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Question:
All the leaves on the crape myrtle tree have changed and since I watered regularly I suspect cotton root. Suggestion to replace crape myrtle with something resistant? Perhaps a yaupon holly, possumhaw holly, or Texas Mountain Laurel.
Answer:
Is this all leaves or just some leaves on the tree? Yes, both crape myrtles and wisteria are moderately susceptible to cotton root-rot fungus (Phymatotrichum omnivorum). However, the extremely hot and dry weather that we had earlier this year and also last year could have caused the plants demise unless you kept them watered well.
COMMENTS ON MONTEZUMA CYPRESS (a highly recommended tree for Texas) I came upon your Web site while looking for sites with T. mucronatum information. In 1972, I learned that the timbers (vigas) in the Missions of El Paso are of a taxodium type which came as a surprise to all involved with some work being done on these old buildings. You see, only 30 miles away in the Organ Mountains of Southern NM the Ponderosa Pine and the Douglas Fir are common and large. It would seem that the Mission builders would have harvested trees from the nearby mountains long before they would trek down into the lower Rio Grande valley for Taxodium. In 1985 while working with the P.R. of China on a project to collect seed off of all the remaining non-cultivated Metasequoia for the purpose of saving its remaining gene pool, I learned that there was a large Metasequoia in the Las Cruces area, about 40 miles from these El Paso Missions. The tree was reported to be over 90 feet tall with a crown spread of 100 feet and a DBH of 5 feet. Of course I made a point of visiting the tree in short order, only to find that it was not a Metasequoia, but was in fact a Taxodium mucronatum. This tree is growing on a former natural levee of the Rio Grande (scs soil map info.) and is currently surrounded by a subdivision built in the mid 1960's. I have since started looking for more evidence of Taxodium in New Mexico and Northern Mexico as it became apparent to me at least that the El Paso Mission builders did not go south for their vigas but instead collected from trees in the nearby valleys.
The result has been satisfying in that I've found T. mucronatum in the San Luis Mountains of Northern Chihuahua Mex. about 5 miles from the New Mexico border and finally after hundreds of miles of hiking and climbing, two more specimens in a watershed of the Gila National Forest of New Mexico. They are side by side, approx. 100 feet tall with DBH of 5.5 feet and growing at an elevation of approx. 6000 feet, zone 6.
On checking the Climate/Weather Data of the region I've found that this area should have recorded an extreme low on more then one occasion of minus 19 degrees below zero F. which is far colder then Taxodium mucronatum from the lower Rio Grande or Monterrey Mexico material can tolerate. You see I've collected seed from its whole natural range and tested the progeny here at my growing grounds in Los Lunas, they all seem to have a tolerable limit to cold at about zero to 5 above before damaged. The New Mexico provenance has been tested at the Starhill Forest Arboretum in central Illinois down to minus 20 degrees F. with no damage and at my nursery in Los Lunas, NM down to minus 13 degrees which occurred 5 nights in a row, with zero temps by 9 p.m.
I will agree with your statement about the growth rate being faster then T. distichum with our trees reaching 20 feet in 4 years with only a 160 day growing season. I planted one seedling in 1988 at the NMSU Botanical Garden and it is now 40 feet tall with the same in crown spread. It's a progeny of the Las Cruces tree.
Michael Martin Melendrez
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