Moisture meter can indicate watering schedule for lemon tree
Q: I have a 4-year-old lemon tree about 6 feet high with lots of lemons about the size of large marbles. I also have a lot of lemons the size of peas that are dropping to the ground. I never had this before. None of the first group have dropped off. I water twice a week. Is that too much or not enough? the blistered area and into fresh wood, you may see a pinkish discoloration in the fresh wood.
The tree will continue to decline if this is so. I would remove the tree and find a warmer spot to grow citrus that does not have much winter wind. Wind makes winter freezing temperatures worse.
I would also make sure the soil drains freely when water is applied and use wood chips as a surface mulch to help keep the soil healthy.
Q: I have a 23-year-old ash on a drip system. It is watered twice per week, using 10 emitters, and dispensing about 50 gallons. The tree is on a southern exposure and planted in a rock mulch. The tree’s limbs have begun to lose leaves and are dying. Is the tree old or am I doing something wrong?
A: As hot weather is upon us, I don’t believe that 50 gallons per week will be enough water to support this older, larger tree. That is probably enough emitters if they are spaced 2 to 3 feet apart under the canopy of the tree.
If the emitters are grouped closely together, much of that water will be wasted. You want to wet about half the area under the canopy of the tree each time you water and to a depth of 18 to 24 inches.
In early May, you should have increased the frequency of applied water from once a week (beginning the first week of February) to twice a week for most trees and shrubs.
This tree may have ash decline. This disease of ash, first found on Modesto ash in the valley back in 1985, has been found on other ash varieties like Arizona ash introduced into the valley.
Little is known yet about this disease, but most pathologists seem to agree it is not controllable and will eventually kill the tree or cause it to become a hazard. The tree should be removed before it becomes a safety hazard.
Increasing fertilizer and water to the plant won’t revive it unless the tree is not receiving enough water in the first place so try that first. Putting ash trees in less stressful environments such as lawns or supplying enough water to the tree roots, seems to help prolong its health.
I am telling people this tree is shortlived in our environment, 10 to 20 years, until this problem is resolved. This should not be confused with limb dieback that occurs to many large trees when converting from lawns to desert landscaping.
Q: I have a 20-year-old trumpet vine that I’m trying to remove and establish a new garden. The vine has been dug but I find shoots coming up from roots and I simply cannot remove them all. Is there a way to eliminate the deepest roots without poisoning the ground?
A: Trumpet vine is considered “invasive” in some parts of the country. This is in places where there is enough rainfall to support their growth without irrigation. Some people have trouble establishing it in our desert climate and soils.
The only “organic” method of killing trumpet vine roots is to cut off the top of the plant close to the ground and force it to sucker. As this new growth suckers from the ground, you’ll remove it with a shovel or hoe. By doing this repeatedly, and as soon as new growth emerges, you’ll eventually kill the roots.
As you have already guessed, this will require a lot of work on your part for a long time to come. My experience is that it can take you two to three years to kill the roots this way.
Another method is to leave the “mother plant” and dig up suckers as they emerge. Leaving the “mother plant” helps direct the growth and suppresses the development of suckers from the ground. The plant eventually “gives up” growing into new areas.
You can apply chemicals to the plant to kill the roots. None of them will contaminate the soil. If these chemicals accidentally land on the soil surface, there will be residue left behind but it would be minimal if the application is directed toward the plant.
If you are careful applying these chemicals, none of these need to reach the soil. This method relies on spraying or dabbing an herbicide or weed killer on fresh cuts made to the plant. It uses herbicides to replace work using a shovel and a hoe.
Herbicides used for this include some of the “dandelion killers” that contain dicamba or triclopyr in their list of ingredients. The label should state that this chemical can be used for this purpose. The manufacturer may market these products as “dandelion killer,” “brush killer” or similar wording. These chemicals are diluted as stated on the label unless it is a ready to use product.
Roundup is also used for this job and applied in the same manner. Follow the same dilution that is recommended on the label if it is a concentrate. Repeat applications will be necessary because the plant will respond to your death threats by sending up new growth in different locations.
So, be prepared to follow up by cutting back this new growth and reapplying the chemicals as needed. Bob Morris is a horticulture expert living in Las Vegas and professor emeritus for the University of Nevada. Visit his blog at xtremehorticulture.blogspot.com. Send questions to Extremehort@aol.com.