Category: IPM

The two-spot cotton leafhopper is spreading fast across the Southeast, threatening hibiscus and other ornamentals with hopperburn damage.

At Clemson’s Pee Dee REC, Dr. Zee Ahmed, along with his graduate students Nisha Yadav and Peilin Tan and research specialist Shawn Chandler, tested six insecticides, providing growers with the first science-based guidance for managing this pest in hibiscus nursery production.

Key grower takeaways:

1. Scout regularly with a 10x–30x lens

2. Match treatments to insect life stages

3. Rotate insecticides by IRAC group

4. Integrate biological & cultural controls

Figure 1: Field guide to the TSCL showing approximate adult size, life cycle stages and timing, key identification feature of two dark wing spots, common feeding damage symptoms, host plant range, scouting methods, and cultural/chemical control options.

Figure 2: Scan the QR code to access the complete field guide for TSCL, along with additional field guides on ornamental pests.

Read More: https://news.clemson.edu/clemson-launches-first-chemical-trial-to-combat-invasive-leafhopper-in-ornamentals/”

Amrasca bigutulla, commonly know as the two-spot cotton leafhopper, has been detected in several states in the southeastern US, including Alabama, Georgia, Florida, and South Carolina. This species is native to southeast Asia, where it is an important pest of cotton and okra. The arrival of the insect in the continental U.S. is a concern for cotton and vegetable production, although its impact on yield remains unclear. 

Adults are characterized by two black dots on the distal part of the forewings. Females oviposit on leaf tissues, and upon hatching, nymphs grow through four developmental stages in about 8 or 9 days. Adults live an additional 11 or 12 days. The short life cycle enables two  -spot cotton leafhoppers to produce multiple generations throughout the season.

Figure 1. Adults and nymphs of  two-spot cotton leafhopper feeding under cotton leaves. 

Both nymphs and adults feed on the underside of cotton leaves by injecting its mouth part in the tissue and consuming plants sap (Figure 2). Feeding can cause the cotton leaves to turn yellow. The detection of two-spot cotton leafhoppers is a concern for cotton production in the southeastern US. In addition to quantifying potential impacts on yield, future research will focus on monitoring two-spot cotton leafhopper populations throughout the season, developing economic thresholds and treatment recommendations to provide management solutions for cotton growers.

Figure 2. Mild (left) and severe (right) injury of two-spot cotton leafhopper in cotton.  

In greenhouse, nursery, and ornamental crop production, anticipating pest threats is crucial to protecting plant health, maintaining market access, and ensuring operational efficiency. The 2026 Insecticide, Miticide & Fungicide (IMF) Guide provides an updated, science-based framework for pest management, including chemical class charts, resistance management strategies, and pest-specific recommendations. It reinforces Integrated Pest Management (IPM) principles, accurate identification, consistent monitoring, cultural and biological controls, and strategic chemical rotations to reduce resistance risk, preserve beneficial organisms, and maintain compliance with state and federal regulations.
A complete guide is available here: 2026 Insecticide, Miticide & Fungicide Guide.

This year, Dr. Zee Ahmed, Assistant Professor of Turf and Ornamental Entomology at Clemson University, took proactive pest management a step further with the release of a specialized field guide on Thrips parvispinus, a pest still under regulatory concern in the United States. Designed for growers, inspectors, and extension agents, the guide equips stakeholders with tools to detect infestations early, before they escalate into costly outbreaks. Early detection not only minimizes unnecessary insecticide applications but also slows the development of resistance and helps avoid potential trade or quarantine complications.

Together, the 2026 IMF Guide and Dr. Ahmed’s field guide form a powerful one-two punch: a comprehensive management framework paired with a targeted diagnostic tool. For stakeholders, this means better decision-making, reduced chemical dependency, and a stronger position in meeting both production and regulatory demands, assuring healthier crops, healthier markets, and a healthier future for the industry.

