C.O.R.N. Newsletter: 2024-19

Winter wheat maturation is about 10-14 days ahead of normal (Figure 1), with harvest beginning late last week in southern Ohio. Last year, winter wheat yield was extremely high with a state average of 90 bu./acre (USDA NASS, 2024). During the previous five years, the state average wheat yield ranged from 56 to 85 bu./acre (average of 73 bu./acre). Last year, we attributed high yields to low rainfall (and consequently low disease) and cool temperatures, leading to a long grain-fill period. This year, we’ve experienced warmer temperatures, greater disease, and shorter grain-fill periods. Between March 1 and June 16, 2024, there were 1,000, 1,135, and 912 growing degree days at the Northwest Agricultural Research Station, Western Agricultural Research Station, and Wooster Campus, respectively (Table 1). During the same time period last year, there were 738, 816, and 617 growing degree days at the Northwest Agricultural Research Station, Western Agricultural Research Station, and Wooster Campus, respectively.

This year, wheat yield will likely be lower than last year. However, earlier wheat harvest opens opportunities for a second crop following wheat. In Ohio, double-crop soybeans are the most common crop after wheat harvest, but other crops, such as sunflower, may be planted. The two primary requirements for successful double cropping are: 1) There must be time for the production of a second crop, and 2) There must be adequate water to produce two crops, whether from stored soil moisture, rainfall, or irrigation. The first requirement will likely be met, with earlier wheat harvest and a predicted later first freeze date, but continued dry weather in areas of the state may be problematic. However, several management practices will help maximize double crop yield potential.

Double crop soybean management considerations.

1. Soybean relative maturity. Relative maturity (RM) has little effect on yield when soybeans are planted during the first three weeks of May. However, the effect of RM can be larger for late plantings. When planting soybean late, the latest maturing variety that will reach physiological maturity before the first killing frost is recommended. This is to allow the soybean plants to grow vegetatively as long as possible to produce nodes where pods can form before vegetative growth is slowed due to flowering and pod formation.

2. Row spacing. Double-crop soybeans should be produced in narrow rows- 7.5 or 15-inch row spacing. The later soybeans are planted, the greater the yield increase due to narrow rows. Soybeans grown in narrow rows produce more grain because they capture more sunlight energy, which drives photosynthesis.

3. Seeding rate. Soybean plant population at harvest for mid-to-late June plantings should be between 130,000-150,000 plants/acre. The harvest population for early July plantings should be greater than 180,000 plants/acre. Harvest population is a function of seeding rate, quality of the planter operation, and seed germination percentage and depends on such things as soil moisture condition, seed-soil contact, and disease pressure.

Double-crop sunflower management considerations.

In addition to double cropping with soybean, other alternatives may become feasible within the crop system. In 2022-2023, field experiments were established to study sunflowers’ viability as a double crop after wheat or barley harvest in Ohio (Figure 2).

The study had three commercial high oleic sunflower varieties: “ultra-early” maturity (N4H161 CL), “early” maturity (N4H302 E), and “mid-early” maturity (CP 455 E). These varieties were studied across three seeding rates: 17,000 seeds per Acre, 22,000 seeds per Acre, and 27,000 seeds per Acre. Preliminary results showed sunflower yields ranging between 1,012 lbs./Ac and 2,740 lbs./Ac (Table 3). The average yields per site were in the 1,400 to 1,900 lbs./Ac range, with the two highest yield sites being comparable to the average U.S. sunflower seed yields in the past two years.

From the preliminary results on the sunflower work, crop production challenges have included weather, equipment availability, bird damage, plant lodging, and variable/low stand counts which have possibly limiting crop yields. This project is in progress and will be planted again in 2024, more results are forthcoming. Future considerations for sunflowers should include consistency of results across sites/years, variety selection, seeding rate, germination, fertility, bird control, seed/oil quality, and marketing options as major priorities.

Reference:

United States Department of Agriculture (USDA) National Agricultural Statistics Service (NASS) 2024. Quick Stats. Available at: https://quickstats.nass.usda.gov/results/58FEB025-0AD4-3B92-9F18-30D377D14279

Allen County – Drainage installation, drainage water recycling, and soil health will be the focus of a field day being held on Wednesday, July 24, 2024, beginning at 9 a.m. at The Ohio State University at Lima.

Field demonstrations will be conducted by the Ohio Chapter of Land Improvement Contractors of America in an open house-style format throughout the day and a variety of conservation practices will be on display featuring Extension and industry experts. The event is free and open to the public and parking will be available on site. Registration is required to attend. The event and registration details are available at go.osu.edu/limadrainageday.

