C.O.R.N. Newsletter: 2016-11
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Planting and Pollinators
Beekeepers in Ohio benefitted from the generally mild winter of 2015-2016. In Columbus we lost less than 20% of our colonies over winter. Spring is the only reliably good season for bees in Ohio. Colonies that survived the winter and new colonies brought up from the Gulf Coast or California are currently in the process of harvesting nectar and pollen from spring-blooming trees and weeds. Little honey will be made from this spring bounty as most will be eaten by the bees themselves as they multiply and grow into large productive colonies that will be able to make a honey crop off of clovers, black locust, alfalfa and soybean in the coming months. Additionally, robust colonies will be needed to pollinate the fruit trees soon and pumpkins, squash and cucumbers later in the summer.
Spring build-up of honey bee colonies can be directly threatened by corn planting. Insecticide seed treatments used on corn seed generate an insecticidal dust when they are planted. Bees may encounter a cloud of insecticidal dust as they cross corn fields to visit the dandelions and blooming trees in field margins. Insecticidal dust can also settle on these flowers that bees are visiting. Insecticides formulated as dusts are the absolute worst for honey bees because they do not immediately kill the bees that encounter the insecticide. Rather than causing immediate death, the dust is packed up with the pollen and brought back to the colony where it is fed to young bees inside the colony.
In spring of 2015, we sampled pollen from ten bee yards in the counties west of Columbus. During corn planting, all colonies were bringing back pollen containing corn seed treatment insecticides. While no spectacular bee-kills were observed in our colonies, we did observe a significant increase in the number of dead bees appearing in front of colonies during the week of corn planting in 2015. While the long-term consequences of planting-related mortality are not clear, it is an unwelcome additional stress on bee colonies that are already under stress from mites, diseases and nutritional problems.
Corn growers can limit exposure of seed treatment dust to honeybees by 1) starting with clean and weed-free fields; 2) following recommendations for using talc; 3) avoid planting on windy days; and 4) following proper disposal procedures when finished.
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Rusts on Wheat and Barley: An Update
Last Thursday I received reports of, and confirmed through pictures, stripe rust in southern Ohio. Reports coming in today suggest that the disease has since spread and may even be increasing in severity. This is very early for Ohio and is a cause for concern, especially since this disease develops best and spreads quickly under cool, rainy conditions, similar to what we have had over the last few weeks and will likely continue to have this week. Developing this early (before heading) on a susceptible variety under favorable weather, this disease has the potential to cause substantial yield loss.
Reports and pictures coming in today also indicate that rust is developing on barley. This has led to questions about rust spreading from wheat to barley and vice versa. Both crops can be affected by leaf rust, stripe rust, and stem rust, but the fungi are different. In other words, the leaf rust pathogen does not cause stripe rust and the stripe rust pathogen does not cause stem rust. In addition, the wheat rust fungi generally do not jump from wheat to barley or vice versa. Each crop has its own specialized and specific set of rust fungi. For instance, wheat leaf and stripe rust are caused by Puccinia triticina and Puccinia striiformis f. sp. tritici, respectively, “strains” that are specific for wheat, whereas leaf and stripe rust of barley are caused by Puccinia hordei and Puccinia striiformis f. sp. hordei, respectively, “strains” specific for barley.
However, regardless of the rust disease and the crop, the important thing to note is that they can all be managed with the same set of fungicides, but applications have to be well-timed in order to be effective against any of these diseases - once symptoms are seen, the earlier, the better in most cases. Please refer to the updated factsheet # PLPATH-CER-12 for more on rusts diseases of wheat (http://ohioline.osu.edu/factsheet/plpath-cer-12) and click on the link below for a comparative look at different rust diseases of wheat and barley:
https://www.ars.usda.gov/SP2UserFiles/ad_hoc/36400500Cerealrusts/Rust_Diseases_National.pdf
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Rainfastness of Fungicides in Wheat
Recent reports of leaf and stripe rust and the fact that the wheat crop is approaching flowering have producers thinking about applying a fungicide to protect their crop. However, it has rained consistently over the last several days and there is more rain in the forecast for the rest of this week. In addition to increasing disease risk, frequent rainfall may reduce fungicide efficacy by washing it off of the plant surface or diluting it to a less effective concentration. However, the extent to which these occur depends on how soon and how much it rains after the product is applied, the formulation of the product and whether it is applied with a surfactant, the properties of the fungicide, and the characteristics of the plant surface being treated.