Figure 1. Field Guide for Thrips parvispinus (Ahmed, 2025): A visual diagnostic reference to aid in proactive detection in ornamental and edible crops.

The spotted lanternfly (SLF) has been established in 19 U.S. states since its first detection in Pennsylvania in 2014. It was confirmed in North Carolina in 2022, Tennessee in 2023, Georgia in 2024 and South Carolina in 2025. While other neighboring states in the southeastern U.S. don’t yet have confirmed established populations, the risk of establishment remains high.

Dr. Zee Ahmed (Clemson University) and his colleagues—Dr.   Shimat Joseph (University of Georgia), Dr. Midhula Gireesh (University of Tennessee), Karla Addesso (Tennessee State University) and Alejandro Del Pozo-Valdivia (Virginia Tech) developed a management calendar to support early detection and proactive control efforts for ornamental growers in the Southeastern U.S. This seasonal framework offers practical guidance to help growers address SLF concerns proactively from late summer 2025 through summer 2026.

Here is the link  Spotted Lanternfly Management Calendar for Ornamental Growers in the Southeastern U.S.

Dr. Zee Ahmed (Clemson University) and Dr. JC Chong (SePRO Corporation) have co-authored a new article in the July 2025 issue of GrowerTalks, offering practical strategies for managing scale insects in nurseries and landscapes.

Key highlights include:

• Identifying the most common scale insects
• Understanding why the crawler stage is the most vulnerable and effective target for control
• Monitoring crawler emergence using sticky bands
• Selecting insecticides that minimize impact on beneficial insects

With over 1,100 species in North America, scale insects are often difficult to detect and manage. This guide helps growers improve treatment timing and reduce long-term infestations.

Read the full article: “Target Scale Insect Crawlers to Prevent Sticky Situations” (https://www.growertalks.com/Article/?articleid=27527) in GrowerTalks, July 31, 2025.

Figure 1: Comparison of different types of scale insects

Figure 2: Top 35 scale insect species on ornamental plants: voltinism and approximate crawler emergence timing

Mealybugs may be small, but their impact in greenhouse production can be massive. These sap-sucking pests often sneak in as nearly invisible crawlers and quickly establish persistent infestations—nestling behind leaves, burrowing into root zones, and hiding in plant debris. Once entrenched, they can be notoriously difficult to manage.

At the Turf and Ornamental Entomology Laboratory, we’ve seen firsthand how challenging mealybug outbreaks can be for growers. That’s why PhD students Powlomee Mondal and Peilin Tan, under the guidance of Dr. Zee Ahmed, compiled a comprehensive guide to help greenhouse professionals tackle these pests head-on.

What’s Inside the Strategy

In the article, Managing Mealybugs in the Greenhouse, we outline a science-based, step-by-step approach that includes:

• Accurate species identification to tailor control strategies
• Timed applications based on pest life cycles
• Rotation of systemic and contact insecticides to prevent resistance
• Sanitation protocols, including bench-washing and debris removal
• Efficacy data to guide product selection and application timing

This guide is designed to empower growers with practical, research-backed tactics that reduce pest pressure while preserving plant health and minimizing chemical overuse.

Read the Full Article

Mondal, P., Tan, P. and Ahmed, Z., 2025. How to manage mealybugs in the greenhouse. Greenhouse Management, [online] 24 June. Available at: https://www.greenhousemag.com/article/managing-mealybugs-pest-control-greenhouse/ [Accessed 4 Jul. 2025].

Grower Input Needed:

In addition to the article, Peilin Tan is conducting a brief survey to better understand the current challenges and research needs related to mealybug management in greenhouse systems. The survey consists of nine multiple-choice questions and does not collect any personal information.

We would greatly appreciate your participation:
Take the Survey

Figure 1: Scale insects.

Figure 2: Mealy bug species globally, in the USA, and in greenhouses.

Figure 3: Mealybug species considered greenhouse pests.

