Disease

Soybean Vein Necrosis Virus and Downy Mildew

Soybean field

Article is taken from  https://agcrops.osu.edu/newsletter/corn-newsletter/2024-26/soybean-vein-necrosis-virus-and-downy-mildew by Horacio Lopez-Nicora

As we progressed with our field scouting this past week, it has become evident that Soybean Vein Necrosis Virus (SVNV) is making a noticeable presence in our soybean crops across various regions. SVNV, a viral disease primarily spread by thrips, manifests typically as yellowing and necrosis along the veins of the soybean leaves. Initial symptoms include chlorotic lesions that evolve, resulting in a necrotic, vein-associated appearance. The impact of SVNV on overall yield is still under investigation, but early infection is generally more detrimental. Growers should be vigilant about thrip populations and adopt integrated pest management strategies, including the use of resistant varieties if available, to mitigate the spread of this virus.

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Lep Monitoring Network – News on WBC and CEW, Update # 15

Article taken from https://agcrops.osu.edu/newsletter/corn-newsletter/2024-25/lep-monitoring-network-%E2%80%93-news-wbc-and-cew-update-15 by Stephanie Pflaum, Amy Raudenbush, Maddie Brillhart, Nic Baumer, Lee Beers, CCA, Trevor Corboy, Allen Gahler, Don Hammersmith, Mary Jo Hassen, Alan Leininger, Ed Lentz, CCA, Sarah Noggle, Les Ober, CCA, Jordan Penrose, Mike Sunderman, Frank Thayer, Kyle Verhoff, Brooks Warner, Jacob Winters, Curtis Young, CCA, Andy Michel, Kelley Tilmon

We have just finished out our 15th week of monitoring for Ohio pests at the Lep Network. This past week, we have seen a continuation of WBC numbers trending down and a slight increase in the CEW average. As was mentioned last week, WBC populations across Ohio have most likely hit their peak numbers of the season and a decline should be expected. While we are most likely beginning to round out of the peak for this pest, any counties with averages that are still above 7 should continue scouting until their county numbers have significantly declined.

Western Bean Cutworm numbers are peaking in many counties across the state
This past week was our 6th week monitoring for WBC in Ohio. The statewide average for WBC decreased again from 1.9 during the week ending on July 21st to 1.0 for the week ending July 28th. The counties with the highest averages are Sandusky (19.0), Huron (7.0) and Henry (4.8) (Figure 1). While we are relatively certain that we have surpassed the peak in WBC moths for this year and are starting the decline, it is still important to be scouting for WBC egg masses (Figure 2). As mentioned above, if this week’s average topped 7 moths in your county, see below for tips on how to scout for this damaging pest. Counties that should continue scouting this week are: Huron and Sandusky.

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Risk of Corn Grain Contamination with Vomitoxin in Ohio in 2024: Projection for the Weeks of July 21 and 29

Corn contaminated by vomitoxin

Article is taken from https://agcrops.osu.edu/newsletter/corn-newsletter/2024-24/risk-corn-grain-contamination-vomitoxin-ohio-2024-projection by Pierce Paul, Jason Hartschuh, CCA, Aaron Wilson, Stephanie Karhoff, CCA

This week we continue providing updates pertaining to the projected risk of grain contamination with the mycotoxin deoxynivalenol (DON), which is commonly referred to as vomitoxin. This week, the focus is on fields reaching the silking or R1 growth stage between July 21 and August 4. Using temperature and RH data from CFAES weather stations across the state of Ohio as predictors, the chance (or probability) of vomitoxin contamination of corn grain was estimated using models developed in the Paul lab. Models were run separately on data from each of nine weather stations for 15 silking dates from July 21 to August 4. Predictions generated by these models should only be applied to corn pollinating during the 15-day pre-silking model prediction window, which may be specific for each area of the state and field within that area.

Based on weather data collected from CFAES weather stations located in Ashtabula (LAT: 41.8846, LON: -80.6978), Franklin (LAT: 40.0112, LON: -83.0442), Noble (LAT: 39.7478, LON: -81.5167), Jackson (LAT:  39.0519, LON: -82.6367), Sandusky (LAT: 41.3503, LON: -83.1219), Wood (Latitude:  41.2847, Longitude: -83.8444), Pike (LAT: 39.0681, LON: -83.0144), Clark (LAT: 39.8633, LON: -83.6721), and Wayne (LAT: 40.7787, LON: -81.9308) Counties, OH, grain developing in corn fields in close proximity to the stations that reach the R1 growth stage between July 21 and August 4 are at high risk of being contaminated with at least 1 ppm DON.     

Our models were not developed to predict whether vomitoxin will be 2, 5, 8, or 10 ppm, they only predict whether vomitoxin will be ≥ 1 ppm. Whether or not contamination will be considerable higher that 1% will depend on other factors such as hybrid maturity and susceptibility, field location, tillage, and crop rotation, as well as weather conditions. Under favorable weather conditions, a highly susceptible hybrid planted no-till into corn stubble will likely be contaminated with vomitoxin well above 1 ppm compared to a tilled field of a moderately resistant hybrid planted after beans.

