Newly planted catalpa tree

Asked September 7, 2017, 9:47 PM EDT

We just paid $600 for two 10 ft catalpa trees to be professionally planted. The leaves are starting to look like the attached picture. They were also put in a drip system when planted. Do these leaves indicate ocer or under watering? Disease? We do live just outside of Fort Lupton however the landscaper said these would be appropriate trees for our soil. Really don't want to lose these trees. Any ideas?

Weld County Colorado trees and shrubs

7 Responses

Thanks for contacting us about your new catalpas. The recommendation you received is accurate; these are wonderful trees for our soil and climate. What you’re seeing is consistent with stress (not disease) on the tree. Summer is a hard time to plant new trees here; our soil and climate is generally dry and hot at this time (and we have much more of that to come). Transplant shock is common. The dry, brown areas on the leaves will not recover and may begin shedding.

The tree is losing more water than it’s taking up. Trees transpire through leaves, and the roots have to keep up with supplying water. If that is out of balance, the leaves begin to dry out. The tree is trying to conserve its energy in the roots, trunk and branches and can give up some leaves to do that. However, the leaves are also supplying the roots with needed nutrients from photosynthesis, so the leaves are much needed. It’s all about balance, and even having a surplus in the roots, which your new trees do not yet have. You can use a probe/screwdriver to test the soil for drying out, and adjust watering. Yellowing leaves can mean too much water, wilting and browning can mean too little.

Your new trees need extra care and monitoring while they are getting established. We highly recommend fall and winter watering. They do not need fertilizing. Make sure the irrigation system is putting water out where the roots are (not right next to the trunk). Mulching is recommended to maintain soil temperature and moisture, but it should not be up against the trunk. Hopefully you can see the trunk flare (where the trunk begins to spread out into the roots) just above soil level. The new trees may have root damage, and need the opportunity to begin growing new roots. The larger the tree, the longer it’s going to take to become established. I’m including links that go into more detail on these points.

Enjoy your catalpas. While they are getting established the next few years, you may see very few flowers (but they are fabulous when they arrive!). Don’t hesitate to reply with further questions.

Karin

This weekend we noticed wasps swarming the trees. We find little bugs and small worms on the leaves. These are the only trees in our property with these parasites. What can we do to get rid of these pests?

This weekend we noticed wasps swarming the trees. We find little bugs and small worms on the leaves. These are the only trees in our property with these parasites. What can we do to get rid of these pests?

The wasps are taking advantage (feeding on) honeydew produced by one of the other insects. The wasps are not hurting the tree, and only need to be dealt with if they are harming your family. Nature will take its course and all these insects will die when the cold weather comes. As to the "little bugs and small worms" on the leaves, can you send another great up-close picture like you did before showing them? That will help me identify them.

Thanks, Karin

These are the bugs that are on R leaves. They seem to be destroying all the leaves. Soil is damp at the base of the trees due to a drip system which waters 5 days a week.

This appears to be one of the life stages of grape mealybug. In Colorado, this insect is usually found on grapes on the Western Slope, but outbreaks can also occur on different species of trees, including catalpa anywhere in the state. This insect is producing the honeydew that has attracted the wasps and other insects (the sweet honeydew is a food source for them). The honeydew does not cause any damage in our climate, but the mealybugs are tiny sapsuckers that use their mouthparts to draw up the sap in the leaves, removing the nutrients from the leaves. At this point in the season, the leaves are not providing as much photosynthesis (therefore, nutrition) to the tree and will soon be falling off the tree, taking the insects with them. Mealybugs in general are difficult to control, and these are no exception. You can try hosing off the leaves using a spray that knocks some off and this will also eliminate some of the honeydew attracting other insects. In the spring, watch for egg clusters (they will look like small, cottony mases in the crevices of twigs and around buds). If you see any of that, use a horticultural oil to smother the insect eggs. A good, local nursery will have both organic and synthetic options for you. The links below have good information on mealybugs in general, specific information on the grape mealybug (you will notice that this is directed primarily at grape/fruit agriculture where this is a primary pest), and then one on horticulture oils.

I apologize for the delay in responding. Identifying this particular insect required some assistance!

Karin

Another thought: You mentioned these trees are being irrigated 5 times per week. It's time to cut back the water by half. Not only will this help prepare the trees for the winter, but will offer less sap to the mealybugs and may help reduce populations. We recommend fall and winter watering for trees, especially trees that are not yet established. Once per month when the irrigation is off, water the trees on a warm day so it penetrates the soil and can be taken up by the tree. More info here: