Category: Soybeans

Scouting Smarter: June Insect Pressure and Threshold Tips

Hayden Schug, Agriculture Agent | hschug@umd.edu
University of Maryland Extension, Charles County

As Maryland’s corn and soybean fields move into early vegetative and reproductive stages, June marks a key time for pest scouting. Early detection and threshold-based decisions are the foundation of a strong Integrated Pest Management (IPM) strategy, and this month brings several common threats that row crop producers should be on the lookout for.

Begin scouting for stink bugs in corn, especially along field edges. These pests often move in from neighboring wheat fields during harvest or from forested areas. They tend to show up first along borders and gradually move toward the field interior, so edge-focused scouting is important early on. From V1 to V6, the treatment threshold is 13 stink bugs per 100 plants; this drops to 10 per 100 plants from V14 to VT. Pyrethroids have shown good knockdown efficacy against stink bugs, but keep in mind that they tend to have a short residual period.

Soybean fields are also entering critical scouting windows. VE to V3 soybeans are susceptible to early defoliation from bean leaf beetles, grasshoppers, and other chewing pests. While the damage may look concerning, soybeans can tolerate up to 30 percent defoliation before bloom without experiencing yield loss. Be sure to scout multiple locations across the field, not just the edges, as field borders often exaggerate pest pressure.

Slugs have caused some issues this spring in Southern Maryland. While most fields are planted by June, it’s still worth noting that slugs can remain a concern, especially in no-till systems with heavy residue. Ensuring good furrow closure is key to preventing slugs from accessing germinating seeds. Using row cleaners to clear residue from around the furrow can also help reduce slug habitat and early pressure. If damage is suspected, conducting stand counts can help determine whether replanting is necessary as soybeans can compensate for stand loss. 

Alfalfa should be scouted for potato leafhoppers beginning in late May/early June. Regular scouting is very important, once hopper burn becomes visible in the field, yield loss has already occurred. Unlike alfalfa weevil, where the first harvest often reduces populations enough to avoid further issues, potato leafhoppers have multiple generations each year and can quickly reinfest fields after harvest or treatment, so continued scouting is necessary. For a dynamic threshold calculator and detailed scouting tips, check out this resource from Penn State Extension, https://extension.psu.edu/potato-leafhopper-on-alfalfa.

Hot and dry weather can also accelerate the development of secondary pests, particularly spider mites along field edges. While not typically a major issue in June, early flare-ups can occur during periods of drought stress. It’s worth inspecting leaf undersides in stressed areas to catch hot spots before populations expand.

Effective scouting depends on consistent, thoughtful observation. Early morning or evening visits often reveal pests that remain hidden during the heat of the day. Scouting beyond the field edge helps avoid over- or underestimating pest populations. Most importantly, only apply insecticides when economic thresholds are met. Doing so helps reduce unnecessary costs, preserves beneficial insects, and slows the development of pesticide resistance.

Considerations for Preplant Control of Palmer amaranth and other Pigweeds in Soybean

small seeding plants growing in a tilled field
Kurt Vollmer, Weed Management Extension Specialist|kvollmer@umd.edu
University of Maryland Extension

Palmer amaranth and other pigweeds have emerged and are thriving. These weeds can quickly become too large and dense to control with many herbicides, so fields should be scouted and control measures implemented immediately. A contact herbicide, such as paraquat, applied at a spray volume of 20 gal/A can be used to control small plants prior to planting.

Soil-applied, residual herbicides may also be included as part of the preplant application. Flumioxazin or sulfentrazone-based products plus metribuzin or pyroxasulfone or S-metolachlor plus metribuzin have proven to provide effective control of Palmer amaranth and other pigweeds. However, planting should not be delayed too long after application, as herbicide efficacy will wane over time. If possible, incorporate with at least 0.5 inches if irrigation to activate the herbicides. Consult the label before mixing any herbicides, and be aware of any rotational restrictions before applying these herbicides, especially to double-crop soybean. Applicators should also be aware of potential drift issues to sensitive areas.  

