Dr. Nicole Fiorellino, Extension Agronomist University of Maryland, College Park
With the arrival of a new seed lubricant product (DUST, Low Mu Tech, Calamus, IA), we evaluated its performance against two common seed lubricants, Graphite and Fluency (Bayer Crop Science, USA), and untreated check (UTC) plots in both corn and soybeans in 2019 at Wye Research and Education Center in Queenstown, MD. DUST is a soy protein lubricant and is reported to contribute to early plant vigor as well as be a cleaner alternative to commonly available seed lubricants such as graphite, which can create a mess for users of the product. As such, we utilized a completely randomized design with five replicates and evaluated emergence and early season vigor at 7, 14, and 21 days after planting (DAP). Stand counts were reported as number of 1,000 plants per acre, with plants counted in a 30 ft length of one corn row and plants counted in an area the size of 1/1000 of an acre in soybean plots. Early season vigor was assessed through collection of normalized difference vegetation index (NDVI) readings using a handheld Greenseeker sensor held approximately 1 m from the surface of the ground as the operator walked down the length of one corn or soybean row per plot. Corn was harvested when moisture approached 15% and yields are reported in bushels per acre corrected to 15% moisture.
Differences among seed lubricant treatments for plant population, early season vigor, and crop yield were analyzed using a mixed model analysis of variance using replication as a random variable using SAS 9.4 software. Coefficient of variation (CV%) are reported as a measure of variability at a test site and values less than 10% indicate enough precision existed to determine a significant difference.
Corn
Soybeans
Results
Based on the measurements observed in 2019, the DUST soy protein seed lubricant is comparable to other seed lubricants commonly used in Maryland for corn and soybean planting. There were no differences in emergence or yield among the treatments for either corn, indicating all seed lubricants perform as well as each other and a control plot with no seed lubricant used. Additionally, there was no effect of seed lubricant on early season vigor, as indicated by the company. Additional extension reports will include soybean yield data and economic analysis of the products, as there is a difference in price and amount of product recommended for use and if product performance is similar, as indicated by these results, then product cost will be a deciding factor for use.
Dr. Nicole Fiorellino, Extension Agronomist
University of Maryland, College Park
The University of Maryland offers a fee-based, corn hybrid performance testing program to local and national seed companies. The results from these replicated trials provide agronomic performance information about corn hybrids tested at five locations in Maryland considered representative of the state’s geography and weather conditions. During 2019, 56 hybrids were tested using three maturity groups: early season (17 hybrids), mid-season (14 hybrids), and full season (25 hybrids). Check hybrids were included in each of the five tests.
This year’s weather was welcomed compared to last year’s extreme precipitation. As reported in the results document, there was much less rainfall in 2019, with precipitation at all locations very similar to the long term average for each location. We experienced some drought at the end of summer (August through September in some locations), but yields did not seem to be impacted by this. Averaged over the five locations, yield for early (17), mid (14), and full (25) season hybrids was 196 bu/ac, 199 bu/ac, and 206 bu/ac, respectively. Compared to 2018, these yields were +11%, -1%, and +5%, respectively, to those observed for early, mid, and full season hybrids this season. Average yield for all hybrids tested at all five locations was 201 bu/ac or 10 bushels shy of the record yield of 211 bu/ac in 2011. Two locations had average yield greater than 210 bu/ac (Keedysville – 220 bu/ac and Clarksville – 236 bu/ac) with Clarksville average yield surpassing the record best location yield of 232 bu/ac at attained at Wye in 2016.
A list of hybrids and their performance across the state and at each individual location is presented in the results document, which can be downloaded from the MD Crops website at psla.umd.edu/extension/md-crops. You may also request a printed copy from your local Extension office.
Attached is the summary for the November WASDE published on November 8. After months of volatile WASDE estimates caused by weather and political events, the changes in estimates for the November WASDE are fairly small. Corn yield/acre estimate was down 1.4 bushels/acre to 167 bushels/acre. But the estimates for all areas of demand were also down slightly. The net effect is ending stocks down 19 million bushel to 1,910 million bushel and a stocks to use ratio of 13.7%.
Production and supply estimates for Soybeans were unchanged. Crushings were down slightly which increase the ending stocks 15 million bushel and a modest increase in the stocks to use ratio to 11.9%.
