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As summer progresses into late summer, many parts of Texas experience prolonged periods of hot, dry weather with fewer rainfall events. These conditions not only place ornamental plants under drought stress but also create the perfect environment for spider mites to thrive. Unlike many insect pests that are suppressed by frequent rain, spider mite populations often explode during extended periods of dry heat, making August and September a critical time for greenhouse and nursery growers to intensify scouting efforts. The two-spotted spider mite (Tetranychus urticae) is one of the most common and economically important pests of ornamental crops. Feeding on more than 200 plant species, it attacks popular nursery and greenhouse crops including roses, hibiscus, lantana, marigold, salvia, verbena, hydrangea, and many bedding plants. Spider mites feed by piercing individual plant cells and removing their contents, producing characteristic yellow or white stippling on leaves. As infestations worsen, foliage develops a bronze appearance, leaves become dry and brittle, and severe infestations produce fine webbing that can cover leaves, stems, and flowers. Warm temperatures accelerate spider mite development, allowing a generation to be completed in as little as 7–10 days under favorable conditions. This rapid life cycle means that a few mites can quickly develop into damaging populations if left undetected. Dry weather also reduces the natural washing effect of rainfall, allowing mites to survive and reproduce unchecked. Routine scouting is the most effective defense. Inspect susceptible crops weekly, paying particular attention to the undersides of leaves where mites feed and lay eggs. A 10× hand lens can help detect early infestations before visible damage becomes widespread. Early detection allows timely intervention and greatly improves management success. An integrated pest management (IPM) approach provides the best long-term control. Maintain adequate irrigation to minimize plant stress, remove heavily infested plant material, and eliminate weeds that can serve as alternative hosts. In greenhouses, reducing excessive heat and maintaining appropriate humidity can help slow spider mite population growth. Biological control can be highly effective, especially in protected environments. Predatory mites such as Neoseiulus californicus provide excellent suppression when released early, before pest populations become established. Conserving these beneficials by selecting compatible pesticides is essential for successful biological control. When chemical control is necessary, rotate miticides with different modes of action to delay the development of resistance. Thorough coverage of the undersides of leaves is critical, as both mites and their eggs are concentrated in these protected areas. Late summer is the time when spider mites can quickly turn from a minor nuisance into a serious production problem. By combining vigilant scouting with cultural, biological, and chemical management tactics, growers can protect plant quality and minimize losses during one of the most challenging periods of the growing season.
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One of the most common complaints from homeowners during the growing season is the appearance of a black, soot-like coating on leaves, stems, patios, vehicles, and outdoor furniture beneath landscape plants. While many assume this black growth is a plant disease, the real culprit is often an insect infestation. Sooty mold is a fungal growth that develops on honeydew, a sticky, sugar-rich waste product excreted by sap-feeding insects. Common honeydew-producing pests in Texas landscapes include aphids, whiteflies, scales, mealybugs, and psyllids. As these insects feed on plant sap, they remove more sugar than they can utilize and excrete the excess as honeydew. Sooty mold fungi then colonize this sticky residue, forming a dark coating on plant surfaces. The mold itself does not infect plant tissues or directly damage leaves. However, heavy accumulations can block sunlight and reduce photosynthesis, leading to decreased plant vigor and aesthetic quality. In severe cases, leaves may yellow, growth may slow, and plants can become stressed, particularly when combined with other environmental challenges. Several landscape plants are commonly affected by sooty mold in Texas, including crape myrtle, gardenia, holly, hibiscus, magnolia, citrus, and many ornamental trees and shrubs. Crape myrtle bark scale, for example, is a frequent cause of heavy honeydew production and subsequent sooty mold development on crape myrtles. Likewise, whiteflies and aphids often contribute to outbreaks on ornamentals and flowering plants. Successful management requires addressing the underlying insect problem rather than focusing solely on the mold. Begin by inspecting plants carefully, especially the undersides of leaves and stems, where many sap-feeding insects congregate. Look for live insects, cast skins, sticky honeydew, or ant activity. Ants are often attracted to honeydew and may indicate the presence of hidden pest populations. An integrated pest management (IPM) approach is the most effective strategy. Encourage natural enemies such as lady beetles, lacewings, parasitic wasps, and predatory bugs that help suppress aphids, scales, and whiteflies. Avoid unnecessary broad-spectrum insecticide applications that may disrupt beneficial insect populations. When pest numbers exceed acceptable levels, select insecticides based on the target pest and follow all label directions. Once the insect population is reduced, honeydew production will decline, and existing sooty mold will gradually weather away through rainfall, irrigation, and normal leaf growth. In some situations, washing leaves with water can improve appearance, but this will not solve the problem if the insects remain active. When blackened leaves appear in the landscape, remember that sooty mold is usually a symptom rather than the primary issue. Identifying and managing the honeydew-producing insects will provide the most effective long-term solution and help maintain healthy, attractive landscape plants throughout the season.
Figure: Sooty mold on crape myrtle leaves (A) caused by crape myrtle aphid (B), and sooty mold on crape myrtle stem/bark caused by crape myrtle bark scale (C)
Texas has moved into summer earlier than usual, with high temperatures arriving well before the traditional peak season. While warm weather accelerates plant growth, it also creates ideal conditions for many insect and mite pests. For nursery growers, greenhouse producers, and landscape managers, early heat can mean earlier and more severe pest outbreaks. Many pests develop faster under high temperatures, allowing them to complete more generations in a shorter period. At the same time, heat and water stress can weaken plants, making them more susceptible to pest infestations. This combination often leads to increased pest pressure during early summer. Some of the most common pests to watch include spider mites, thrips, whiteflies, leafhoppers, and scale insects.
