Timing for Aerial and “Over-the-Top” Cover Crop Applications

This time of year we begin advising on proper seeding times when using aerial equipment. When aerial seeding, consider the ideal planting window for the cover crop being planted. For example, brassicas and most non-overwintering legumes typically need 4-6 (and preferably 8-10) weeks of growth prior to winter termination to reach their full potential.

Map shows average first 28⁰ date across the country. Continued temps in the 20’s will stop many cover crops from continued growth. See pg. 17 of our Management Guide for USDA Hardiness Zones of different cover crop options.

This planting period must be taken into account to coincide with the proper maturity stage of the crop in the field. Moisture or irrigation is critical when surface seeding to make up for lack of seed-to-soil contact. When time could be a hurdle, aerial and “over-the-top” seedings offer a worthy alternative. Assuming seeding intervals match, the ideal time to aerial seed into cash crops are:

  • Corn: Formation of black layer, or when at least 50% of sunlight reaches soil surface. This can be adjusted earlier if needed, as we’ve seen more timing flexibility into corn than soybeans. Sunlight is imperative, but moisture is even more important as the calendar turns to late Aug. and Sept.
  • Soybeans: Between leaf senescence and 5% leaf drop, but that depends to some degree on row width and soybean architecture. Delaying applications into soybeans decreases seed-to-soil contact and increases risk of poor moisture retention needed for maximizing germination. Getting cover crop seed below the leaves that drop is crucial for success!
  • Sunflowers: Back of the seed head turns yellow

When crop stage and seeding calendar do not align, always err on the side of earlier applications, especially when a moisture event is forecasted or irrigation can be planned. It’s better to have the cover crop seed in the field to begin the germination process vs. planting later, where seed may have to compete with excess cash crop residue from harvest.

Other Considerations:

  • For other cash crops, concentrate on sunlight infiltration to the soil surface. Sunlight and moisture are the limiting factors for bare surface applications.
  • Seed size and density is important as well. Larger seeded cover crops like peas present more challenges getting proper seed-to-soil contact.

Residue and overall irregularity of the soil surface also has an effect. We’ve noticed that some level of residue on the soil and “roughness” of the soil surface significantly increases the ability of cover crop seed to “catch”. The quicker we get adequate seed placement, the greater our chances of success.

Hypoxia Zone the Biggest Ever?  In case you missed it, National Oceanic and Atmospheric Administration (NOAA) scientists determined this years’ Dead Zone in the Gulf of Mexico is the largest ever, reported last week. Depending on media source, the context of these articles are drastically different. Google “hypoxia gulf of mexico” or see the stories below:

While it’s unclear what potential short term impact this news may have, it reinforces the need for our agricultural industry to accelerate the adoption of nutrient management practices. Cover crops are a key tool in the toolbox for doing so.

The Path to Clean, Quality Seed

The small seed industry continues to field frequent questions regarding seed quality and cleanliness. The current momentum behind cover crops has opened doors for new outlets and non-conventional channels for seed to find its way to growers. While many of these new avenues involve small grains, other species aren’t clear of potential seed quality concerns.

Besides the adage “Buyer Beware”, we want to share a couple things we are doing to instill confidence in our customers across the country:







We are members of ASTA (American Seed Trade Association) and our own Scott Wohltman chairs the Cover Crop Working Group. ASTA works diligently to not only represent the seed industry, but also communicates to the ag community, and the general public, the safeguards in place within the agricultural seed supply chain while advocating for U.S. growers in today’s global market.

Look for more communication on the work of ASTA members’ further efforts to certify or confirm seed distributors who meet the rising demands of increasing safety measures against weeds. The rise of palmer amaranth and other problematic weed species has highlighted the differences between good and bad in the industry.










We’ve also developed material to underscore the practices and checkpoints La Crosse Seed verifies to make 100% certain the bag and tag delivered to our customer’s door meets the quality standards both you and we require.

Click to view our infographic and short video explaining our Secure Sourced & Supplied Seed Process. You can also click the button below or click here for more information.
Our Secure Sourced & Supplied Seed Process



Webinar Recap: Herbicide Rotational Restrictions with Cover Crops

We recently had the opportunity to lead a webinar with No-Till Farmer magazine on Herbicide Rotational Restrictions with Cover Crops. As a sponsor of the magazine, we’ve earned the chance to lead webinars the last couple years. Although we submitted several important topics to highlight in an industry presentation, the No-Till folks thought the idea of digging in more on herbicide interactions was a venture they couldn’t pass up.

The hour presentation gave our Eastern Cover Crop Lead, Scott Wohltman, time to talk about herbicides that typically cause more issues with planting cover crops. It also presented an opportunity to hit on how the different herbicide classes normally give us in the industry a “heads up” on likely issues following specific pesticide applications.