Official Flyer

The field day will also feature the implementation and demonstration of conservation practices aimed towards water quality improvements and ecological protection. Experts will cover two main practices: drainage water recycling and saturated buffers. The DWR system will feature a recently constructed 5 million gallon-capacity water retention pond that will collect runoff and drainage water from about 40 acres. The stored water can be used later in the growing season for irrigating crops. Representatives from Valley Irrigation will discuss a center-pivot irrigation system. These practices have been implemented as part of the agricultural nutrient runoff treatments project funded by the U.S. Environmental Protection Agency through an assistance agreement with the Ohio Environmental Protection Agency. Lunch will be provided and will include a short program.

The organizing team includes Ohio State Lima, Ohio State University Extension in Allen County, Allen County Soil and Water Conservation District, and OLICA.

For more details and/or sponsorship information, contact Nic Baumer, agriculture and natural resources Extension educator, at baumer.15@osu.edu or Dr. Vinayak Shedekar, assistant professor of agricultural water management, at shedekar.1@osu.edu.

About the farm

The field day will take place at the Ohio State Lima Regenerative Farm, which started in 2020 and provides research and educational opportunities focused on regenerative farming practices. The farm at Ohio State Lima is a learning laboratory for farmers to see how regenerative ag can work in the real world and how conservation practices can improve outcomes both on individual farms and collectively.

Adequate drainage is a necessary step in the transformation of the farmland towards a regenerative farm. The team envisioned a project to implement farm drainage and associated conservation practices on about 120 acres in four years as part of a project funded by the Sustainability Institute at Ohio State. The project provides a unique opportunity to demonstrate quality construction and installation practices for farm drainage through a partnership with OLICA and its associate members.

As we reach the middle of June, there is growing concern for human and livestock welfare as we approach our first heat wave of the season. With forecast highs in the mid to upper 90s and little relief in the evenings in the coming week, steps need to be taken to ensure everyone stays cool and safe.

Looking at the numbers:

• On April 24, 2024, the Occupational Safety and Health Administration (OSHA), under the Department of Labor, presented a draft of the framework that addresses heightened efforts to keep workers safe in the heat. This particularly focuses on dangers to agricultural workers. Since 2022, OSHA has conducted almost 5,000 inspections that were heat-related.
• A study using the Census of Fatal Occupational Injuries database found that heat-related deaths are 35 times higher in farm workers when compared to workers in other industries.
• Ohio State University researchers have estimated that economic loss to the United States livestock and poultry industries due to heat stress can range from $1.9 to $2.7 billion annually.

Keeping an eye on the weather forecast is the first step to prevention. Much attention is given to tornados, severe storms, and floods. However, according to the National Weather Service, heat-related deaths are still the greatest weather-related cause of death in the U.S.

Heat advisories and excessive heat warnings are both based on the heat index which is a combination of air temperature and humidity. Heat advisories are issued when indices are expected to be 100 degrees Fahrenheit or higher for at least two days while excessive heat warnings are issued for indices of 105 Fahrenheit and higher for at least two days.

Heat exhaustion and heat stroke are real possibilities with indices this high while also possible at lower levels depending on the health of the individual. Here are some best management practices to keep you and your livestock more comfortable:

Farmers and employees:

1. Start the day well hydrated and keep drinking water regularly throughout the day. If you wait until you are thirsty, you have waited too long.
2. Keep particularly strenuous tasks (especially those requiring additional personal protective equipment) to the cooler parts of the day when possible.
3. Increase the number of breaks and slowly build up a tolerance to working in the heat, especially in the first few high heat events in the season.

Livestock:

1. Ensure all ventilation equipment in barns is well maintained and functioning properly. If temperature alarms are present, test them.
2. Always have fresh, clean water available to the animals.
3. Shade must be available for animals not confined in structures.
4. Consider changing feeding times for animals. Feed intake produces heat. This usually peaks 4 to 6 hours after feeding. Receiving more of the daily ration after the heat of the day will help relieve some of this added stress.

Prevention of heat-related illness is ideal, but awareness of the signs to watch for is also important to be prepared for action. According to OSHA, heat exhaustion symptoms include fatigue, irritability, thirst, nausea, dizziness, heavy sweating, and elevated body temperature or fast heart rate. If you or someone you are with is experiencing these symptoms, move to a cooler area and cool the body by loosening clothing, drinking water, fanning, or use cool, wet towels. If symptoms persist, seek medical attention.