The U.S. cut flower market was valued at approximately 9.2 billion USD in 2021 and is projected to grow to nearly 12.8 billion USD by 2028, with a steady compound annual growth rate of 4.8%. While irises make up a smaller share of this market, their visual appeal and versatility give them lasting economic and cultural value. Some varieties even pull double duty—producing rhizomes used in perfumes and traditional medicine. For South Carolina, ornamental horticulture is more than just aesthetics—it’s a key part of the state’s thriving green industry. Irises—particularly a wide range of native and cultivated varieties/cultivars—play a notable role in this sector, contributing to landscape diversity, wetland restoration, and the ornamental plant trade.

However, iris growers across the region may be facing an unseen threat. We recently discovered a dipteran leafminer, tentatively identified as Cerodontha sp., causing significant damage in iris production areas. A quick survey of major plant outlets in Florence, SC revealed that most Louisiana iris plants were infested, with damage easily mistaken for abiotic stress like overwatering or nutrient issues (Figure 1).

What to Look For:

• Yellowing and wilting of iris leaf blades (Figure 2)
• Short, whitish serpentine tunnels near the base of leaves (Figure 2)
• Iris plants failing to bloom

Detecting and monitoring the leafminer life cycle in your area is the first step in effective management. Many growers have had difficulty managing leafminers, and a key early task is confirming whether the symptoms observed are actually caused by leafminers. This involves locating mines and inspecting them for visible life stages such as larvae, pupae, or empty trails. Misdiagnosing the symptoms or mistiming treatments can significantly reduce control efficacy, especially when insecticides are applied during periods when the pest is in the egg, pupal, or inactive larval stage—times when it’s least vulnerable and least exposed to control measures.

If you find damage on your irises:

Please contact Dr. Zee Ahmed at mahmed2@clemson.edu or (352) 283-0173 for support with identification and management.

Stink bug overview and identification

The brown stink bug, Euschistus servus, and southern green stink bug, Nezara viridula, can be damaging pests of field corn in South Carolina. While it has a high potential for injury, it is considered a sporadic pest because it does not occur at damaging levels in every field every year. Due to the sporadic nature of this pest, it is important to understand potential risk factors for infestation and have a plan in place before the growing season to be ready to address it efficiently and effectively if damaging populations occur.

Stink bugs are shield-shaped insects, which are similar in shape and size across species. As the name suggests, the brown stink bug is dark brown in color. There is a beneficial stink bug species that may be confused with brown stink bugs, but can be distinguished by the presence of pointed and sharp shoulders (i.e. pronotum), which the pest brown stink bug does not have. Nymphal brown stink bugs are light green in color and have a distinctive brown patch on their abdomen. Southern green stink bugs are slightly larger than brown stink bugs and green in color. The nymph of southern green stink bugs have a series of pink, white, and black spots on their abdomen, which can easily distinguish them from other species. Other species that can occur in corn but are either far less common or not pests of corn in South Carolina are the brown marmorated stink bug, green stink bug, and rice stink bug.

Left: adult brown stink bug. Image credit: Gerald Holmes, Strawberry Center, Cal Poly San Luis Obispo, Bugwood.org. Right: fourth instar brown stink bug nymph. Image credit: Herb Pilcher, USDA Agricultural Research Service, Bugwood.org

Left: Adult southern green stink bug; note the presence of tachinid fly eggs. Right: fourth instar southern green stink bug nymph. Image credits: Russ Ottens, University of Georgia, Bugwood.org.

Injury to field corn

Field corn is susceptible to injury during three key stages of field corn development: 1) emergence (VE) – six-leaf stage (V6), 2) two weeks prior to tasselling (VT) during the earliest stages of ear development, and 3) the first two reproductive stages of development (R1 and R2). During the early vegetative stages (i.e. VE-V6), stink bugs feed directly on the growth point of young plants, which can lead to stunted plants, tillers, leaf holes, deformities, or plant death in severe cases. Prior to tasseling and pollen shed, feeding on the early stages of ear development leads to a characteristically “banana-shaped” ear, which limits overall yield potential and can expose the ear to secondary pests and pathogens. It is important to note that during these stages, the ear is not yet visible, but stink bugs can use their straw-like mouthparts to penetrate into it. Beyond pollination, direct feeding on kernels has limited potential to directly impact yield but can introduce grain quality issues in the form of fungi and mycotoxin contamination if bugs are at a high enough density.

