Month: March 2025

Follow up – Tar Spot on Sweet Corn

Three weeks ago an article was posted in VegNet outlining a relatively new disease on sweet corn, Tar Spot (https://u.osu.edu/vegnetnews/2025/03/08/tar-spot-on-sweet-corn/).

In order to understand the magnitude and distribution of this disease across Ohio, a short survey was available for growers to anonymously send in their experience with Tar Spot so that a more accurate understanding of this disease could be made, informing potential research in 2025. If you would like to add to our understanding of this disease on your farm, here is the link to follow: https://osu.az1.qualtrics.com/jfe/form/SV_d5NMkdMmASqJza6

Two growers responded to the survey from west central and north central Ohio stating they:

-have had issues with Tar Spot since at least 2023 (primarily “late” planted)
-have sprayed fungicides on the crop since at least 2023
-believe this disease is impacting ear quality and sales

As a result of this information, a group of OSU researchers and Extension educators have decided to go forward with planning a Tar Spot evaluation and yield impact study at three locations in 2025. The study will be guided by Dr. Pierce Paul, Tar Spot researcher, Professor and Chair of Plant Pathology, and Dr. Andres Sanabria Velazquez, Associate Professor in Plant Pathology. Contributing to the study design, data collection and analysis will be Dr. Logan Minter (Associate Professor in Extension, Field Specialist), Jim Jasinski (Professor in Extension), Mike Gastier and Pressley Buurma (Extension Educators).

Sites for the Tar Spot trials will be South Centers at Piketon, Western Ag Research Station (South Charleston), and Muck Crops Research Station (Willard), evaluating both fresh market and shipping sweet corn hybrids. More details of these trials will be released soon.

April’s Women in Ag Wednesday Webinar

Join us on April 2, 2025, for the next session on… Tips and Tricks for Building Healthy Soils

Join Manbir Rakkar, OSU Assistant Professor of Soil Fertility and Nutrient Management, for a session that will discuss the importance of soil health and outline strategies for promoting healthy soils. 

Register for the entire series using this link once. go.osu.edu/wiawednesdaywebinars2025  

The 2025 Series will take place on the first Wednesday of each month.​

10:30 am – 11:30 am​

Via Zoom Platform

​

Observations of Pepper Seedling Development in Stabilized Plugs, not Standard Loose Rooting Medium

On a March 1, 2025 in this blog, we summarized our initial impressions of pepper seedling development in stabilized plugs instead of a standard loose medium and explained that our upcoming use of stabilized plugs was prompted by collaboration with researchers at UC-Davis and The OSU in which we are working to better understand and breed for yield under water and heat stress in bell pepper. Here, we provide a brief update on seedling development in stabilized plugs provided by https://ihort.com/q-plug/. Images below collected 3/22/25 reinforce the idea that seedlings produced in the plugs may be uniform, straightforward to irrigate, easy to handle, and field-ready sooner after seeding (requiring less time in the greenhouse and adding flexibility to seeding schedules). Additional tests are required to verify these preliminary, early-stage speculations. These and other stabilized plugs can be used with seed (varying in size) and cuttings. Please contact https://ihort.com/q-plug/ or Matt Kleinhenz (kleinhenz.1@osu.edu, 330.263.3810) for more information.

 

Tar Spot on Sweet Corn 

The past few months have been full of opportunities for growers to attend local, statewide, regional or even national fruit and vegetable conferences to learn new skills and get updates on current production and pest management practices. I recently attended a conference where Dr. Julie Kikkert, Cornell University, gave a very interesting presentation on Tar Spot in sweet corn. During her talk, gears began turning in my head as I considered if this disease was also a problem under the radar for Ohio sweet corn growers.

