Host an Event Volunteer Join Tickets

Support the plant database you love!

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 Trees Questions

Failure to thrive of newly planted magnolia in Irving TX
November 10, 2009 - I planted four Little Gem Magnolia (Magnolia Grandiflora) in my back yard during first week of October 2009. One of them seem to be dying because its leaves have turned very brown and the leaves are c...
view the full question and answer

Replacements for Ashe Junipers in Georgetown, TX
November 03, 2012 - We have cut down several cedar trees on our property in Williamson County Texas. We would like to replace the cedar trees with another variety of tree. Do you have recommendations for what type of t...
view the full question and answer

Mystery Fruit in Ashland Oregon
November 10, 2010 - Hi, I live in Oregon and while I was picking wild apples I came across what I thought was a lemon tree. I picked some of the smaller fruits that grew in pairs and had a small, yellow lemon appearance ...
view the full question and answer

Flashing barrier to Bermuda in tree bed
September 16, 2007 - I'm building a 6-ft-diameter planting bed on a gentle slope on blackland clay, at the center of which I plan to install a cedar elm. I'm using the wedge-shaped stones from the home-improvement stor...
view the full question and answer

Want to identify caterpillar that is stripping prickly ash in Flatonia, Tx.
April 05, 2011 - What is the 5/16ths long 1/8th inch long pale opaque green caterpillar that strips prickly ash? It has tiny black dots down its spine and along each side. It has stripped two large trees? Will th...
view the full question and answer

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