Controlling Leaf Curl Plum Aphids – Leaf Curl Plum Aphid Treatment And Prevention


By: Bonnie L. Grant, Certified Urban Agriculturist

Leaf curl plum aphids are found on both plum and prune plants. The most obvious sign of these aphids on plum trees is the curled leaves they cause by their feeding. Fruit tree management is necessary for good production. Large populations of these pests can minimize tree growth and fruit sugar production.

Control plum aphids with a mixture of cultural and physical methods, with chemical formulas reserved for extreme infestations.

Leaf Curl Plum Aphid

Aphids on plum trees that are found inside curled leaves are leaf curl plum aphids. The pests are tiny and have shiny bodies that range from pale green to light yellow in color. The insect produces a high volume of honeydew, which is the excretion of the aphid. This in turn attracts ants that feed on the sweet liquid and causes a fungus to form that produces sooty mold.

Plum aphids cause leaves to curl as they suck the tree’s fluids. The eggs of the aphids overwinter on plum and prune trees but may move to other plant hosts as adults. Leaf curl plum aphid treatments may help minimize fruit loss and increase plant vigor if the pest is properly identified and treatments begin at the correct time.

Aphids on Plum Trees

Damage to fruit trees by these aphids starts with the feeding on young terminal shoots. This can affect the growth of the tree and reduce the foliar canopy as the new leaves curl and die.

It is important to control plum aphids, as populations can quickly get out of hand and serious infestations drain plant reserves.

The aphids hatch just at bud break on the tree and begin feeding immediately on shoots and then on the underside of leaves. The curled leaves create a shelter for the pests. Early observation of the shoots can help indicate if you have leaf curl plum aphids and increase the chance of management of the insects.

Leaf Curl Plum Aphid Treatments

You can apply cultural methods to control leaf curl plum aphids. Use quick hard blasts of water to rinse off the insects. Limit nitrogen fertilizers, which force the formation of tip growth, one of the insect’s favorite plant parts.

There are also several biological treatments in the form of natural predators. Lady beetles, green lacewings, and syrphid fly larvae are another way to control plum aphids.

If necessary, use dormant season chemical treatments of horticultural oil. Severe aphid infestations require growing season applications of a leaf curl plum aphid treatment such as neem oil, imidacloprid, pyrethrins or non-toxic insecticidal soap.

How to Control Plum Aphids

Apply superior type horticultural oil according to the directions in the dormant season. Spray in early November and then monitor the plant during the remainder of the dormant period. Read the manufacturer’s instructions for rate of application and amount of dilution.

During the growing season, once the buds have broken, use repeated applications of leaf curl plum aphid treatment. Best results are found when you alternate one treatment with another to reduce resistance build up in the insects.

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The key to staying on top of the leaf curl plum aphid (Brachycaudus helichrysi https://pnwhandbooks.org/insect/tree-fruit/plum-prune/plum-prune-aphid) is to do dormant sprays in the winter and rake up fallen leaves in the fall. If you have had plum leaf curl aphid problems in the past, you need to start monitoring in the early spring so that you can stay on top of the pest. The sooner you treat the trees in season, the less damage you will have. You can do a spray at petal fall with insecticidal soap or neem, but it will be less effective than a dormant spray as aphids are protected by leaves. You can cut off affected growing tips. Treat it as a heading cut, and prune back to just above a bud so that the branch sends out side shoots. Start with either a spray at petal fall or attempt to wash the aphids from the leaves with a strong stream of water. In the fall, rake up fallen leaves, and spray with a dormant oil in late winter next year. For more information, see the OSU publication on managing insects and pests in the home garden: https://catalog.extension.oregonstate.edu/ec631

As I had sprayed a dormant spray this past winter and still have the problem, I assume I should spray multiple times? and which months would be best to spray?

(I will go ahead and prune the infected tips of the branches as you had suggested and try to get ahead of it for next year)


Related Discussions

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Bpgreen

I need to start checking to see if somebody else gave the same advice I'm planning to give before I hit submit.

Digit

Not necessarily, BPGreen - I'm reassured that others may 2nd my comments and so may the original poster. Further, the link you sent offers appropriate cautions - Phytoxicity, for instance. And, "do not use extra strength, grease-cutting, or anti-bacterial soap."

Also the recipe: "one teaspoon of liquid soap such as mild Dove®, Pure Ivory Soap®, or Dr. Bonners® or pure castille soap, per quart of water." This makes me wonder whether 3 tablespoons is too much. That's just over double what the author is suggesting.

Here's what Loyola U says about treating spider mites on hibiscus: "Use Palmolive or Dawn or Sunlight soap at one to two tbs. per gallon to smother the insects on the plants. If you need to use more than 2 tbsp/gal, remember to later rinse off the plant. Spray twice a week until bugs are gone." I think Sweetmagnoliame would be well advised to rinse the tree before it is hit with strong sunlight.

