Pecan trees in the Houston area show yellow leaves for several distinct reasons, and the right response is completely different for each. Misdiagnosing it can cost the tree.
1. Iron chlorosis (most common)
Houston's clay soil is alkaline — high pH locks up iron, even if the soil contains plenty of it. Pecans need iron to make chlorophyll, and without it, leaves turn yellow while the veins stay green (the diagnostic pattern).
Look for: Yellow leaves with prominent green veins, especially in spring and early summer. New growth is most affected.
Fix: Soil-applied iron chelate (specifically iron-EDDHA, the form that works in alkaline soil). Foliar iron sprays are a short-term band-aid; soil treatment is the long-term fix.
2. Pecan scab
A fungal disease that causes black or brown spots on leaves and pecan husks. Late-stage infection can cause leaf yellowing and drop, especially in wet humid years.
Look for: Black or olive-green spots on leaves and on the green pecan husks. Affected leaves yellow at the edges, then drop.
Fix: Selective pruning to improve airflow, fungicide spray programs, and replacing severely affected trees with scab-resistant cultivars over time.
3. Drought stress
Pecans are water-hungry — a mature pecan can use 100+ gallons per day in summer. Houston droughts (2023, 2024) put trees under serious water stress.
Look for: Whole leaves yellowing uniformly, no veinal pattern. Often accompanied by leaf drop and small or absent pecans.
Fix: Deep watering — slow soak around the drip line, not at the trunk. Once a week in dry summers is usually enough for established trees. Mulch the root zone (out to the drip line) to reduce evaporation.
4. Root stress / construction damage
Pecans have shallow root systems that extend well past the canopy. Construction (paving, trenching, foundation work, even compacted soil from heavy equipment) damages roots that show up months later as yellow canopy.
Look for: Sudden onset of yellowing in the year after nearby construction, often accompanied by some dieback at branch tips.
Fix: Recovery is slow. Vertical mulching (drilling holes in the root zone and filling with compost) helps. Sometimes the tree won't recover and removal becomes necessary.
5. Normal seasonal change
In late October and November, pecan leaves turn yellow and gold before dropping. This is normal — it's autumn. If yellowing is happening in fall and the tree was healthy all summer, you don't need to do anything.
How to tell which
| Pattern | Likely cause |
|---|---|
| Yellow with green veins, spring | Iron chlorosis |
| Black spots + yellow drop | Pecan scab |
| Uniform yellow, dry summer | Drought stress |
| Yellow after construction | Root damage |
| Yellow + gold, October-November | Normal autumn |
When to call us
If you're not sure which pattern fits — or if multiple are happening at once — we do free pecan assessments. Pecans are a specialty species: we work them in Pecan Grove, Richmond, and across the Houston metro regularly. Call (281) 626-9111 if your pecan needs a real diagnosis.