Insecticide Notes

Thrips control: Thrips are difficult to control in almost any situation, but they are particularly difficult to control in crops grown in high tunnels because some of the more effective insecticides for thrips control are not allowed in greenhouses or high tunnels. In outdoor crops, products that provide fairly effective thrips control are Radiant (spinetoram), Assail (acetamiprid), and Movento (spirotetramat), but these three products are not allowed for use in high tunnels. Pyrethroids such as Baythroid (beta-cyfluthrin) and Brigade (bifenthrin) are allowed in high tunnels and can provide some control of thrips, but they are restricted use products that can be applied only by certified applicators. Other options for thrips control that are restricted-use products are Vydate, which can be used on peppers and cucurbits, and Lannate (methomyl), which can be used on peppers, tomatoes, and most cucurbits. Exirel (cyantraniliprole) is allowed for use on peppers and tomatoes grown to maturity in high tunnels, but it provides only suppression, not control, of thrips. Once a thrips population is large and causing damage, then biological control is not a realistic option, but growers who have thrips problems every year should consider a biocontrol program at the start of the new season next year, using Orius bugs or predatory mites obtained from a commercial insectary.

Japanese beetles are starting to show up in abundance in raspberries and sweet corn as well as in peaches, apples, and other crops and in landscape plants. Damage by Japanese beetle is best prevented by insecticide applications directed at the first beetles to invade an area, before they send out messages to other beetles to aggregate. Some of the most effective products have been around for a long time: carbaryl (Sevin and others) and pyrethrins plus PBO (EverGreen Pro and others). If traps are used to remove beetles from an area, they should be set up at a distance away from the crop rather than adjacent to the crop because they can attract many beetles in to the area around the trap.

Colorado potato beetle: There are recent reports from Ohio farms that pyrethroids are no longer providing adequate control of Colorado potato beetles (CPB). Pyrethroids include Warrior, Baythroid, Brigade, Mustang Maxx, Asana, and Pounce. There are several newer insecticides that are effective for control of CPB populations, but most of these are best at killing the larvae rather than the adults of CPB. Products that provide good control of larvae are Agri-Mek (abamectin), Radiant (spinetoram), Coragen (chlorantraniliprole), Rimon (novaluron), and azadirachtin products such as Aza-Direct and Neemix. Among somewhat older insecticides, the neonicotinoids are still effective at most locations; these are listed in the table below. The neonicotinoids are generally more effective by soil application, which provide true systemic control, whereas application by foliar sprays provides translaminar control but not true systemic control throughout the plant. Some of the neonicotinoids are allowed only for soil applications, some for only foliar sprays, and some for either method. If used for soil application, usually at planting time, then later foliar applications are not allowed.

-Celeste Welty, Extension Entomologist

Current Insect Concerns

As the earliest sweet corn plantings are in or approaching the silking stage, be aware that the corn earworm is present at some locations, as detected by pheromone traps that attract the adult moth. Although the number of moths beings caught is low, these small populations can concentrate on the few patches of early sweet corn, and can cause significant damage. Once the large acreage of field corn begins to silk, then the pest population will be spread out over a much larger area and the pest pressure on sweet corn is usually reduced. Trap counts can be found at this website:

Some vegetable growers are concerned about thrips invading their crops if strawberries are nearby because some strawberry farms had severe problems with thrips this year. The thrips that infests strawberries is the eastern flower thrips. This thrips does not show up every year in the midwestern USA but can arrive in large numbers in the spring by being blown in on weather fronts that move from the southern USA. Thrips are known as an occasional pest of tomatoes. They are not known to damage bell peppers or sweet corn or melons, but there are reports of them currently being found in flowers of these crops.

Pests that seem to be currently showing typical activity are squash vine borer, which has been active for the past 3 weeks, and which will be infesting squash, pumpkins, and gourds. Black cutworm moths have been detected at higher than usual density during the past 2 weeks when the weather has been hot, and can be a concern in potato, radish, and other root crops. Populations of the variegated cutworm have also increased greatly in the past week. The adult of true armyworm has been detected at much higher than usual numbers in traps for the past 2 weeks but no reports have been received of it damaging sweet corn or other grassy crops. Japanese beetles are being seen in sweet corn and in various shade trees during the past week.