Cnetter

In the mean time, you can wash the aphids of with just a strong jet of water. While this won't keep them away forever, but it's a pretty good control. Aphids are fragile and break easily. I learned about this way back in the DRS days and it worked good enough for my roses.

David52 Zone 6

Do you have the kind that make the leaves curl up? I get those on plum and peach.

If you can remember, a spray of dormant oil in the early spring before they flower / leaf out will really help with over all numbers.

I just sprayed mine with insecticidal soap, I mix up a 2 gallons of the stuff and spray all the fruit trees as well as some of the vegetables, the fruit for aphids and the veggies for flea beetles, this time of year.

I am already seeing 2" grass hoppers. Yikes.

Lilacs_of_may

I have the dreaded black aphids on my cherry tree. I released several hundred lady bugs around the cherry tree, my peach tree, and a couple dozen around my veggie patch last night. Tonight, I saw maybe half a dozen. They had a smorgasbord of aphids! Why did they fly away?

Let me know how the soap thing works out.

Beeone

Not to be technical, but I don't think the soap smothers the aphids, it dissolves their "waxy" covering, causing them to dessicate and die. Never used it but I would expect it to work since an aphid is probably a waxy shell holding in 90% water.

Other things that work well include malathion and many of the other common insecticides for yard & garden, although if you can soap or wash them off, you shouldn't have the impact on the beneficials that insecticides do and a good crop of lady bug larvae will do an amazing job of cleaning up the aphids.

Digit

Yeah, it's those "monstrous" looking larva of the cute little lady bug that stays put, Beeone .

Tender aphids can bring most any plant to its knees but it doesn't take much to blast aphids to Kingdom Come. (Of course, I'd be in trouble too if someone covered me with shampoo and set me outside, in say 20% humidity, to enjoy 8 or 12 hours of naked exposure.

digitS'
Consarn it! I ain't givin' up without a fight!

Jan_barber61_yahoo_com

I have the same problem this year on my plum tree,its loaded with aphids.The leafs are curled up and a mess.The tree is next to some of my veggies to,no fruit on my tree this year came,last year i had so much fruit on it the family really enjoyed them.Help!!

David52 Zone 6

I have severe aphid problems on both plum and cherry trees as well, and the way it works, the aphids get well established before the predators get going, the end result is stunted growth for the tree that year. Just big, curly, yucky blobs of sap and leaves at each growing tip.

So I'm working on timing an initial spray to keep the aphids in check until the predators get going. I imagine its temp related, but in practice, its a question of looking at the plants as the leaves come out, then spraying them when you first see aphids.

You can use soapy water or something like malathion.

Rosietheriveter_hotmail_com

After reading soulutions on this topic, I pondered for a bit. while looking at my power washer. the light bulb went on. I blasted them off, it did no damage to the tree, or leaves as I put it on a not so harsh spray setting. I'll check in the morning again to see if any more appear.

Dllfb

My aphid problem started on my italian plum tree last summer. I'm so disgusted I'm ready to chop it down. I gave it the dormant oil in late March and since that time
I have had to spray malathon three times for aphids already, in 3 months. And I give it a good soaking! Is this normal? My cherry trees and apple tree located near it are just fine (touch wood.) Just this blasted tree. Any other suggestions.

David52 Zone 6

I have had that same problem, a single plum tree and two cherry trees, and this year, I sprayed just after the trees flowered and the new leaf buds were just starting.

Made all the difference in the world. Now, the predator population is high enough to keep the aphids in check.

I did have to re-spray the plum about a month later in early June, but thats it.

Bob_in_colorado

Another alternative is a product called Pyola. It safe up to the day of harvest and kills insects in every stage of life. Larval and beyond.

Chrysanthemum extract and canola oil. Mix with water and spray.

I've used it. It's very good.

Albert_135 39.17°N 119.76°W 4695ft.

How does one spray the curled bunches of leaves with the black infestation?

The strongest spray does seem to remove them all. Does one spray daily? In the morning or evening? If one sprays with soap will those not removed be hindered from spreading?

David52 Zone 6

For those curled blobs with the black aphids, the only way I've found to deal with it is snip the whole mess off, then when the tree starts up with new growth, start to spray it.

I use a pesticide called 'Eight" - see label at the link

In the future, read up in this thread to see when to first spray them. Those curly balled up aphids are a serious pest and will stunt the tree growth.

Here is a link that might be useful: .pdf of the label

Highalttransplant

I never got around to spraying the trees this spring, and I am paying for it now. The peach tree has the curled up deformed leaves. Even though I can't see any aphids on them, it sure looks like they have been there. I saw a ladybug on there yesterday, so I guess nature is trying to balance things out, but you're right, David, it's definitely going to set the tree back this season. Oh, plus, not a single peach on there.

The leaves on the apple trees look okay, but I know they will have their own set of problems later in the season. Last year, the birds pecked holes in every single apple, and the wasps moved in to finish the job!

I'm starting to think that fruit trees aren't worth the effort .