There were only slight changes in Wheat estimates.
Attached is the summary for the September World Agricultural Supply and Demand Estimates (WASDE) that was published on October 10. Corn harvested acres and yields were slightly adjusted. The estimate for beginning stocks were down 331 million bushels. Estimate for total use was down 90 million bushel. Other minor changes result in an estimate of endings stock 261 million bushel lower and a decrease in the estimate of Ending Stocks to Use Ratio from 15.5% in September to 13.8% in October.
Soybean harvested acres estimate decreased from 75.9 to 75.6 million acres. Yield estimate was adjusted up 1 bushel per acre. Beginning stock estimate was adjusted down and ending stocks estimate was down 180 million bushel, which significantly decreased the stocks-to-use ratio from 15.9% to 11.4%. In June, the estimated Stocks to Use Ratio was 24.9% and has been decreasing every month. But market prices have not responded significantly because of the uncertainty in the soybean market caused by the trade war.
There were only slight changes in Wheat estimates.
Maria Cramer, Edwin Afful, Galen Dively, and Kelly Hamby Department of Entomology, University of Maryland
Overview
Background: Due to their low cost, pyrethroid insecticides are often applied when other chemical applications are made. For example, they may be included in tank mixes with herbicides in early whorl corn and with fungicides during tasseling. These pyrethroid sprays often target stink bugs; however, the timing of these treatments is not ideal for stink bug management. Pyrethoid insecticides may harm beneficial insects that help keep pest populations in check and repeated use of pyrethroids can contribute to insecticide resistance.
Methods: In this study, we examined the effect of Bifenture EC® (pyrethroid active ingredient: bifenthrin) applied with herbicides in V6 corn and with fungicides in tasseling corn. We evaluated impacts on pests and beneficials at both application timings. Yield was measured at harvest.
Preliminary Results:At both application timings, Bifenture EC® did not improve insect pest management because pests were not present at economic levels. We did not find evidence for flare-ups of aphids or spider mites, but a rainy late summer made it unlikely that we would see many of these pests. There were no yield differences between the treatments.
Background
As a result of the low cost of pyrethroid insecticides, preventative applications are common, especially in tank mixes with other routine chemical inputs, such as herbicides and fungicides. However, lower grain prices and low insect pest pressure make it less likely that pyrethroid applications will provide economic returns. Bt hybrids1 and neonicotinoid seed treatments control many of the pests targeted by pyrethroid insecticides. Because they have broad spectrum activity, pyrethroids can negatively impact natural enemies2 which can result in flare-ups of secondary pests3. Tank mix timings may be less effective than applying when insect populations reach threshold. For example, when pyrethroids are combined with herbicide applications, they are too late to control early-season stink bugs and other seedling pests. When pyrethroids are combined with fungicide sprays at tasseling, few insect pests are present at damaging levels. Stink bugs may feed on the developing ear at this time, causing deformed “cowhorned” ears; however, this is rarely a problem in Maryland and stink bug damage is generally not economic throughout a field because feeding is primarily concentrated at the field edge4. Insecticide applications at tasseling have a high potential to affect beneficial insects, especially pollinators and natural enemies that are attracted to corn pollen.
Objectives: Our objectives were to determine the effect of pyrethroids applied preventatively in tank-mixes on corn pests, beneficials, and yield.
Methods: This study was conducted in 2018 and 2019 at the University of Maryland research farm in Beltsville, MD. For each application timing, we planted four replicate plots of a standard Bt field corn hybrid, DeKalb 55-84 RIB (SmartStax RIB complete Bt insect control in addition to fungicide and insecticide seed treatments) at 29,999 seeds per acre. Standard agronomic practices for the region were used.
Herbicide (same as above) + Insecticide (Bifenture EC® 6.4 oz/acre)
Treatments were applied at V6/V7. We visually surveyed corn plants for pest and beneficial insects before and after application. We also placed sentinel European corn borer (ECB) egg masses in the field to assess predation rates before and after treatment.
The fungicide timing compared two treatments:
Fungicide alone (Trivapro® 13.7 oz/acre)
Fungicide (same as above) + Insecticide (Bifenture EC® 6.4 oz/acre)
Treatments were applied at green silk. We inspected the ear zone and silks for pests and beneficial insects before application. After application, we recorded the number of ears with pest damage and the kernel area damaged. We also counted stink bug adults and cowhorned ears. Six weeks after application, we visually assessed plants for spider mite and aphid colonies.