Replay Webinar Now
To view the webinar, click the button above or visit http://bit.ly/2sY1sdb

Over the years, we’ve learned a ton from industry experts like Mike Plumer, Dan Towery and numerous others from extension and land grant universities. Scott was able to reference many of those individuals during the webinar. Their work on top of all the feedback we hear from our customers and partners across the Midwest gave us the foundation for sharing the information our team uses in the field.

If you have questions, comments, concerns or disagreements with anything presented, please let us know by emailing info@laxseed.com. We would love to hear your feedback – the more we learn the better.


Concerns About Residual Herbicide?
One method to address this is to do a bioassay. If you are unclear whether or not a cover crop will germinate, this is a great way to test establishment. We now have Herbicide Carryover Bioassay Kits available for Soil First customers. To request kits, contact us.

Management Tips to Combat Slugs

Management Tips to Combat Slugs
We are hearing more reports of slug damage from cereal rye fields across the Midwest. We do highlight some management considerations in our newly released Soil First™ Management Guide (Edition 6) on pg. 29. To view that information click here 
Need Access to Cover Crop Management Info in the Field?
We encourage you to save and reference our new management guide here

Besides the points on pg. 29, we’d like to elaborate as we continue to hear what’s helping fight slugs. Here are things to think about, which often go against the practical, traditional cropping systems we see across the Corn Belt:

  • Cover crops give slugs an alternate food source vs. attacking the growing cash crop. This works when the cover crop is allowed to mature to the point of seed production. While this isn’t for everyone, we’ve witnessed it this past spring. Standing green cover attracts beneficial insects (ground beetles, etc.) which feed on slugs.
  • Enhance your rotation. Varying your crop rotation often disrupts life cycles and perennial timing issues we see with many pests. The more varied the cropping cycle, the less pests (like slugs) can adapt.
  • Lastly, consider these options that many growers continue to use with some level of success:
    • Metaldehyde (Deadline and others). About 5 lbs./acre broadcast. Slugs eat the pellets and die from dehydration. Industry research shows this product doesn’t have any harmful effects on many of slugs’ natural predators.
    • Nitrogen. Applying liquid N at night (when slugs are most active) has worked in many areas. Using 28% or 32% mixed with water for a couple nights (maybe a third) in a row should be the plan. N basically melts the slugs.

Prevent Plant? Maintain Soil Health with These Useful Tips

When fields are open during late spring/summer, whether part of a planned system or created by unfortunate weather, it’s critical to keep soils covered, taking advantage of the longer seeding window and maintaining soil health benefits.

Keep these items in mind if prevent plant is a possibility within your operation:

1. DO SOMETHING. Leaving ground fallow greatly increases risk of erosion and improves the likelihood of leaching nitrates, sulfates and other nutrients that could be used by the following year’s crop. Bare ground also encourages risk of “Fallow Syndrome” the following year. Fallow Syndrome occurs when there’s no plant growth in an area for an extended period. Populations of “good fungi”, called active mycorrhizae, are reduced because they need actively growing roots to survive. These fungi depend on host plants to complete their life cycle. Adding a grass (ryegrass, oats, etc.) or legume such as peas or hairy vetch are extremely beneficial and will better support the good fungi in the soil.

2. DETERMINE YOUR GOALS. There are many “cover crop” options available to use. The crop rotation goals of the producer should help steer the decision. Normally, crop harvest can often limit the time we have available to plant a cover crop, but because our planting window is now early, just about everything can be considered. Again, this should depend on what the producer wants to accomplish with the cover crop planting.

3. UNDERSTAND THE GUIDELINES. If taking the full prevented plant option, haying or grazing is not allowed until after Nov. 1 (or other dates in the Midwest, depending on state or region). Check with your state or county FSA office for further info on grazing restrictions with this program.

4. THINK ABOUT HERBICIDE RESTRICTIONS. Consider herbicides already applied on acres not yet planted. In many cases, cover crops and other non-traditional crops will not be listed on the herbicide label. Many universities are doing more work on this topic to determine what options farmers have in the case of “prevent plant” or other cropping systems that offer quick seeding windows. If a cover crop is being planted for erosion control and won’t be harvested, the grower then assumes the risk if that cover crop doesn’t appear on the herbicide label. However, if that cover crop will be harvested as forage, either mechanically or by livestock, then rotational restrictions on the label must be followed. For more information on herbicide rotational restrictions, refer to FAQ #5 in the Soil First® Management Guide.