Cultivation can be effective on small seedlings (<3 inches), but larger plants are likely to re-grow if roots or stem remain in contact with the soil. Since Palmer amaranth can emerge throughout the growing season, repeated cultivation is necessary for control. However, local research has shown that spring tillage can result in higher Palmer amaranth densities compared to no-till systems. Other practices such as spring disking, chisel plowing, or vertical tillage will not provide adequate control. 

Regardless of the control method used, be sure to scout in a timely manner after each operation to determine if additional control is needed. Tank mixing at least two effective modes of action, such as Enlist One + Liberty, and an additional residual herbicide, is recommended for both postemergence control and herbicide resistance management. Reducing soybean row spacing from 30 inches to 15 inches will also allow for faster canopy development, which will help negate the need for additional weed control.

Soybean Replant Decisions: Weighing the Economics Before Turning the Planter Around

Nathan Glenn, Agriculture Agent Associate | nglenn@umd.edu
University of Maryland Extension, Howard County

Cool, wet conditions and early-season pest or disease pressure across Maryland may have resulted in thin or uneven soybean stands, prompting farmers to ask: Should I replant? The answer hinges on one key question:

Will the expected gross return of a replanted stand be greater than the gross return of the existing thin or uneven stand?

A replant decision isn’t just agronomic—it’s economic. Later planting dates usually mean lower yield potential, and replanting incurs additional costs. Making a data-driven decision requires careful scouting, accurate calculations, and a clear understanding of potential return on investment. Here’s what you can do:

Step 1: Identify the Cause of the Poor Stand

Before replanting, determine why the original stand failed. Cold soil temps, soil crusting, slug damage, herbicide injury, seedling disease, and insect damage are common culprits. Without addressing the root cause, a replant may suffer the same fate. Consider seed treatments, adjusting planting depth, or changing varieties if necessary. I have seen slug damage in every soybean field I have been in so far this year, but it seems like they might outgrow it, especially with this warm, dry weather forecasted in central Maryland over the next 10 days. Sometimes all you need is better weather!

Step 2: Conduct Accurate Stand Counts

Two common methods can help determine how many plants per acre you currently have:

  1. Traditional Row Length Method:
  • Count the number of plants in a length of row that equals 1/1,000th of an acre.
  • Example: In 30-inch rows, count plants in 17 feet, 5 inches.
  • Multiply the count by 1,000 to get plants/acre.
  1. Hula Hoop Method:
  • Toss a hoop (typically 30-inch diameter) randomly in the field.
  • Count the number of plants inside the hoop.
  • Multiply by a conversion factor (8,900 for 30-inch hoop) to estimate plants/acre.

Step 3: Estimate Yield Potential of the Current Stand

Use your plant population and uniformity to estimate yield potential:

Yield potential of a soybean field with reduced stands at 7.5 inch and 30 inch row spacings

Population

Drilled (7.5 inch rows)

Planter (30 inch rows)

160,000

100

100

120,000

100

100

80,000

96

100

60,000

92

94

40,000

87

88

20,000

77

81

10,000

58

72

 Adapted from Table 1.6-3, The Agronomy Guide, Penn State Extension

Yield potential of full-season soybeans due to uneven deficient stands (i.e. gaps)

Percent stand lost to gaps

140,000 plants/acre

105,000 plants/acre

70,000 plants/acre

0

100

97

95

10

98

96

93

20

96

93

91

30

93

90

88

40

89

86

83

50

84

81

78

60

78

75

73

 Adapted from Table 1.6-4, The Agronomy Guide, Penn State Extension

Step 4: Estimate Yield Potential of a Replanted Stand

Later planting reduces yield potential even in ideal conditions. Use the table below:

Approximate yield reduction of soybeans due to delayed planting date

Date

Percent of full yield potential

10-May

100

20-May

98

30-May

95

10-Jun

88

20-Jun

76

30-Jun*

70

10-Jul*

60

This table quantifies the estimated yield penalty as planting date is delayed. Adapted from Table 1.6-5, The Agronomy Guide, Penn State Extension. * Relevant only in areas where double cropping is practiced. 

