Eastern Ohio Vegetable Field Walk

Barnesville, OH

OSU Agricultural Extension Educators and vegetable producers in eastern Ohio welcomed Ohio State University Extension specialist July 25th for a vegetable production field day originating at Captina Produce Auction south of Barnesville. The Captina Auction began in 2005 and has increased production and sales each year since its beginning. A new 60’ addition was added this past winter to provide needed floor space to accommodate increased production. Approximately 100 acres of local vegetable produce is grown and marketed through the auction each year, predominantly by Amish growers.

The produce auction is named Captina Produce Auction due to its proximity to Captina Creek, a very high quality watershed and important water source in the community.  The local Amish growers have a very good reputation in their farming practices as well as the quality of produce they provide to homeowners, roadside stands, wholesalers and local grocers. 

Captina Produce Auction

Celeste Welty, entomologist, Sally Miller, plant pathologist, Matt Kleinhenz, vegetable crop physiology and management specialist, Doug Doohan, weed control specialist, and Jim Jasinski, integrated pest management coordinator came to provide a wealth of information to vegetable producers in the area.  The team provided diagnostic information for various insects, diseases and weeds encountered during the day along with many other recommendations for common vegetable production problems.

Dr. Doug Doohan addressed a question about using pesticides in vegetable production and effects on the environment. He was adamant that safety is always the first concern, but very positive and confident that safety measures are taken into consideration, with extensive testing, before products are marketed. Therefore, when growers use products at labeled rates, and as directed on the label, environmental impacts are negligible. Doug also provided valuable information for producers to help them control and reduce weeds. Timely applications of glyphosate in the fall can really be helpful to decrease hard to kill weeds such as Canada thistle he said. Eradicating weeds before plants are allowed to set seed is a practice all producers should strive for. One plant can produce thousands of seeds in a growing season if left unchecked.

Downy mildew, a potentially devastating cucurbit disease, was identified and eventually confirmed on cucumbers leaves as a result of the field walk.  This diagnosis, led into a discussion about downy mildew and Dr. Sally Miller made the point that the disease does not overwinter in Ohio. It blows in on wind currents from the south where it can overwinter and from Canada, where it is thought to overwinter in greenhouses. Downy eventually makes its way to Ohio during the growing season so growers were encouraged to keep close watch to detect the disease. It was brought up by the specialists, downy mildew might not be as devastating to an early cucumber crop in mid-July, but later crops are at much greater risk from this late season disease.

Observing pumpkins during the field day

Next to the cucumbers with downy mildew there was a very clean pumpkin patch that had not been sprayed with a fungicide. Dr. Miller discussed the different strains of downy mildew on cucumbers verses pumpkins.  Even though they are both in the cucurbit family, the variant of the downy mildew that infects each one is different.  This brought up a point of preventative fungicide sprays.  Once a field is severely contaminated, it usually is too late for fungicides.  A preventative spray program was recommended to keep the pumpkin field healthy and utilize various modes of action to prevent resistance.


Vegetable production discussion

Dr. Matt Kleinhenz provided information to the group about extending the growing season using hi-tunnels and discussed production and use of grafted vegetable plants. There is a growing market out there for this technology he said. Matt discussed how superior yields and increased disease resistance can be provided when the correct root stock is used. Heirloom tomato varieties, for example, really benefit when they are grafted to a root stock that has resistance to many problems growers deal with.


Dr. Celeste Welty discussed many insects with producers during the day. She provided specimen displays of beneficial insects and unwanted pests so each person could learn to identify ones they did not know. She said, many insects in vegetable crops are beneficial

Celeste Welty discussing traps

insects and growers need to know the difference. Integrated pest management starts with correct identification of the insect. At one-point a question was asked about cucumber beetles. Celeste discussed the different beetles and explained the process of how damage to cucurbit crops takes place. Early monitoring and control measures for this pest were stressed.  At the edge of a sweet corn field a Scentry Helothis trap was viewed by participants and Dr. Welty explained procedures for using this trap. This type trap is not to reduce pest numbers like many traps we use, but this is used to capture male moths and monitor flight numbers by using a pheromone to attract them into the trap. Threshold numbers were discussed and she explained how producers can use this information to make the most-timely applications of sprays to reduce corn earworm and European corn borer damage.  (Instructions can be found at)  http://u.osu.edu/pestmanagement/files/2014/12/CornTrapInstructions2009-u47rp3.pdf

The field walk provided growers a wealth of knowledge and the specialists were thanked for their participation and willingness to share information with growers in eastern Ohio.

