2018 Central Ohio Fall Weather Predictions and El Nino Update

The most recent edition of OSU Agronomy’s C.O.R.N. newsletter published by my Extension colleagues gave the September and October weather predictions that will impact harvest of agronomic crops.  The backyard grower, community gardener, and urban farmer can use this data to make plans for season extended plantings by applying frost dates and predicted temperatures and rainfall amounts into the planting schedule.

September/October Temperature and Precipitation Forecasts

(credit Jim Noel, C.O.R.N Newsletter, 2018-28)

  • September
    • Temperatures will be a little warmer than normal, with normal predicted rainfall
  • October
    • Temperatures and rainfall are both predicted a little above normal
    • Frost and freeze dates are predicted to be in the normal range



What does this mean for plantings? 

  • Make sure to keep row cover or other season extension fabric on hand and monitor overnight temperatures carefully as we reach the October 10th – 20th time period to allow maturity and harvest of late summer plantings of green beans or zucchini.
  • General above average temperatures should allow for harvest into fall of late summer plantings if protected as needed.
  • Watch for frost or freeze events to plan harvest of sweet potatoes prior to overnight cold temperatures which may damage tubers and decrease storage life.
  • Timing of over wintered spinach plantings should target early to mid-October for completion.


El Nino Update (8/9/18)

El Nino winters in central Ohio average warmer than normal temperatures with less than normal snowfall.  Currently the National Weather Service has an El Nino Watch in place.

  • Fall – 60% chance of El Nino formation in September – November
  • Winter – 70% chance of El Nino formation in winter.

Source: National Weather Service Climate Prediction Center

Pumpkin Field Day (Aug. 23rd) – Last Call

No matter if you have been growing pumpkins for over a decade or new to the crop, there will be something interesting to ponder at the Pumpkin Field Day on Aug. 23rdfrom 6-8 pm at the Western Ag Research Station in South Charleston. The station is located at 7721 South Charleston Pike, South Charleston, 45368.

New this year will be a presentation and demonstration of cover crops used in conjunction with pumpkin production by Extension educator Alan Sundermeier.  When it comes to weed biology and control, Brian Reeb from Horticulture and Crop Science will be on hand to help growers minimize weed issues.

In the later half of the growing season, plant and fruit diseases figure prominently into crop management. Dr. Claudio Vrisman of Plant Pathology will be at the field day to discuss and diagnose common diseases of pumpkins, such as powdery mildew, downy mildew, plectosporium and others.

To round out the field day, IPM Program coordinator Jim Jasinski will talk briefly about two powdery mildew fungicide trials at the station, and then allow growers to walk through the trials to evaluate disease control. Growers will also be afforded an opportunity to walk through the 27 pumpkin and squash hybrid trial where current and new hybrids can be seen and evaluated for size and color first hand.

Wagons will take attendees out to the field where the trialsare being conducted, and light refreshments will be provided.

Registration for the field day is required by Aug. 20thplease visit this site surveymonkey.com/r/pumpkinreg18 and let us know you plan to be there. If you can’t register online, call 937-462-8016 and leave a message.

There is a $5 fee for attending which will be collected prior to the event at the research station. We welcome you on site to check in at 5:30pm and then officially start the field day promptly at 6pm. Looking forward to seeing you there!  For more information, contact Jim Jasinski, jasinski.4@osu.edu.

Cucumber Downy Mildew in Medina County, OH

Tape mount from the underside of a cucumber leaf with downy mildew. Characteristic branched sporangiophores (center) and oval, brown sporangia. Micrograph by Francesca Rotondo.

Downy mildew was confirmed today on cucumbers in Medina County – the field is in the Homerville area and symptoms were just beginning to show.  The pathogen that causes cucurbit downy mildew, Pseudoperonospora cubensis, was sporulating well on the underside of leaves (see photo).

This is the second confirmation of downy mildew on cucumbers in Ohio this year – the first was on August 11 in Huron County.  Please see my August 11 post in this blog for management recommendations.