Sampling for pests and beneficials (left) and; sentinel European corn borer egg mass (right).
Results
In the herbicide-timing study in 2019 we observed no effect on beneficial insects from the treatments (Figure 1). The most abundant beneficial species were minute pirate bugs and pink spotted lady beetles, which are very mobile and may have recolonized treated plots after treatment. Similarly, treatments did not affect predation on the sentinel egg masses, suggesting that the pyrethroid application may not have affected predators’ ability to locate and consume eggs. Across the treatments, 30-50% of egg masses were consumed by predators.
Minute pirate bug on European corn borer egg mass.
The treatments did not impact the number of beneficials at the herbicide timing (N.S.). The pyrethroid insecticide significantly reduced the number of plant hoppers and plant bugs from less than 4 per plant on average to less than 2 per plant (significantly different p<0.05, *), though these insects are not economic pests at this stage. There were never more than 2 stink bugs per 90 plants, well below the treatment threshold of 13 per 100 plants4.
In the fungicide-timing study in 2019, beneficials, especially minute pirate bugs, were abundant at the time of application (3 in every 10 plants), while stink bugs, the presumed target pest, were very rare (1 stink bug in every 68 plants). In 2018, stink bugs were similarly scarce. Overall pest abundance was low (1 in every 35 plants). After application, there was no difference in the incidence or amount of the corn ear damaged by worms, stink bugs, or sap beetles between treatments. Average stink bug and earworm incidence was roughly 1 in 10 ears, while sap beetle was even less frequent. Cowhorned ears and adult stink bugs were almost non-existent in both treatments.
Six weeks after application we found no differences in aphid or spider mite populations between the treatments, suggesting that pyrethroid applications at tasseling did not cause secondary pest outbreaks. We sampled after a period of dry weather; however, the late summer was rainy at Beltsville, which likely suppressed spider mite and aphid populations. Under drought-stress, reductions in the natural enemy population from pyrethroid use might contribute to flare-ups of aphids and spider mites.
Figure 1. Herbicide timing. July 3, 2019, Beltsville MD. Mean number of insects per 10 plants in V7 corn after treatment. N.S.=not significant. H=herbicide; P=pyrethroid.
Yield
For the herbicide timing and fungicide-timing (Figure 2) studies, treatments did not affect yields in either 2018 or 2019.
Conclusions
Figure 2. Herbicide timing (left) and fungicide timing (right), 2018 and 2019, Beltsville MD. Mean yield per acre under two treatments. Yields were not significantly different by treatment in either study. For the fungicide-timing study, 2019 yields were significantly higher than in 2018. N.S.=Not Significant. H=Herbicide; F=Fungicide; P=Pyrethroid.
Results from the 2018 and 2019 studies suggest that pyrethroid applications do not provide yield benefits in corn when tank-mixed with herbicides or fungicides, likely due to the lack of insect pest pressure at these spray timings. Beneficial insects were abundant in the crop at each of these timings and did not appear to be affected by the pyrethroids in the herbicide plots. Repeated preventative use of pyrethroids in the same field could potentially hinder the natural biocontrol of corn pests.
Lady beetle larva (a predatory insect) in silks.
Sources
1 DiFonzo, C. 2017. Handy Bt Trait Table for U.S. Corn Production, http://msuent.com/assets/pdf/BtTraitTable15March2017.pdf
2Croft, B.A., M.E. Whalon. 1982. Selective toxicity of pyrethroid insecticides to arthropod natural enemies and pests of agricultural crops. Entomophaga. 27(1): 3-21.
3Reisig, D.C., J.S. Bacheler, D.A. Herbert, T. Kuhar, S. Malone, C. Philips, R. Weisz. 2012.Efficacy and value of prophylactic vs. integrated pest management approaches for management of cereal leaf beetle (Coleoptera: Chrysomelidae) in wheat and ramifications for adoption by growers. J. Econ. Entomol. 105(5): 1612-1619
4Reisig, D.C. 2018. New stink bug thresholds in corn, https://entomology.ces.ncsu.edu/2018/04/new-stink-bug-thresholds-in-corn/
Attached is the summary for the September World Agricultural Supply and Demand Estimates (WASDE) that was published on September 12. Corn harvested acre estimate was unchanged but yield estimate was adjusted down 1.3 bushel per acre to 168. Other estimate adjustments were insignificant.
