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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
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Spring in Texas often brings warm temperatures along with frequent rain and storm events, creating highly favorable conditions for increased pest pressure in nurseries, greenhouses, and landscape systems. Elevated humidity and excess moisture significantly enhance pest development, survival, and reproduction, making this season particularly challenging for growers. These environmental conditions not only accelerate pest life cycles but also create ideal microhabitats for hidden and soil-associated pests, increasing the risk of sudden infestations and economic losses. Favorable Conditions for Pest OutbreaksSoft-bodied insects such as aphids, whiteflies, and thrips thrive under warm, humid conditions commonly observed during spring. The flush of new plant growth during this period provides tender, nutrient-rich tissues that are highly attractive for feeding and reproduction. As a result, pest populations can increase rapidly within a short period, often going unnoticed until visible damage appears. Without timely monitoring and intervention, these pests can quickly reach damaging levels and affect plant quality and marketability. Soil and Moisture Associated Pests Prolonged wet conditions create ideal environments for pests such as fungus gnats and shore flies, particularly in greenhouse and nursery production systems. Their larvae develop in moist growing media, feeding on organic matter and plant roots, which can weaken plants and reduce overall vigor. Additionally, pests like the European pepper moth benefit from high moisture conditions, as their larvae remain concealed in the lower canopy or within the growing media. This hidden feeding behavior, combined with favorable environmental conditions, makes early detection difficult and allows populations to build up before noticeable symptoms appear. Pest Spread and Increased Activity Rainfall and storm events can also contribute to the spread of pests within production systems. Splashing water can move infested soil, plant debris, eggs, and larvae between containers or across growing areas, facilitating rapid dispersal. Furthermore, outdoor pests such as caterpillars and beetles often become more active following rainfall, increasing feeding activity and the likelihood of damage. Wind and storm movement can also aid in dispersing adult insects into new areas, compounding pest pressure. Challenges in Pest Control Frequent rainfall presents additional challenges by reducing the effectiveness of insecticide applications. Rain can wash off residues from plant surfaces, shortening the duration of control and requiring more precise timing of applications. High humidity may also affect product performance and pest exposure, making control less consistent during extended wet periods. Take-Home Message Overall, rainy spring weather creates ideal conditions for pest outbreaks by enhancing survival, reproduction, and spread, while simultaneously reducing control effectiveness. Under these conditions, consistent scouting, proper irrigation management, and timely, integrated interventions are essential to minimize pest impact and maintain plant quality and marketability. Rafia Khan, Ph. D. Assistant Professor and Extension Specialist Texas A&M AgriLife Research and Extension Center, Overton, TX Rafia Khan, Ph. D Assistant Professor and Extension Specialist The European pepper moth (Duponchelia fovealis) is an emerging pest of concern in greenhouse and nursery production systems, particularly in ornamental crops. Accurate identification and early recognition of injury symptoms are critical for timely management, as infestations often go unnoticed until significant damage has occurred. Identification Adult moths are relatively small, with a wingspan of approximately 19-23 mm. They are typically tan to brown in color. The front wings have two cream-colored bands; outer one has a finger-like projection. Their abdomen has white colored rings. The adults are weak fliers and hold their wings flat in a triangular shape at rest. Due to their size and coloration, adults can be easily overlooked among plant material. Eggs are very small, oval, and pale in color, and are usually laid in concealed locations such as the undersides of leaves, along leaf veins, or near the base of plants. These eggs are difficult to detect without close inspection. Larvae are the most damaging stage and are more commonly encountered than adults. Newly hatched larvae are small and translucent, but as they mature, they become creamy white to light brown with a distinct dark brown head capsule. Fully grown larvae can reach up to 15–20 mm in length. Larvae are typically found in protected areas such as the lower canopy, at the crown of the plant, or within the growing media. Their cryptic behavior makes them difficult to detect during routine scouting. Pupation occurs in silken cocoons that may be found in soil, plant debris, or along container edges. These cocoons are often covered with particles of soil or plant material, further aiding concealment. Injury Pattern The European pepper moth primarily causes damage during the larval stage. Feeding typically begins on lower leaves and stems, often near the base of the plant. Early symptoms include small chewing marks on foliage, which can be easily mistaken for minor or incidental damage. As larvae grow, feeding becomes more aggressive and extensive. Leaves may become skeletonized or exhibit irregular holes. Larvae may also bore into stems at or just above the soil line, causing girdling. This type of injury disrupts water and nutrient movement within the plant, often leading to wilting, stunted growth, or plant collapse. One of the distinguishing signs of infestation is the presence of webbing produced by larvae. This webbing is often mixed with frass (insect excrement) and plant debris, creating a messy appearance around the crown and lower foliage. In potted ornamentals, larvae may also feed within the growing medium, damaging roots and lower stems, which further contributes to plant decline. Plant injury is often concentrated in hidden areas, making early detection difficult. By the time symptoms such as wilting or significant defoliation are visible, larval populations may already be well established. In ornamental crops, even moderate feeding damage and contamination with frass can significantly reduce aesthetic quality, leading to reduced marketability or complete crop loss. Recognizing these identification features and injury patterns is essential for early detection and effective management of this increasingly important pest.
Photo credit, Rafia Khan
Rafia Khan, Ph.D. Assistant Professor and Extension Specialist Texas A&M AgriLife Research and Extension Center, Overton, TX Winter can feel like a break from pest pressure, but for nursery and greenhouse growers, many insects are still present and waiting for the right conditions. Protected structures, mild winter weather, and overwintering life stages allow many pests to survive on plants, in pots, in growing areas, in debris, and in weeds. If these pest populations are not addressed, they often resume early and aggressively in spring. Common winter pests include aphids, thrips, mealybugs, scale insects, whiteflies, spider mites, and greenhouse moth pests such as the European pepper moth. These insects can survive on plant material, in potting media, or within greenhouse structures, often going unnoticed until populations increase. Programmed scouting remains the foundation of winter Integrated Pest Management (IPM). Monitoring efforts should be focused on current in-house plants and newly arrived plant material. Inspect leaf undersides, stems, and growing points, and use sticky cards to detect flying insects early. Cultural practices play a key role in reducing pest pressure during winter. Sanitation, such as the removal of plant debris, leftover shipped plants, weeds, volunteer plants, and unused containers, should be removed from the production sites as they may harbor pests. Manage irrigation carefully to avoid conditions favorable for fungus gnats and root pests, and inspect incoming plants before placing them into production areas. When treatments are necessary, applying products strategically and rotating insecticide modes of action helps protect product performance and avoid costly resistance issues. Winter is also the best time for growers to step back and evaluate what worked and what didn’t during the past season. Reviewing pest records, adjusting management plans, and training employees to recognize early pest signs can pay off quickly. Investing time in winter pest management reduces carryover populations, improves plant quality, and helps operations enter spring with fewer surprises and lower control costs. Figure: Some greenhouse pests in winter. European pepper moth larva (A) and adult (B), Thrips (C), and mealybug (D) |
AuthorTNLA Staff Archives
September 2026
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