Step 5: Estimate the Costs of Each Option

Costs of Keeping the reduced stand:

  • Reduced herbicide efficacy due to open canopy
  • Increased weed competition
  • Yield reduction

Costs of replanting:

  • Seed: $60–$80/acre
  • Fuel and labor: $10–$15/acre
  • Machinery wear: $5–$10/acre
  • Additional herbicide or pesticide: varies
  • Total estimated replant cost: $75–$120/acre

Step 6: Use a Soybean Replant Decision Worksheet

Here’s how the math works, step by step:

Example Scenario:

  • Current stand: 70,000 plants/acre, 20% gaps, 30 inch rows
  • Expected market price: $10.50/bu
  • Expected yield of a full stand: 60 bu/acre

Current Stand:

  • 91% of normal yield (70,000 plants w/20% gaps)
  • 60 bu/ac × 0.91 = 54.6 bu/ac
  • Added costs = $0
  • Gross return = 54.6 bu × $10.50 = $573.30/ac

Replant Option:

  • Planted June 10 → 88% yield potential
  • 60 bu × 0.88 = 52.8 bu/ac
  • Gross return = 52.8 bu × $10.50 = $554.40/ac
  • Added costs = $100/ac
  • Gross return = $554.40 – $100 = $454.40/ac

Conclusion: Do not replant—your current stand is more profitable by $118 per acre

Final Thoughts

Soybean replant decisions should always be based on data, not emotion. Accurately assess plant population, uniformity, yield potential, and costs. Many reduced stands still yield competitively, especially when gaps are minimal and plants are healthy.

For help making the best decision for your farm, contact your local Extension office or agronomist.

University of Maryland Researchers Encourage Farmers to Participate in TAPS program

Researchers at the University of Maryland are inviting growers across the state to participate in their University of Maryland – Testing Ag Performance Solutions (UMD-TAPS) program this year. The program is supported by the Maryland Soybean Board and will run throughout the summer.

Piloted at the University of Nebraska-Lincoln, the TAPS program provides farmers with a zero-risk opportunity to advance their agricultural management skills and knowledge. It serves as a growing season contest and research framework, designed to uncover how producers’ management decisions drive crop yields, farm profitability, and input-use efficiency.

Growers must make decisions about variety selection, fertility, pest management, and irrigation and their management decisions will be executed in small plots at the Wye Research and Education Center. Decisions made by all participants will be executed in one field, in a true head-to-head competition. The goal is to identify which suite of management decisions will become the most profitable, efficient, and highest yielding.

Researchers at the Maryland Agricultural Experimentation Station (MAES) WYE Research and Education Center will lead the program and gather data on each plot to share with farmers.

When the season ends, growers will participate in an awards dinner where they will gain access to valuable data sets to help them enhance their agricultural operations.

The irrigated corn competition is limited to 20 teams and the irrigated soybean competition is limited to 15 teams. Due to limited availability, researchers urge teams to sign up as soon as possible.

Interested applicants can sign up by following this link: bit.ly/UMDTAPS25. For any questions, please reach out to Dr. Nicole Fiorellino at nfiorell@umd.edu.

2024 Soybean & Corn Pest Management Survey

Farmers and crop consultants are encouraged to complete this survey

This survey is intended to estimate the impact of pests on soybeans and currently used management strategies. Your perspective is valuable in making these estimates as accurate as possible. Your responses will be kept confidential and only aggregated responses for the state will be published. You can find last year’s estimates at https://midsouthentomologist.org.msstate.edu/Volume17/Vol-17-1_TOC.html.

The survey can be completed online at https://delaware.ca1.qualtrics.com/jfe/form/SV_8GnhiHa4rn9ToPP or by following the QR code. If you have any questions, please contact us by email or phone. We look forward to hearing from you.