SWD and BMSB monitoring updates (by Jim Jasinski & Celeste Welty)

The OSU IPM Program and Department of Entomology faculty have been working together to set up an expanded statewide monitoring network for both Brown Marmorated Stink Bug (BMSB) and Spotted Wing Drosophila (SWD), especially in those counties that have not yet positively found and identified these two new pests.

The BMSB network has been up and running at several sites since mid May.  The clear sticky traps (picture below) are baited with two lures and placed along wooded edges of crop fields, a place where the stink bugs are active before invading a field. To date, 25 of the 38 sites have reported catching at least one BMSB at their location, 3 sites have reported zero catch of BMSB, and no reports are yet posted for 10 sites.  The levels of infestation are fairly low at all sites but are likely to increase as the crops develop. We will keep you informed if there are changes. Take a look at the trap counts, by county,  here. Until this past week, only adult BMSB were being found on traps and in crops, but now we are finding young nymphs as well as adults. BMSB have been found in bell peppers, sweet corn, and peaches in Columbus this past week.

The SWD network has been up and running at most sites since the first week of June. Scentry jar traps (picture below) baited with Scentry lures and with diluted apple cider vinegar as the drowning solution are used at all sites, in plantings of raspberry, blackberry, blueberry, peach, and strawberry. Typically two traps are placed per field, one at the edge and one in the interior of the field. To date, 16 sites have reported on their catch, showing that SWD has been detected at 4 sites (Clinton, Franklin, Greene, and Wayne Counties), and zero SWD at 12 sites. An additional 10 sites have not yet reported their results. Although it is still early in the growing season, this is a lower incidence level compared to this time of the season in the past few years.  We’ll continue to update this blog as the SWD population builds. Take a look at the trap totals here.

Phytophthora Blight First 2018 Report in Ohio – Huron County

Phytophthora blight was diagnosed last week in pepper plants from Huron County, Ohio.  This is several weeks earlier than we normally see Phytophthora blight in northern Ohio, but heavy rains and periods of high temperatures likely contributed to an early appearance of the disease.  Growers should scout both peppers and cucurbits for typical symptoms of Phytophthora blight  Phytophthora is a water mold that thrives under conditions of high moisture and high temperature. It produces motile spores (zoospores) that are attracted to plants, then form a structure that allows them to infect, and aggressively attack any type of plant tissue. Zoospores can be splashed onto leaves, stems and fruits during rain events and overhead irrigation. Phytophthora blight is often seen first in low spots or other poorly drained areas of production fields, but the disease also occurs on well-drained, even sandy soils if the environmental conditions are right.  An integrated, preventative program to manage Phytophthora blight is more effective than in-season rescue treatments with fungicides.  During the growing season, fungicide application is the main option for management of Phytophthora blight (see below). In small plantings prompt removal of diseased plants is also recommended.

Effective management of Phytophthora blight in peppers requires an integrated approach:

Crop rotation.  Phytophthora produces structures called oospores that can survive for a number of years in the soil.  Plan to rotate out of peppers, cucurbits or green beans for 4-5 years if Phytophthora blight has been a problem.

Resistant varieties.  A few pepper varieties are resistant to the root rot phase of the disease.  In general, these varieties are susceptible to the crown rot phase, which affects foliage and fruits. Varieties with moderate to good resistance to Phytophthora blight are: Paladin, Aristotle, Declaration, Intruder, Vanguard (bell); Hechicero (jalapeño); and Sequioa (ancho).

Well-drained soil. Avoiding standing water is critical to limiting the movement of Phytophthora from plant to plant.

Avoid surface water for irrigation. We have found Phytophthora in irrigation ditches and ponds as early as late June in vegetable production-intensive areas in Ohio.  Using surface water for irrigation is risky, especially if Phytophthora is present in fields near surface water sources.