Early vegetative injury from stink bug feeding. Left: plants stunted with multiple tillers. Right: Severely stunted plants. Image credit: Tim Bryant, Clemson University. 

Banana-shaped ears as a result of stink bug feeding during late vegetative stages prior to tasseling. Image credit: Tim Bryant, Clemson University. 

Discolored kernels and fungal growth as a result of stink bug feeding during early reproductive stages of corn development. Image credit: Tim Bryant, Clemson University. 

Population dynamics and management

Identifying at-risk fields can help save time in deciding when and where to scout for stink bugs. During early vegetative stages, fields that are planted into heavy cover crop residue can potentially be at higher risk for large populations and injury. Proper seed slot closure can be affected by this heavy cover and expose more sensitive portions of the plant to feeding, increasing injury potential. Fields that were planted with soybeans in the previous season can also be at a higher risk for early-season infestations. Later in the season, the interface of wheat and corn is at high risk for stink bug infestations. Wheat is an excellent early-season host for stink bugs, which can easily move into nearby corn during wheat harvest. Wheat harvest often coincides with the later vegetative stages of corn development, which are susceptible to stink bug injury.

For early vegetative infestations, insecticidal seed treatments, which are applied almost universally to commercial corn seed, can provide some protection from early season injury. Generally, fields with a history of stink bug pressure or at risk of injury from soil pests may benefit from increased seed treatment rates. Additionally, foliar insecticides can effectively manage stink bugs throughout the season, but it is critical to scout and only apply an insecticide at the economic threshold level for the given growth stage. The economic threshold is 1 bug per 10 plants from V1 to V6, 1 per 4 plants from V12-VT, and 1 per 2 plants at R1 and R2. The two most important considerations for applying an insecticide are achieving good coverage and timing the application properly. Ensuring canopy penetration is especially critical during the later stages of corn development. Bifenthrin is generally the most effective material to target brown stink bugs specifically. Applying an insecticide only at the economic threshold level will also preserve naturally occurring biological control agents in the field that broad-spectrum insecticides would otherwise kill.

For more detailed biology and management information on brown stink bugs in field corn, see this Land-Grant Press article.

Contributing Author: Dr. Francis Reay-Jones

More than 80% of field corn grown in the U.S. has been genetically engineered to express one or more insecticidal toxins from Bacillus thuringiensis, called Bt toxins. Bt corn was first commercialized in the U.S. in 1996, expressing a single Bt toxin targeting the European corn borer. Newer Bt corn hybrids express two or more Bt toxins, which has increased the number of target pests to include the corn earworm and the fall armyworm. Benefits of planting Bt corn can include protecting yield from insect damage, reducing the need to use insecticide, and improved grain quality. However, such benefits can be impacted by the development of resistance in target insects.

Dr. Francis Reay-Jones is continuing this year to evaluate the efficacy of Bt traits and the impact Bt toxins have on the life cycle of the corn earworm, with implications on resistance evolution. “We have been conducting field efficacy trials with a range of Bt traits since 2009. Since then, we have seen some traits become less effective over time because corn earworm has developed resistance. We saw in particular a shift in 2015 when resistance to some of the Cry toxins expressed in Bt corn became more widespread not just in South Carolina, but across the southeastern U.S.” Although the corn earworm is generally not a significant economic pest of field corn, the same species is a serious pest in cotton, where it is known as bollworm. Because Bt cotton expresses the same or similar toxins as Bt corn, selection for resistance in Bt corn is likely driving resistance issues to Bt cotton. “Planting a non-Bt refuge is the only tool we have to manage resistance. Preventing resistance development in Bt corn is crucial so that the insect does not cause more damage to Bt cotton later in the season, where the corn earworm (or bollworm) is a major economic pest.”

