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Corn Newsletter : 2018-14
Head Scab Update: Week of May 21Author(s): Pierce Paul
For those fields of wheat flowering and fields of barley head-out today (May 22), the risk for head scab is moderate in the northern-most counties and in the eastern portion of central Ohio (according to the scab forecasting system at http://www.wheatscab.psu.edu). Persistent rainfall and high relative humidity over the last several days are the primary reasons for the moderate-risk prediction in these regions. However, thanks to relatively cool temperatures, and dryer conditions in some cases, the risk remains low in most other areas of the state.
Remember, the scab fungus requires moisture in the form of rainfall or high relative humidity and warm temperature to produce spores in crop residue, and for those spores to spread to wheat and barley heads, germinate, and infect. However, since infection occurs primarily between pollination and early grain-fill, scab risk is linked not only to weather conditions, but also to crop growth and development. Consequently, fields of wheat that are not yet at the flowering growth stage and fields of barley that are not yet at the heading growth stage are at low risk for head scab.
However, this picture will likely change over the next few days as it warms up, continues to rain, and more fields reach the flowering/heading growth stage. Continue to keep your eyes on the weather and the forecasting system, and be prepared to apply a fungicide. The forecasting system uses average conditions during the 15 days immediately before flowering to assess the risk of scab. Although it has been relatively cool over the last 10-12 days, with the rainfall and humidity we have experienced so far in most areas, it would only take a few (3-5) days of warm, wet conditions for the risk of scab to increase.
Wheat fields flowering and fields of barley still heading later this week and into the weekend (May 24-27) in the northern half of the state will likely be at the greatest risk for scab. Be prepared to protect them. Prosaro and Caramba are the two fungicides recommended for head scab management, and you will have a 4-5-day window from the day the crop reaches the critical growth stage (heading for barley and flowering for wheat) to make an application. Do remember to stay away from the strobilurins when the risk for scab is high as this group of fungicides has 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 and interpret the scab forecasting system.
Sidedressing Manure into Newly Planted and Emerged CornAuthor(s): Glen Arnold, CCA
Ohio State University Extension has conducted manure research on growing crops for several years in an effort to make better use of the available nutrients. Incorporating manure into growing corn can boost crop yields, reduce nutrient losses, and give livestock producers or commercial manure applicators another window of time to apply manure to farm fields.
Our research started with using manure tankers modified with narrow wheels and in recent years progressed to using drag hoses on emerged corn. We now feel confident that liquid livestock manure can be surface applied or incorporated into corn from the day of planting to the V4 stage of development.
In Darke County, Harrod Farms has used a drag hose to apply swine finishing manure to their corn fields in the 2014-2017 growing seasons with great success. The corn was generally at the V3 stage of growth when the manure was incorporated as a sidedress.
Harrod Farms Plot Results
Harrod Farms Four-Year Manure Incorporation Drag Hose Corn Plots
Swine Finishing Manure
Average yield: bu/acre
The manure treatments have averaged 14.8 bushels per acre more than the 28% UAN treatments. The Harrods incorporated approximately 6,500 gallons of swine finishing manure per acre to provide all the sidedress nitrogen needed. The fields received 10 gallons per acre of 28% UAN as row starter. Harrod Farms plants their corn fields at an angle to make the drag hose work best for the commercial manure applicator.
In addition to providing the sidedress nitrogen, the manure application also provided almost precisely the amount of phosphorus and potash needed for both the corn crop and the soybean crop the following season.
Additional on-farm manure sidedress plot results can be obtained by clicking on the On-farm Research link on the OSU Extension Agronomics Crops team website at http://agcrops.osu.edu/ or follow OSU extension’s manure research on Facebook at: Ohio State Extension Environmental and Manure Management.
OSU Extension’s Nutrient Stewardship YouTube site is: www.youtube.com/channel/UC7jUsQNGM8fCHjbZUdT9pKw
Additional drag hose videos can be found at:
Alfalfa Fiber Content Estimates in Ohio
Lead Author: Angela Arnold
Alfalfa development over the past week has continued at a a rapid pace and caused an increase in neutral detergent fiber (NDF) values. Alfalfa NDF was estimated in different counties in Ohio using the height and stage of alfalfa, as described in last week’s article about estimating alfalfa fiber content. The table below indicates average NDF and stage of alfalfa in four different counties in Ohio. It is time to harvest high quality alfalfa in western Ohio!
Vegetative / Early Bud
Alfalfa producers should keep a close watch on alfalfa development as warmer temperatures persist in the region. Producers should consider harvesting as soon as a weather window opens up. It is likely several alfalfa fields around the state will be harvested this week if weather permits.
Grass fields are ready for harvest. In fact, orchardgrass is already flowering in western Ohio. Grasses that have reached the early heading stage are already past the prime for high producing lactating dairy cows; however, grass in early heading is still good for feeding to many other classes of livestock with lower requirements than lactating dairy cows. Begin harvesting grasses as soon as you see a good harvest window.
There have also been some reports of alfalfa weevil damage / feeding across the state. In addition to keeping a close watch on alfalfa development for making harvest decisions, producers should be monitoring alfalfa weevil to determine if harvesting earlier is warranted. If alfalfa weevil damage is at or over the economic threshold, growers should consider cutting earlier to eliminate the risk of losing quality due to weevil feeding. Visit HERE for a factsheet on alfalfa weevil.