Mexican bean beetle on snap beans

Snap beans are being defoliated by the Mexican bean beetle on some farms in southwestern Ohio. The adult is a round lady beetle that is dull orange with brown spots. The larva is soft-bodied, bright yellow, covered by dark branched spines. Both adult and larvae feed on leaves between leaf veins, resulting in a skeletonized pattern of damage. According to information from the University of Florida, snap beans can tolerate up to 20% defoliation before pod set and 10% after pod set; economic thresholds have been estimated as 1 to 1.5 larvae per plant. Recent tests in Virginia showed that the most effective conventional insecticides for control of Mexican bean beetle are Assail (acetamiprid), Hero (zeta-cypermethrin + bifenthrin), Sivanto (flupyradifurone), and Closer (sulfoxaflor); among choices for organic production, spinosad (Entrust) was slightly better than Azera (azadirachtin + pyrethrins), Grandevo (Chromobacterium subtsugae strain PRAA4-1), or Pyganic (pyrethrins), but these were just slightly better than untreated plants.

Western bean cutworm in sweet corn

Last week, we posted an article about western bean cutworm as a new caterpillar pest of sweet corn. The latest reports in our pest trapping network show a record high catch of 85 moths of western bean cutworm moths for the week of 16-22 July in a pheromone trap at Fremont in north central Ohio. The catch in this trap fell to only 2 moths in the following week, 23-29 July. At sites where this many moths are trapped, it is important to scout plantings in the emerging-tassel stage; look for egg masses and young larvae on the flag leaf. Insecticide treatment should be considered if eggs are found; our tentative threshold for western bean cutworm is 1% of plants infested for fresh market corn, or 4% of plants infested for processing sweet corn. Pictures and additional details on western bean cutworm can be found in our OSU fact sheet: http://ohioline.osu.edu/factsheet/ENT-40 .

Silk-clipping beetles in sweet corn

In late July and early August in Ohio, many sweet corn fields are not being threatened by either of the two key pests, the corn earworm and the European corn borer, thus it might seem as if there is no need for insecticide sprays. However, growers should be checking on the presence of silk-clipping beetles: primarily the western corn rootworm beetle and the Japanese beetle, and also the southern corn rootworm beetle and the northern corn rootworm beetle. The critical time to scout for these beetles is during the early silk stage, as pollen is being shed. Examine 50 ears in small plantings (< 2 acres) or 100 ears in large plantings (> 2 acres). Treatment by spraying insecticide to prevent silk clipping by beetles is needed during the early-silk stage if the average number of beetles is 2 or more Japanese beetles per ear or 5 or more corn rootworm beetles per ear.

Cucurbit Powdery Mildew: A Little Late this Year but Start Scouting Now

We are just now finding powdery mildew on squash and pumpkins, several weeks later in the season than we have seen it during the past few years. Sofar disease incidence and severity have been relatively low in commercial fields, as well as in OSU research plots.  The fungus that causes cucurbit powdery mildew does not overwinter in Ohio, so the disease does not appear until spores arrive on wind currents from warmer growing areas.  This fungus is an unusual plant pathogen in that it is inhibited by free water – so the frequent rains we have been experiencing may have kept this disease at bay for the time being. However, it is here now and will undoubtedly flare up in susceptible cucurbits unless they are treated with fungicides. Signs of infection are small circular powdery growths (mycelium and spores of the pathogen) on either side of the leaf. These spots enlarge and can eventually cover most of the leaf surface and kill the leaves.  Stems and leaf petioles are also susceptible, but the disease is not observed on fruit.  In pumpkins, powdery mildew may also attack the “handles”, which can be further damaged by secondary pathogens.

