Questions on: Flowering Crab

Ron Smith, Horticulturist, NDSU Extension Service


Q: My husband was given a flowering crab by his students when he retired last June. It appears to be growing well, but has not blossomed. Is there a period they must grow before blossoming or could there be a problem with this tree? (e-mail reference)

A: Be patient and give it another year or two. It will flower, so donít worry.


Q: I just purchased a new house that has a flowering crab in the front. Itís about two feet from the house. Is it planted too close to my foundation? (E-mail reference)

A: You have nothing to worry about unless your foundation is in bad shape.


Q: I have a two-year-old flowering crab apple tree that was given to our family to mark the birth of our first son. Now the tree looks horrible. The leaves are all spotted, yellow and sickly looking and some of the branches are black. Is there any hope of curing this poor thing? (E-mail reference)

A: Clean up all fallen leaves and fruit this fall. Next March, spray the tree with lime sulfur. It does a good job of sanitizing the tree's surface so be complete in the coverage. After the leaves have elongated, spray the tree with a bordeaux mixture, which is a fungicide that will prevent some of the disease problems you are citing. Also, don't be afraid to prune it next spring before leaf out.


Q: I'm looking for advice on when and how to properly trim a flower crab tree. I have five of them in my front yard in close proximity to each other. They are approximately 15 to 20 feet tall and spread. They seem a bit overgrown and branchy. Should I prune them? What time of year is best and what guidelines or methods should I follow for pruning them? (Fargo, N.D.)

A: The best time to prune is in the early spring before they leaf out. A balmy day in late February or March would be a good time. Prune to open the crown so it can get more sunlight by removing some of the inner branches. Always cut back to lateral branches and never leave any stubs.


Q: I planted three royalty flowering crab12 years ago. In the last few weeks I've noticed the leaves look unhealthy, very spotted and some in various stages of dying out. We sprayed the trees with Daconil after contacting our nursery because they thought it might be a fungus. That was more than a week ago. Since then the trees have lost about a third of their leaves. I see no signs of bugs or worms. (E-mail reference)

A: Unfortunately, fungicides will not cure any disease that has already started to show symptoms. They are effective at preventing diseases from starting and keeping the pathogen from spreading to new growth. The best you can do at this point is to practice good sanitation. Clean up all fallen foliage and fruit. Next spring spray the trees with lime sulfur before new growth begins. Then, as new growth emerges, spray the trees with the appropriate fungicide and repeat in 10 days.


Q: I have a red splendor flowering crab that appears to be having problems with defoliation. I believe it has apple scab. Also, it appears to have fireblight on some new growth tips and at the flowering spurs. Should we leave the tree alone until winter and look for cankers on the branches or trunk or should we prune out affected shoots? Is spraying with an antibiotic such as streptomycin still recommended to control fireblight? (E-mail reference)

A: Go ahead and carefully remove the infected branches. Sterilize the pruner between each cut. Immediately place the infected branches in a plastic garbage bag and get rid of it.

Streptomycin is still recommended as a control but limit the application of nitrogen fertilizer in the root zone area under and beyond the tree canopy to limit succulent growth.


Q: I have a beautiful white flowering crab that is probably 40 years old. It is in perfect condition and everyone who comes to my house gasps in awe when they see it blooming. However, I can't grow grass under it because it drops about 6 inches of apple blossoms just as the grass starts to grow. If I rake the blossoms up, I inadvertently rake up a lot of newly sprouted grass. If I don't rake, they smother the grass. Either way, I'm left with lots of bare patches. This has been going on since I moved to the house in 1986. What else can I plant under the flowering crab? Should I wait until the tree is done losing its blossoms, clean up the area and plant annuals? That would mean a lot of annuals. I estimate at least 20 flats because it's a very large tree. (E-mail reference)

A: The grass under my crabapple suffers the same fate. Itís mostly from the falling fruit not the blossoms. You should be able to grow perennials and annuals under the tree and the herbaceous perennials should be able to stand the onslaught of falling flower petals.


Q: About five years ago my flowering crab broke off at the base of the soil (wind I guess). It started to grow again and is now about 8 feet tall but has never bloomed since. What do I need to do to get it to bloom again? It was about three years old before if broke off and used to bloom beautifully. (E-mail reference)

A: The tree was apparently grafted or budded onto a different species for rootstock but now the day length or other environmental conditions are not conducive to it blooming.


Q: We have a flowering crab in our front yard. It produces too many apples and makes a complete mess out of the sidewalk and therefore the entrance to the house. I need to do something. It is a beautiful tree but the apples are a mess. Your article says you can spray it with Sevin. Where do I find it? At a local flower shop? Help! (E-mail reference)

A: Your chance of success with Sevin is about as good as hitting a home run playing in the major leagues. It SOMETIMES works but not always and not with all crabapple cultivars.

I have the same problem. My solution is to remove the tree. I don't like the mess on the lawn nor the yellow jackets that are attracted to the rotting apples.


Q: I have a flowering crab tree that blossomed this spring and now the leaves seem to be drying. Could you please tell me what is wrong? (Rolette, N.D.)

A: Your tree is suffering from a fungal disease known as apple scab. It is likely too late to do anything about it now, but you might rake up all fallen leaves this autumn, and spray next season with lime-sulfur prior to leaf break. As the new growth emerges, spray with Captan or benomyl.


Q: Could you tell me what is wrong with my flowering crab? Every spring it blossoms, but then the buds start dropping and no little fruit sets. (Faulkton, S.D.)

A: Your tree has a bad case of apple scab. Remove all fallen leaves and fruit this fall and spray next spring at leaf-out with Captan, a fungicide.


Q: I am writing in regards to a flowering crab tree that we are having problems with. The leaves start to turn yellow with brown spots on them. Can you please tell me what is wrong with it and how to correct this problem? (Callaway, Minn.)

A: Sounds like an apple scab infection to me. The basics for controlling this fungus are:

1.Good leaf litter clean up every spring.
2.Spray with captan or benomyl at bloom period and three more times at 10-day
intervals.
3.Reapply fungicides if late afternoon showers and still air in summer prevail.


Q: Is there anything I can do to get my flowering crab to stop producing so many berries? (Battle Lake, N.D., e-mail)

A: You can try using the insecticide Sevin, spraying at three-quarter blossom, and again a week later. Do so early in the morning or later in the evening, when the honeybees are not active. This may reduce the apple population by about 75 percent, depending on the cultivar or variety it happens to be.


Q: Can you tell me how to get rid of the suckers that keep appearing around my yard from a flowering crab that we removed? (Eureka, S.D., e-mail)

A: Treat the lawn area with a broadleaf herbicide that contains 2,4-D as if you were controlling weeds. It will likely take two to three years to completely get rid of the sprouting suckers, but it will be worth it, so hang in there!


Q: We have three flowering crabs, and two are beautiful but one isn't. The one seems to have less leaves and is lighter in color than the others. I have tried fertilizer spikes and more water, but it didn't seem to help. What should I do next? (Rogers, N.D.)

A: I would suggest aerating out around the dripline of the tree next spring. Spray the tree with lime-sulfur before leaf break next spring. This is a "tonic" recommendation that often solves these unidentifiable problems!


Q: I am enclosing leaves from a flowering crab tree. It seems to be sick. (Wimbledon, N.D.)

A: Your crabapple has a very bad case of apple scab (Venturia inaequalis). It is turning out to be a very prolific disease this year due to our wet weather.

Spray the tree immediately with Captan. Then, most importantly, clean up all fallen leaf litter this autumn—or in early spring before seasonal leaf-out occurs. I would also recommend a spray with lime-sulfur at that time, before leaf opening.

Once the leaves open, begin a vigorous program of preventative sprays with Captan or Captan plus benomyl. Continue every 10 days as long as the weather is conducive to disease development.


Q: Is there a spray available locally to use after our flowering crab tree has blossomed, to prevent it from forming fruit? Its so pretty in the spring and so messy in the fall. (Jamestown, N.D.)

A: There are a couple of sprays available, but the timing is past for them. Sevin, a common insecticide, has been used at full blossom, and Florel, a fruit eliminator, has also been used for the same purpose. Both have limitations and limited successes. It appears that timing is extremely critical, as well as the cultivar of crabapple. Order either of these materials in March next year to be ready for the spring blooms to open, and see what kind of luck you can have.


Q. I look forward to reading your "Hortiscope" articles in my paper.

I have a 4-year-old, 5 foot ash tree with leaves that are drying and curling up and it looks like its dying. Can I save this tree? Also, next to it is a flowering crab tree, the center branches keep dying. I have cut the branches off but the whole tree is yellow and sick looking. I have only the lower branches left at ground level. Would there be a connection of the disease between the two trees? Should I remove and destroy both trees? I have two other ash trees in my yard, 10 to 12 feet high and they seem to be doing OK. Any advice you can give will be most helpful. (Garrison, N.D.)

A. Your crabapple tree is beyond hope--go ahead and remove it. The small green ash looks as if it is planted too deeply, or it has been the object of over-watering. It could also be a  possible root rot fungus.

Your large green ash leaf looks "normal" for this time of year, with "normal" stippling from earlier ash plant bug activity.


Q. I am sending a clipping from our apple tree. We have sprayed it with Sevin several times, but don't see much improvement. Is it from the tough winter or are we losing our apple tree?

A big flowering crab tree, probably about 30 years old, has leaves turning yellow and dropping off all summer long.

We have sprayed a viny lawn weed with Trimac and it seems all it does is tint the leaves a bit. If the solution is made stronger the grass will get a yellow tint, but the weeds still seem to exist. What do we do? Hankinson, ND)

A. I will start with the lawn weed. It is ground ivy, a very deep-rooted perennial. It should be controlled by Trimec. Make sure of two things:

1.You are using a formulation that contains Dicamba

2.You are using a wetting agent to get better uptake by the plant.

Next, your flowering crab looks as if it could stand a shot of fertilizer. See the enclosed extension publication H-1035, "Fertilizing Trees," for guidelines for carrying this out.

Finally, stop spraying your apple tree with Sevin insecticide. You don't have insect problems. The new growth appears to be perfectly healthy. I think the old growth is   suffering from environmental setback the weather! Be patient.


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