Local Contact: David Owens, University of Delaware     

Email:            owensd@udel.edu                  bcsam@udel.edu        

Phone:            C: (302) 698-7125        

Local Contact: Kelly Hamby, University of Maryland

Email:       kahamby@umd.edu

Phone:      C: (925) 354 0483

Evaluation of Early Maturity Group Soybeans in Maryland

Andrew Kness, Senior Agriculture Agent | akness@umd.edu and Nicole Fiorellino, Assistant Professor & Extension Agronomist
University of Maryland

Figure 1. Aerial photo of soybean maturity groups 1.5-3.0 showing different rates of senescence on September 4, 2024. Photo: A. Kness.

In recent years, many growers have expressed interest in and experimented with early maturing soybean maturity groups. The concept is appealing to some growers because it allows for an early harvest and earlier establishment of cover crops and/or small grains. However, there are a lot of questions related to how these early maturity groups can perform in our climate at our latitude and little data exists from our region to reference. With funding from the Maryland Soybean Board, we evaluated the agronomic characteristics of early maturity soybeans grown in a Maryland climate for their potential integration into Maryland grain rotations.

Soybean varieties ranging from maturity group (MG) 1.5-3.0 from two seed suppliers (Hubner and Pioneer) were planted on May 30, 2024 at the Wye Research and Education Center. All MG 1.5 and MG 2.0 Hubner brand plots were harvested on September 24 with remaining plots harvested on October 7th. Wheat was planted in the plots harvested at the first timing on October 10th and planted in the second harvest timing plots on October 23rd.

Mixed model analysis of variance was used to analyze the yield data, including brand (Hubner or Pioneer), maturity group, and interaction of the two. Significant effect of maturity group only (P=0.0008) with means separation by Tukey’s HSD (Figure 2).

Yields for all MGs were very strong; ranging from 55 bu/ac to nearly 70 bu/ac. Maturity group 3.0 yielded significantly more than MG 2 and 1.5 and similar to MG 2.5. Maturity groups 1.5 and 2.0 yielded similarly to each other.

Figure 2.  Average soybean yield by maturity group from 2024 trials.

This is only the first year of this study and we will conduct this research again in 2025. These preliminary data shows encouraging results and potential for early MG soybeans, which could offer some added benefits to establishing an early cover crop or a timelier planting of a subsequent wheat crop. Earlier cover crop establishment would have an environmental benefit in that more nutrients could be captured and saved for the next crop. Earlier establishment of wheat or other small grains, would also allow for more fall tiller development, which have the potential to contribute to more yield in the spring. We will see how the planting dates affect wheat yield in these plots next summer.

We would like to thank the Maryland Soybean Board for sponsoring this research, Hubner Seed for donating seed, and the farm crew at Wye Research and Education Center for supporting this project.

Assessing Herbicide Tank Mixes for Postemergence Weed Control in Soybean

Kurt Vollmer, Extension Weed Management Specialist | kvollmer@umd.edu
University of Maryland Extension

Research was conducted at the Wye Research and Education Center to evaluate herbicide tank mixes for postemergence weed control in herbicide-tolerant soybean. As herbicide-resistant weeds continue to drive weed management decisions, options are needed to not only provide effective weed control, but also preserve the value of available herbicides.

Figure 1. Example probabilities of developing resistance when using Herbicide A, Herbicide B, and Herbicides A and B. Using two different herbicide groups decreases the probability that a weed will become resistant to both herbicide groups.

Tank mixing multiple, effective herbicide groups is one tactic that can be used to impede herbicide resistance. By including multiple, effective herbicide groups when making an application, there is a lower probability that a weed species will develop resistance to all herbicides used (Fig. 1). Furthermore, tank-mixing different herbicide groups can have a synergistic effect, where the combined effect of two or more groups is greater than the effects of each herbicide alone. For example, previous research has shown Enlist One + Liberty to be more effective in controlling as common ragweed and Palmer amaranth, compared to each individual herbicide.

