 5:13PM
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soonergirl1968(7a OKC)

Dawn - After reading your response, I went back out and did some more checking. I think my problem is two-fold. What I assumed was the same culprit killing everything, I now think is two separate issue with similar symptoms.

I'm pretty sure I do, in fact, have spider mites on the roses. The head gardner at Horn's told me they were really bad right now and her knockouts had them worse than other roses so she pulled them all out. I didn't see them at first - they are REALLY tiny!! What I thought my have been powdery mildew on the rose leaves, I believe is actually the spider mite's webbing. I think what I was rubbing off the leaves earlier, which was causing red discoloration on my fingers, were the mites themselves. Now I see them moving around. So I think this is my rose problem.

My second issue, on the shade plants, I'm not quite as sure about unfortunately. I dug down about 6-8 inches around the affected plants to see just how much water was draining and how much was sitting. The soil is moist but by NO MEANS wet. It doesn't even clump when you squeeze it in your hand. It seems - to me - perfect. However, I will cut back watering and continue with my fungicide treatments to see if I can at least stop it (whatever THAT may be) from killing any more plants. I will go ahead and remove any damaged leaves but leave the stems as they seem to be alive. Maybe they will come back next year. I hate to pull a plant still showing signs os life.

Thank you so much for all your help. You really took a lot of time to help walk me through this and I truly appreciate it. If another possibility occurs to you, please let me know. I'm still not convinced it's a watering issue, but what do I know. :)

    Bookmark   June 29, 2009 at 6:27PM
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Okiedawn OK Zone 7


I am happy to help. And I am delighted you didn't find anything stringy in the soil that would have indicated cotton root rot because it is devastatingly efficient at killing plants. Once you said sand, and not clay, I was breathing easier on that one.

Did the person at Horn's to whom you spoke recommend anything for spider mites? If you prefer the organic approach, a spray containing Spinosad probably would work as would neem oil, which is easier to find. If you are not organic, you could check and see if Kelthane, which is a chemical miticide, is still available and, if so, if it is labeled for use on roses.

Sometimes, with a lighter infestation you can knock them off the back of the leaves with a sharp spray of water. You might have to do it daily for a while. Spider mites prefer hot, dry, plants, so moister, more humid ones are not as attractive to them. I use an adjustable nozzle so I can send a stronger, more concentrated spray of water on the backs of the leaves).

I'm not convinced we're right about the cause of your plants' illness/death being fungal or a watering issue, but at least a fungicide won't hurt and might help. As for the watering, it would just depend. And, by the way, have you checked all your sprinkler heads to make sure they're working properly? Maybe the part of the garden where the 3 beds are most affected just aren't getting as much water as you think. I still lean towards thinking too little water and not too much, but I don't have a lot of sandy soil....only a very narrow band of it in the midst of all the clay. What I know about my narrow band of sandy soil is that I have lost plants there because it drained too quickly and I didn't water them often enough our first summer here. I've never had disease issues in that band of sandy soil either. In the clay, though we have had lots of fungal stuff because it holds water like mad during rainy periods.


    Bookmark   June 29, 2009 at 9:22PM
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soonergirl1968(7a OKC)

Hi Dawn - I sprayed my roses last night for spider mites and am happy to say all bugs seemed to be dead this morning. I've spent the last 4 hours "cleaning up" my plants. I've removed all affected leaves and debris so I can see any new damage more easily (fingers crossed there is none.)

I check my sprinkler heads frequently and make sure all are functioning properly. They do have to cover a lot of territory which is why I was watering every day. Fortunately, I have a well or my water bill would be astronomical. The soil where the grass grows dries out VERY quickly but the beds (which have new imported soil) retain moisture much better. I personally think the level of moisture in the beds is fine but people keep telling me I water too much. I also water my front yard (zoysia) and beds everyday but they get much more sun and are doing very well.

I'm curious to know how often people in Oklahoma water their beds (shade and sun?) I read online not to water more than 2X a week but I'm wondering if they're taking into account our 100+ degree summers? Guess I'm just going to have to dig holes around the yard periodically to test the moisture level until I get it right.


    Bookmark   June 30, 2009 at 1:02PM
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devilwoman(7a Warr Acres OK)

When people say to water only once or twice a week they mean to water A LOT that once or twice. The idea is to put out enough water to seep way down into the soil. This will encourage deep root growth which helps plants survive hot, dry weather better. If you water a little very often the water will stay near the surface where it evaporates and dries out more quickly, and your plants' roots will also stay near the surface where they too will dry out more quickly.