David52 Zone 6

I have over a dozen fruit trees, and last year they all bore fruit. It was sorta over-whelming. But we managed to freeze, can and dehydrate all of it.

I think the best were the apples - everything I have, with the exception of Pink Lady, are varieties that you can't find in stores. Just fantastic tastes. I need to figure out a way to store them for months fresh - I know it can be done.

This year, we had a brief warm up, things flowered, then it got cold again, then warm again and many of them flowered, not as prolifically, again. So I'm going to get a small crop this year as well.

No peaches. We only get those once every 5 years. And apricots, well, my tree is 15 years old and I've had 15 apricots.

Ad3333

I have several strawberry trees (arbutus unedo) in San Diego that recently were infested with aphids and the dreaded sooty mold. Being new to gardening, I was looking for an alternative to harsh pesticides. After researching here, I tried a mild pesticidal soap using a hose end sprayer (the kind that automatically mixes the dilution of a mild liquid soap like Palmolive or Ivory at about 3 tablespoons per gallon) as a spray bottle wouldn't have reached the top of these 15-foot trees.

I was skeptical at first but was very pleased that this actually worked. I applied early in the morning and then rinsed thoroughly in the evening I have read that spraying during the middle of the day can cause sunburn on the leaves. I felt like I was giving my trees a bubble bath but sure enough, this actually worked and the hose end sprayer made the application very easy.

Reading that eggs will remain and hatch within a week, I did notice a few tiny aphids a week later and re-applied. It sounds like it is important to treat 2-3 times, about 1 week apart, to kill off hatching eggs and avoiding another infestation.

So far so good, the flowers on the tree have returned and new leaves have emerged. I will use this easy and mild treatment every time moving forward.

Thought I would share my experience.

Digit

Very Good to Know. After reading this, I went back into the kitchen to share my first Pantano Romanesco tomato with DW.

As I'm washing the cutting board, I realize that I'm using Palmolive Green dishsoap . . .

Six and a half years . . . do you realize that kids came home from the 1st grade yesterday who weren't even born when I suggested that, Boris Yeltsin had just died, and Rupert Murdoch had just purchased Dow Jones & the Wall Street Journal? (Nothing much changed around here. o)

Amester

Just wanted to point out that there's a difference between the regular soft-bodied aphids and woolly aphids - which do you have? If they're woolly, the spray of water will get rid of them in the short term. But woollies will have a host plant to overwinter on and show right back up on your trees in the spring. I kept blasting and NEEM-ing my apple tree to pieces until I realized that an old, ragged rosebush was hosting them - I dug it up, tossed it, and haven't seen a woolly in two years. Had I not wanted to toss the rose, I'd have probably gone the Eight route. I'm as organic as they come, hate chemicals of every kind but they were horrible.
Best of luck!

Ad3333

I'm pretty sure they're soft-bodied, the house and trees are all brand new. So far so good after the second dish soap bubble bath, I haven't seen a single aphid and the strawberry trees are flowering just two weeks post-treatment. I'm still shocked the diswashing soap diluted with water worked as well as it did in killing aphids - I also read somewhere to be sure only mild is used, which is why I chose Palmolive and Ivory - no degreasers like Dawn or others.

Dm_kelly

This was an interesting thread read. I never had aphids until last year. My plan of attack was to rip out the veggies (they LOVE my brussels sprouts), use insecticide which I'm opposed to, and trim the infected leaves off of the fruit trees which was very time intensive and made for an ugly tree. I like the blasting them with soap water option because my small infestation from last year only got bigger this year.

Ad3333

Just a quick update - I've had to re-treat after a month or so but the aphid population is far less and it's so easy to re-treat. I've also caught the recent influx before they could cause damage as I have learned to have an eye for them now. They are born pregnant (literally!) and reproduce within a week. I suppose it's all about catching them early and keeping the population low, whether using pesticides or soap. I definitely like the idea of not using pesticides for this insect, the soap definitely works. And with the hose-end sprayer that blends the proper dilution of soap and water, it only takes a few minutes. Glad I found this thread!


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Control

Controlling aphids is most successful when predator populations are preserved. Apply a sticky band around the trunk of the fruit tree to prevent ants from reaching aphids that they may be protecting. Bait the ants near the base of the tree to destroy whole colonies. Spray trees that are infested with aphids with narrow range oil or neem oil, then allow predators to keep populations low. In the future, monitor ant activity and bait them when needed or maintain the tree's sticky band so that predators meet no resistance when hunting aphids. Planting a thick stand of yarrow, dill or other umbrella-shaped flowers near troubled trees will attract ladybugs, which are natural enemies of aphids.

Kristi Waterworth started her writing career in 1995 as a journalist for a local newspaper. From there, her meandering career path led to a 9 1/2 year stint in the real estate industry. Since 2010, she's written on a wide range of personal finance topics. Waterworth received a Bachelor of Arts in American history from Columbia College.


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