Why Are My Tree's Leaves Turning Yellow? (Iron Chlorosis in Fulshear & Katy)

What iron chlorosis looks like

Leaves turn light green to yellow while the veins stay darker green, giving a netted look. It usually starts on new growth and the outer canopy. In bad cases leaves turn almost white, brown at the edges and drop early, and branches start to die back.

Trees commonly affected around Fulshear and Katy include pin oaks, water oaks, sweetgums, magnolias, maples and some fruit trees.

Why it happens

It's usually not that the soil lacks iron. Our soils are often alkaline (high pH), and at high pH iron gets locked into forms that roots can't absorb. Wet, compacted clay, over-irrigation, and concrete or construction lime near the roots make it worse.

How it's treated

Trunk injection puts iron (or manganese) directly into the tree's vascular system — fast results, and it typically lasts a season or more.

Soil treatment with chelated iron and soil acidifiers works more slowly but addresses the root zone.

Fixing the underlying problem — drainage, compaction, overwatering — keeps it from coming back.

Spraying iron on the leaves gives a short green-up but doesn't last.

When yellow leaves mean something else

Leaves that yellow all over (veins included), wilt, or drop suddenly can mean root damage, drought, overwatering or disease. Yellowing in fall is normal for many trees. If you're not sure, have it looked at — see tree health & diagnosis and tree fertilization, or call 361-850-3643.

How to tell chlorosis from other yellowing

• New leaves yellow, veins stay green: iron chlorosis. This is the classic pattern.
• Older, inner leaves yellow first and evenly: more likely a nitrogen shortage or normal shedding.
• Whole canopy pale, wilting or dropping leaves: think roots and water. Too much water does this as often as too little.
• One branch or one side only: look for damage to that limb or to the roots on that side.

What you can do yourself

• Check the watering. Lawn irrigation that runs every day keeps clay soil soggy, and roots in soggy soil cannot take up iron. Water deeply and less often.
• Mulch the root zone. Two to four inches of wood mulch out to the drip line, kept off the trunk, improves the soil over time.
• Go easy on fertilizer. High-phosphorus lawn fertilizer can make iron harder for roots to absorb.
• Use the right iron. In alkaline soil, ordinary iron products get locked up quickly. Chelated iron made for high-pH soil stays available longer.

How long treatment takes

Trunk injection usually shows greener leaves within a few weeks in the growing season. Soil treatments work over months, and severe cases often need both. Chlorosis left for years weakens a tree: growth slows, branches die back, and pests and disease move in.

Tree fertilization is $50 with our current discount, regular $100. If you are not sure it is chlorosis, start with a tree health diagnostic.

Common questions

← More tree care tips