Tangerine Leaves Curling

Q. Please help me to recover my tangerine tree leaves curling inwards. Most have very small black spots on them. l observed the leaves and don`t see any insects. l do deep hose watering during hot summer days.

Picture of tangerine leaves curling and dropping

A. There are lots of reasons for citrus leaves curling. This problem is near legendary for citrus leaves but the reason is usually environmental and not from insects or disease. I’m not saying it can’t happen but it’s less likely.

Citrus troubleshooting guide Arizona

Cold weather

            Since this question was sent to me at the end of winter, cold weather comes to mind. Cold temperatures can cause leaves to roll. Some say cold weather can cause leaf spotting as well. If leaf rolling was during the summer, guess what? High temperatures can also cause citrus leaves to roll.

Watering

            Moisture stress can cause leaf roll and leaf drop. When timing irrigations, make sure the soil is no longer wet when the irrigation water is applied. In the same token, make sure the soil does not get too dry between irrigations. Dry and wet soils can cause leaf rolling.

            What’s more important, in my opinion, is overall tree health. Plants in poor health are more susceptible to problems than those that are healthy.

Soil problems

            In the picture you sent, I noticed the condition of the soil surrounding these trees. The soil looked pretty bad, even by Las Vegas standards. Poor soil conditions leads to poor plant health in the future.

            Good soil health begins at the time of planting. I realize your tree has already been planted but soil improvement surrounding the roots at the time of planting is a huge future investment in plant health for years to come. In the future, excavate the planting hole 3 to 4 feet in diameter and 18 inches deep at the center. Mix good compost with your excavated soil at a rate of about 1:1; for every shovelful of soil, mix one shovelful of compost.

What to do?

            What can you do now? Put a half bag of compost on the soil surrounding the tree. On top of this, put a 4 to 6 inch layer of woodchips and water it in. Woodchips, where irrigation water is present, improves the soil health where most of the feeder roots of your tree are living.

Spreading good quality compost at the base of trees for its fertilizer content

            Improving the soil improves water, fertilizer and nutrient uptake by these roots which in turn improves the overall health of the tree. Soil improvement using this method helps remove some irrigation problems that could be causing leaf rolling. Overall, this means fewer problems for your citrus in the future.

Community mulch pile at the University Orchard North Las Vegas

            Get these woodchips free by visiting Cooperative Extension locations south of the airport or in North Las Vegas at the University Orchard in the Aliante community. For more information about these free woodchips call the extension hotline at 702 – 257 – 5555.