Click on table to enlarge.

Powdery mildew is managed using powdery mildew-resistant varieties and fungicides.  Development of insensitivity to overused fungicides is common in populations of the fungus that causes this disease, so it is important that a fungicide resistance management program is followed. Remember to alternate fungicides in different FRAC (Fungicide Resistance Action Committee) groups, indicating different modes of action against the fungus. It is important to apply fungicides when the disease first appears and incidence is low. Fungicides that are effective against cucurbit powdery mildew can be found in the Midwest Vegetable Production Guide for Commercial Growers; product ratings are on page 117.  Our evaluations of efficacy of powdery mildew fungicides at three locations (Wooster, Columbus, South Charleston) in Ohio in 2016 indicated that five products consistently provided very good control (> 93%) of powdery mildew  on pumpkins in all three locations (see table).  Three products were very good in Wooster and Columbus but fair in South Charleston; control by Fontelis was 73% in South Charleston, while the others provided less than 55% control at that location.  Both Bravo and Pristine performed poorly in all three locations.

Cucumber Downy Mildew Confirmed in Southeastern Ohio – Belmont County

We confirmed downy mildew in cucumbers collected yesterday from a small commercial field in Belmont County, near Barnesville.  Disease incidence and severity were high in this field, which had not been treated with any fungicides. The outbreak followed several days of intense rainfall in the previous week.

Map of cucurbit downy mildew outbreaks – CDM ipmPIPE, July 26, 2017.

This is the first report of cucumber downy mildew in central or southern Ohio, and was found during a field walk sponsored by OSU Extension and the Captina Produce Auction.  Ohio growers should assume that cucumber/melon downy mildew is more widespread than we have been able to report, and should protect these crops with appropriate fungicides as listed in my post on July 28.  We have not seen downy mildew on squash, pumpkins or watermelon in Ohio to date, and the downy mildew pathogen population currently affecting cucumbers and melons in Ohio is not likely attack pumpkins or squash.  A pumpkin field near the cucumber planting that was highly diseased was not affected, and we have not found downy mildew in our sentinel plots, despite the presence of infected cucumbers for several weeks.  However, downy mildew populations that can damage pumpkins and squash are likely to move in from the southeastern U.S. later in the season.

We depend on county educators, growers and consultants to let us know when cucurbit downy mildew is suspected, particularly in counties where it has not been reported.  Our lab will diagnose samples at no cost to Ohio growers, so we appreciate receiving samples that, if downy mildew is confirmed, will enable us to alert the cucurbit growing community.

Can Microbial Inoculants (Biostimulants) Enhance Vegetable Yield and/or Quality?

Currently, growers can choose from among nearly two-hundred microbe-containing crop biostimulants advertised to enhance yield and/or limit crop stress. That’s difficult. The production and sale of these products are largely unregulated (unlike biopesticides used in biocontrol). Also, research-based and grower-focused information on biostimulants is limited. People look for input and resources to help them select, use, and evaluate the efficacy of microbe-containing crop biostimulants when applied to field- or high-tunnel grown crops. Contact Matt Kleinhenz and watch for newsletter and other updates regarding various grower-university-product manufacturer efforts to provide that assistance.

Beware of western bean cutworm on sweet corn

The western bean cutworm has slowly but steadily been advancing into Ohio from the western USA over the past 10 years. It is still at low density at most sites in northwestern and northeastern Ohio, and not yet detected at some southern Ohio sites, but growers should be aware of its possible presence in sweet corn fields. This caterpillar feeds on kernels of ears in both sweet corn and field corn. Feeding damage is usually at the tip end but can be in the middle or butt end of the ear. The western bean cutworm can be found as several larvae per ear, because it is not cannibalistic; this makes it different than the corn earworm, which also feeds on kernels at the tip of the ear, but which typically is found as a single larva per ear because it cannibalizes other corn earworm larvae.

The newer BT sweet corn hybrids in the Attribute II series (from Syngenta) provide genetic control of the western bean cutworm, but BT sweet corn hybrids in the Performance series (from Seminis) and the older Attribute series (from Syngenta) do not control this pest.