Heat stroke is the most serious of heat-related illnesses. Regardless of age, over 20% of those suffering from heat stroke will die. In addition to the symptoms of heat exhaustion, a heat stroke victim will also show signs of confusion, slurred speech, unconsciousness, seizures, or hot, dry skin. If these additional symptoms are observed, take the same action as heat exhaustion, and dial 911 immediately.

We’re entering a period of hot, dry weather and the long-term forecast for this season suggests that these conditions are likely to persist during the summer and through harvest. With variable planting dates across the state, there is also a range in current crop growth stages and overall status, which means there are also different weed management activities taking place over the next month. There are some considerations to keep in mind as we aim to manage weeds when temperatures are high, and rainfall is scarce.

• Residual Herbicides – The incorporation or activation of residual herbicides can be insufficient in areas that receive less than ~ 0.5 to 1 inch of rainfall. Without some sort of incorporation or activating rainfall, the product does not enter the soil solution and is not available for uptake by germinating weeds. A layered residual strategy for the control of waterhemp is still recommended, especially where crops were planted early and preemergence herbicides are starting to decrease in concentration and lose efficacy. Rain will still be needed to incorporate these later-applied residual herbicides into the soil profile for maximum efficacy.  

• POST Applications – Plants respond to drought stress in part by increasing the thickness of the cuticle, or the waxy outer layer of the leaf, to preserve water. This can result in decreased herbicide absorption, and translocation and metabolism within the plant are also affected. Systemic herbicides are especially at risk of reduced efficacy in these conditions. The use of the right adjuvant product and rate can help to increase absorption by improving leaf coverage and product uptake. Follow the label and herbicide/adjuvant manufacturer recommendations to determine the best adjuvant type and rate in these conditions. Some labels also include specific information related to applications in dry weather. Be aware that an increase in activity from the use of adjuvants can also lead to increased crop injury, and that applications early or late in the day may reduce the risk of injury. Contact herbicides are also more active when applied during hot weather, and crop injury from applications of these products may increase as well. Where residual herbicides were less effective due to lack of rainfall, a two-pass POST program should be considered to manage the potentially higher weed densities.

• Weed Emergence – Dry conditions can delay the emergence of weeds to some degree, especially those in the upper portion of the soil, and those that emerge from smaller seeds. Larger seeded species and those at lower depths will be less affected, as they have more energy reserves and access to more water for imbibition and growth, respectively. In dry weather patterns, weed emergence flushes may occur periodically following rainfall events.

• To Wait or Not to Wait – One question that often comes in when rainfall is limited is whether it’s better to apply POST herbicides soon, when weeds are smaller, or to wait until after a rain event and the potential following flush of weed emergence. Weeds are most effectively controlled when they are smaller and are actively growing. Drought and heat stress can impede control efforts and herbicide efficacy, and large weeds are more difficult to control. This is especially true if the stress-inducing conditions persist and weeds “harden off”. For this reason, it is a good strategy to wait for the extremely high temperatures to pass before making an application, for greater crop safety and herbicide efficacy, and to ensure weeds are actively growing. However, it’s not necessarily better to wait for a rain before making a POST pass. As mentioned, plants that persist through hot and dry weather often produce thicker cuticles, and it can be difficult for herbicides to get into the plant and be effective. For this reason, it might be best to spray when weeds are as small as possible unless there is some definite rain in the forecast.

• Antagonism – Dry conditions can increase issues from antagonism, especially when using POST grass (clethodim) and broadleaf (2,4-D, dicamba, etc.) herbicides together. When applied together, control from these herbicides can be reduced, especially when applied to larger grasses with smaller root systems. Sequential applications that separate these products can help overcome this antagonism. Waiting seven days between applications when the broadleaf herbicide is applied first, and about one day when the grass herbicide is applied first, can reduce antagonism concerns.

• Dicamba Restrictions – There are two main considerations when making applications of dicamba at this time of year. The first is to avoid applications when temperatures exceed 85 degrees, to reduce the risk of off-target movement and injury of sensitive plants. The second consideration is the upcoming cutoff date. The three dicamba products labeled for over-the-top use in soybean (Xtendimax, Engenia, and Tavium) cannot be applied after June 30^th in Ohio. There is also a growth stage cutoff, which may have been surpassed at this point depending on the planting date. The growth stage cutoff for Tavium applications to dicamba-resistant soybean is through V4, and up to R1 for XtendiMax.

Here are some more resources with information related to weed management in hot, dry weather:

• Adjuvants with Herbicides: When and Why They Are Needed https://cropprotectionnetwork.org/publications/adjuvants-with-herbicides-when-and-why-they-are-needed
• The Weed Control Guide for OH, IN, IL, and MO https://extensionpubs.osu.edu/category-2c-agricultural-weed-control/