Soybean harvested acres estimate was unchanged but yield estimate was adjusted down 0.6 bushels per acre. Beginning stock estimate was adjusted down and ending stocks estimate was down a significant 115 million bushel which significantly decreased the stocks-to-use ration from 18.8% to 15.9% which gave a bump to market prices. Today, Friday 13, China announced exemptions for soybean and pork tariffs which should further help our situation.
Alyssa Koehler, Extension Field Crops Pathologist University of Delaware
We are entering that time of year to begin scouting for stalk rots in corn. Stalk rot signs and symptoms do not appear until later in the season. After pollination, the ear becomes the major sink of sugars produced by the plant. If a stress event occurs, plants will divert or remobilize sugars from the stalk and roots to meet the needs of the developing ear. Often the pathogens that cause stalk rots are opportunistic and take advantage of plants that have been weakened by potential stress events (drought, flooding, hail, insect damage, foliar disease damage). It is also possible to have multiple stalk rot organisms in the same plant.
Yield losses occur when stalks become brittle and lodge close to harvest. Stalk rots can also result in premature plant senescence and reduced grain fill. When plants are a few weeks from physiological maturity (kernel black layer), stalk rots can be scouted by walking the field in a W pattern and randomly checking stalks with either the pinch or push test (aim to check 10-20 plants for every 10-20 acres). For the pinch test, pinch the stalk between the lowest two internodes to see if it can withstand the pressure, if the stalk collapses, it fails. To complete a push test, push the stalk 30 degrees from vertical (around 8 inches) and see how many spring back to upright or lodge. In cases where more than 10% of plants fail the test, you may want to consider harvesting at higher moisture and drying grain after harvest to avoid yield loss due to lodging.
Since stalk rots are linked to stress, the best management strategies are to reduce stress by planting optimal stand populations, irrigating when possible, managing insect pests and foliar diseases, and using a balanced nutritional program. Planting hybrids with some level of foliar disease resistance can also help to reduce plant stress and encourage strong stalk development.
Kelly Hamby1, Galen Dively1, David Owens2, Ben Beale3, Peter Coffey3, Andrew Kness3, Alan Leslie3, Erika Taylor3, Kelly Nichols3, Matthew Morris3, and Emily Zobel3
1University of Maryland Department of Entomology 2University of Delaware Extension Entomology 3University of Maryland Extension
Moth flight activity for the corn earworm, also known as the soybean podworm and one species of sorghum headworm, has increased during the past week. Pest pressure varies across the state and Delmarva region. The early surge in activity is attributed to the record temperatures during June and July, which have accelerated larval development and shortened the generation time of this insect. Corn earworm has already caused significant damage to ears of sweet corn and early planted field corn. Note that Bt hybrids expressing single or multiple Cry proteins no longer control earworms due to the development of resistance; only hybrids expressing the Vip3a Bt protein provide good ear protection. These hybrids represent a relatively small portion of the planted acreage. Thus, significantly more adult moths are now recruited in corn compared to levels a decade ago.
Corn earworms are strongly attracted to and prefer fresh corn silks for egg laying. Outbreaks in other crops often follow a midsummer drought, which causes the corn to ripen earlier and become less attractive to the moths. As early planted corn fields dry down, moths will move into other vegetable and grain crops.
Podworms in Soybeans:
Corn earworm feeding on soybean pod. Image: Clemson University
In soybeans, female corn earworm moths prefer to lay eggs in open-canopied, late-blooming fields, and are most attracted to soybeans for egg laying from flowering to early pod-set. Drought conditions also delay soybean maturity and prevent normal canopy growth, so peak moth activity is more likely to coincide with blooming of open-canopied fields. In irrigated fields, activity may be greater along pivot tracks and dry corners. Corn earworm larvae can damage flowers; however, because soybeans produce more flowers than needed, flowering sprays are rarely necessary. Podworms cause the most damage when large larvae are feeding on full seed pods with large seeds (see information from NCSU).
What to do? Scout bean fields, paying special attention to those fields with a more open canopy in areas where the nearby maturing corn is no longer attractive to earworm moths.
