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Friday - August 24, 2012

From: Phoenix, AZ
Region: Southeast
Topic: Compost and Mulch, Watering, Shrubs
Title: Ailing Tecoma stans from Phoenix AZ
Answered by: Barbara Medford

QUESTION:

I have several young Tecoma plants in my Phoenix, AZ garden. I planted them in June and have tended to them over the summer. They are watered twice daily. On some of the plants, I've noticed two oddities with the leaves. While most of the leaves are fine, the leaves towards the top and side of the bush appear to be devoid of the green leaf material so that it looks like a skeleton of the leaf - not all the leaf, just part of the leaf. The other problem has several leaves that have a cocoon like appearance although there doesn't appear to be an occupant. There are tiny black specks (excrement?)on some of the leaves. I have removed the unhealthy looking leaves and even cut the entire leaf section off. Within a couple days, the same problems can be found. I cannot see anything eating the leaves day or at night. Do you have any idea what is going on with my Tecomas? Thanks!

ANSWER:

We realize you are having too much heat and intermittent sandstorms in Phoenix, but Tecoma stans (Yellow bells) is a desert plant, native to Arizona. It would have been better to have planted them in the cooler part of the year, like from November to January. Woody plants are very susceptible to transplant shock

Previously answered question on Tecoma stans (Yellow bells). Too much water, from Florida.

Please read this article from the University of Illinois on Chlorosis, which often is the result of nitrogen deficiency in the plant.

So, we have established three possible reasons for the failure of your yellow bells to thrive and all are linked to the time and method of planting. If your plant was not planted to allow for good drainage, such as adding compost or other organic material to the soil, the roots are drowning. The loss of green in the leaves is lack of chlorophyll, again a result of too much water on those roots.

From another previous answer:

"Chlorosis is a yellowing of leaf tissue due to a lack of chlorophyll. Possible causes of chlorosis include poor drainage, damaged roots, compacted roots, high alkalinity, and nutrient deficiencies in the plant. Nutrient deficiencies may occur because there is an insufficient amount in the soil or because the nutrients are unavailable due to a high pH (alkaline soil). Or the nutrients may not be absorbed due to injured roots or poor root growth."

Our recommendations:

1. Since you can't undo planting a woody plant in June, let a lesson be learned: Don't do it again.

2. If you didn't plant with organic material, put a good quality shredded bark mulch over the roots. This will shelter the roots from heat and, as it decomposes, it will sink down into the soil and help amend it.

3. Since your soil is almost certainly alkaline, take the planting provisos above to heart for all planting. Drainage, especially for desert plants, is vital for accessibility of moisture and nutrients. Compost, compost, compost.

4. Cut out all that water, probably a thorough watering once a week is sufficient. And no fertilizer. Most native plants do not need fertilizer and this plant particularly dislikes it.

From the Image Gallery

Yellow bells
Tecoma stans