The best defense remains a strong Integrated Pest Management (IPM) program. Frequent scouting is critical during hot weather. Inspect plants regularly, especially new growth and leaf undersides, and use monitoring tools such as sticky cards or pheromone traps for early detection. In addition, minimizing plant stress through proper irrigation and balanced fertility can improve plant resilience. When treatments are necessary, rotate insecticides with different modes of action to help delay resistance development and preserve beneficial insects. Early detection and timely intervention are key. During hot summer weather, successful pest management starts with protecting plant health and staying proactive rather than reactive.  Rafia Khan, Ph. D.
Assistant Professor and Extension Specialist Texas A&M AgriLife Research and Extension Center, Overton, TX Excess rainfall during spring and summer can significantly increase pest pressure in nurseries, greenhouses, and landscapes. Warm temperatures combined with high humidity and prolonged moisture create favorable conditions for rapid pest development, survival, and spread. Soft-bodied insects such as aphids, whiteflies, thrips, and mites often become more active during wet weather periods. Excess moisture promotes lush plant growth and tender foliage, which are highly attractive to many pests. Standing water and saturated growing media can also encourage European pepper moth, fungus gnats and shore flies, particularly in greenhouse production systems. Wet conditions can make pest management more challenging. Rain may reduce the effectiveness of contact insecticides by washing away spray residues, often requiring repeated applications. Prolonged wet weather can also limit access to production areas, making routine scouting and timely pesticide applications difficult. High humidity and dense plant canopies further complicate early pest detection. Many pests, including thrips and mites, remain hidden within flowers, buds, or on the undersides of leaves, allowing populations to build unnoticed. In addition, storm events and strong winds may contribute to the movement and spread of invasive pests into new production areas. Excess rainfall may also disrupt beneficial insect activity. Natural enemies such as predators and parasitoids are often less active during prolonged storms and humid conditions, reducing natural pest suppression and allowing pest populations to increase rapidly once environmental conditions improve. Implementing proactive integrated pest management (IPM) practices is essential during periods of excessive rainfall. Regular scouting and monitoring with sticky traps can help detect pest populations early. Improving drainage, increasing air circulation, maintaining proper sanitation, avoiding overwatering, and removing heavily infested plant material can reduce favorable conditions for pests. Rotating insecticides with different modes of action and conserving beneficial insects are also important strategies for long-term pest management and resistance prevention. As weather patterns continue to become increasingly unpredictable, adopting management practices and maintaining consistent monitoring programs will remain Rafia Khan, Ph. D.
Assistant Professor and Extension Specialist Texas A&M AgriLife Research and Extension Center, Overton, TX When growers and landscape professionals think about insects, the first thought is often pests and the damage they cause. However, not all insects are harmful. Many beneficial insects play an important role in naturally suppressing pest populations in greenhouses, nurseries, and landscapes. These “good bugs” are valuable partners in Integrated Pest Management (IPM) programs and can help reduce reliance on chemical insecticides. Beneficial insects are a key component of Integrated Pest Management (IPM) programs. They help suppress pests naturally and can improve long-term pest management success when properly conserved or introduced into production systems. Two important groups of beneficial insects are predators and parasitoids. Predators actively consume pests throughout their life cycle. Common examples include lady beetles, green lacewings, minute pirate bugs, predatory mites, and hover fly larvae. These natural enemies feed on aphids, whiteflies, spider mites, scales, thrips, and other soft-bodied pests commonly encountered in Texas greenhouses and landscapes. Parasitoids are specialized insects, usually tiny wasps, that develop inside or on a host insect and eventually kill it. Several parasitoid species are commercially available and widely used in greenhouse biological control programs, especially for whitefly and aphid management. Parasitoids are specialized insects, usually tiny wasps, that develop inside or on a host insect and eventually kill it. Several parasitoid species are commercially available and widely used in greenhouse biological control programs, especially for whitefly and aphid management. Greenhouse environments often provide ideal conditions for biological control because temperature, humidity, and pest populations can be monitored more closely. In landscapes and nurseries, conserving naturally occurring beneficial insects can also provide significant pest suppression over time. Unfortunately, beneficial populations are frequently disrupted by unnecessary or repeated applications of broad-spectrum insecticides. One of the biggest challenges in pest management is recognizing when beneficial insects are already helping control a pest problem. In some situations, professionals may apply insecticides before evaluating predator or parasitoid activity. This can eliminate natural enemies and create secondary pest outbreaks or pest resurgence. In addition, repeated use of the same insecticide groups can contribute to pesticide resistance, making future pest management more difficult. Scouting remains one of the most important tools in preserving beneficial insects. Correct identification of both pests and beneficials allows professionals to make informed treatment decisions. When insecticide applications are necessary, selecting reduced-risk or selective products can help preserve natural enemy populations while still managing key pests. Habitat also plays a role in supporting beneficial insects. Flowering plants, reduced dust, proper irrigation management, and minimizing unnecessary pesticide exposure can all encourage beneficial activity in landscapes and production systems. Biological control is not always a complete replacement for insecticides, but it is an effective management tool when incorporated into a broader IPM strategy. As greenhouse and landscape industries continue to face challenges from invasive pests, environmental concerns, and pesticide resistance, beneficial insects should not be viewed as forgotten tools. Instead, they should be recognized as valuable partners in sustainable pest management programs. Photo credit: Rafia Khan, Ph. D. Assistant Professor and Extension Specialist Texas A&M AgriLife Research and Extension Center Overton, TX. |
AuthorKim Cabrera, TNLA Marketing Manager Archives
July 2026
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