What's wrong with my plum tree? - Ask Extension
I have a plum tree that has grown up in my backyard as a root sprout from a now-removed parent tree on the other side of my fence. It's about 8-10 ye...
Knowledgebase
What's wrong with my plum tree? #857428
Asked January 16, 2024, 11:07 AM EST
I have a plum tree that has grown up in my backyard as a root sprout from a now-removed parent tree on the other side of my fence. It's about 8-10 years old and occupies a space in the center of the yard between the fences, without any meaningful interference from any other trees or plants.
It flowers every spring and seems to have healthy leaves, and certainly it grows every year, so it seems generally healthy. But it always drops 90% of its fruit (or more) once they reach about the size of a dime, and most of the ones that hang on drop just as they start to ripen.
I've never sprayed anything on the tree, or bothered to fertilize it. I know that most of the fruit that survive the initial purge have plum curculio scars, and I've even seen the little buggers from time to time. But could they be causing the vast majority of the fruit to drop?
The tree has always weeped this huge amount of resin, way more than should be normal. I prune it once in February and usually just to try to keep enough space beneath it to still mow the grass. I certainly never run into it with a mower or anything that would explain the massive amounts of resin. Is this a response to the bugs? Is it something else? Is it related to the lack of fruit?
I've attached a few pictures I took last year including one of a dead branch tip, which also happens most years around May-June. First the branch tip gets swollen like a fat lip, then it just dies off as pictured. Maybe a dozen or so branch tips do this each year; maybe more as the tree has gotten bigger, but it's a relatively small percentage of the branch tips that do this.
It's just one tree, and it's not like I need to fix it and get fruit and all, but it would be nice. If there's a disease I can treat for, or if it's just the weevils and I can treat for them, that would be great. If it's just a weird tree, well, at least it's pretty. Thanks!
Wake County North Carolina
Expert Response
Hello and thank you for contacting us!
I am sorry about your plum tree and the lack of fruit. I did some research and the based on your message I think you have a few problems with;
1. age (plums only live 10-20 yrs in NC)
2. plums are moderately easy to grow so they are high maintenance
in our NC conditions.
3. brown rot fungus
4. plum gouger weevil (is this what you are seeing?)
5. plum curculio scars (will stop fruit development)
The weeping of resin may be the work of the Plum Gouger, a small weevil (Coccotorus scutellaris Leconte) which makes numerous feeding punctures in developing fruit resulting in a flow of clear ooze from the wound. It may lay eggs in the puncture where larvae develop within the pit. Any fruit that is currenlty oozing should be removed and destroyed. It is very important to clean up all fruit incluing ones still on the tree in the fall to control this pest, raking up leaves in the fall may also help. There are no recommended chemicals to control this weevil. Here is a link for details;
https://extension.wvu.edu/lawn-gardening-pests/pests/plum-curculio
You may also have brown rot - a fungus.
Brown rot blossom blight is a common and destructive disease of all stone fruits including flowering cherry and plum as well as their fruit bearing relatives.
The brown rot fungus can attack blossoms, fruit, leaves, twigs and branches. Disease symptoms appear in the spring after the blossoms open. Diseased flowers wilt, turn brown and are covered with masses of spores. The disease spreads into twigs causing small branch dieback. Profuse gumming may appear on infected branches. Fruit infections appear as soft brown spots and can engulf the whole fruit. Infected fruit and flowers shrink into "mummies" and may persist on the tree until next year.
Brown rot is caused by a fungus that over winters on infected plant parts. In the spring during wet weather masses of spores are produced that can infect the blossoms and young shoots. The disease will continue infection cycles during wet periods in the spring.
A combination of cultural methods and treatments are needed to control this disease in our wet rainy northwest climate.
Sanitation is very important. Remove and destroy all infected twigs and branches. Remove all rotted fruit. Prune back the limb about 4 inches from the brown rot. Always keep a 10% (1 part bleach to 9 parts water) bleach solution or isopropyl alcohol with you to clean your pruners.
Remove wild or neglected stone fruit trees that serve as disease reservoirs. This is highly contagious and will eventually infect all your plums.
Use wettable sulfur or lime sulfur during periods of wet weather. Follow the instructions for both solution strength and when and how to use it during the year.
Apply three to four treatments of an approved fungicide (some are systemic) starting at bud break in the early spring and continue at regular intervals during the spring until dry weather. Thoroughly treat all leaf and twig surfaces. Treatments during blossoming are essential for good control. (You will not get any fruit this year). The wetter and rainier the spring, the worse the disease problem is. Also apply a dormant oil treatment before fall rains.
It is suggested to spray during the fall once a month through January if possible. You need about 40 degrees, dry (for 8 hours) and windless day to spray. Usually in January there are a couple of warm weeks. If possible, weather cooperating, I spray dormant oil (winter) and lime sulfur separately. If the weather stays nice for spraying, a week later I use Neem oil (- use concentrated and follow the instructions. Alternate between lime sulfur and Neem oil. DO NOT USE NEEM when the bees are out during blossom time - it will kill them.
Here is a link to Brown Rot in plums; https://content.ces.ncsu.edu/disease-and-insect-management-in-the-home-orchard
Here is a link to details for plum trees in NC; https://plants.ces.ncsu.edu/plants/prunus-americana/
Here are some basics. Do you think your plum tree has the following conditions?
I am sorry about your plum tree and the lack of fruit. I did some research and the based on your message I think you have a few problems with;
1. age (plums only live 10-20 yrs in NC)
2. plums are moderately easy to grow so they are high maintenance
in our NC conditions.
3. brown rot fungus
4. plum gouger weevil (is this what you are seeing?)
5. plum curculio scars (will stop fruit development)
The weeping of resin may be the work of the Plum Gouger, a small weevil (Coccotorus scutellaris Leconte) which makes numerous feeding punctures in developing fruit resulting in a flow of clear ooze from the wound. It may lay eggs in the puncture where larvae develop within the pit. Any fruit that is currenlty oozing should be removed and destroyed. It is very important to clean up all fruit incluing ones still on the tree in the fall to control this pest, raking up leaves in the fall may also help. There are no recommended chemicals to control this weevil. Here is a link for details;
https://extension.wvu.edu/lawn-gardening-pests/pests/plum-curculio
You may also have brown rot - a fungus.
Brown rot blossom blight is a common and destructive disease of all stone fruits including flowering cherry and plum as well as their fruit bearing relatives.
The brown rot fungus can attack blossoms, fruit, leaves, twigs and branches. Disease symptoms appear in the spring after the blossoms open. Diseased flowers wilt, turn brown and are covered with masses of spores. The disease spreads into twigs causing small branch dieback. Profuse gumming may appear on infected branches. Fruit infections appear as soft brown spots and can engulf the whole fruit. Infected fruit and flowers shrink into "mummies" and may persist on the tree until next year.
Brown rot is caused by a fungus that over winters on infected plant parts. In the spring during wet weather masses of spores are produced that can infect the blossoms and young shoots. The disease will continue infection cycles during wet periods in the spring.
A combination of cultural methods and treatments are needed to control this disease in our wet rainy northwest climate.
Sanitation is very important. Remove and destroy all infected twigs and branches. Remove all rotted fruit. Prune back the limb about 4 inches from the brown rot. Always keep a 10% (1 part bleach to 9 parts water) bleach solution or isopropyl alcohol with you to clean your pruners.
Remove wild or neglected stone fruit trees that serve as disease reservoirs. This is highly contagious and will eventually infect all your plums.
Use wettable sulfur or lime sulfur during periods of wet weather. Follow the instructions for both solution strength and when and how to use it during the year.
Apply three to four treatments of an approved fungicide (some are systemic) starting at bud break in the early spring and continue at regular intervals during the spring until dry weather. Thoroughly treat all leaf and twig surfaces. Treatments during blossoming are essential for good control. (You will not get any fruit this year). The wetter and rainier the spring, the worse the disease problem is. Also apply a dormant oil treatment before fall rains.
It is suggested to spray during the fall once a month through January if possible. You need about 40 degrees, dry (for 8 hours) and windless day to spray. Usually in January there are a couple of warm weeks. If possible, weather cooperating, I spray dormant oil (winter) and lime sulfur separately. If the weather stays nice for spraying, a week later I use Neem oil (- use concentrated and follow the instructions. Alternate between lime sulfur and Neem oil. DO NOT USE NEEM when the bees are out during blossom time - it will kill them.
Here is a link to Brown Rot in plums; https://content.ces.ncsu.edu/disease-and-insect-management-in-the-home-orchard
Here is a link to details for plum trees in NC; https://plants.ces.ncsu.edu/plants/prunus-americana/
Here are some basics. Do you think your plum tree has the following conditions?
- Sun, well drained soil
- Target pH 6.5
- Relatively short lived, 10 – 20 years, begin bearing in 4-5 years
- Tend to bloom very early - frost often damages blossoms
Do you know what variety you have?
Recommended Varieties
- Methley - tend to bloom early best in NC
- Auburn varieties: AU Amber, AU Homeside, AU Roadside, AU Producer
- Morris
- Frontier