The Rainfastness of a fungicide (or pesticide in general) refers to “the time needed between an application and a rain event for the product to maintain its effectiveness when compared to the same product applied in the absence of rain”. Quite often this information is vague or missing from product labels. For instance, some sources may say that the product is rainfast “as soon as it dries” or anywhere from 15 min to 2 hours after application. There is no simple answer to the question of rainfastness, as it depends on the product and treatment conditions. However, we have done some research on the rainfastness of Prosaro (plus a surfactant) for head scab control in wheat under wet field conditions and under dry greenhouse conditions. Our results showed that when Prosaro was applied as a protectant, before the fungus infected the wheat head, the rainfastness was 15 minutes under dry conditions, and when applied after infection had already occurred, the rainfastness was 30 minutes. However, when tested under wet field conditions (dew on the wheat heads), the ranfastness was about 60 minutes.
Results from our study on the rainfastness of Prosaro for head scab control should not be directly extrapolated to other fungicides, other diseases, or other plant parts. However, it can be used as a guide for making decisions about fungicide applications under rainy conditions, showing that rainfastness is generally shorter if the canopy is dry, about 15 min, and much longer, an hour or more, when the canopy is wet. To be on the safe side, if at all possible, try to apply the fungicide at least an hour before it rains.
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Wheat is beginning to head out: time to start monitoring the risk for Scab
Wheat is now heading out in some fields, particularly in Southern Ohio, and will likely begin flowering in various parts of the state over the next two to three weeks. On average, it usually takes about 5 days from full head emergence (Feekes 10.5) to flowering, and flowering is usually over in about the same number of days. However, flowering could take a bit longer to occur and the flowering window could be much wider under cool conditions similar to those forecasted for the next week or so. Once wheat begins to flower, scab and vomitoxin become our biggest concerns. It is therefore time for a refresher on head scab, and some useful tips to help you use the scab forecasting system to monitor the risk of this disease.
Scab develops best and the risk is highest when wet, humid weather conditions occur during flowering. These conditions favor the production of spore by the scab fungus, Fusarium graminearum, infection of the wheat heads, development of the disease, and production of vomitoxin. Scab not only affects wheat, it also affects barley and other small grains, causing significant grain yield and quality losses, particularly if the variety is susceptible and the right fungicide is not applied at the correct growth stage. Unlike foliar diseases, you cannot wait until you see scab symptoms to make a fungicide application. It usually takes two to three weeks for symptoms to develop; by that time it is too late to apply a fungicide. If it rains and you cannot apply the fungicide at the recommended flowering stage for wheat or heading for barley, you can still get good control with applications made about 4-6 days after the recommended time.
Use the scab risk tool at http://www.wheatscab.psu.edu/ to help you monitor the risk for scab and as a guide for making fungicide application. The tool is currently showing that the risk is moderate to high (yellow and red colors on the map) across most of the state for wheat flowering today and will continue to be moderate to high over the next three days. Most of our wheat is not yet at the flowering growth stage, but continue to monitoring the crop to see when flowering begins and keep your eyes on the forecasting system to see how the risk changes as the crop approaches flowering. Prosaro and Caramba are the two fungicides recommended for head scab control. Stay away from the strobilurins when the risk for scab is high as they have been linked to higher grain contamination with vomitoxin. Click on the links below to see updated factsheet # PLPATH-CER-06 for more on head scab of wheat and barley and factsheet # PLPATH-CER-03 for guidelines on how to use the scab forecasting system.
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Adjusting Corn Management Practices for a Late Start
As of Sunday May 8, 30 percent of Ohio’s corn crop was planted, which is 14 percent behind last year and 5 percent behind the five-year average (https://www.nass.usda.gov/Statistics_by_State/Ohio/Publications/Crop_Progress_&_Condition/index.php). Weather forecasts indicate more rain this week possibly continuing through Thursday. As prospects for a timely start to spring planting diminish, especially in northern Ohio, growers need to reassess their planting strategies and consider adjustments. Since delayed planting reduces the yield potential of corn, the foremost attention should be given to management practices that will expedite crop establishment. The following are some suggestions and guidelines to consider in dealing with a late planting season.
Although the penalty for late planting is important, care should be taken to avoid tillage and planting operations when soil is wet. Yield reductions resulting from "mudding the seed in" are usually much greater than those resulting from a slight planting delay. Yields may be reduced somewhat this year due to delayed planting, but effects of soil compaction can reduce yield for several years to come. (Keep in mind that we typically don’t see significant yield reductions due to late planting until mid-May or even later in some years).
If you originally planned to apply nitrogen pre-plant, consider alternatives so that planting is not further delayed when favorable planting conditions occur. Although application of anhydrous N is usually recommended prior to April 15 in order to minimize potential injury to emerging corn, anhydrous N may be applied as close as a week before planting (unless hot, dry weather is predicted). In late planting seasons associated with wet cool soil conditions, growers should consider side-dressing anhydrous N (or UAN liquid solutions) and applying a minimum of 30 lb/N broadcast or banded to stimulate early seedling growth. These approaches will allow greater time for planting. Similarly, crop requirements for P and K can often be met with starter applications placed in bands two inches to the side and two inches below the seed. Application of P and K is only necessary with the starter if they are deficient in the soil, and the greatest probability of yield response from P and K starter is in a no-till situation. Remember the longer our planting is delayed, the less beneficial a starter with P and K will be, because later planting dates typically have higher soil temperatures.