Furthermore, including a residual herbicide in the tank when making a postemergence application may be necessary for full-season control of certain weeds, such as Palmer amaranth. Including herbicides with both foliar and residual activity, such as fomesafen (Reflex), in tank with other effective herbicides can help to preserve the utility of these herbicides.

This research examined the effectiveness of tank mixing of herbicides with foliar (2,4-D, fomesafen) and residual (fomesafen, ­S-metolachlor) for early and late postemergence weed control in soybean. Plots (10 ft. x 25 ft.) were arranged in a randomized complete block design with 4 replicates. Herbicide treatments consisted of applying Reflex (fomesafen), Reflex + Dual Magnum (S-metolachlor), Reflex + Enlist One (2,4-D) or a three way mix of Reflex + Dual + Enlist One (Table 1). The entire study area received 1 pt/A Dual Magnum within 24 hours of soybean planting Enlist E3 soybeans on June 4, 2024. Early postemergence (EPOST) applications were made 2 weeks after planting and late postemergence (LPOST) applications 4 weeks after planting.

Table 1. Postemergence herbicide treatments for resistant weed mitigation and control in soybean.

Herbicide(s)RateTiminga
Reflex1.5 ptEPOST or LPOST
Reflex + Dual1.5 pt + 1.5 ptEPOST or LPOST
Reflex + Enlist1.5 pt + 2 ptEPOST or LPOST
Reflex + Enlist + Dual1.5 pt + 2 pt + 1.5 ptEPOST or LPOST
a Herbicide treatments were applied early postemergence (EPOST) 2 weeks after planting or late postemergence (LPOST) 4 weeks after planting soybeans on June 4, 2024.

Broadleaf Weed Control

Application timing did not affect common lambsquarters or morningglory control. Reflex + Enlist or Reflex + Enlist + Dual controlled common lambsquarters better compared to Reflex alone, and morningglory species better than Reflex or Reflex + Dual (Fig. 2).

Figure 2. Control of common lambsquarters and morningglory species 7 weeks after soybean planting. Bars of the same color with the same letter are not significantly different according to Tukey’s HSD (α = 0.05).

Giant Foxtail Control

Applications made EPOST provided better control compared to applications made LPOST (Fig. 2), but giant foxtail control varied from 38% to 78%, with no significant differences among herbicide treatments (Fig. 3). It should be noted that Enlist One does not control grasses. Both Dual Magnum and Reflex can provide some grass activity, but only if applied PRE. Better foxtail control with EPOST treatments could be attributed to overlapping residual control with these treatments. Overlapping herbicides is a tactic that involves sequential applications of herbicides with soil-residual activity to lengthen herbicidal activity before the first herbicide dissipates. As Dual Magnum was included in both PRE and POST applications, the EPOST applications likely provided better overlapping residual control due a shorter application window between the PRE and POST applications (2 weeks for EPOST and 4 weeks for LPOST).

Figure 3. Giant foxtail control following early and late postemergence applications 7 weeks after soybean planting. Bars of the same color with the same letter are not significantly different according to Tukey’s HSD (α = 0.05). 

This research highlights the value of adding multiple herbicide groups to the tank at the time of POST applications (Fig. 4). While additional work is needed to confirm the results of this study, the following factors should be considered when deciding which herbicides to include in the tank:

  • The types of weeds are prevalent in the field. Should the spray program focus primarily on broadleaf weeds, grasses, or both?
  • The emergence period for the weeds being controlled. Will a single POST application negate the need for additional treatment, or should an herbicide with residual activity be included?
  • Each herbicide must be effective alone on the target weed. Including multiple herbicides will not be as effective if a weed already has significant resistance to one of the herbicides in the mix.
Figure 4. Weed control with early postemergence applications of a) Reflex + Dual and b) Reflex + Enlist + Dual 7 weeks after planting. Photo credit: Logan Bledsoe.