I water once a week, on the weekend. The only plant that usually gets any water in between weekend waterings is my hydrangea. If I come home in the evening and the hydrangea's leaves are droopy I'll let the hose trickle right at the base of the plant for about 30 minutes which will perk it back up. The rest of my flowers and the veggie garden only get watered once a week, but I try to make sure I give it around the equivalent of an inch of rain each time I do water. In fact, the weekend my daughter came up to visit (June 13-14) I completely forgot to water the veggie garden at all! So it went two weeks between watering (and no rain at my house either!). Some of the leaves, notably the okra, did look just a tiny bit droopy after going two weeks without water, but everything else looked pretty normal.

One way to determine how long you have to run a sprinkler to water enough is to place either a rain gauge or straight glass (you want one that does not vary along the height of the glass, no flaring top or bottom) in the middle of your garden. Run the sprinkler until you see one inch of water in the gauge or glass. Then you can time how long that took and, so long as you set the sprinkler output to the same level each time, you know how long you have to water to get that much in the garden.

Also, slower is better. If your sprinkler output is too fast then you can overwhelm the ground's ability to soak up the water, and it just runs off (and is wasted) or else your plants end up in standing water (which few plants like). This is pretty easy to watch for. You don't want to see water running, like in tiny streams, off the ground nor do you want to see pools of water standing on the surface.

The best time to water, especially in hot weather, is first thing in the morning. In fact, the ideal situation would be to start your watering such that it finishes just about the time the sun comes up. This minimizes the loss to evaporation because it's the coolest part of the day but then gives the sun all day to dry off the plant leaves to help prevent fungus.

One of the ladies I work with asked me last week how often I water. I told her once a week. Her eyes got big and her jaw dropped open. She'd been watering every day and sometimes twice a day. She decided to move a small okra plant. When she dug it up she found it only had roots about two inches down but widely spread in all directions. This is the effect of too shallow watering. A plant's roots will go wherever necessary to find water. She was insuring that they didn't have to go down at all, just wide. The deeper you go into the ground the more moisture you will find. Deep roots will still be finding some moisture when the surface ground is bone dry.


    Bookmark   July 1, 2009 at 3:02PM
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I'm watering about once a week now, but that's only started in the last two weeks. Before that, if it didn't rain I was watering 2x per week. The reason is that I feel as the plants mature, they've had more of a chance to get their root system established and can fend for themselves for longer.

The corn that I just planted 10 days ago I've been watering more frequently, along with the basil that only sprouted about 10 days ago. Young stuff gets watered more. And when I'm out watering the corn or basil I'll water the sweet potato slips too and the hubbard squash that I planted a month ago because they're all in the same area and fairly new.

The squash, melons and pumpkins I planted two months ago will just have to make it on their own and get watered every week or 10 days even. For one thing, my parents took my hoses a while ago and I can't reach all of my plants with the hose I bought recently. I should probably go get my hose back from them. :)

Everything I have is mulched in real well. Each squash, melon or pumpkin hill has at least one wheelbarrow load of manure and bedding layered around it as a mulch. And half of the hills have 2-3 inches of wood chip mulch between the hills. My tomatoes, flower beds and raised beds are full of wood chip mulch too, 1-3 inches thick. I feel under the mulch before watering and even in the worst heat it took over a week for my front circle bed to dry out (which is where I have a dozen watermelons).

Containers get watered every day or every other day, depending on how busy I am and if I forget about them. The aloe gets watered once a week or so depending on how their leaves feel. I've mulched my container plants too and arranged them as much as possible where they'll shade each other. Most of them are on the back porch where they face east and get shade all afternoon and evening.

    Bookmark   July 1, 2009 at 4:16PM
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Okiedawn OK Zone 7


I'm glad the spray seemed to take care of the spider mites because mites can be very persistent. Now, keep an eye open for them because they often cycle back up anywhere from a few days to a couple of weeks after being knocked back with a spray.

Debra already covered the issue of watering once or twice a week DEEPLY to encourage roots to go down deep. If you water shallowly every day, the water may penetrate a half-inch, an inch or even less than a half-inch depending on how fast water percolates down through your soil. Since the roots are going to go to where the water is, your plants remain shallow rooted and NEED to be watered daily because they are so close to the soil surface that they dry out quickly. It would be "perfect" if you could water enough twice a week for the water from each session to go down roughly 6" in the soil. That would encourage your plants to go down more deeply and that, in turn, would help them handle drier, hotter periods better.

