What Vegetable Growers Need to Know About New Isocycloseram Insecticides
By Veronica Yurchak, Vegetable Specialist, University of Maryland
Recently registered products with Syngenta’s new Plinazolin ® technology introduce a new mode of action for vegetable crops, offering growers an important resistance-management tool ahead of the 2026 season. Below is an overview of the different formulations, how this new mode of action works, regional performance, and key considerations to keep in mind as you plan your spray programs.
Plinazolin technology contains the novel active ingredient isocycloseram, which belongs to IRAC Group 30 (isoxazolines). The EPA has approved four formulations labeled for use in vegetables. Three formulations are foliar-applied products for use in brassicas, fruiting vegetables, cucurbits, and leafy greens (Incipio ™), potatoes (Zivalgo ™), and onions (Vertento ™). An additional formulation has also been registered for use as a seed treatment in beans and peas (Equento ™). All products are expected to be registered and available within Maryland ahead of the 2026 growing season.
New mode of action – How it works
As the first Group 30 insecticide registered for foliar application in vegetables, isocycloseram has no known resistance or cross-resistance with other insecticides and can therefore play an important role in managing insect pest resistance challenges in various vegetable crops. After application, isocycloseram remains active on plant surfaces. Insects are then exposed when feeding on treated leaves, stems, or fruit, or when crawling across treated surfaces. Once inside the insect, the pesticide quickly overstimulates the nervous system, leading to paralysis and eventual death. While it acts primarily as a contact insecticide, some limited movement into plant tissues does occur. Because ingestion of treated plant material is the main route of exposure, Plinazolin products are mainly effective against chewing pests, with additional efficacy against some sucking pests.
Pest Control Efficacy & Resistance Management
Regional efficacy trials have demonstrated strong performance against several key vegetable pests. In Maryland and Virginia, foliar applications have provided very good control of stink bugs, thrips, and spider mites in tomatoes. Virginia trials have also shown very good control of Colorado potato beetle in potatoes and flea beetle in Chinese cabbage. In New York onion trials, isocycloseram delivered similar control of allium leafminer as compared to the leading recommended products. Additional trials have further indicated good control of fruitworm (Helicoverpa zea) in tomatoes as well as other caterpillar pests in various cole crops.
Despite good H. zea control in tomatoes, control of corn earworm (H. zea) in sweet corn has been less consistent, and there are currently no isocycloseram products registered for foliar use in sweet corn. Isocycloseram products are also not registered for use on many piercing-sucking pests due to inconsistent/weak pest control performance. For example, trials have shown inadequate control of both aphids and whiteflies and products are therefore not recommended/registered for controlling these pests.
As with any new chemistry, stewardship is critical. Growers should carefully follow label directions and rotate among insecticide modes of action throughout the season. Rotate between different IRAC groups for successive pest generations and avoid more than two consecutive applications of the same mode of action. Specific application requirements for resistance management are included on the label for several pests, including diamondback moths. To further delay resistance development, insecticides should be used as a part of a diverse integrated pest management strategy inclusive of both chemical and non-chemical pest control tactics.
Protecting Pollinators and Non-Target Organisms
Isocycloseram is highly toxic to bees and other pollinating insects exposed to direct treatment or to residues on blooming crops and weeds. Avoid applications to blooming crops, restrict spray timing to hours when bees are less active (very early mornings and evenings), and implement buffer zones and measures to reduce drift. While non-target data is limited, it should be expected that isocycloseram applications will negatively impact insect natural enemies.
As part of the EPA strategy to protect endangered species, newly registered or renewed insecticides may be subject to additional application restrictions. Directions for determining additional restrictions for all isocycloseram products can be found under the “Restrictions and Precautions” section of the approved labels.
Human Toxicity
The EPA completed human health risk assessments as part of the registration of isocycloseram and found “no human health risks of concern when isocycloseram is used according to the registered labels.” This means that under expected uses, dietary exposure (through food residues) and other general human exposure should not pose a health risk when label directions are followed. PPE requirements for mixers, loaders, applicators, and other handlers include: long-sleeved shirt and pants and shoes plus socks. No personal respiratory protective equipment or eye protection is required under normal conditions.
When workers are facing concentrations above the exposure limit, they must use appropriate certified respirators. There is no signal word associated with this product, as those falling into the lowest toxicity category (Category IV) do not require a signal word.
This article is featured in the Vegetable and Fruit News, Vol. 17, Issue 1.