Our purple tulip Magnolia has scale, an infestation as repulsive as it sounds. It’s equally harmful and can ultimately kill the tree if left unchecked. We’ve been researching organic solutions, preferring beneficial insects if possible.
From the reading I’ve done, the scale may have been present months ago. Beautiful blossoms covered the Magnolia last spring, with no signs of the scale. In late June, however, I noticed some damage to of the leaves of the inner tree and only then did I discover the scale. We have all the tell-tale signs, now that I know what to look for:
- Crusty bumps along the branches
- Sticky leaves caused by scale excretions
- Ants on the leaves. They eat the sweet excretions and are known to defend the scale since they provide a food source.
Here are a few more details from the College of Agriculture Sciences at Penn State:
Magnolia scales are usually massed on the undersides of 1 and 2-year-old twigs, with heavy infestations completely encrusting branches. Other indicators of a scale infestation include reduced foliage and flower production, undersized leaves and twigs, and a black sooty mold on the foliage. After digesting the plant fluid, the scale excretes a clear sticky liquid called honeydew, which provides an ideal substrate for the black sooty mold fungus to develop. Magnolia scale infestations often go unnoticed until the leaves and twigs of the host plant turn black with sooty mold. The honeydew also provides a food source, attracting ants, bees, wasps and flies.
Healthy Magnolia Branch
Scale Infestation on Magnolia Branch
Ants Eating the Excreted Honeydew
The more I read, the more discouraged I become. Even the less organic solutions are often ineffective. I read an extensive article saying that Predatory Beetles worked well, only to learn they are no longer commercially available. Aphytis melinus is another possibility, and probably our next, best option. Pruning away the worst of the branches seems like a good idea, too. I would hate to have this spread to our larger magnolia just a few feet away.
Suggestions welcome!
Gardening Nirvana 
I feel your pain ;-(. Hope you can fix this 😉
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Me too! Thanks for commenting.
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Oh no, that is a conundrum and nasty looking too. Ants seem to be taking over. We’ve even seen them at New House Builds this year. The odd ones find their way on to our front stoop. I give them the heave-ho with my trusty broom but you turn around and there’s five of his cousins right behind you, I could stand there and sweep all day. What do you do for ants Alys?
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I’m not surprised to hear you are seeing them at New House Builds. I think the nests are disturbed from all the digging, so they come up and try to relocate. If you have several over and over again, it probably means you have a nest near by. Look for tell-tale signs of little piles of fine earth. White vinegar is a good, organic deterrent for ants. It’s also inexpensive, especially when you by it in large jugs.
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I have never about vinegar, thanks for the tip. Do you just leave out a bowl or soak a cloth and lay it in the garden? I will have to get to Costco and get a big one!
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http://frugalliving.about.com/od/doityourself/tp/Get_Rid_of_Ants_Cheaply.htm
Do this will discourage them from crossing your deck or patio. They don’t like the smell and it also destroys the trail scent, so cousins can’t find it.
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http://frugalliving.about.com/od/doityourself/tp/Get_Rid_of_Ants_Cheaply.htm
Doing this will discourage them from crossing your deck or patio. They don’t like the smell and it also destroys the trail scent, so cousins can’t find it.
You can also leave bowls near the ant source. They don’t like the smell so they’ll vacate to greener pastures.
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That sounds like a good plan, they seem to be coming from the edge of the driveway, living in the crack where the pavement meets the road. They march right up the stairs to the front door. I’ll let you know how it works, thanks Alys.
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Please do. Good luck!
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I realize this is completely unrelated to the topic at hand, but I wanted to say that I’m saddened by the news from Toronto. It’s horrible to hear of that kind of violence. It seemed for many years, gun violence in Canada was rare. Sending healing thoughts your way.
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Alys, you are always so caring. I’m sure the families are in pain. I’ve been to Toronto a few times, it’s a giant city with many great things about it and saddly some ugly things. You don’t hear about gun violence too much but we also had an incident in Edmonton a few weeks back. I guess there will always be those who don’t want to work for what they have. Usually it’s gangs killing gangs, but it is getting scarier. Thanks for your thoughts.
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Gang violence is a growing problem in many large cities, including ours. NPR had a fascinating program on the culture of gang violence and the social implications. Desperate people behaving badly in a culture where they’ve known nothing else. Sadly, many a bystander, sometimes children as young as two or three, get caught in the cross hairs as well.
I’m sorry to hear you’ve also seen this in Edmonton.
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Sorry to hear you have these pests! We have scale insects on an Acer tree which we noticed when my husband rescued it from a pot it had outgrown and planted it in the garden. Sorry if this is too gross but I scraped a lot of them off with my thumb nail and then back of a small knife when my fingers got too sticky…yuk! They are still present though in not so great a number. The large red Acer also has some but not many and it doesnt seem to affect the tree at all. I’m off to check out two magnolias in the front garden!
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I hope your Magnolias are okay. Our large tree is untouched. You were brave to scrape them off with your nail.
We went out last night at dusk and pruned off many of the branches. Some of them were thick with scale, while others only have a few. We’re still going to order beneficial insects. According to my reading, late July/early August is when the eggs hatch. We need to act now!
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I have never seen beneficial insects for sale on our local garden centres but I must look into it online as it is an excellent idea. You go get them!
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Here is a source in the UK: http://www.greengardener.co.uk/
Let me know if you give anything a try.
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Hey thank you very much! I will have a good look and let you know if I try anything. Happy gardening to you!
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Thanks! To you, too.
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