Keep time expended on tillage passes and other preparatory operations to a minimum. The above work will provide minimal benefits if it results in further planting delays. No-till offers the best option for planting on time this year. Field seedbed preparation should be limited to leveling ruts that may have been left by the previous year’s harvest - disk or field cultivate very lightly to level. Most newer planters provide relatively good seed placement in "trashy" or crusted seedbeds.
Don't worry about switching hybrid maturities unless planting is delayed to late May. If planting is possible before May 20, plant full season hybrids first to allow them to exploit the growing season more fully. Research in Ohio and other Corn Belt states generally indicates that earlier maturity hybrids lose less yield potential with late plantings than the later maturing, full season hybrids.
In delayed planting situations, use the optimal seeding rates for the yield potential of each field. Recommended seeding rates for early planting dates are often 5-10% higher than the desired harvest population because of the potential for greater seedling mortality. However, soil temperatures are usually warmer in late planted fields, and as a result germination and emergence should be more rapid and uniform. So, as planting is delayed, seeding rates may be lowered (decreased to 3% higher than the desired harvest population) in anticipation of a higher percentage of seedlings emerging.
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Heat Unit Accumulation and Corn Emergence
There have been reports of slow corn emergence in some areas and that corn planted more than three weeks ago is not yet emerging. Is this cause for concern? Not necessarily. Corn requires about 100 growing degrees days (GDDs) to emerge (emergence requirements can vary from 90 to 150 GDDs). To determine daily GDD accumulation, calculate the average daily temperature (high + low)/2 and subtract the base temperature which is 50 degrees F for corn. If the daily low temperature is above 50 degrees, and the high is 86 or less, then this calculation is performed using actual temperatures. If the low temperature is less than 50 degrees, use 50 degrees as the low in the formula. Similarly, if the high temperature is above 86 degrees, use 86 degrees in the formula. The high cutoff temperature (86 degrees F) is used because growth rates of corn do not increase above 86 degrees F. Growth at the low temperature cutoff (50 degrees F) is already near zero, so it does not continue to slow as temperatures drop further.
If it takes a corn hybrid 100 GDDs to emerge, and daily high and low temperatures average 70 and 50 degrees following planting, 10 GDDs accumulate per day, and corn should emerge in about 10 days (100 GDDs to emerge/10 GDDs per day = 10 days). However, if daily high and low temperatures are cooler, averaging 60 and 45 degrees after planting, 5 GDDs accumulate per day, and it may take nearly 3 weeks (100 GDDs to emerge/5 GDDs per day = 20 days) for corn to emerge.
Given this relationship between GDD accumulation and emergence, growers should not be too surprised if their mid to late April planted corn will require more time to emerge than later planted corn. While there have been periods since mid- April when air temperatures have been warmer than average, with maximum high temperatures above 70 degrees, soil temperatures (as measured at the 2-inch soil depth) may be considerably cooler, in the 50 to 60 degree F range. Seedling emergence is dependent on soil temperature and air temperature. Also, keep in mind that these estimates of emergence based on GDDs are approximate and can be influenced by various factors including residue cover, tillage, and soil organic matter (soil “color”) and moisture content.
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Rainy day entertainment – get up to speed on pigweed ID
When you finish every possible indoor task during this rainy spell, take a few minutes and check out our latest video on pigweed identification. The video compares four aspects of pigweed biology that we use to differentiate between redroot pigweed, waterhemp, and Palmer amaranth – pubescence, petiole length, leaf shape, and inflorescence (seedhead) characteristics. Find it at the OSU weed management website – http://u.osu.edu/osuweeds. There are far worse ways to spend a few minutes.
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Fertilizer Applicator Certification Training Materials Available Online
The number of individuals who have been trained for the Ohio Fertilizer Applicator Certification by Ohio State University Extension Agriculture and Natural Resources staff has reached 11,859 as of April 30, 2016. The ongoing training has generated a lot of positive response from farmers who attended. Requests have come in to make short review videos of key parts of the training available for review. The videos which range from 5 to 15 minutes in length have been posted to https://agcrops.osu.edu/video/fact-videos. In addition to the videos, the website also has copies of the training manual and other materials that can be printed from the 2016 sessions.