The Season for Slugs
Late planting in many areas, the small size of both soybean and corn plants, and damp, cool conditions in some areas all lead to a greater damage potential from slugs. Although all fields should be scouted for slugs, focus on no-till fields or those fields with cover crops, a history of slug problems, poor weed control, or a lot of residue left on the field. We don’t have good economic thresholds for slugs in corn or soybean, yet the following guidelines are to helpful in scouting for their presence and intensity. Egg and adult sampling should occur until late May/early June when newly hatched juveniles that are particularly damaging are found. Eggs look like small, pearly BBs and are near the soil surface, buried only slightly under thin soil or residue. Juvenile slugs are quite small.
The most important time to sample for the smaller juvenile slugs is when defoliation is occurring. The best technique to sample juvenile slugs is to visit the field at dusk or immediately after dark (a flashlight helps). Juvenile slugs are easily found feeding on the plants or crawling over the crop residue. Although there are various sampling procedures involving embedded soil traps with or without beer, these traps do not give a good estimate of juvenile slugs; they are more appropriate for adult slugs.
There are few rescue treatments available for severe slug damage. If caught early enough, fields may be replanted. There are two available poisoned bait options, those containing metaldehyde (Deadline MPs and others), and those with iron phosphate (an organic option). See our slug fact sheet HERE for more information.
Cressleaf Groundsel in Wheat and Hay
It’s definitely a big year for cressleaf groundsel (Senecio glabellus), the yellow-flowered weed that can be seen about everywhere right now. While it is most often found in no-till corn and soybean fields that have not yet been treated with burndown herbicides, there seems to be an above-average number of wheat and hayfields and pastures with substantial populations.
Cressleaf groundsel can be identified by its hollow and grooved stem with a purplish color, and yellow sunflower-type flowers. It is a winter annual that emerges in late summer into fall, and can infest late-summer seedings of forages and hay, and fall seedings of wheat. It can be controlled with herbicides in most crops, ideally in the fall or early spring when plants are small and most susceptible to herbicides.
At this time of the year, plants are flowering and will be going to seed, thus ending their life cycle. Applying herbicides to hay fields at this time probably won’t do much to reduce the risk of toxicity to animals (and it’s too late to apply any herbicides to wheat). Plants that have flowered are more difficult to control, and will still be there even if killed by herbicides. Major management goals at this time are mowing infestations soon enough to prevent seed production, and deciding what the risk of toxicity in hay or straw is based on the level of infestation. Cressleaf groundsel should not be present in hay fields following the first cutting. However, it is advisable to scout fields in late fall for the presence of newly emerged plants, and treat with herbicides if necessary.
Cressleaf groundsel is poisonous to cattle, horses, goats, sheep, and humans due to the presence of pyrrolizidine alkaloids (PAs). Symptoms include weight loss, unthriftiness, poor hair coat, anorexia, behavioral changes, sunscald, aimless walking, diarrhea, jaundice, liver damage, and possibly death. All parts of the plant are toxic. Drying or ensiling the plants during the hay or straw making process does not reduce the toxicity of cressleaf groundsel. Historically, no confirmed cases of poisoning by S. glabellus have been reported by the Ohio Department of Agriculture’s Animal Disease Diagnostic Laboratory, although liver lesions suggestive of PA poisoning have been observed on rare occasions.
Although the presence of the occasional plant in a hay or wheat field is probably not cause for concern, producers are advised to avoid harvesting areas of the field that have high concentrations of the plants. Or bale and discard hay or straw from those areas of the field, if this is more desirable than leaving the plant residue in the field.
This is not a new problem, and we have a fact sheet available on cressleaf groundsel at the OSU Weed Management website – http://u.osu.edu/osuweeds. Hover over “weeds”, and then click on “other” to get to it.
This article was originally published in issue 2016-13.
Kudzu Bug Monitoring Update
Additional Authors: Ed Brown, Marcus McCartney, Kevin Fletcher
The kudzu bug is currently being monitored for in nine counties in Ohio including Adams, Athens, Butler, Clermont, Madison, Meigs, Montgomery, Ross and Washington. Traps were set in May and will be checked weekly through June. Overall, zero kudzu bugs have been found on traps in the monitoring counties. Figure 1 illustrates the average number of kudzu bug / total number of traps located in each county participating in the kudzu bug monitoring (highlighted in red).
Although the kudzu bug has yet to be found in Ohio; the distribution has been rapidly expanding. It is now found in Kentucky, and the I-75 corridor connects Ohio to the Southeastern US where it is very prevalent. The kudzu bug is a serious invasive pest of soybean causing a reduction to yield with heavy infestation. Both immature and adult kudzu bugs feed on soybean plants with piercing-sucking mouth parts. Adult kudzu bugs can be identified by their globular shape and greenish-brown color (see below). In addition to soybean, the kudzu bug also feeds on the kudzu plant, an invasive weed. If you suspect kudzu bug in your county please contact your local extension office.
About the C.O.R.N. Newsletter
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.
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.
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