We still have not confirmed downy mildew on squash or pumpkins, but we have received quite a few lookalikes, most of which were bacterial spot or angular leaf spot (also a bacterial disease). Bacterial diseases will not be controlled using any of the fungicides recommended for downy mildew, with the exception of copper-based products. However, these are only partially effective against downy mildew and bacterial diseases. If you are not sure about your diagnosis, send samples to the OSU Vegetable Pathology Lab – diagnoses are free for OH growers.

Building a Shared Understanding of Soil Balancing

Everyone would welcome a holistic, reliable, and relatively straightforward way to enhance and maintain soil health on many farms, regardless of their size, product, management approach (conventional, organic) and other characteristics. Some farmers and consultants have long said that Soil Balancing (SB) is that way, a means to loosen and enliven soil, provide essential nutrients, limit weed problems, and enhance crop yield and quality. However, university researchers have largely been unable to support that overall claim or recommend Soil Balancing as the guiding philosophy when making soil, fertility, weed, and certain crop management decisions. With USDA support and the help of many growers, consultants, and others in the industry, an OSU team has been taking another look at the situation, possibly the most comprehensive, collaborative, and long-running evaluation to date.

As outlined in three previous VegNet articles and other references on SB, the philosophy calls for achieving an optimum ratio of calcium, magnesium, and potassium in the soil. This may require large amounts of limestone and/or gypsum and multiple years to “move the needle” on soil chemistry, physics, and biology (and their follow-on effects on weeds and crops) in a positive direction. Regardless, some see the payoff as significant. Importantly, evaluating the economics of Soil Balancing is one component of the OSU-led effort, which began in 2015 and is set to provide valuable new insights. Look for summaries in upcoming publications, programs, and other resources.

A Stakeholder Advisory Committee including farmers, consultants, and university professionals from Ohio and other states has guided the OSU team throughout its work, helping to design experiments and interpret and share findings. Committee members and others visited project research plots on farms near Wooster and at the OARDC and discussed project emerging project findings on August 9 and 10. In this picture, the group discusses the status of plots containing butternut squash, edamame soybean, and dwarf popcorn. For more information, see https://u.osu.edu/vegprolab/research-areas/soil-balancing/ or http://organicfarmingresearchnetwork.org.ohio-state.edu/network_activities/soil_balancing/ or contact Matt Kleinhenz (330.263.3810; kleinhenz.1@osu.edu).

Organic Options for Cucurbit Powdery Mildew Management

Powdery mildew is a scourge of summer for squash, pumpkins, and other cucurbits.  Organic growers should always start with varieties with some degree of resistance to powdery mildew – seed catalogues often call partial resistance “tolerance”.  Although resistance will generally not be complete, efforts to manage powdery mildew with organic-acceptable products will be more productive if growers start with a variety that can put up a fight on its own than one that is highly susceptible.

Dr. Meg McGrath, Cornell University, has summarized field research results throughout the US for organic-approved products tested against various diseases of vegetables and herbs.  Her summary for zucchini powdery mildew research in NY includes the following:

Best results are obtained when these products are used preventatively or at the very first signs of powdery mildew, usually in mid-July in Ohio.  If you wait until powdery mildew has progressed to the stage you see in the photo above, it will probably be too late to get it under control.

Cucumber Downy Mildew – First Ohio Report for 2018

Cucumber downy mildew – early 

This has been a very unusual year for cucurbit downy mildew. The disease usually appears on cucumbers like clockwork on or around July 4 in one of the northern Ohio counties, but this year we found it for the first time only yesterday, August 10, in Huron County – with just two mature lesions in one of our cucumber research plots on the OSU OARDC Muck Crops Experiment Station in Celeryville. We have been expecting it due to reports in MI, IN, PA, and Kentucky during the last few weeks.