While resistance in corn earworm is widespread to most Cry toxins used in Bt corn and Bt cotton, one toxin, called Vip3A, remains highly effective. Trials in South Carolina continued this year to evaluate Bt corn hybrids expressing Vip3A. Examination of hundreds of corn ears in 2023 showed that these hybrids remain highly effective, with no ear injury found due to corn earworm feeding. In corn, this toxin is expressed in Trecepta, Optimum Leptra, and Agrisure Viptera products. While Vip3A remains effective, reports of unexpected injury in recent years in the mid-south underline the need for continued resistance monitoring. Vip3A toxins are also expressed in new Bt cotton varieties, and planting of non-Bt refuge in corn is crucial, since only a single Bt toxin is currently available with very good activity for this key pest.

Dr. Tom Bilbo, Clemson’s vegetable and strawberry entomologist stationed at the Coastal Research and Education Center in Charleston, began his research and extension program late in 2021. Since starting here at Clemson, Dr. Bilbo has rapidly expanded his program and has started addressing a number of different economically important pest concerns for vegetable and strawberry growers. “The primary goal of my research program is to enhance sustainable food production through protection of yields from crop pests and enhancement of yields through conservation of beneficial insects” Dr. Biblo says. The primary areas of focus for his research are 1) developing new biological control strategies for key pests, 2) reducing pest potential through modification of farming practices and systems, and 3) improving insecticide use and managing insecticide resistance. When it comes to Extension and stakeholder interaction, focus areas include 1) identifying key entomological issues in vegetables and strawberries, 2) encouraging adoption of improved practices through demonstration of efficacy and profitability, and 3) improving stakeholder knowledge of advances in IPM and IRM.

“Overall, my research uses our understanding of insect ecology to reduce pest problems and enhance the role of beneficial species, especially predators and parasitoids” Dr. Bilbo says, “much of my research is conducted on commercial farms in coordination with local growers.” The reason for much of the research being conducted with collaborating growers in twofold. 1) Insect ecology entails insects moving around, and insects don’t care about the arbitrary plot borders researchers construct. So small plot experiment station trials make it difficult to tease apart treatment effects as well as not being a realistic representation of how insects behave on vegetable and fruit farms. 2) On-farm trials allow Dr. Bilbo to build relationships with growers to understand the pest problems better and create management strategies that are feasible, economical, and effective.

Some of Dr. Bilbo’s on-going projects include pest management in brassicas, strawberry, tomato, watermelon, and cucurbits. In brassicas, the primary focus is effective integrated management of the diamondback moth, the major economic pest of most brassica crops worldwide. His work on diamondback moth includes determining how predator and parasitoid activity varies with the use of intercropped flowers (to optimize flower plantings), evaluating mating disruption as a potential management strategy, and determining which plants are best at attracting natural enemies of diamondback moths and other pests in both spring and fall crops. Much of this diamondback moth research is conducted in collaboration with specialists at NC State, Virginia Tech, and Tennessee State University. These types of regional efforts allow for a greater understanding of pest status and management options on a larger spatial scale.

In strawberry, his primary research focus is on enhancing the role of beneficial predatory mites to manage spider mites. A survey of commercial farms for the presence of these beneficial mites will provide a baseline level of knowledge on their natural occurrence and role in suppressing pest mites. Other projects include evaluation of tomato and watermelon cultivars for spider mite preference, evaluating pheromone traps for pickleworm moth in cucurbit crops, continued Bt resistance monitoring in corn earworm, and conducting insecticide trials to evaluate new and existing products for important pests. All of this research and subsequent extension work to disseminate the results of these studies will directly benefit vegetable growers in South Carolina by maximizing their pest management and providing a full range of tools to effectively address those pests.