By watering shallowly every day, you are 'training' your plants to be shallow-rooted which means they'll wilt easily and they'll not develop the stamina to handle hard times. Also, if they are perennials, trees, shrubs, etc., the shallow roots will hurt them in the winter because shallow roots closer to the soil surface are more likely to freeze in cold weather.

To make the transition from watering daily to watering once or twice a week, cut back and water every other day. The key is to water longer so the water goes more deeply. To figure out how deeply the water is going, if your soil is loose and sandy, you can stick your index finger down and see if it is wet 2" or 3" down. To check more deeply use a trowel, or dig a small hole. After you've watered every other day but more deeply for about a week, then cut back to every third day and water more deeply yet. This will encourage deep roots and deep roots are more drought- and cold-tolerant.

Everyone's soil and plants are different, so you'll have to get to know your soil and your plants and learn how often they need water and how much water they need. Learning to manage watering needs properly is one of the best skills you'll ever develop as a gardener.

Parts of my landscape get watered once or twice a week. Parts don't get watered at all. Some parts get water about once a month, and that includes some shrubs, perennials and vines. Even my vegetable garden might get watered only once a week.

I am careful, though, not to plant any big water guzzling ornamentals because I live in a part of the state where moderate drought is common every summer, and severe to exception drought occurs about 2 to 3 years out of 5. I lean towards natives that can survive only on rainfall once established (That leaves me more water available for the large vegetable garden.)

The watering of containers varies. It depends on what kind of soil-less mix I made up for that specific plant and container and also it depends on the plants in the container and what their watering needs are. Their watering needs can vary, too, depending on if they are in full sun vs. part shade for example. Each plants has a certain way it looks when it is "happy" and a different way it looks when it is "unhappy". Once you learn to recognize those happy and unhappy looks, you'll be able to tell at a glance if a plant in a container needs water.

For what it is worth, more new gardeners kill or otherwise harm their plants by either overwatering, overfertilizing or doing both than by underwatering, underfeeding or both. In the gardening world, this overwatering and overfeeding practice is known as "loving your plants to death". "Loving your plants to death" doesn't mean you're a bad gardener at all really means that you're trying too hard to be a good gardener.

We all were brand new gardeners at some point, so when it comes to "loving our plants to death", many of us can say "Been There, Done That, Got The T-Shirt".


    Bookmark   July 1, 2009 at 5:04PM
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soonergirl1968(7a OKC)

Debra, Gamebird & Dawn - Thank you for all your advice and suggestions. This is only my second summer in this house and I am still trying to figure everything out in the yard department. In fact, on the lawn care forum I'm soliciting advice on what to do about my grass situation in my shade-covered back yard. (You know the Oklahoma routine...fescue...brown patch...yellow grass...reseed fescue...etc.

Quite frankly, my last house (of 12 years) was a typical subdivision house - no shade, bermuda, typical Okie soil. Gardening there was easy! Never had any problems! Grass was green, no weeds, no disease.

I bought my current house 1.) because it's a beautiful 80 year-old home which I love, and 2.) for the AMAZING OAK TREES! Unfortunately, along with the oak trees, came the sandy soil, shady yard and the headache of dealing with fungus and disease. But I am determined to figure it out, and I will...eventually. :)

I am going to put cups around the yard (as you suggested) this evening so when the sprinkler runs in the morning, I can see how much water is actually falling. I am also checking soil moisture (using a trowel 6-8" deep) in various locations around the yard to check after 1 day, 2 days etc. I think it's just going to be a trial and error thing.

As far as "loving my plants to death," I am 100% guilty. I had to start from scratch with this house and have completely sodded, seeded and landscaped .75 acres in the last year. Needless to say, I've spent a FORTUNE and don't want anything to die so I baby my plants! My dad tells me to just leave them alone, but I can't myself!! :)

    Bookmark   July 1, 2009 at 6:15PM
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Okiedawn OK Zone 7


At some point, with that many big old mature oak trees, your lot will get too shady even for the shade-loving grasses. At that point, you can switch to groundcovers or mulched beds of groundcovers/perennials, etc.

Often, when you have a lot of fungal issues, it is because the plants get a lot of shade and moisture lingers on the leaf surfaces longer than it would in more sun.

Hey, maybe you should listen to your dad. (grinning) Don't worry, we'll help you reform and learn to "chill". Then, one of these days, you'll be the one advising newer gardeners to stop loving their plants to death. : )


    Bookmark   July 1, 2009 at 8:05PM
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