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:

http://ohioline.osu.edu/factsheet/ENT-40

 

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.

Cucumber Downy Mildew in Wood County, Ohio

We have just reported to the Cucurbit Downy Mildew ipmPIPE the first case of downy mildew on cucumbers in Wood County. While the sample was just received today, the grower estimated that symptoms were first present July 7, about a week after the first report of downy mildew on cucumbers upwind in southeastern Michigan. The multiple rainstorms last week likely delivered the downy mildew pathogen from long distances and also moved it about locally, while the overcast, humid conditions favored pathogen survival and infection. Although predicted weather patterns for this week in northern Ohio are not as favorable for downy mildew as last week, growers should assume the pathogen is present and take  or continue measures to protect cucumbers and melons from downy mildew.  We have not yet found or had reports of downy mildew in central or southern Ohio on any crops, and no reports of the disease on squash, pumpkins, cantaloupe or watermelon in northern Ohio. That being said, cantaloupe is second to cucumber in susceptibility to downy mildew, and should be protected by fungicides in this area.  See my posts on June 28 and July 8 for more information on cucurbit downy mildew management.

Single lesion of downy mildew on cucumber leaf from Wooster sentinel plot.

We also found downy mildew at a very early stage of development in our sentinel plot in Wooster today (see photo).  There were only a few lesions present and it took a keen eye to spot them.  When scouting for downy mildew in cucumbers, look for this type of early lesion.  If the diseases progresses significantly it will be difficult to avoid yield losses despite fungicide applications.

If you suspect downy mildew in any cucurbit or basil, please send us a sample for confirmation.  It is best if the sample is wrapped lightly in a damp paper towel and shipped in a box by overnight mail or courier to: Sally Miller, OSU-OARDC, Dept. Plant Pathology, 1680 Madison Ave, Wooster, OH 44691; 330-466-5249.

ODA Sets Pesticide Collection Sites

REYNOLDSBURG, Ohio (Jul. 13, 2017) – The Ohio Department of Agriculture will be sponsoring a collection for farmers wishing to dispose of unwanted pesticides for the following locations:

Delaware County – Aug. 10 from 9:00 a.m. to 3:00 p.m. at the Delaware County Fairgrounds (entrance off U.S. 23), 236 Pennsylvania Ave., Delaware, OH 43015.

Putnam County – Aug. 15 from 9:00 a.m. to 3:00 p.m. at the OSU Extension Putnam County Office (gated parking lot on east side of the building), 1206 East 2nd Street, Ottawa, OH 45857.

Athens County – Aug. 22 from 9:00 a.m. to 3:00 p.m. at the Albany Independent Fairgrounds, 5201 Washington Road, Albany, OH 45710.

The pesticide collection and disposal service is free of charge, but only farm chemicals will be accepted. Paint, antifreeze, solvents, and household or non-farm pesticides will not be accepted.

Pesticide collections are sponsored by the department in conjunction with the U.S. Environmental Protection Agency. To pre-register, or for more information, contact the Ohio Department of Agriculture at 614-728-6987.

Dayton Urban Farm Tour – July 20

The Ohio sustainable farm tour will have one stop in Dayton at The Urban Renewal Farm (TURF), located at 216 S. Torrence street, on July 20th from 10 am to noon. Participants will learn about a unique project to repurpose an abandoned factory into an urban farm. See how the farm grows tomatoes, peppers, kale, onions, lettuce, carrots, and turnips in raised beds in the parking lot and learn about plans and challenges of converting the factory to a year round growing facility. For more information, contact Jim Wellman at (937) 516-1819 or jwellman1@hotmail.com.

More information about the raised bed farm located in the parking lot of an abandoned factory can be found at www.facebook.com/daytonyurbanrenewalfarm. Although not required, registration is encouraged at www.surveymonkey.com/r/TURF17.

The Urban Renewal Farm.

Prevent Anthracnose in Peppers and Tomatoes

Hot rainy weather and fields with a history of anthracnose mean high risk for for this disease in peppers and tomatoes.  Anthracnose, caused by species of the plant pathogenic fungus Colletotrichum,  causes no obvious leaf lesions on tomato foliage and only occasionally on pepper foliage under high disease pressure.  However, pepper and tomato fruits are very susceptible to the disease.  The fungus can be introduced on seeds, and survives over the winter in temperate climates associated with crop debris.  Fruits are infected when green; pepper fruits develop large lesions with salmon-colored spores when green or ripe, but tomato fruits do not develop the typical sunken lesions until they begin to ripen.  Spores of the fungus are moved about by splashing rain, so rainstorms can promote disease spread throughout a field.  Mechanically harvested processing tomatoes are particularly prone to anthracnose problems since fruits ripen at different rates but are harvested all at once.  Management practices include thorough scouting, sanitation/removal of diseased fruits, and fungicide applications.  There are some differences in susceptibility of pepper and tomato varieties to anthracnose, but none are highly resistant.

