C.O.R.N. Newsletter: 2024-24
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Battle for the Belt: Season 2, Episode 17 – Crop Progress Update
Episode 17 of Battle for the Belt is now available: https://www.youtube.com/watch?v=hHBjPAml2uM
In Episode 17, we spoke with Dr. Laura Lindsey, Ohio State Soybean Extension Specialist, and Dr. Osler Ortez, Ohio State Corn Extension Specialist, to go over crop progress at the Western Agricultural Research Station in Clark County, Ohio.
Corn Progress
Crop staging on July 17th at the Western Agricultural Research Station shows corn at V7 through R3 state depending on the planting date:- First planting date (March 25): milk stage (R3)
- Second planting date (April 16): blister stage (R2)
- Third planting date (May 6): silking stage (R1)
- Fourth planting date (May 24): V14 stage, 14 developed leaves
- Fifth planting date (June 17): V7 stage, 7 developed leaves.
Next - what these corn stages mean?
The V7 growth stage is identified by the 7th leaf having an visible-open collar. At this stage, the crop is increasing in nitrogen uptake. The V14 growth stage row number has already been determined, and ear shoots have been growing since V6 and is identified by having an open leaf collar on the 14th leaf. At V15, potential kernels per ear is established but is determined through the environmental conditions during grain fill. To consider a plant to be at R1, the ear must have one or more silks coming out of the husk. The R1 stage is the only reproductive stage that is not designated by the ear. Silk will be receptive to pollen for about 10 days. At R1 the ear is only 40 to 45% of its maximum length. R1 is the appropriate time to apply fungicides if there is disease present. At the blister stage (Figure 1), the kernel is ivory colored and the inside is a clear liquid. The embryo is growing but cannot be seen without a magnifier. This occurs about 10 to 14 days after silking begins. R2 plants have reached maximum height and vegetative dry matter, and the ear has reached its maximum length. The milk stage occurs between 18 to 22 days after R1. The moisture content of the kernels is about 80% at the beginning of R3 (Figure 2). The kernel begins to add color and become yellow but the inside is white and translucent. The silks have turned brown at this stage. Kernel abortion is still possible at R3 if carbohydrate supply is low. Growth stage details were sourced from “Corn Growth and Development”.
Soybean Progress
The soybeans, in comparison to corn, will continue to grow vegetatively even though the plant is in reproductive stages. Soybean stages at the Western station follow:
- First planting date (March 25): R4 stage (full pod)
- Second planting date (April 16): R4 stage (full pod)
- Third planting date (May 6): R3 stage (beginning pod)
- Fourth planting date (May 24): R2 stage (full flowering)
- Fifth planting date (June 17): V4 stage (four unfolded trifoliate leaves).
An interesting observation from this field is that in the March 25 planted soybeans, the lower portion of the plant has pods that are at the R5.3 growth stage (or later) with seeds developing but the top of the plant is still at R4 (Figure 3). Soybean staging is done on the top four nodes of the plant with fully developed leaves, but since the soybean continues to grow vegetatively, the plant can stay in the same stage for long periods of time. This is why our first three planting dates are in similar stages but were planted six weeks apart. There is a wide spectrum of stage in these plots, but the earlier planting dates are at about the same stage which is interesting considering the lower part of the canopy of each planting date are very different developmentally. We do not know what that means in terms of yield, but we are tracking pods in the lower canopy to evaluate the seed fill through the season.
Next - what these soybean stages mean?
The V4 growth stage is determined by having four open trifoliates. At this stage plants can recover from 100% defoliation with low risk of yield loss. The R2 growth stage has an open flower at one of the two uppermost nodes on the main stem with a fully developed leaf. Flowering usually will continue for about three to five weeks. The R3 growth stage is observed when a pod is 3/16 of an inch long at one of the four uppermost nodes on the main stem with a fully developed leaf. The plant can have developing pods, withering flowers, new open flowers, and flower buds at this stage. The R4 growth stage is observed with a pod that is ¾ inch long at one of the four uppermost nodes on the main stem with a fully developed leaf. Flowering continues on the upper node branches and peak nitrogen uptake rates happen between R4 and R5 ranging from 3-4 pounds per acre per day. Details of soybean stages were sourced from “A Visual Guide to Soybean Growth Stages”
A summary of planting dates and stages at all three research locations is presented in Table 1.
