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Garden Pest Problem

Posted by JMcCanne Oklahoma (My Page) on
Sun, Aug 5, 12 at 18:10

Hello-

I'm new to this forum, and I'm hoping ya'll can help me. I lost two trees this year to carpenter ants and now I'm having some trouble in my garden too. I planted a sky pencil holly and an azalea at the corner of my garden. They were both doing great and then both died suddenly, even with watering. This afternoon I pulled up the dead azalea and found all these bugs crawling around in the soil. I saw beetles, ants and a brown bug that I can't identify. It looks like a brown beetle, no wings. I'm rather new to gardening, so I don't know what is normal to have crawling around on the roots of plants and in the soil.

I plan on taking a soil sample to OSU to have it tested and I also poured some diatomaceous earth into the ground where the azalea was.

Any suggestions or advice?
Thank you
Jenni


Follow-Up Postings:

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RE: Garden Pest Problem

Hi Jenni,

Welcome to the forum.

First of all, let's clear up the misconception that carpenter ants kill trees. They do not. They move into trees that have become stressed and ill and already have decay or rot inside, and sometimes once they are in there they even will tunnel into the heartwood of the tree. But they are just a symptom that the tree was dying and they took advantage of that and moved in. Most trees are dying inside before you see external symptoms. Just because we are in Oklahoma and I know what our weather has been like the last two summers, I suspect it is most likely that drought stress or heat stress killed your trees.

You didn't say what kind of trees they were, and knowing that will help in regards to understand why a seemingly healthy tree died. If they happen to be oaks, I have a good idea what got them. Actually, I have a couple.

I suspect the same thing happened with your azalea, and the younger and less well-established it was, the more likely that last year's and this year's drought got it too. The pests then would move in to feed on the dead wood or whatever. All kinds of insects exist everywhere, so it is hard to guess what the ones you're seeing might be. I am going to link a website where lots of people have had great success navigating the website and identifying pests they have seen.

In these very difficult weather conditions, plants of all kinds have been dying, usually because of a lack of water or because of heat stress. It takes a huge amount of water, and proper watering techniques, to keep plants alive in summers like we've had the last two years. I've had plenty of friends lose plants even after insisting they watered them enough, but in these conditions sometimes it is impossible to water enough and you can lose plants anyway. For the friends who live in my neighborhood and who have lost plants, I know they didn't water enough because I saw how brown everything in their landscape got. Usually people water too lightly and by the time they figure out they should have been watering more deeply, it is too late.

To help your remaining plants survive, be sure to water long, slowly and deeply less often as opposed to giving them a little bit of water every day or two. A very respected horticulturalist down in Texas recently stated that trees and shrubs need a lot of water right now and suggested watering them deeply three times a week, which is one time more per week than I've been doing, so I will water my trees and shrubs a bit more than I have been because I respect his opinion....and the part of Texas he's talking about isn't even as dry as we are here in Oklahoma.

Much of your watering technique needs to be tailored to your soils, and using the optimal watering technique goes hand in hand with amending your soil so that it both drains well (to avoid root rot caused by excessively wet soil) and to allow the roots to grow and spread and be able to take up moisture well. Very sandy soils can drain too quickly in heat and drought like this, and adding lots of organic matter will help that soil hold moisture better, as will a good, deep layer of mulch on top of the soil. Clay soil is even more difficult. It will hold too much water in rainy periods or with very heavy irrigation, but can dry as hard as concrete in hot, dry weather and water can just pool or pond on top of it or run downhill without being absorbed deeply into the soil. The solution? Adding lots of organic matter to help the soil both drain better and to allow better root growth and better uptake of the available moisture. If your soil was not well-amended before the plants were planted in the first place, that could be the biggest problem.

If your plants are less than 3-5 years old, drought likely got them. If they were older, it still probably got them but had to work harder to get them.

Are you sure no one used weed-and-feed products near your plants? If it wasn't drought that got them, or something peculiar like a gas leak, then it could be a strong herbicide got them. While there are insects that will kill plants, even when they kill them, they usually are a secondary problem. Healthy plants can resist many kinds of insects, but sick or drought/heat-stressed plants cannot.