Monitoring of western bean cutworm is a two-part process. First, the adult moths can be monitored with a pheromone trap using a commercially available lure that lasts for 4 weeks. A bucket type of universal moth trap can be used, or a trap can be made from a one-gallon plastic milk jug with part of the sides removed, with an inch of dilute antifreeze solution in the bottom as a drowning and preserving agent. This pest has one generation per year, with adults usually first detected in late June, peak activity in late July, and moth activity ending by late August. Trap reports on western bean cutworm from several Ohio locations can be found using this link: https://docs.google.com/spreadsheets/d/10gh3rHahdxLKkXQapGyEPxWsjHYRmgsezOoFHnwtyEo/edit#gid=441280294

On any farm where the western bean cutworm moth is detected in traps, scouting should be done to monitor eggs and hatching larvae. Scouting should concentrate on plantings in the emerging-tassel stage. Look at 20 consecutive plants in each of 5 random locations per field. Examine the flag leaf, where eggs are usually laid. Eggs are laid in masses. Eggs are white when fresh, then they darken to purple when ready to hatch. Hatch will occur within 24-48 hours once eggs turn purple. Our tentative threshold for sweet corn is to consider treatment if eggs or larvae are found on more than 1% of plants for fresh-market or on more than 4% of plants for the processing market. Insecticide applications must occur after egg hatch, or after tassel emergence, but before larvae enter the ear.

Pictures and additional details on western bean cutworm can be found in our OSU fact sheet:



2017 Pumpkin Field Day

The season is marching on and the annual Pumpkin Field day has been set for August 17th from 6-8PM at the Western Ag Research Station in South Charleston.

This year’s field day will offer beginning and experienced growers valuable research updates regarding disease management, insect management, weed control, and new pumpkin and winter squash varieties.  We will have Celeste Welty (entomology), Claudio Vrisman (plant pathology), Bryan Reeb (weed control), and Jim Jasinski (IPM Program and emcee) on hand to share their knowledge and answer your questions.

The field day will feature some traditional and new projects on the wagon tour, including a seven-treatment powdery mildew fungicide demonstration trial, a powdery mildew drip irrigation trial, a pumpkin variety trial with 20 hybrids ranging from small to large fruit, and a winter squash variety trial with 11 entries. There will also be presentations on how to identify and control weeds, insects, and diseases on this crop. After the formal presentations, attendees will be encouraged to walk around the plots and interact with the specialists and other growers.

There is a fee of $5 per person; refreshments and handouts will be provided.

Pre-registration is requested by August 15th at www.surveymonkey.com/r/pumpkin17.

Here is the rough agenda for the field day:
5:30 Begin check in
6:00 Welcome, introductions, outline of field day
6:05 Board wagons and head to the plots
6:10 Orientation to plots, begin presentations
7:10 End formal presentations, begin plot walks
7:55 Board wagons, complete evaluations
8:00 Field day ends, travel safe!

See the preliminary flyer below for a few more details. Looking forward to seeing you there. Contact Jim Jasinski (jasinski.4@osu.edu) or 937-462-8016 for more information.

Pumpkin field day flyer – draft.

Downy Mildew Confirmed on Melons in Wayne County and Cucumbers in Henry County, OH

Downy mildew on cantaloupe.

Downy mildew continues to spread on cucumbers in Ohio, with a confirmed report in Henry County this week.  The disease is likely to be widespread on cucumbers in northern Ohio, particularly after last week’s rainy, humid weather.  As usually happens within a few weeks of cucumber downy mildew outbreaks, we are now finding downy mildew on cantaloupe.  Chris Smedley and the Wayne County IPM Scouting team found widespread and fairly severe downy mildew in commercial melons in the northwestern part of Wayne County, where we first reported downy mildew on cucumbers on June 28.  As noted in previous posts, it is imperative that growers protect melons as well as cucumbers with downy mildew-effective fungicides such as Orondis Opti and Ranman if they are in an area where downy mildew risk is high, such as northern Ohio.  See my June 28 post for a list of recommended fungicides. Remember to follow label instructions and alternate products with different modes of action.