Table 1. Weekly weather conditions for each planting date at the Western Agricultural Research Station, Northwest Agricultural Research Station, and Wooster Campus, with day of planting, soil, air temperature averages, and Growing Degree Days (GDDs) from July 15th to July 21st. Information from CFAES Weather System (https://weather.cfaes.osu.edu/). Location
Precipitation
(Inches)
(July 15-
July 21)
2-inch soil temperature
(July 15-July 21)
Air Temperature
(July 15-
July 21)
Planting date
GDDs
(Cumulative)
Soybean
Stage
Corn
Stage
Western,
Clark County
0.67
Max: 83°F
Mean: 76°F
Minimum: 69°FMax: 91°F
Mean: 72°F
Minimum: 55°F
March 25th
April 16th
May 6th
May 24th
June 17th
1974
1865
1628
1322
876
R4
R4
R3
R2
V4
R3
R2
R1
V14
V7
Northwest,
Wood County
0
Max: 72°F
Mean: 77°F
Minimum: 65°FMax: 87°F
Mean: 73°F
Minimum: 54°F
May 16th
May 23rd
June 10th
June 17th
June 24th
1496
1330
1001
857
630
R2
R1
V4
V3
V1
V15
V12
V7
V6
V5
Wooster, Wayne County
0.13
Max: 81°F
Mean: 76°F
Minimum: 70°FMax: 87°F
Mean: 72°F
Minimum: 52°FApril 22nd
May 3rd
May 21st
June 4th
June 20th
1565
1459
1223
1005
706
R3
R2
R2
V6
V3
R2
R1
V14
V9
V6
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Worsening Drought Conditions Across Southern Ohio
As I write this article on Monday afternoon, showers and a few embedded storms are rolling across the Buckeye State. However, for southern and southeastern Ohio, this has largely not been the case for the last several weeks. Precipitation over the past 30-to-60-days is running 25-75% of normal, with some parts of Pickaway, Ross, Noble, Morgan, Washington, Monroe, and Belmont Counties receiving less than 2 inches over this period (Figure 1). As a result, the latest US Drought Monitor depicts about 8% of Ohio in D2-Severe Drought and
abnormally dry conditions or worse being felt by approximately 70% of the state. This has led to notable crop stress on drier ground, deep cracks in the ground from the lack of soil moisture, poor pasture conditions, and short-cuttings of hay. Producers are encouraged to provide observations from their locations by submitting a Condition Monitoring Observer Report (go.osu.edu/drought_cmor). For more information and resources, please visit our Drought Conditions and Resources Knowledge Exchange page or visit the State Climate Office of Ohio. Weather Forecast
Scattered showers and storms are possible on Tuesday through Thursday this week, before high pressure and drier air moves in for the weekend. However, widespread heavy rain is not expected. The Weather Prediction Center is currently forecasting 0.01-0.50” for the state over the next 7 days (Figure 2), though locally heavier amounts are possible. Temperatures will generally rise into the low to mid 80s each day with overnight lows in the 60s, about average for mid to late July.The 8-14 day outlook from the Climate Prediction Center and the 16-Day Rainfall Outlook from NOAA/NWS/Ohio River Forecast Center show temperatures are likely to be above average with precipitation probability leaning toward wetter than average (Figure 3). Climate averages include a high-temperature range of 83-86°F, a low-temperature range of 60-66°F, and weekly total precipitation of 0.90-1.20”.
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Regional Crop Updates: July 16-22
Insect and disease pressure remains relatively low across the state, but dry conditions worsen in Southern and Northeastern Ohio. Field issues Ohio State University Extension Educators and Specialists have seen this past week include uneven crop growth and development and weather stress. Keep reading for region-specific details.
Southeast – Dean Kreager of OSU Extension Licking County reported that rainfall has been highly variable, with some areas receiving near normal levels and others remaining very dry. Lack of soil moisture has slowed hay regrowth and is also impacting corn and soybean fields. Corn is in fair condition ranging from VT (tassel) to R2 (blister) with low levels of tar spot reported. Soybean is in fair condition. Main weed issues are currently giant ragweed and johnsongrass.
Central & West Central – Ryan McMichael of OSU Extension Mercer County reported that most counties in the region have adequate soil moisture levels, with Madison and Pickaway Counties being the exception. Nearly all corn has reached tasseling and is in good condition. Soybean is also in good condition and is mainly between R1 (flowering) and R3 (beginning pod).
