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A Tree Care Check List for May

Gatorbag type watering products and soaker hoses are efficient ways to irrigate trees during periods of water restrictions.

By fits and starts, spring has arrived and settled in. How long it lasts is anyone’s guess. Our trees would best benefit from a long period of mild days and cool nights, with a few of those days and nights bringing much needed rainfall—enough to address the needs of our yards and the greater need of area lakes. With that said, let’s continue to hope for the best and prepare for the challenges we are accustomed to addressing. Here is tree care checklist for May.


Even with Stage 3 and Stage 4 water restrictions in many North Central Texas cities, there is plenty of opportunity to provide adequate water for your trees.

Established native and adapted trees only need the equivalent of 2 to 3 inches of rainfall each month. That is less than one-third the amount of water typically applied to area lawns. If your trees’ root systems share the soil with turf areas, proper watering of your lawn will also provide all the water your trees will need. The same applies to trees that share root space with shrubs, perennials, and seasonal color. It is important that the 2 to 3 inches of equivalent rainfall be applied at a rate that accedes 1 inch per application. Irrigating at rates less than that discourages deep root growth and does not leach the soil of the salts left behind by the previous watering.

Do not let water restrictions discourage you from planting new trees. While the two best times of the year to plant trees—November and March, have passed us by, trees can be successfully planted throughout the year. Most municipalities allow hand watering of trees with few or no restrictions. Gatorbags and like products, along with soaker hoses are good alternatives to hand watering. New homes with new landscapes need trees. The sooner they are planted, the quicker they produce cooling shade. July and August are the only months when delaying tree planting should be considered. Only then do extreme day (and night) temperatures, drying winds, and the compromised root system of a transplanted tree make successful planting a significant challenge for many gardeners. Most new trees make the conversion to established tree after three years.


Forest Tent Caterpillars are finishing their annual communal feast this month. Rarely do they do enough damage to warrant action. Being said, that is little comfort when you see them massed on the trunk or lower branches of you recently planted Red Oak. Should that be the case, take advantage of their togetherness tendencies and physically remove them rather than dragging out the insecticide spray gear.

Webworm activity usually begins in May. These caterpillars weave a protective web around the leaves they consume.

Should we have any significant numbers of Webworms, they should appear this month. Pecan trees are the primary targets of this insect. Their silky tents usually appear in the lower canopies of mature Pecans as they strip the foliage inside the protective structure. Webworm populations have been negligible the past few years, so this spring may be the time they make their comeback. Spraying insecticides to manage Webworms can be more than what even the most avid gardener is willing to take on. Few people have the necessary equipment to make a thorough application, and the silky tents tend to protect the caterpillars from contact with the insecticide. Contact your Arborilogical Services certified arborist should you need a professional approach to managing this pest.

Bagworms decorate thier homes with leaf parts and berries as they forage and move through trees.

Bagworms also make their yearly debut in May. They are commonly found on conifers—Eastern Red Cedar in particular in North Central Texas. However, they will eat almost any plant material they are lucky enough to hang from. If you have previously found Bagworms on plants in your landscape, keep a watchful eye out for the heavy feeders in May and June. A single adult female bagworm is capable of laying thousands of eggs. Once the eggs hatch the pencil-tip sized caterpillars begin to feed and decorate their “camper” with the leftover trimmings. Bagworms can be managed with a number of insecticides. BT (Bacillus thuringiensis) is effective should you prefer the organic approach. Orthene is effective as both a contact insecticide and systemic insecticide. As with the previously mentioned Webworms, contact your certified arborist if applying insecticides to manage Bagworms is outside your gardening comfort level.

Crepe Myrtle Bark Scale is a relatively new insect pest affecting one of Texas’ favorite summer flowering trees. It was first documented on Crepe Myrtles at a commercial property in Richardson, Texas in 2004. Since then it has spread through most of the North Central Texas counties and as far south as College Station. By 2013, the scale insect was also confirmed in New Orleans and Germantown, Tennessee. The black sooty mold that grows on the honeydew exuded by the insect is the most evident sign of the bugs’ presence.

The mold can be found on Crepe Myrtle leaves, twigs, branches, and trunks. The insect itself can be found on the twigs and branches. Though small, they are white and cottony, and when rubbed produce a confirming red “blood”. Most contact insecticides will manage the insect, but imidacloprid, the systemic active ingredient in Merit, may be the best method of control since Crepe Myrtle Bark Scale likes to hide in the trees’ natural crooks and crevasses and under the pealing bark. Imidacloprid is also a choice of convenience since a single application will continue to manage the insect (and other insect pests) for 9 to 12 months.


Continue to prune out deadwood in trees negatively affected by the late spring freeze. Crepe Myrtles, Vitex, Pomegranate, and the Ashes are the most obvious. Any Mexican or Washingtonia Palms failing to show new green growth at the growing tip by the end of May should be removed before they fall. Freeze damaged palms tend to decay rapidly and become hazardous quickly.

Palms with green growing tips have survived the winter extremes. Palms that show no growth by the end of May will soon become hazardous.

Now that most trees have fully leafed out, inspect clearances over streets and walkways and do the necessary pruning before that official letter arrives from your city’s code enforcement department. In addition, check to see that there is adequate roof and structure clearance; and if you have above ground utilities, make sure your service line (the one running from the pole to your electricity meter) and those utility lines in the alley have the proper clearance distances from your tree canopies.

Continue to paint pruning cuts on Red Oaks and Live Oaks when pruning cannot be avoided. Otherwise, delay pruning these two Oaks until July.


May, and spring in general, is an opportune time to fertilize all trees. They are using stored energy from the previous year to generate new foliage and woody growth. Providing them with a fertile soil that contains plenty of all the necessary nutrients helps them maximize those efforts. There are numerous products available to the do-it-yourselfers and many of those fertilizers are formulated specifically for our area soils. Your certified arborist can help you with any specific fertilization needs your tree may need.

Deep-Root Fertilization provides nutrients to the root zone and aerates compacted soils.

Here is a word of caution:  Never use a “weed and feed“ product that contains any post-emergent herbicides.  Post-emergent herbicides are designed to kill existing broadleaf weeds in turf grass.  Unfortunately, trees and shrubs that share root space with turf grass will pick up those same weed-killing herbicides.  The herbicides are toxic to trees, negatively affecting the foliage, sometimes for years.  Occasionally trees die from the herbicides contained in weed and feed products.

Arborilogical Services has a Deep Root Fertilization program that can be designed to meet the specific needs of your trees. The product is injected into the trees’ root zones. The process fertilizes the tree, improves the soil, and aerates compacted soil with each application. Deep Root Fertilization is a benefit to all trees, but it is particularly helpful for trees that are stressed.

Summer is coming, and with it, there will be new and renewed tree care challenges. Let’s grow some shade and enjoy spring and the month of May—as long as we can.

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Arborilogical Services

Arborilogical Services shares information and news about trees, tree maintenance and the tree industry. Arborilogical is the expert tree care company your trees deserve. 

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