Plant on raised beds. Prepared properly, raised beds will help prevent standing water near pepper plants.  If possible beds should be domed, and there should be no depressions in the soil surrounding the plants.

Sanitation.  Phytophthora can be moved from an infested field to a clean one on soil clinging to boots, equipment, etc.  Power washing to remove soil is a good first step, followed by rinsing with a sanitizer.  Do not build cull piles containing discarded peppers or cucurbits – plant material needs to be disposed of, preferably by burying, far from fields and surface waters.

Fungicides.  There are a number of fungicides labeled for use on peppers to manage Phytophthora blight  (see table below).  The newest product, Orondis, has very good efficacy against this disease. It is available as a pre-mix with either Revus (Orondis Ultra), Ridomil (Orondis Gold) or Bravo (Orondis Opti). There are many restrictions on the use of Orondis – including the number of applications (no more than 1/3 of total applications for Phytophthora blight) and when it can be applied (to the soil or to the foliage but not both).  Orondis Ultra and Orondis Gold can be applied in transplant water or through the drip, although Orondis does not move much in soil and emitters need to be right next to the plant.  If the pepper variety is susceptible to Phytophthora blight, it may be a good idea to apply Orondis Gold or Orondis Ultra at planting, and follow up later with a program containing at least two of the fungicides with activity against Phytophthora (see table). If the pepper variety is resistant to Phytophthora, any of the three Orondis products can be used in a foliar fungicide program that includes other effective fungicides. The Bravo component of Orondis Opti will not help with Phytophthora blight, but will control anthracnose.  Orondis Gold is considerably more expensive than Orondis Ultra and Orondis Opti, and resistance in Phytophthora to the Ridomil component of Orondis Gold has been found in numerous locations.

For in-season control where an at-plant application of one of the Orondis products has not been made, foliar applications can be very effective if undertaken preventatively. Results of our research in 2016/2017 on squash indicated that Orondis Ultra could be alternated with Presidio, Ranman or Tanos + Kocide with equivalent results (see chart Squash Phytoph Orondis foliar 1 slide-2eauh2g). 

Spray Drift 102

A few weeks ago, in Drift 101, I suggested that farmers should be cautious before concluding that sick crops are a result of herbicide drift from neighboring fields. Symptoms attributed to drift may be caused by other factors. Nutrient deficiencies may cause chlorosis (yellowing) and necrosis (tissue death), symptoms easily misinterpreted as resulting from herbicide exposure (

The herbicides 2,4-D and dicamba invariably cause distorted growth of foliage (Figure 1), but so can various environmental pollutants especially when those are concentrated in the greenhouse (Figure 2).

Figure 1: Typical response of tomato foliage to low-dose (simulated drift) of 2,4-D.

Figure 2: Distorted growth of greenhouse tomato thought caused by fumes from incomplete combustion from wood heater. Photo courtesy of M. Badertscher (OSUE Hardin Co).

Likewise flood conditions, during which root systems are completed saturated with water for prolonged periods, are known to induce leaf twisting and formation of adventitious roots (Figure 3), symptoms associated with exposure to 2,4-D (Figures 1 & 4).

Figure 3: Adventitious root formation on stem of tomato following 3 days of flooding conditions (root zone saturation).

Figure 4: Adventitious root formation on stem of tomato following exposure to low-dose 2,4-D.

Even when herbicides are the cause, symptoms can occasionally be misleading and point incorrectly to a nearby field. Consider the case of glyphosate, still the most commonly used herbicide in the Midwest. Glyphosate is quickly absorbed by crop leaves and translocated to growing points. On most crops glyphosate damage becomes obvious 4 or more days after drift because new growth is chlorotic. On tomato, chlorosis most often appears as bands across the base of the leaflets (Figure 5). However in a small number of drift events, chlorosis may not appear at all; instead glyphosate induces leaf and petiole curling and twisting, symptoms reminiscent of 2,4-D or other synthetic-auxin herbicides.

Figure 5: Characteristic basal-chlorosis of new tomato leaflets caused by glyphosate drift.

Figure 6: Occasional ‘auxin-mimic’ symptoms that occur in a small percentage of glyphosate drift events.