Northeast – Lee Beers of OSU Extension Trumbull County reports that growers took advantage of drier weather and continued hay harvest along with fungicide application for corn and soybean. Overall, the region has low disease and insect pressure, and both corn and soybean are in fair condition. Large portions of the area remain dry though as corn pollination continues.
Northwest – Field Specialist Stephanie Karhoff reported that corn is in good condition and anywhere between V9 and R2 (blister). Low levels of tar spot and common rust were observed in the lower canopy this past week, but overall disease and insect pressure remain low. Soybean is in fair to good condition with variable growth and development. Parts of the region also reported yellowing in soybeans. Dry weather this past week was favorable for second cutting alfalfa, and forage quality and yield were both strong for second cutting.
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Check Roots for Soybean Cyst Nematode: What’s Your Number?
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.
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.
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Risk of Corn Grain Contamination with Vomitoxin in Ohio in 2024: Projection for the Weeks of July 21 and 29
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.
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Lep Monitoring Network – Time to Scout for Western Bean Cutworm, Update # 14
We have just finished out our fourteenth week of monitoring at the Lep Network. This past week, we saw WBC numbers trending down and CEW numbers close to zero across the state. Western bean cutworm numbers topped out with Sandusky County having the highest average by far of 38 moths. As for corn earworm, Putnam was the only county to report any CEW sightings for this past week and averaged 0.3 moths in the county. Western bean cutworm 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 declined.
Western Bean Cutworm numbers are peaking in many counties across the state
This past week was our fifth week monitoring for WBC in Ohio. The statewide average for WBC decreased substantially from 9.3 during the week ending on July 14th to only 1.9 for the week ending July 21st. The counties with the highest averages are Sandusky (38.0) and Lorain (8.0) (Figure 1). Here at the Lep Network, we are fairly certain that we have already seen our peak in WBC moths for this year and are starting the decline. Despite this shift in numbers, it is still important to be scouting for WBC egg masses (Figure 2), especially if this week's average topped 7 moths in your county. Counties that should continue scouting this week are: Defiance, Huron, Lorain, Sandusky, Wayne, and Wood.How to scout for WBC egg masses:
- Identify fields with corn that is pre-tassel or just starting to tassel as these pests need tassels to feed on until the full ear forms.
- Examine the upper 3 – 4 leaves of 20 plants in 5 different field locations (100 plants for field), for egg masses (Figure 2).
- Record the number of egg masses found. Newly laid egg masses are a white/cream color that darken as they mature to a dark purplish color.
- If 5% of plants have egg masses, a treatment may be necessary. Be sure to time the treatment when the majority of the egg masses are mature (purple).
To view a more detailed video on scouting – click here: https://youtu.be/qGjpwtfkObM?si=CFPzX1rlqt6jzyJw
Western bean cutworm moth map
Week 5 - July 15th to July 22nd, 2024
Corn Earworm
This is our seventh week monitoring for CEW pests in Ohio. The statewide average for CEW has continued to decrease from 0.8 during the week ending on July 14th to just 0.02 for the week ending July 21st. The only county with any recorded moths was Putnam (0.3) (Figure 3). Expect reports for CEW to continue to be low for the remainder of its season. To learn more about the corn earworm, check out one of our previous newsletters: https://agcrops.osu.edu/newsletter/corn-newsletter/2019-27/corn-earworm-field-corn-watch-moldsCorn earworm moth map
Week 7 - July 15th to July 22nd, 2024
Crop Observation and Recommendation Network
C.O.R.N. Newsletter is a summary of crop observations, related information, and appropriate recommendations for Ohio crop producers and industry. C.O.R.N. Newsletter is produced by the Ohio State University Extension Agronomy Team, state specialists at The Ohio State University and the Ohio Agricultural Research and Development Center (OARDC). C.O.R.N. Newsletter questions are directed to Extension and OARDC state specialists and associates at Ohio State.
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Disclaimer
The information presented here, along with any trade names used, is supplied with the understanding that no discrimination is intended and no endorsement is made by Ohio State University Extension is implied. Although every attempt is made to produce information that is complete, timely, and accurate, the pesticide user bears responsibility of consulting the pesticide label and adhering to those directions.
CFAES provides research and related educational programs to clientele on a nondiscriminatory basis. For more information, visit cfaesdiversity.osu.edu. For an accessible format of this publication, visit cfaes.osu.edu/accessibility.