5. USE MIXES. Cover crop mixes allow for diversity and opportunity to spread out risk. Mixes also allow for reduced weather risks, help break pest cycles and prevent erosion that some monoculture species are vulnerable to. Added benefits include nitrogen fixing and improved soil health as well.


As always, double check your plans with your crop insurance agent to ensure compliance. For late planting dates and other information for your state, see below:
Iowa, Minnesota, Wisconsin: http://bit.ly/2s3PfAz
Illinois, Indiana, Michigan, Ohio: http://bit.ly/2sgEtZN
Kansas, Missouri, Nebraska, Colorado: http://bit.ly/2slX0Vp
Montana, North Dakota, South Dakota, Wyoming: http://bit.ly/2s3S7Nu

For more info on insurance programs, including early and final planting dates by county and state, visit: http://bit.ly/2nrxecb

Spring Cover Crop Reminders

Cover crops typically mean additional residue in spring, which brings about additional management considerations, detailed below.

Cover crops and green manure can harbor insects, diseases and nematodes harmful to subsequent cash crops. Armyworms, cutworms and other pests present additional management considerations after grass cover crops (i.e., annual ryegrass), cereal grains and even legumes (crimson clover, hairy vetch) due in large part to soil surface residue.

Armyworms can lay eggs in grassy cover crop fields, and young caterpillars attack corn mid-spring through early summer. Armyworms also move into corn from surrounding wheat fields, causing damage primarily along field edges.

There are labeled armyworm insecticides available and many growers include this with burndown application, however, armyworm populations may not yet be sufficient to warrant the cost.

Instead, scout fields often after corn planting. While it may be difficult to find armyworms, inspecting their damage is easier. Refer to local threshold recommendations to determine if and when to apply insecticide (foliar applications have proven successful).

Slugs & Voles
Slugs and voles may increase with introduction of cover crops and no-till. Many growing practices that leave surface residue can lead to enhanced habitat for these pests. For growers practicing no-till or reduced tillage, have solutions that don’t result in added deep tillage (minimal tillage may be necessary in some situations).

Below are steps to help cover croppers minimize occurrence of slugs and voles, especially in fields where it’s been a problem previously:

  • Plant cash crop early. Faster establishment = less feeding from slugs as crop will be too large to feed.
  • Keep roadsides & ditches/waterways mowed. This will decrease vole protection, especially when breeding is heavy and numbers are growing.
  • Control or terminate cover crops 3-4 weeks before planting to decrease residue.
  • Ensure seed slot is closed and firm. This will reduce direct feeding on the seed (may require deeper seed placement than usual).

Early cover crop termination and residue management at planting can reduce risk of pest damage. Insecticide may be required if planting into standing cover or within 3-4 weeks of termination. However, remember that surface residue creates a more diverse soil ecosystem versus conventional tillage systems and often attracts beneficial insects too. For nematodes and diseases, select products to meet your goals, plan early and manage accordingly.

How much and when nitrogen (N) will be available after grass cover crops is a common question with no easy answer. The rate and extent of N release from decomposing grass cover crops depend on many factors, including plant stage at termination, carbon to nitrogen (C:N) ratio and weather.

Plants in the vegetative stage have higher N concentration than those in the reproductive stage and decompose faster. The C:N ratio determines timing of N release from these residues. High C:N cover crop residues (>25:1) will first use and deplete N from soil or recent fertilizer N additions. Only after some time will N begin to release back to the soil.

For grass cover crops, terminate in the vegetative stage if the following cash crop is a grass, such as corn. If the cover crop reaches the reproductive phase before termination, more N will be used after termination and an additional starter N fertilizer application will be needed. This is crucial for the health of newly seeded cash crops.

Not all N scavenged by the cover crop will be available the next season, so fertilizer N rate should not be reduced by the amount of N kept from leaching (some scavenged N goes toward building soil organic matter). Grass cover crops, while in the vegetative stage, have C:N ratios around 10:1-15:1 and release N rapidly after termination. Roughly 50% of N in the above-ground biomass will be available over a window of 1-2 months, depending on weather.

Pesticides used now on cash crops can still impact cover crop establishment later – especially if cover crops are seeded prior to harvest. When interseeding cover crops it’s important to follow pesticide guidelines; those herbicides can affect cover crop germination, and established cover crops within the cash crop will alter the chemical options one can use. The industry continues to use information from several universities, listed below. We strongly encourage keeping these close:

University of Wisconsin: http://bit.ly/2pugapH
Purdue University: http://bit.ly/2pGUrvS
Penn State University: http://bit.ly/2oN43AO
Iowa State University: http://bit.ly/1VhrWdK
University of Nebraska: http://bit.ly/1oBFdTy
If using seeding equipment from your NRCS or SWCD office, consider reserving soon. It’s evident that machinery rental programs are working in many areas. However, most offices will tell you that the earlier they’re made aware of equipment needs, the easier it is for everyone coordinating these efforts come late summer.