Bacterial spot of pumpkin

We have been receiving many samples of cucurbits suspected of downy mildew during the past month, including cucumbers, squash and pumpkins, but nearly all of these had bacterial spot or angular leaf spot.  While we expect that these bacterial diseases will continue to be a problem, growers and scouts should be on the lookout for downy mildew in all cucurbit types.  Symptoms caused by bacterial diseases, Alternaria and sometimes anthracnose can look like downy mildew.  If you are unsure, send a sample to the OSU Vegetable Pathology Lab in Wooster for confirmation. There is no fee for Ohio residents. You can also text or email photos – please be sure the images are sharp, as close up as possible, and include both the upper an lower side of the leaf – to me at 330-466-5249 or miller.769@osu.edu.  We can’t always diagnose from photos but they can be a good place to start.

Most growers have been protecting cucurbits for the last few weeks with a protectant fungicide such as chlorothalanil (Bravo, Echo, Equus, Initiate versions), which will also help manage anthracnose and Alternaria leaf spot.  At this late date and with confirmed cases in Ohio and our surrounding states, growers should consider including additional fungicides in their spray programs.  The chart below shows our 2017 bioassay results for fungicide efficacy against downy mildew. Always rotate fungicides with different modes of action and follow label instructions. Remember that Orondis Opti applications are restricted to 1/3 of the total fungicide applications. Under highly conducive environmental conditions, apply fungicides on a 5-7 day schedule.  When the risk is lower due to hot, dry, sunny weather, or downy mildew has not been reported in the area, the schedule may be stretched to 7-10 days.

Information on fungicides for vegetables, including Fungicide Resistance Action Committee (FRAC) code and greenhouse use can be found in a table beginning on page 79 of the 2018 Midwest Vegetable Production Guide for Commercial Growers. Pre-harvest intervals are shown for each crop/fungicide combination throughout the guide.

Options for organic cucurbit production are limited.  Many organic-approved products include cucurbit downy mildew on their labels, but most are not very effective or ineffective.  A copper-based fungicide such as Champ usually is the most effective in research trials, but generally control is not complete. These products must be applied preventatively, before the downy mildew pathogen infects the plants. Cultivars with some resistance to downy mildew should be used. Dr. Meg McGrath of Cornell University has summarized recent research throughout the US on organic-approved products for control of downy mildew and other diseases of vegetable and herb crops.


Corn earworm alert!!!

Very large numbers of corn earworm moths have been detected in pheromone traps for the past few days.

Corn earworm moths in Hartstack trap.

Reports from South Charleston in southwestern Ohio are for 185 moths on 8/10 for just one night, after 560 moths total in the previous 3 nights. In Columbus, we had 343 moths in 2 nights, 8/9 and 8/10, after 106 moths the previous 2 nights. These moth numbers mean that sweet corn fields that are in the early silk stage will become heavily infested by corn earworm unless preventive measures are taken as soon as possible.

Now that most of Ohio’s grain corn is starting to dry out, any patches of sweet corn are likely to be attacked by this pest. Once corn earworm is detected, silking sweet corn should be sprayed with insecticide every 2-6 days. The choice of an appropriate spray interval is as important as the choice of product to use. Details about the most appropriate spray interval based on pheromone traps are shown in the chart below:

Corn earworm decision chart.

Our testing of insecticides for corn earworm control over the past 12 years has shown that pyrethroids (Warrior, Asana, Pounce, Mustang Maxx, Brigade, Baythroid, Hero) are generally effective for earworm control in years when the population is low to moderate but generally not effective in years when the population is high. If pyrethroids are used, they should be used at the maximum labeled rate. Among pyrethroids, Hero is generally the most effective; it is a pre-mix of two different pyrethroids (Mustang Maxx, Brigade). Alternatives to pyrethroids are Coragen, Radiant, and Blackhawk. Organic growers can use Entrust or a B.t. such as Javelin or Dipel.

For plantings of B.t. transgenic hybrids (the Attribute II series and the Seminis Performance series), we have found that the B.t. provides adequate control of corn earworm when populations are low, but only fair control when earworm populations reach high density. These hybrids provide the best control when silks are fresh but less control when silks begin to dry. Thus sprays during the later part of the silking period are helpful to prevent earworm infestation in the transgenic hybrids.