These model predictions can be used to help you determine if a fungicide for vomitoxin management would be beneficial. However, no single management strategy will be fully effective again vomitoxin. Even with a fungicide application, hybrid resistance is critical for achieving low vomitoxin levels at harvest. Treated fields planted with partially resistant hybrids will often have lower levels of vomitoxin at harvest than treated fields planted with susceptible hybrids. Two of the most effective products for vomitoxin management are Proline and Miravis Neo. These fungicides tend to be most effective when applied at R1 when silks are still wet. Applications made after silks are dry and brown are considerably less effective at reducing vomitoxin. The fungicide must penetrate the canopy and reach the corn silks to be effective.

These models are the first step towards the development of a prediction tool that would be available to growers to run on a daily basis during pollination to assess vomitoxin risk at their field location. The current model development has been generously supported by the Corn Marketing Board through your corn check-off. As more data are collected, models will be developed to predict the risk of higher levels of contamination (2 ppm, 5 ppm, etc etc).

More information on vomitoxin risk assessment and management in corn can be found in this corn newsletter article: https://agcrops.osu.edu/newsletter/corn-newsletter/2024-22/risk-corn-grain-contamination-vomitoxin-ohio-2024-july-8

Estimates of the risk of DON contamination of corn grain are provided at no cost within the state of Ohio. The model developers, The Ohio State University, and funding agencies cannot guarantee prediction accuracy. Users should always consult extension educators and state and field specialist when making disease and mycotoxin management decisions.

Check Roots for Soybean Cyst Nematode: What’s Your Number?

Soybean Cyst Nematode in hand

Article is taken from https://agcrops.osu.edu/newsletter/corn-newsletter/2024-24/check-roots-soybean-cyst-nematode-what%E2%80%99s-your-number by Horacio Lopez-Nicora

Soybean cyst nematode (SCN) is quietly expanding its presence in Ohio, with increasing numbers across the state. Fields affected by SCN might not show aboveground visible symptoms, but SCN females can be detected attached to soybean roots six to eight weeks after planting. We encourage Ohio soybean growers to actively manage SCN by checking roots for the presence of SCN. If you’re unsure whether you have SCN in your fields, take a walk through your fields with a shovel, digging up plants every 30 to 50 paces. Carefully remove soil from the roots (a water bucket can help) and look for SCN females (Fig. 1). Initially white to cream, turning yellow and eventually brown, SCN females are significantly smaller than nitrogen-fixing nodules (Fig. 1). The SCN females will eventually fill with over 200 eggs, transforming into cysts that protect the eggs and allow them to survive for several years in infested fields. We encourage growers, agronomists, and crop consultants to check soybean roots for SCN throughout July, August, and September.

Figure 1. Soybean roots infested with SCN. Note the significantly smaller lemon-shape SCN female (red circle) attached to roots compared to larger nitrogen-fixing nodules (yellow circle).

Figure 1. Soybean roots infested with SCN. Note the significantly smaller lemon-shape SCN female (red circle) attached to roots compared to larger nitrogen-fixing nodules (yellow circle).

Knowing if you have SCN is the first step in managing it effectively. Watch this video to learn how to check your roots for SCN females. If SCN is detected in your field, a fall soil sample can determine your SCN numbers and help tailor appropriate management strategies. If you are already planting SCN-resistant varieties, checking roots can help evaluate the effectiveness of your resistance management or identify if the SCN population in your field is adapting to those resistant varieties (a shift in virulence).

Maintaining low SCN levels is much easier than reducing high numbers below damage thresholds. With support from the Ohio Soybean Council and The SCN Coalition, we can process up to two soil samples per grower for SCN testing, free of charge [read more here]. Share your #SCNRootCheck photos on social media by tagging @TheSCNCoalition on Twitter and Facebook, and @Ohiosoycouncil on Twitter and @ohiosoybeancouncil on Facebook.

Tar Spot and Fungicide Survey for Farmers and Crop Consultants

From Iowa State University Extension:

Planting is nearly here and folks are busy – but we are hoping you can help us with a tar spot and fungicide survey. This survey is the creative component for a Masters of Agronomy student, Kelsey Richie. She is hoping to get a better understanding of how tar spots may affect farmers’ decisions around fungicides. There are two surveys, one for farmers and one for crop specialists. If you could spare some time to complete the survey, it would be greatly appreciated.

The survey is only open until May 1st, so please give your input soon.

If African Swine Fever Comes to Your Neighborhood, Are You Prepared?

Learn the signs and what to do if African Swine Fever or another foreign animal disease affects your herd. This program addresses the steps you should take, the state and federal response, and biosecurity planning. Presentations provided by Ohio Department of Agriculture, USDA, and The Ohio State University.

WHO: Veterinarians with swine clientele & small swine producers (Even if you have just a pig or two this information is for you! But, producers of any size are welcome to attend.)

WHERE AND WHEN: All Presentations 6-7:30 p.m.

  • December 8th  Licking County Extension Office; 771 E Main St, Suite 103, Newark
  • January 12th  Clinton County Extension Office; 111 S Nelson Ave, Suite 2, Wilmington
  • February 2nd  Champaign County Extension Office; 1512 S US Highway 68, Suite B100, Urbana
  • February 16th  Putnam County Extension Office; 1206 E 2nd St, Ottawa
  • January 19th  OSU – ATI; 1328 Dover Rd, Wooster

Brochure attached. There is no cost to attend and no RSVP is required. Light refreshments are provided by Ohio Pork Council. Any questions? Contact Dr. Kristy Shaw at 614.728.6253 or kristy.shaw@agri.ohio.gov.

Small Swine Producer Flyer11.2021.