Crop Protection Network

 

 

Tar Spot was initially detected in Ohio in 2018 on field corn and is mostly distributed in the northwest and northcentral parts of the state (https://agcrops.osu.edu/newsletter/corn-newsletter/2020-03/tar-spot-corn). Tar Spot is currently found in 14 states and mostly thought of as a pathogen on field corn, due primarily to the length of exposure as the ear matures on the stalk. Since sweet corn is harvested immature, the question of Tar Spot impacting quality and yield seems remote but possible. Late planted sweet corn in Ohio (ca. late June or early July), is most likely to be affected but other factors such as prior crop, tillage and weather can play a part in the disease severity.

From CORN article

If the prior crop was field or sweet corn then the risk of Tar Spot increases, as does the risk if there was no primary tillage performed which could serve to bury inoculum (old, infected corn leaves).  In the later part of the season, if weather conditions turn cool and wet, this favors disease development. Proximity to large acreages of field corn may also be a factor as air borne spores can travel miles to infect other corn plants. At this time there are no resistant field or sweet corn hybrids but there may be some tolerance among hybrids. Fungicides can be applied to late planted sweet corn crops that are effective against this pathogen but the matter of economics and Pre Harvest Interval comes into play. https://cropprotectionnetwork.org/publications/fungicide-efficacy-for-control-of-corn-diseases

What can be done?

At this point, several members of the OSU Specialty Crops team are looking to set up multiple late planted sweet corn hybrid trials on OSU research stations from southern to northern Ohio to determine the extent of foliar Tar Spot infestation and if any impacts on ear production or quality can be observed.

Since this pathogen is new to Ohio sweet corn growers, we are also interested in feedback from growers who have seen this pathogen on their crop in 2024. In order to collect this information anonymously, please use the 9-question feedback form at this link: https://osu.az1.qualtrics.com/jfe/form/SV_d5NMkdMmASqJza6

 The survey questions are listed below. The last question on the form is open ended if growers have any other thoughts to share on this disease. In a few weeks, I will summarize the observations and concerns of the growers who responded.

Q1. Did you see Tar Spot on sweet corn last year?

Q2. What was the previous crop?

Q3. What tillage was performed in the field?

Q4. What was the planting date of the infected sweet corn hybrid?

Q5. When was the sweet corn harvested?

Q6. What was the name of the sweet corn hybrid?

Q7. Did the Tar Spot infection affect the ear quality in your opinion?

Q8. What county is your farm located?

Q9. Anything else to tell us about Tar Spot on your farm in 2024?

First Impressions of a Stabilized Seedling Plug

The OSU Vegetable Production Systems Laboratory (VPSL) is pleased to be working with researchers at UC-Davis (A. Van Deynze) and The OSU (L. McHale, K. Mercer) to better understand and breed for yield under water and heat stress in bell pepper. The process will involve producing many seedlings of dozens of experimental lines (beginning with raw, untreated seed) and placing them in well- and minimally-irrigated field plots in CA and OH. A loose, peat-based rooting medium like often used on many Ohio farms and by the VPSL will not be used during seedling production. Instead, stabilized plugs provided by https://ihort.com/q-plug/ will be used. The VPSL is completing initial, small-scale tests with Q Plugs which, we are told, can produce seedlings that are stronger and field-ready in less time, and provide other attributes. Our initial impressions as we learn how to utilize Q Plugs most effectively are encouraging. We have appreciated their uniformity, ease of handling, ability to retain moisture without being wet, and the root growth they appear to facilitate. Q Plugs are available in different shapes and sizes and must be seated in matching prefabricated trays. Rigorous study is needed to verify but our preliminary, early-stage observations suggest that the ratio of root-to-shoot growth will be different and, perhaps, more favorable than when loose medium is used, in our experience. Using a stabilized seedling plug, it MAY be possible to transplant sooner and reduce transplant shock; however, these speculations must be properly tested. Pictures of young pepper seedlings in Q Plugs taken 3/1/25 are below. Please note that greenhouse temperatures were sub-optimal Jan 23 – Feb 6. Please contact https://ihort.com/q-plug/ or Matt Kleinhenz (kleinhenz.1@osu.edu, 330.263.3810) for more information.