Acknowledgements

Support for this project was made possible by funding from the Maryland Soybean Board as well as technical support from Jadon Cook, Logan Bledsoe, Sam Denherder, and the University of Maryland Wye Research and Education Center.

Commercial products are mentioned in this article solely for the purpose of providing specific information. Mention of a product does not constitute a guarantee or warranty of products. Reference to commercial products or trade names is made with the understanding that no discrimination is intended and no endorsement by University of Maryland Extension is implied.

Maryland Regional Crop Reports: September 2024

Reports are for crop conditions up to September 5, 2024.

Western Maryland

August brought us more rain than June and July combined. The hay and pasture fields responded, and there is hope for continued grazing and another cutting. The soybeans are probably the greatest beneficiary of the moisture. They are looking great as their pods fill. Modern varieties are a wonder to behold. Corn silage harvest began earlier this year thanks to the heat and drought. Many folks are glad they planted a little extra corn, primarily due to the need for forage and the low grain price forecast. Running it through livestock will add value. Triticale and oats are going in the ground for both fall and spring forage. Cool mornings and mild days have raised our countenance here in Western Maryland.—Jeff Semler, Washington Co.

Central Maryland 

August has finally brought some much needed rain; although amounts have been scattered throughout the region. A storm last week caused crop damage in some areas of the region. While it won’t be a year for record-breaking yields, most of the corn and soybeans are looking fairly good. The majority of corn is in the dent stage and is starting to dry down. Silage chopping has begun. Full season soybeans are in the beginning seed stage (R5).—Kelly Nichols, Montgomery Co.

Northern Maryland

About 6” of rain fell in August, which really woke up soybeans, especially later planted beans and double crops. Unfortunately, the rains have ceased, with the last measurable rainfall coming over two weeks ago. Rain is predicted for this weekend, so fingers crossed for good rainfall to finish out what could be a strong late season bean crop. Corn is rapidly drying down and a few acres have been harvested but the majority of corn is still 25% moisture or better. We are about another 10-14 days before the combines are rolling hard. Tar spot was also confirmed in the region at the end of August, consistent with the two years prior. A lot of good dry hay was put up over the last two weeks.—Andy Kness, Harford Co.

Upper and Mid Shore

July’s much-needed rains tapered off, leaving August with sporadic showers that varied significantly depending on your neck of the woods. This inconsistency has led to some challenging conditions for crops. Signs of water stress have become apparent; soybean leaves are cupping and corn leaves are curling from lack of moisture. In response, center pivots on irrigated fields have been fired up again, helping to maximize yield potential after a brief respite in July. Corn is drying down, with some early-planted fields already harvested. Soybeans are also moving along, with early maturing varieties starting to turn and double crop beans filling out their pods. The dry conditions earlier in the season provided the perfect environment for Palmer amaranth to thrive and compete with the crops. They can clearly be seen towering over the soybean and even corn in both conventional and organic fields. The region has also noticed more spotted lanternfly activity as these pests hit their final growth stage and take to the air. While they’re mostly just a nuisance in agronomic crops, controlling them can really help out your local fruit and vegetable grower, who would surely appreciate the effort.—Dwayne Joseph, Kent Co.

Lower Shore

Corn is drying down, but harvest has not yet begun. Due to low grain prices, farmers are inclined to let corn completely dry in the field, rather than take a moisture price hit at the mills. Drought stress during vegetative and early reproductive phases hurt corn. Yield is anticipated to be poor, and ears look small. Soybean is looking better than corn, especially double-crop soybean planted after wheat. There have not been reports of serious pest or weed damage. Cover crops are being flown into some corn fields via airplane.—Sarah Hirsh, Somerset Co.

Southern Maryland

Conditions remain very dry across the majority of Southern Maryland. Corn harvest is in full swing with reports of average to well below average yields. Yields vary greatly within and between fields depending on soil type and where isolated showers happened to fall. Grain quality is a major concern this year. Growers are encouraged to get corn off as early as possible. Beans continue to put up the good fight. Many full season beans are yellowing and drying down. Double crop beans will need some more help to fill out pods. Farmers have been scouting for pod worms and stink bugs. Thankfully, only a few fields have reached threshold and required a treatment so far. Weeds continue to require attention as fields have taken longer to canopy if at all, allowing greater opportunity for weeds to gain their share of the limelight. We continue to see ragweed, pigweeds of all types, and morning glory present. Deer damage is readily apparent in later planted beans that are failing to re-grow or canopy following deer feeding. Forages have struggled this summer with many fields of cool season grasses requiring replanting this fall or next spring.—Ben Beale, St. Mary’s Co.

*Regions (counties):
Western: Garrett, Allegany, Washington. Central: Frederick, Montgomery, Howard. Northern: Harford, Baltimore, Carroll. Upper & Mid Shore: Cecil, Kent, Caroline, Queen Anne, Talbot. Lower Shore: Dorchester, Somerset, Wicomico. Southern: St. Mary’s, Anne Arundel, Charles, Calvert, Prince George’s

Maryland Regional Crop Reports: August 2024

Reports are for crop conditions up to August 1, 2024.

Western Maryland

Welcome rains have sporadically arrived in Washington County. This has been the story for much of the summer. It depends on your location and how much rain you receive, out of which storms. Earlier in the spring, the southern part of the county was blessed more than the part that hugs the Mason-Dixon Line. July has seen that trend nearly turned on its head. Wheat is off, and test weights and yields were good. Many acres of optimistic double-crop beans were planted again. Moisture has dictated the success of those plantings. It is too soon to make any predictions on corn yields, but in many places, plants are shorter, but the ears might fill just fine. So we wait. In two weeks, choppers will start running, and corn silage will be our first indicator of yields. Peach harvest started a little early, and they are smaller, and yields are lower, but they are sweet.—Jeff Semler, Washington Co.

Central Maryland 

Corn and soybeans are well into reproductive stages and further along than previous years. Most of the region has experienced drought conditions throughout the growing season. Some growers have begun chopping early corn silage given how far hot dry weather has pushed the crop. Very limited disease pressure throughout the region. Recent rains have been welcomed, where received. Most precipitation events have been sporadically distributed to say the least.—Mark Townsend, Frederick Co.

Northern Maryland

We ended July with around 3” of rain here at the Harford County Extension office. Rains were more periodic in July; however, that is not the case for the entire region—rains continue to be scarce the further west into Baltimore and Carroll County you go and the rain that has fallen across our region has been very scattered and localized. You can find corn that looks very good and you can find corn that looks very poor all in the same county. I do believe that most places are “holding on” in terms of yield—I think we will fare OK and we may have avoided a complete disaster but corn yields will certainly be off of our norm. Soybeans are flowering and look good; if they can fill all the pods they’re initiating then soybean yields should be strong; the next few weeks will make or break them.—Andy Kness, Harford Co.

Upper and Mid Shore

The first couple of weeks in July brought us more of the high temperatures we’ve been experiencing, but unlike June, we were finally blessed with some much-needed rain across the region. While some areas received more rain than others, it was all welcome. The timing couldn’t have been better, as most of the corn was entering the reproductive stages right at the start of the month. Due to this, late-planted corn is likely to yield better than the earlier-planted corn. Both full-season soybeans and corn are now in their reproductive stages. Most of the corn has finished pollination and is moving into kernel development. On the small grains front, yields were either on par with or lower than last year, with not many reports of fields outdoing last year’s yields. The recent rains have also triggered a flush of weeds. If you look out over the soybean canopy, you’ll see those notorious pigweeds, common lambsquarters, morningglories, and annual grasses making an appearance, especially in the lesser-managed fields.—Dwayne Joseph, Kent

Lower Shore

We have had periodic rains the last few weeks and much of the drought damaged corn is greening up. Farmers are optimistic that the corn will pull through and have average yields. The later planted corn the better, in terms of less drought damage. Most corn is now in reproductive stages. Some corn is being aerially sprayed with fungicides. Milo is heading out. Soybean also faced drought damage, but is looking good with the recent rains. Double crop beans are starting to take off with growth. Substantial weed or pest pressure has not been reported..—Sarah Hirsh, Somerset Co.

Southern Maryland

The region is finally getting some relief from the hot dry conditions we have experienced since June. Rain showers have been scattered, so some areas are better off than others. Unfortunately, some of the rains have come a bit late for corn which was past pollination. For the conditions this year, the crop overall looks much better than should be expected. Soybeans follow much of the same story. Many full season beans could never get off the ground with a lack of moisture and constant deer predation. These plants are now trying to canopy and flower but are way behind schedule for this time of year. Weeds, especially annual grasses, marestail, Palmer amaranth and common ragweed have taken advantage of the extra sunlight and lack of canopy closure to germinate. Many fields are speckled with these weeds coming in later in the season.  Double crops beans struggled to germinate in the dry conditions or were planted late. They have made good strides in the last couple of weeks. Vegetable crops are coming off now with a consolidated harvest season due to the hot temperatures as of late squeezing the harvest window.—Ben Beale, St. Mary’s Co.

*Regions (counties):
Western: Garrett, Allegany, Washington. Central: Frederick, Montgomery, Howard. Northern: Harford, Baltimore, Carroll. Upper & Mid Shore: Cecil, Kent, Caroline, Queen Anne, Talbot. Lower Shore: Dorchester, Somerset, Wicomico. Southern: St. Mary’s, Anne Arundel, Charles, Calvert, Prince George’s

Podworms in Soybeans

Emily Zobel, Senior Agriculture Agent Associate | ezobel@umd.edu
University of Maryland Extension, Dorchester County

The second generation of corn earworms/podworms/headworms (Helicoverpa zea Boddie, Figure 1) will soon emerge from corn fields and other crops. On soybeans, the podworms may feed on foliage, flowers, and fruit. Female moths will lay eggs over the entire plant, but caterpillars prefer to feed on tender vegetative terminals and/or flower clusters. Fields in bloom to pod-set stage with an open canopy and stressed soybeans during this second-generation flight typically reach the highest populations and are at the most risk. Due to our early summer weather this year, more fields might be at risk compared to last year. Podworm populations can be spotty, so one field may have high podworm populations while the field next to it may have low podworm populations. The only way to know what is happening in a particular field is to sample it. You can sample pod worms using either a sweep net or drop cloth.

Figure 1. Corn earworm/soybean podworm moths are robust, light brownish-tan with a 1” to 1 1/2” wingspan. They have a prominent dark spot on each forewing. They tend to be active during the evening and dark hours but can be commonly seen in fields during the day. Photo by Ronald Smith, Auburn University, Bugwood.org.

Thresholds are generally around 2-3 worms per 15 sweeps. NC State University (NCSU) has a nice podworm threshold calculator that helps you customize your threshold based on treatment cost, row width, and price of the bean into consideration: https://bit.ly/NCSUwormthershold. Davis Owen, Delaware Extension Entomologist, recommended applying Besiege or Elevest at their low rates last year to control soybean podworms. Pyrethroids are not guaranteed to provide good efficacy.

Even though fields in the bloom stage are at risk for high populations of podworms, it is generally recommended not to spray during this stage and instead wait for the end of flowering or early pod set to treat. Soybean plants produce more flowers than they can convert into pods. A study conducted by NCSU has found that soybean plants can compensate for this loss of flowers due to caterpillar feeding damage. No yield losses were recorded even with caterpillar levels three times higher than the economic threshold for podding-stage soybeans. Also, young caterpillars tend to have a high mortality rate. They are often difficult to reach with chemical controls while feeding within flower clusters.

Continue to scout during pod growth and fill, as serious yield loss can occur when large caterpillars coincide with soybean seeds that have achieved almost full size.