These videos are provided as review materials for anyone interested in soil fertility information related to plant production, water quality impacts and have completed the necessary Ohio Department of Agriculture forms. To attain Fertilizer Applicator Certification you must attend a workshop where training is offered. To learn more about who needs certification, and trainings near you, visit the Ohio Nutrient Education website
The current video series covers the following topics:
1. Introduction: Fertilizer Applicator Certification Laws-- SB150 and SB1
2. Calculate 12 and 24-hour Precipitation Forecasts
3. Water Quality and Agriculture
4. Agriculture and Types of Water Quality Impairments
5. Why the Focus on Agriculture?
6. Edge of Field Studies
7. Soil Sampling
8. Soil Sampling and the Lab
9. Tri-State Fertilizer Recommendations and Phosphorous Management
10. Training Exercise 1: Reading a Soil Test Result for Phosphorous
11. Training Exercise 2: Making a Fertilizer Recommendation
12. Water Quality and the Fate of Nitrogen
13. Determining the Nitrogen Rate and Timing for Ohio
14. Tools for predicting Crop Nitrogen Need
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Rapid Transition from El Nino to La Nina Continues
May 23 - May 31 Rainfall 1.0-1.5 inchesMay 23 - May 31 Temperatures +1F to +3FMay 10 - May 22 Rainfall 1.5-2.5 inches north / 2-4 inches southMay 10 - May 22 Temperatures -1F to -3FDates Weather Element OutlookThe trend this spring has been on the warmer and wetter side except for a drier period in the last 30 days in parts of the state. The images below show departures from normal over the region the last 30, 60 and 90 days at 4 km resolution.
After a very warm March we have been running behind on the growing degree days as provided by the NOAA Midwest Climate Center... http://mrcc.isws.illinois.edu/cliwatch/special_topics/agriculture.html#mgdd . The area from Illinois through Indiana into Ohio has been most impacted by growing degrees days. Four inch soil temperatures are mostly in the 50s.The dryness from April appears to shift north into the Great Lakes allowing a boundary to sit in the region more often than not the next several weeks. Therefore, it appears May will likely now stay on the wetter side and impact planting that has not been done especially in southern and western areas of Ohio. Overall we have revised May from warmer and drier to normal temperatures and wetter than normal.
We have been talking about the rapid transition away from a strong El Nino toward La Nina conditions in the Pacific Ocean. This is occurring. The problem is when these rapid transitions occur, the skill of our climate models decreases. In addition, spring is the lowest skill of the year for weather and climate models. Saying that, it appears there are changes in the temperature and precipitation forecasts for May!
The outlook through May 22 calls for temperatures below normal and rainfall normal to above normal. The outlook from May 23 through May 31 calls for temperatures above normal and rainfall normal to above normal. Normal rainfall is about an inch per week.
The good news is freeze season is over. However, some very patchy frost is possible May 15/16 in low lying areas in northern Ohio but nothing that will be of impact.
The outlook for summer remains with above normal temperatures and and turn to drier weather. In fact, the likely scenario is that we will do a classic abrupt switch from damp to very warm and dry in very short order somewhere between late May to late June.
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June Small Grains Field Days
There are three excellent field day opportunities being planned for small grain producers across the state. The three days cover a variety of production issues, nutrient management practices, and small grain uses. Locations are in Pickaway, Wayne and Wood Counties. Be sure to check out the location closest to you! For detailed information visit: https://agcrops.osu.edu/events
June 1, Pickaway County, On-Farm Wheat Field Day, 19076 Florence Chapel Pike, Circleville at 9 am.
Topics include: Wheat freeze tolerance, minimum wheat stand, wheat fertility, Wheat disease identification and management and Ohio Wheat Performance Test. Registration is free, but we are requesting registration by Friday, May 20 for lunch count. Lunch will be held at Jackson Township Hall. Please register through the Pickaway County Extension office (740-474-7534 or estadt.3@osu.edu).
June 14, Wayne County, Small Grains Field Day, OARDC Schaffter Farm at 3240 Oil City Rd., Wooster. Registration at 9:30 am with program starts at 10:00am.
Topics that will be covered at the Small Grains Field Day include: Malting Barley, Small Grains as Cover Crops and Alternative Forages, Wheat Production Agronomics, Wheat and Barley Disease ID and Management, Wheat Breeding and Evaluation Update and demonstration on Small Grain Crimping and Soybean Seeding Demonstration plus Modified Relay Intercropping of Soybeans into Wheat Demonstration. Pre-registration is requested. The cost is $25/person if registered by June 3. Late registration after June 3 is $35/person. Registration includes handout materials, lunch and refreshments. Registration should be sent to the Wayne County Extension office at 428 West Liberty Street, Wooster OH 44691.
June 21, Small Grain Field Day, Northwest Agricultural Research Station, 4240 Range Line Road, Custar. at 9 am.
Topics include wheat breeding, nitrogen and sulfur management, disease identification and management and determining minimum stand requirements. The event is free and open to the public. No pre-registration is required.
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.
Contributors
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 an accessible format of this publication, visit cfaes.osu.edu/accessibility.