-Celeste Welty & Jim Jasinski

Pumpkin Field Day – Aug. 23rd 6-8pm

SOUTH CHARLESTON, Ohio — Each year, researchers from The Ohio State University (OSU) showcase their research during interactive field days open to the public. This year, pumpkin production and management research will be shown at the Pumpkin Field Day at the Western Agricultural Research Station on August 23 from 6 – 8 p.m. for farmers and others to meet researchers, walk through the research plots, and ask questions. The research station is located at 7721 South Charleston Pike, South Charleston, OH.

New technology and information for pumpkin growers will include how to utilize cover crops along with several new plant varieties will be on display and discussed during the field day. Results from a fungicide drip irrigation study, powdery mildew fungicide trial, and disease, weed, and insect management will also be discussed. Ohio State researchers who will be presenting at the field night include Alan Sundermeier, cover crops and soil health; Jim Jasinski, insect and general crop management; Brian Reeb, weed management; and Claudio Vrisman, disease management.

Pre-registration is required by August 20 and there is a $5 per person fee, payable at the event. To pre-register, go to surveymonkey.com/r/pumpkinreg18or call 937-462-8016 and leave a message. The field day will open for registration at 5:30 p.m. and start promptly at 6 p.m. For more information about the field day, contact Jim Jasinski at jasinski.4@osu.edu. See attached flyer for details.

CFAES provides research and related educational programs to clientele on a nondiscriminatory basis. For more information, visit cfaesdiversity.osu.edu.

Pumpkin field night flyer.

Summer Season Extension Using Shade Fabric for Cool Weather Crops

Season Extension is when a vegetable, herb or fruit is grown outside its normal growing season using protection from the elements in some way.  While it is most commonly used over the winter to take advantage of Ohio’s four seasons of growing, it is also applicable in summer when growing vegetables that prefer cooler weather.  A part of the community garden plot opened up after cucurbit production decreased from cucumber beetle damage and bacterial wilt.

Was planted with zucchini and cucumbers from mid-May until late July


The plasticulture fabric was removed, the soil was amended with slow release granular fertilizer and compost, It was then planted with lettuce and pac choi cabbage transplants that had been started under the lights 3 weeks ago.  The cucurbits were productive heavy feeders  so extra fertility was needed, especially in the form of nitrogen, and crop rotation was observed among different vegetable families.

The wood form is 4′ x 8′ in size and 4″ high tall made of untreated wood. The PVC is 1/2″ in diameter and sleeved onto screws. This allows easy use of season extension in a defined space that keeps the fabric off the plants, but is very stable to the elements.


The raised bed form was then covered with shade fabric. This fabric is designed to allow light, air, and water to pass through, but to decrease the amount of sunlight and provide shade to the cooler temperature season lettuce and cabbage during the August maturation period.  Multiple other vegetable crops could be grown with this method including radishes, spinach, arugula and other small brassicas.


30% sunlight reduction shade fabric.  In most cases this fabric should be vented  to allow air movement and prevent heat buildup under the fabric.   It is shown closed in this picture to prevent small mammal feeding damage overnight, but will be clipped part way up the PVC tubing during the day normally.

This fabric will provide protection from the cabbage white butterfly and its associated larval form that feeds heavily on the foliage of brassica family crops.   This means it also will not allow pollinators to enter the space if it is kept fully closed.  This is not a concern as both the lettuce and cabbage will be harvested before they flower and produce seed and have no need for pollinators.

The use of shade fabric for season extension allows harvest of cool weather crops that are otherwise difficult to grow in mid-summer.  The element and insect protection from the fabric allows for a higher quality crop.  An off season, high quality crop has the potential to demand a higher price in a CSA subscription or at the Farmer’s Market booth. The fabric is available in multiple lengths and widths to allow scale up to larger sized production areas if needed.

Make sure to incorporate season extension methods when making your garden plan.  Ohio is a true four season growing environment and with some planning and using season extension, harvest can be achieved all year long.