Sampling should start during mid-August and be repeated at least weekly in each field until a spray decision is made or the pods reach full maturity. Most fields are planted as narrow-row beans, so a 15-inch sweep net is the most practical way to sample for earworms. Walk along the rows, swinging the sweep net so that the opening passes through the foliage. The net is turned 180 degrees after each sweep as you advance with each step to swing the net through the foliage in the opposite direction. Each stroke is counted as one sweep. A series of 25 sweeps should be taken at each of 5 sites in every 40 acres.
Treatment is recommended when counts exceed 3 medium to large podworms per 25 sweeps in narrow row fields, or 5 podworms per 25 sweeps in wide row fields (20 inches or greater). The timing strategy is to wait until most of the larvae are 3/8 inch or more in length, and then treat when pod damage is first evident. This allows for most egg laying and hatching to occur before treatment and reduces the chances of a second spray being needed later. These static thresholds are based on long-term averages for control costs and soybean prices. North Carolina State extension has developed a dynamic online threshold calculator for corn earworm in soybeans that takes into account the sampling method (uses a 15 sweep rather than a 25 sweep sample), row spacing, cost for control, and the value of soybeans, which can be found at:
Since the 2008 season, numerous reports of control failures with pyrethroids (Group 3A) used for earworm control have been reported from the Mid-Atlantic region and states to our south. This insect has developed moderate to high levels of resistance to this class of insecticides, so growers need to consider other modes of action. If a pyrethroid (e.g., Brigade, Warrior, Mustang Maxx, Hero, Baythroid, Tombstone) is used, the highest labeled rate timed for small to medium, rather than large worms, is recommended. Alternative classes such as diamides (Group 28; e.g., Coragen, Prevathon), oxadiazines (Group 22A; e.g., Steward) and spinosyns (Group 5; e.g., Blackhawk, Radiant) will be most effective. These materials are also generally softer on beneficial insects which prey upon other late season soybean pests, such as soybean looper and stink bug. ALWAYS read and follow instruction on the pesticide label; the information presented here does not substitute for label instructions.
Headworms in Sorghum:
Corn earworm female in sorghum. Image: John C. French Sr
Headworms (corn earworm, fall armyworm, and sorghum webworm) are caterpillar pests that infest grain heads. Flowering or heading sorghum is attractive to corn earworm females for egg laying, and headworm issues have been reported in Southern Maryland this year. Headworms feed on the flowers and developing kernels and large larvae can cause significant yield loss.
What to do? Scout sorghum fields from the end of flowering until hard dough.
Sample heads by bending them into a clean white 5 gallon bucket and beating them to dislodge the headworms. Sample 10 heads per location and sample multiple locations per field. If most larvae are small (up to ¼ inch) sample the field again in 3 to 4 days.
Thresholds vary by the size and species of larvae and sorghum value. In general, 2 corn earworm larvae per head would warrant treatment, and Texas A&M has developed a dynamic online threshold calculator that incorporates cost of control, grain value, anticipated yield (heads/acre), and larval size, which can be found at:
As mentioned above, pyrethroids (Group 3A) offer poor to moderate control of corn earworm in the Mid-Atlantic, and will not control heavy infestations or large worms. If a pyrethroid (e.g., Brigade, Warrior, Mustang Maxx) is used, the highest labeled rate is recommended. Alternative classes such as diamides (Group 28; e.g., Prevathon), spinosyns (Group 5; e.g., Blackhawk, Tracer), or carbamates (Group 1A; e.g., Sevin, Lannate) will be most effective. Selective insecticides that are less damaging to beneficials are recommended, such as Prevathon (most recommended) or Blackhawk. ALWAYS read and follow instruction on the pesticide label; the information presented here does not substitute for label instructions.
While scouting for headworms, growers are encouraged to look for sugarcane aphid in sorghum as well. Virginia Tech reported the first confirmed identification of white sugarcane aphid in Amelia County on August 1st. For more information on sugarcane aphid see Agronomy News Volume 8 Issue 1. If sugarcane aphids are also present, we strongly advise using selective insecticides to preserve the natural enemies that slow sugar cane aphid population growth.