Soil residues of environmentally persistent herbicides used in previous growing seasons must also be taken into account. Trace amounts of herbicides in the ALS and AHAS families can cause symptoms similar to those caused by 2,4-D and dicamba. Imazethapyr (Pursuit) is an AHAS herbicide used on soybean that controls weeds at low doses of 3-6 oz/Acre. In our lab, tomato flowering was sensitive to doses of the herbicide equivalent to 1/1000th of the field dose. This finding indicates that soil residues of imazethapyr applied two or more years before planting may still be sufficient to injure field grown tomato, as may drift of the herbicide from a nearby or not-so-nearby application.

Many more similar examples could be provided; hopefully, the take home message is that diagnosing crop injury symptoms is a complicated matter that must take several factors into consideration and can easily lead to mistakes being made. Tread cautiously.

IPM – Insect Pest Scouting and Management – Late May to Early June 2018 – Central Ohio

These insects, some pests, some beneficial, were noted from scouting efforts in central Ohio from mid-May to early June 2018.

Imported Cabbageworm

One of the most common predators of the brassicacea family of vegetables is the larval form of the cabbage white butterfly, called the imported cabbageworm.  The butterfly is a constant presence in Ohio as our most common butterfly species.  It lays eggs on cabbage family plants and the larval forms feed on the foliage.  They can be difficult to spot due to coloration but feeding damage and frass (fecal material) can be observed via scouting.

The focus is on the cabbageworm fecal material, called frass, at the base of the leaf in the bottom of the picture. The cabbageworm can be difficult to locate due to camouflage but the frass and pattern of leaf damage indicates to keep looking to locate the predator.


The butterfly lays very tiny eggs a single egg at a time on the leaves using her ovi-positor.


Egg size with penny added to picture for reference.

Control is by scouting for eggs, which can be difficult, or for by early recognition of larvae and damage.  Hand removal is very effective for small plantings.   Organic control (check the label carefully) is possible with spinosad products.

Virginia Fact Sheet on Spinosad

Imported Cabbageworm Fact Sheet


Cucumber Beetles

Cucumber beetles are a major pest in vegetable plantings. The adults have emerged from their over wintered areas to start feeding on plants and laying eggs in the soil at the base of cucurbit family plants.


Feeding damage to the cotyledons and early true leaves of the cucurbit family from over-wintered cucumber beetle adults prior to egg laying.

Cucumber beetles are a serious pest of cucurbit family plants due to feeding on foliage, flowers and fruit.   Control can be difficult.  They also vector a devastating bacterial wilt disease that can quickly kill plants and has no treatment.

Cucumber Beetle Fact Sheet


Egg Scouting

A good habit to use when scouting for insect pests on plantings is to look at the underside of the leaves for eggs.  Many of the insect pests lay eggs singly or in clusters on the underside of leaves, where if undetected, will hatch into larvae that will feed on the foliage.  This egg cluster was noted on oregano.  I suspect these eggs to be from Box Elder bugs, which do not normally feed on oregano.  Both a Box Elder and related Sugar Maple are in the vicinity of the oregano planting.



Slugs will be more numerous in production areas that have high organic matter content. They can feed and damage foliage. Early control is critical to avoid build up and infestation of a production area during a growing season.

Control of slugs can be achieved with organic products containing iron phosphate.  Slug Factsheet from PSU



This is the larval form of a night moth.  It curls up around the stem of a plant and feeds until the stem is cut in half and the plant has been killed.  They feed at night commonly so a grower would notice a dead plant that looks cut in half.  Digging around the base of the plant can sometimes find the causative agent.

Dusky Cutworm. Found when digging around base of dead cucurbit plant.

Cutworm Fact Sheet


Ground Beetle – Beneficial

Not all insects are pests,  some are beneficial and are feeding on pest and assisting the grower.  Proper identification will allow the backyard grower, community gardener and urban farmer to know what to keep and what to treat.

Ground Beetle Fact Sheet Ohioline


If you have questions or concerns about an insect pest located via scouting, contact your Extension office for assistance with identification.