If something is fundamentally wrong with your soil, that could explain the problem. Often with azaleas, the soil and/or the water is too alkaline for them because they need really acidic soil. When you get your soil test done, look at the soil pH for the first clue about what might have gone wrong with them.

On the linked bug guide website, click on the image on the clickable guide area that most resembles the bugs you saw. When you click on it, it will take you into that area and you can search for the insect that most resembles the bugs you saw. Sometimes I find exactly what I'm looking for here, but sometimes I don't. There's hundreds of thousands (likely millions) of different kinds of bugs, and no guide has them all.

Dawn

Here is a link that might be useful: Bugguide.net


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RE: Garden Pest Problem

I agree with Dawn that they likely succumbed to the heat and drought we have had for the last 2 years. Sky Pencil Holly and Azalea are both very shallow-rooted plants. Consequently, they need to be watered more often than other types, and also because they have not established roots in your soil yet either. So there's a couple of things working against you for these particular shrubs.

Mulching would help some, as well as the frequent slow watering technique Dawn mentioned. In this heat and drought it is essential. Both of these shrubs love acid soil, so I would, at the time of planting, add a good amount of peat moss or pine bark fines to the planting site. A good acid fertilizer would help at initial planting, and once or twice during the growing season. I like the Espoma products, like Holly Tone or Soil Acidifier, for my Hydrangea, Azaleas, and Blueberries. Instead of the liquid ferts, you just apply the dry fert around the perimeter of the plant, according to the package directions (I use less than recommended, because over fertilizing can cause damage to the plant, too) and water it in well. I wouldn't worry about fertilizing this late in the season, though, nor since your plants sound stressed out as it is.

The roots on these two plants tend to grow horizontally rather than vertically like a lot of trees and shrubs. They don't grow deep, so mulching is truly crucial to their survival - especially here in Oklahoma, and especially now during this drought and extreme heat. You can see why mulching and watering needs are necessary. I'd apply at least 3-4" of pine bark, pine needles, oak leaves, etc. A good mulch will keep your soil cooler and keep the moisture in a bit longer.

Once they are established, they probably won't need as much care, other than fertilizing regularly, as they do in the beginning. I rarely have to water my Hydrangea and Azaleas that are planted right next to the house. They've been there for well over 20 years.

I wish you good luck in growing these beautiful shrubs!

Susan


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RE: Garden Pest Problem

The trees were not oaks. One was some kind of non fruit bearing fruit tree and the other - I don't know.

I do have my lawn treated several times a year and this part of the garden is closest to the lawn, but I've had several things die in the same spot for years now. Not just this year. I think I'll start with getting my soil tested to see what's going on.

Thank you for the great advice about fertilizer, watering and mulch. This is my first garden and I'm learning as I go!

Thanks again! Jenni


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RE: Garden Pest Problem

If any of the branches touched the treated lawn that could be the problem also. When we were in the military, we lived in a rented house with a great little pear tree until the landlady had the grass treated and the weight of the pears caused the limbs to drag on the ground when the wind blew. That was the end of the pear tree.


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RE: Garden Pest Problem

Jenni,

The reason I said I might know what the issue was if they were oaks is because down here in parts of southern Oklahoma, hypoxylon canker is killing stressed oak trees. While this form of canker is fairly rare, it is seen a lot more when the oaks are heavily stressed by drought.

If they are treating your lawn with a broadleaf herbicide, which would be found in most weed-n-feed type products, that likely is why you keep losing trees there. If they are putting out a pre-emergent weed killer, which works in a different way, that should not be hurting your trees.

When trees and other perennial plants keep dying in the same portion of a yard, it could be a soil issue, but it also could be that the soil in that area drains very differently from the soil in areas where you don't have problems. It could be that it drains too fast or too slow.

As far as learning as you go, that is true for all of us, even if we have gardened for many years. There is so much to learn, so many exceptions to all the oft-repeated gardening "rules", new plant varieties, new research and new techiques to try, and so many new challenges from weather and pests every year that none of us ever stops learning. That's what I love about this forum---how we all learn from one another.

Dawn


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