Why are my almond tree leaves turning yellow?
Written by
Michael Sullivan
Reviewed by
Prof. Charles Hartman, Ph.D.Yellowing foliage on almond trees is often a sign of overwatering or nutrient deficiencies. Last summer, my neighbor's tree became yellow, and about a month later, the entire tree defoliated. The tree had compacted clay soil that held moisture, ultimately suffocating the root system. Test soil drainage in late summer or early fall by digging a 12-inch hole into the soil and watering it well. If after six hours, water remains in the hole, you should consider amending the soil by mixing in compost.
Common Causes
- Overwatering: Soggy soil blocks oxygen, triggering root rot. Check with a moisture meter before irrigating.
- Nitrogen deficiency: Older leaves yellow first. Apply 10-10-10 fertilizer at 1 oz per tree age in years.
- Iron chlorosis: Yellow between veins in new growth. Treat with chelated iron soil drenches.
Quick Fixes
- Adjust irrigation to 2-3 inches weekly for mature trees.
- Aerate compacted soil with a broadfork to improve drainage.
- Apply gypsum (2 lbs per tree) to break up clay without altering pH.
Root rot due to lack of drainage can be a deadly, invisible killer. Dig around the trunk, if roots smell sour or are black, cut away the affected area of roots and drench with Bacillus amyloliquefaciens. I saved a five-year tree this way. It did lose about 30% of its canopy for a while.
Soil Management
- Test soil pH annually, almonds struggle below 6.0.
- Mulch with 3 inches of straw to regulate moisture.
- Rotate cover crops like clover to fix nitrogen naturally.
Watering Best Practices
- Use drip irrigation to target roots, not foliage.
- Install a rain gauge, skip watering if >1 inch falls weekly.
- Young trees: 3-5 gallons weekly, mature: 2-3 inches.
Do not disregard pests. Spider mites and aphids deplete the plant's nutrients and worsen yellowing. I prepare a solution of 1 tbsp of neem oil + 1 tsp of Castile soap per one gallon of water and apply this diluted solution as a spray (between 6-9 am) two times a week until the pests are gone. If the pest problem is extensive, release a few lacewing insects into the grow space to consume the invaders naturally.
Read the full article: How to Grow Almonds: Simplified Guide for Bountiful Harvests