It is time now to start protecting plants from anthracnose – fungicides must be applied as soon as fruits begin to set, and continued on a weekly schedule as fruits develop.  Fungicides  labeled for use against anthracnose in fruiting vegetables (eggplant, pepper, tomato) are listed in the Midwest Vegetable Production Guide for Commercial Growers.  Several studies have shown the best results with Aprovia Top, Quadris, Quadris Top, Cabrio or Priaxor alternated with chlorothalanil or mancozeb.  Some labels may recommend a spreader-sticker; be sure to read and follow label instructions.

Phytophthora Blight Already a Problem in Cucurbits

Cucumber seedling with Phytophthora blight lesions on the cotyledons; pictured on the left is a positive immunostrip test for Phytophthora.

Cucumber seedling with Phytophthora blight lesions on the cotyledons; pictured on the left is a positive immunostrip test for Phytophthora.Ohio cucurbit growers have been battling Phytophthora blight in squash for at least the past 2 weeks, and yesterday we diagnosed an unusual outbreak in cucumber seedlings. Phytophthora can attack any part of cucurbit plants, but we don’t usually see seedling disease in cucumbers in Ohio.  This may be due in part to an “escape” scenario, since many cucumber crops are planted early before Phytophthora blight pressure builds. In addition, cucumber plants usually hold up well to Phytophthora blight, although fruits are highly susceptible. It looks like this may be another season of high Phytophthora blight pressure.

Management of Phytophthora blight in cucumbers and other cucurbits is complicated by the fact that downy mildew may also be a problem.  Currently we are only seeing downy mildew on cucumbers in northern Ohio, although we expect to find it in melons soon – see my posts on June 28 and July 8. Phytophthora blight is different from downy mildew in a number of ways, and similar in others. One big difference is that Phytophthora movement through the air is limited, unlike downy mildew. Another is that the pathogen survives over the winter in Ohio. Third, Phytophthora has to be introduced into a field, usually by contaminated water or movement of soil. Phytophthora tends to thrive in hot weather and downy mildew in cooler weather, but there is considerable overlap. Phytophthora and the downy mildew pathogen are related; some of the fungicides that are effective against downy mildew are effective to a degree against Phytophthora.  All cucurbits are susceptible to Phytophthora blight, as are peppers and some other vegetable crops. No varieties of cucurbits are resistant to Phytophthora blight, so cultural practices (raised beds, good drainage, clean irrigation water; no cull piles) and fungicides are needed to manage this disease. The pathogen is a “water mold” and moves around readily in wet, and especially flooded fields. The sporangia that contain the zoospores that swim to and infect plants can also be splashed onto stems, leaves and fruit.

Keeping ahead of both diseases is important, but any efforts to manage them can be undone by long periods of wet weather, when it is particularly important to keep a tight schedule of fungicide applications. The Midwest Vegetable Production Guide for Commercial Growers lists the products labeled for these diseases on cucurbits – see page 117 in the 2017 Guide for a chart on relative efficacy of fungicides against different diseases of cucurbits. Dr Mary Hausbeck, Michigan State University, recommends applying fungicides when pickles are 1”, 3” and 5” long to suppress Phytophthora blight. Fungicides with 0-days pre-harvest interval (PHI) – Orondis Ultra, Ranman, Zampro and Zing! – will be useful when fruits are close to harvest. Make sure to note re-entry intervals. While copper in itself is not very effective against Phytophthora blight, tank mixing with a copper fungicide (e.g. Kocide 3000 – also 0 days PHI) improves activity against Phytophthora. Dr. Mohammad Babadoost’s research at the University of Illinois indicates that Revus tank mixed with a copper fungicide and alternated with Ranman + copper, Tanos + copper, or Zampro + copper (7-day intervals) is effective in suppressing Phytophthora blight.

Be sure to read and follow label directions for application of fungicides and other pesticides.  Alternating fungicides with different modes of action is critical to reduce the risk of resistance development in pathogen populations.

Click on table to enlarge.

Cucumber Downy Mildew in Another Northern Ohio County

On July 5, downy mildew was found on cucumbers in Huron County, one week after the first 2017 Ohio report (Wayne County) of the disease. In this case, disease symptoms had just become visible in a low spot in the field, but the sporulation was very strong, indicating a good potential for the pathogen to spread. The disease was also confirmed in Ontario on June 27 and in Michigan on June 29. Given the favorable weather conditions of the last week, with high humidity, overcast skies and rainstorms moving through the state, growers in the northern third of Ohio should assume that the risk of downy mildew in cucumbers and melons is

Downy mildew pathogen sporulation on underside of a cucumber leaf.

very high. See the Cucurbit Downy Mildew ipmPIPE website for a detailed forecast; you can also find the map of outbreaks on this site. As indicated in my post on June 28, growers need to scout fields carefully, especially in low or shady spots that may hold moisture longer than other parts of the field. The only way to manage this disease at this point is through application of effective fungicides – and recommendations are provided in the June 28 post.

There were reports of downy mildew on cucumbers in Erie County in western NY and Columbia County in central PA, but so far there have been no reports of downy mildew on pumpkins or squash in the US Midwest or Northeast.

Reminder: I report outbreaks of cucurbit downy mildew and other veggie diseases as soon as we know about/confirm them on Twitter: @OhioVeggieDoc.