Plant Pest and Fungal Problems

Along with the wonderful warm weather of Spring, we are also seeing damaging fungal diseases and pests emerge on plants.  If left unchecked, these fungal diseases and pests could get out of hand and cause long-term damage to your lawns and landscape plants. Below are just a few to watch for in the Houston area...

Crape Myrtle Bark Scale (CMBS)

Crape Myrtle Bark Scale is a small insect that appears as a white or gray felt-like encrustation sticking to the bark of Crape Myrtles.  They might be found anywhere on our beloved trees, and often appears near pruning sites and branch crotches of more mature wood. It causes extensive honeydew deposits and the growth of black sooty mold, blemishing the beauty of the Crape myrtle.  Although heavy scale infestations are seldom fatal to the Crape Myrtle, the aesthetic impacts are significant. 

Often times, the first sign of CMBS is that black sooty mold on the tree bark, however aphids can also cause this black sooty mold symptom so a close inspection will determine which pest is present. Unfortunately CMBS can be a difficult pest to control and it may take multiple years of treatment, as opposed to the easier controlled aphids.

Bark Scale

Prevention and Treatment for CMBS

- Before buying crape myrtles, inspect the nursery crop carefully for signs of CMBS infestations.  Avoid crape myrtles with significant damage.

- At any time if you notice Crapemyrtle Bark Scale you can mix dishwashing soap with water and scrub the branches with a soft bristle brush.  This will remove many of the female scales and egg masses, making insecticide control more effective.  Washing will also remove much of the black mold that builds up on the bark of infested trees.

- As the crapemyrtles begin to really bloom, drench the soil around the drip line of the affected tree (where the feeder roots are) with an systemic insecticide such as an Annual Tree & Shrub Insect Control.  Just correctly mix with water and apply in a 3-4 foot band from the root zone in towards the tree trunk all the way around the plant.  The best control was achieved between May and July.  When drenching the soil with a systemic insecticide, allow several weeks for the product to reach the plant.

- Winter is an especially good time to treat for scales because the Crape Myrtles are in their dormant season and a higher application rate can be used without damaging the plant.  Cover the tree thoroughly with pesticide during the dormant season, especially when using horticulture oil.

Black Spot on Roses

You may begin to see dark spots on the foliage of your roses during the Spring, which eventually become yellow and drop.  The spots can be very small or large enough to cover the entire leaf.  This problem is called Rose Black Spot and it's caused by fungus.  Some plants can handle the defoliation, but if a newly planted or young specimen loses all of its leaves too early in the season, it could be a lost cause.  It’s best to diagnose early and treat the plant if needed.

Rose: Black Spot by Scot Nelson

Treatment and Prevention of Rose Black Spot

- Remove infected foliage and twigs. Fungal diseases are easily spread from plant to plant and from one leaf to the rest of the leaves. When detected early, removing infected plant tissue is a great way to protect the healthy plants and foliage.

- Keep foliage dry.  While rain is unavoidable, you can control your irrigation system. Always water at the soil level, not on top of the foliage.  Adjust or replace sprinkler heads that spray water into the air and on top of your plants,  Otherwise, water early in the morning so leaves have the daytime to dry off versus watering at night because fungal diseases thrive in the cool, dark night much more than in the daytime.  Or consider having us install a drip irrigation system for you, if you don't already have one, since there are many advantages to that. 

- Fungicides: In some instances, fungicides might be an appropriate treatment.  Early detection and treatment is best.  In the early spring when the leaf buds on the rose bushes first start to push out the little leaves, spray all the rose bushes with a black spot treatment fungicide.  Repeat every 3 weeks during the blooming season.

- If a plant is heavily infected, fungicides may not always solve the problem and you should remove the infected plant so as to protect the rest of your landscape.

There are many other pests & diseases that are prevalent around the Houston area as well.  Prevention is key.  Healthy, well-maintained plants will have the best chance of deterring fungal diseases.  Need help this spring maintaining your landscape?  Not only do we maintain landscapes, but we also keep an eye out for disease and pest problems that might arise.  Living Expression Landscapes can provide you with prompt detection, diagnosis and treatment!

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