Q: I have an African sumac that has sprouts coming up from the roots. Besides trimming them every time they get above the soil level is there anything I can do to stop these sprouts from popping up?
A: I think I have enough information to answer. If these are naturally occurring sprouts and not coming from a damaged area, then I would say no. However, usually if you keep these suckers controlled as soon as you see them and remove them by pulling, not cutting them off with a shears, the number should slow down considerably.
There are chemicals you can apply that are sprout inhibitors but these are usually applied to the trunk or limbs for controlling suckers in those places. Controlling them on the roots with a chemical would be more difficult.
The best way to reduce the numbers is make a commitment to remove them as soon as you see them. Remove them directly from the trunk. This may mean you will have to remove some soil and cut the older ones as close to the root as you can. As you see new sprouts a couple of inches long sticking out of the ground, immediately pull them. They should pull easily when they are young.
If you keep this up and do not let them get large before you remove them, then I think you will see a reduction in numbers and easier maintenance. I wish there was a magic bullet for you, but I doubt it exists.
Q: I have a volunteer gopher plant in my front yard that I nurtured into a bush. I noticed that something is eating its leaves. We have a great many rabbits in our area. Can it be rabbits? I thought that the gopher plant was poisonous even to rabbits.
A: I assume we are thinking of the same plant. It is a euphorbia with white latex sap coming from a damaged stem, similar to the white sap you see in poinsettia, which is also a euphorbia. We tend to react to poisonous plants with fear but there are degrees of toxicity when we call something poisonous.
I watched a floriculture professor of mine on television take a poinsettia leaf and eat it. He didn’t die or even get sick. He was demonstrating that the plant is toxic but it is the “dose that makes the poison.” If he had eaten many leaves, the story would be different. Even table salt is poisonous if we eat enough of it.
So it is possible for an animal to eat poisonous plants and survive. I have heard that some livestock will eat gopher plant in the range with no ill effects. They just don’t eat a lot of it and only when browsing is poor. Just like us, animals like to eat things that tastes good.
Q: What is the best way to control shield bugs in Las Vegas? They were found on my Italian cypress. My concern is that they will invade my garden. The broccoli and cabbage seem to be OK right now but the new garden is going in this week.
A: These can also be called “stink bugs” because they can release an odor from their abdomen when attacked or threatened. Many of these types of insects will damage fruits and vegetables and they have no really good predators. Even birds will leave them alone because of their stink.
We will find lots of bugs on our plants. It is really the numbers that count when it comes to damage. They are just finishing overwintering right now and waiting for a chance to find some food in the new growth and make some babies. I would, at this point, just hand pick them when you see them and put them in a bottle with vinegar or alcohol.
If you do not need to use a pesticide, I wouldn’t. These guys have wings under that shield and can fly from yard to yard. Pesticides used unnecessarily will also kill other insects, good and bad.
If you take a spray bottle with soap and water and spray them directly, it will kill them. This is true of all insects, good and bad. The water is made “wetter,” or it loses its surface tension, and can then flow into the tiny spiracles that insects have on their body for taking in air and breathing. This causes them to basically drown.
Soap and water sprays are good to use but must land directly on the insect to drown it. It will not leave a poisonous residue behind like pesticides can and must be reapplied frequently when insects are seen.
Q: I have a raised bed (5-by-10 feet) dedicated to asparagus. The yield has been magnificent. However, the plot has gotten so overgrown with old asparagus stumps that I have had to totally remove and replace all the soil because cultivation was impossible. My question is how long can an asparagus garden last without being so impacted that it must be replaced; or, is there a way to deal with spent stumps annually to prevent this problem.
A: Asparagus rhizomes are normally planted about 12 inches below the soil surface. If started from seed, the seed is planted in a trench and backfilled as the plants grow so that the developing rhizomes are still about 12 inches deep.
When this is done, the spears can be harvested by cutting below the soil surface with a knife so that these stumps don’t stay on the surface. If you harvest the spears by snapping them or breaking them above the soil surface, then you will get woody stumps remaining above the soil surface and they interfere with future harvesting.
So, in short, if you can harvest by slicing with your knife an inch or so below the surface, I think this will stop your stump problem. The woody part is cut off after harvesting during food preparation. The woody part should compost fairly easily.
Q: I have two red leaf plum trees both about 2 years old. They started the year beautifully. One continues to look normal but the other one has all of a sudden taken a turn that bothers me. The leaves are getting pale pink instead of red and see-throughish. It is a nice full tree yet young. Is it as simple as not enough water or something else? It had a great year last year.
A: It is most likely iron chlorosis. If you want to see if that is the problem, try making a few liquid applications of an iron chelate to some leaves using a spray bottle to see if this turns them dark purple (I am assuming you have a purple leaf plum).
It may take four or five applications with a spray bottle to the same few leaves a couple of days apart since liquid applications to the leaves are not typically as effective as applying it to the soil.
Otherwise buy some iron chelate containing the EDDHA chelate and apply it to the soil in a bucket of water and wash it in around the roots. You should see the growth that comes out after your make the application to the soil turn dark purple.
This discoloration also is possible if the tree roots are being kept too wet by watering too often or you have poor drainage.
Bob Morris is a horticulture expert living in Las Vegas; he is on special assignment in Balkh Province, Afghanistan, for the University of California, Davis. Visit his blog at xtremehorticulture.blogspot.com.