Nicole Fiorellino, Assistant Professor & Extension Agronomist University of Maryland, Dept. of Plant Science and Landscape Architecture
The conditions this growing season have been a major improvement over the conditions we experienced during the 2018 growing season. Generally, the spring weather was favorable for timely planting of corn on the upper and mid-shore, southern Maryland, and northern Maryland regions, with other regions not lagging far behind. The 2019 growing season has generally been good to us, there was early optimism in the monthly crop reports, but by the end of June, warm and dry weather began around the state. Some areas may have received some spotty thunderstorms throughout July, but the July crop reports indicated droughty conditions throughout the state. As we enter into a new month with minimal precipitation thus far, farmers are concerned about the effects from the prolonged dry and warm conditions on corn yield.
Drought-stressed corn in vegetative growth stage. Image: A. Kness, University of Maryland.
Warm temperatures and low rainfall cause stress to growing crops and this weather stress can be a major problem prior to pollination, as stress during this stage will impact the potential number of kernels per row. Warm temperatures, specifically, can cause corn plants to utilize more energy to carry out normal functions. Low rainfall can cause corn ear tips to lose kernels. Poor root development, from poor planting conditions and soil compaction early in the season, can amplify the effects of weather stress observed later in the season. But generally, the potential impact on corn yield from warm, dry weather will depend on the maturity of the corn crop when it experiences the weather stress.
Corn is particularly sensitive to weather stress during the late vegetative growth stages when the number of kernels is determined. Four days of weather stress between V12 and V14 could reduce yields 5 to 10%. Even into tassel emergence, total number of kernels can be affected, with yield reduction from 10 to 25% with four days of weather stress at this stage. Silk emergence and pollination is a critical period of moisture use in corn, with weather stress affecting pollination and leading to kernel abortion – four days of stress during silking could reduce yields up to 50%. Generally after pollination, reduced kernel fill can be expected during weather stress, with four days of weather stress post-pollination possibly reducing yields 30 to 40%. During blister and milk stages, kernel abortion is a concern during weather stress, while shallow or unfilled kernels can occur with stress during the dough stage, and reduced kernel weight is a concern during dent.
In summary, there is potential for reduction in corn yield due to the hot, dry weather but the impacts differ based on the maturity of the corn when it experiences the stress. Weather stress during silking and pollination can have the most severe impact on yield potential, with impacts from weather stress decreasing as corn moves further into reproductive maturity.
The U.S. Environmental Protection Agency (EPA) has just issued a long-term approval for the insecticide sulfoxaflor, which the Agency has characterized as “an effective tool to control challenging pests with fewer environmental impacts.” The following information is from today’s EPA OPP Update.
“After conducting an extensive risk analysis, including the review of one of the agency’s largest datasets on the effects of a pesticide on bees, EPA is approving the use of sulfoxaflor on alfalfa, corn, cacao, grains (millet, oats), pineapple, sorghum, teff, teosinte, tree plantations, citrus, cotton, cucurbits (squash, cucumbers, watermelons, some gourds), soybeans, and strawberries.
EPA is providing long-term certainty for U.S. growers to use an important tool to protect crops and avoid potentially significant economic losses, while maintaining strong protection for pollinators,” said Alexandra Dapolito Dunn, assistant administrator for EPA’s Office of Chemical Safety and Pollution Prevention. “Today’s decision shows the agency’s commitment to making decisions that are based on sound science.”
Sulfoxaflor is an important and highly effective tool for growers that targets difficult pests such as sugarcane aphids and tarnished plant bugs, also known as lygus. These pests can damage crops and cause significant economic loss. Additionally, there are few viable alternatives for sulfoxaflor for these pests. In many cases, alternative insecticides may be effective only if applied repeatedly or in a tank mix, whereas sulfoxaflor often requires fewer applications, resulting in less risk to aquatic and terrestrial wildlife.
EPA’s registration also includes updated requirements for product labels, which will include crop-specific restrictions and pollinator protection language.
*Background*
In 2016, following a 2015 decision of the Ninth Circuit Court of Appeals vacating the registration of sulfoxaflor citing inadequate data on the effects on bees, EPA reevaluated the data and approved registrations that did not include crops that attract bees. The 2016 registration allowed fewer uses than the initial registration and included additional interim restrictions on application while new data on bees were being obtained. Today’s action, adding new uses, restoring previous uses, and removing certain application restrictions is backed by substantial data supporting the use of sulfoxaflor.
For additional information, please visit the EPA website.
