Rent Shop Volunteer Join

Q. Who is Mr. Smarty Plants?

A: There are those who suspect Wildflower Center volunteers are the culpable and capable culprits. Yet, others think staff members play some, albeit small, role. You can torture us with your plant questions, but we will never reveal the Green Guru's secret identity.

Help us grow by giving to the Plant Database Fund or by becoming a member

Did you know you can access the Native Plant Information Network with your web-enabled smartphone?

Share

Ask Mr. Smarty Plants

Ask Mr. Smarty Plants is a free service provided by the staff and volunteers at the Lady Bird Johnson Wildflower Center.

Search Smarty Plants
See a list of all Smarty Plants questions

Please forgive us, but Mr. Smarty Plants has been overwhelmed by a flood of mail and must take a break for awhile to catch up. We hope to be accepting new questions again soon. Thank you!

Need help with plant identification, visit the plant identification page.

 
rate this answer
Not Yet Rated

Thursday - June 20, 2013

From: Bellaire, TX
Region: Southwest
Topic: Diseases and Disorders, Pests, Trees
Title: Changing colors on Mexican Plum trees from Bellaire TX
Answered by: Barbara Medford

QUESTION:

The leaves on my Mexican Plum tree have recently started turning yellow/brown and the veins in leaves are red. Is this a watering issue or disease issue? Mites are on the leaves. This has been a rapid change over the past month. I recently sprayed for the mites and will continue to do so for the next couple of weeks.

ANSWER:

According to this USDA Plant Profile, Prunus mexicana (Mexican plum) grows naturally in Harris County, so the soil, climate and rainfall should be appropriate for it there. The problem sounds to us like chlorosis, a condition usually resulting from some imbalance in the soil.

Please read this article from the University of Illinois Extension on chlorosis. Note the comment that the presence of chlorosis is often due to high alkalinity in the soil. We could not find out if your soil in  Harris County is particularly alkaline, but we usually expect East Texas soils to be more acidic.

Among the steps we would recommend are to use some sort of iron supplement, not too much, as native plants do not ordinarily care for fertilizer. Water less, because it's possible the main problem is lack of drainage in soil where the plants are growing. Watering once a week should be adequate.  Finally, using a good quality organic mulch, spread the mulch over the root area without allowing it to touch the trunk area. This will protect the roots from heat and cold and, as the mulch decomposes, will add some material to the soil to assist in drainage.

In answer to your question on whether this is a watering issue or a disease issue, here are the growing conditions for this plant from our webpage on Prunus mexicana (Mexican plum):

"Growing Conditions

Water Use: Low
Light Requirement: Sun , Part Shade
Soil Moisture: Dry , Moist
Cold Tolerant: yes
Soil Description: Dry to moist, well-drained soils. Sandy, Sandy Loam, Medium Loam, Clay Loam, Clay, Limestone-based"

As you can see, this plant is adaptable as far as soils are concerned, but does not like wet feet. You get more rain in Harris County than we do in Central Texas and if you are also watering, the roots could be standing in water, which they definitely do not like.

Next, on the subject of mites. Please read this article from the University of Missouri Extension on Aphids, Scale and Mites on Home Garden and Landscape Plants. In particular, note that these pests often will attack plants that are already under stress; for instance, if the soil in which the tree is planted does not have good drainage. Also, pay attention to the reminder to carefully read and follow instructions on the use of pesticides. The pesticide you are spraying could very well be killing instead the natural predators of the pests on your plant- ladybugs, for instance.

 

From the Image Gallery


Mexican plum
Prunus mexicana

Mexican plum
Prunus mexicana

Mexican plum
Prunus mexicana

More Diseases and Disorders Questions

Decline in willow tree in West Virginia
June 15, 2008 - I planted a willow tree about three years ago and it was progressing just beautifully with full leaves this spring in a nice green color. We staked it back about three weeks so it would grow straight...
view the full question and answer

Texas wild olive tree
April 05, 2012 - I live in the Phoenix area. My Texas wild olive (Cordia boissieri) is about 5 years old, about 12 feet tall and has beautiful blossoms all year long. However, this past year (through all seasons...
view the full question and answer

Cause of trees losing bark in Arkansas
December 27, 2011 - I live in very rural Arkansas and we did have extreme heat this past summer and since then I have noticed several trees in the woods that have lost huge strips of their bark and I was wondering if it ...
view the full question and answer

Red spider mites in native bluebonnets in Austin
April 02, 2008 - What would you do if the WFC bluebonnets developed a bad case of red spider mites? That is what has happened to many of mine here in Austin. I noticed them the other day and I must have been asleep be...
view the full question and answer

Carolina buckthorn and Neem Oil Spray Damage
April 27, 2015 - It's April, I have a Carolina buckthorn that seemed to be doing well, about 8 feet tall, about 2 years old in part shade. It was putting out new leaves about a month ago and seemed to have infestati...
view the full question and answer

Support the Wildflower Center by Donating Online or Becoming a Member today.