Cover Crop Termination Considerations

Besides mode of action, there are a few factors to consider when selecting the correct burndown herbicide – like resistance and potential carryover.  Below are some factors with key burndown herbicides to keep in mind as the timing window for applications this spring is right around the corner.

  • Weather is probably the biggest consideration. Almost all herbicides work best when plants are actively growing (especially herbicides that are translocated). Cool and cloudy conditions often delay herbicide activity, and dry weather can increase carryover potential.
  • Glyphosate (Group 9) is a common burndown option. Glyphosate kills plants by barring the synthesis of amino acids (which can take up to a couple weeks to completely kill the plant). This chemistry needs to get to the growing point of the plant to be active. Thus, anything that prevents glyphosate from translocating within the plant will reduce its effectiveness:
    • Cold and cloudy weather
    • Premixes with glyphosate that kill plants quickly (like paraquat, for example)
  • Paraquat (Group 22) is another possibility. Paraquat terminates plants by triggering free radicals in the plant to build up and break up plant membranes. This happens quickly, usually within a couple days. Because paraquat is a contact killer, good coverage is needed to get control. Broadleaf control is more assured than with grasses, where a second application may be needed due to regrowth. Paraquat has zero soil activity, so carryover concerns aren’t a problem.
  • Glufosinate (Group 10) kills plants by disrupting ammonia recycling – which causes photosynthesis and other processes in the growing plant to stop. Like glyphosate, control of plants using glufosinate is greatly affected by weather – plants need to be actively growing to achieve adequate results. Good coverage is needed as this is a contact herbicide as well.
  • Group 4 herbicides (Auxenics) have a place in cover crop burndown applications. 2,4-D, dicamba, and clopyralid all fall into this category of herbicides that work primarily on legumes and other broadleaves. Auxenic herbicides kill plants by disrupting metabolic processes within the plant, usually taking at least a week for plants to die. Resistance to Auxenics in waterhemp and other weeds have occurred – and we know that several mustard species aren’t easily controlled with these products. We typically don’t see any carryover issues with Auxenics, although 2,4-D can cause some problems, depending on organic matter and soil pH.
  • Group 5 herbicides (Triazine family, metribuzin, others) work for burndown applications by stopping the photosynthesis process in the plant. These herbicides translocate differently than glyphosate, which means post applications are not as effective. Dry weather can reduce their effectiveness too. Several weeds have selected resistance to Triazine herbicides (like pigweeds, lambsquarters, velvetleaf, etc.). Because of their residual activity, consideration for the following cash crop (and cover crop) is important.
  • PPO Inhibitors (Group 14) like Sharpen and Reflex stop biosynthesis of chlorophyll and other pigments in the plant. PPOs typically work better on broadleaves than grasses, and affected plants usually die within a week. Resistance to PPOs has been witnessed across the country (waterhemp and palmer amaranth), and carryover concerns are valid with PPOs, especially on fall cover crops.
  • ACCase Inhibitors (Group 1) herbicides are used on grasses in post applications, and typically take about 2 weeks for plants to completely die. Examples of these herbicides are sethoxydim, clethodim and quizalofop. Like other herbicide families, ACCase inhibitors work best on actively growing plants. In dry conditions, expect these herbicides to have a reduced effect. Using Group 1’s alongside 2,4-D and other Auxenic herbicides have caused reduced efficacy. Some resistance has been seen in annual ryegrass to ACCase products so caution must be taken.
  • Many other options exist to control cover crops in the spring. Use caution and plan ahead for your best chance at success.

This chart is derived from the University of Wisconsin and Penn State University, with a few additional options our group has added based on experience in the field. If questions, contact us at 800.356.7333 or info@laxseed.com. We have additional resources to help you make the best decisions this spring.

References: Shaner, University of Colorado; Hartzler, Iowa State University; Johnson, Purdue University;  Davis, University of Wisconsin; Curran, Penn State University.

The Importance of Clean, Weed-Free Seed

The Importance of Clean, Weed-Free Seed
We’ve been following reports lately related to noxious, problematic weeds like Palmer Amthe-dirt-9132aranth showing up in cover crops. Be sure to use clean, quality seed for cover crop plantings and keep these things in mind:

  • Use tested, noxious weed-free seed. A tag can tell you a lot. Look for certified noxious and problematic weed-free seed to optimize success and lower risk. Request seed test results to be sure.
  • Growing location matters. Make sure your seed is grown in areas with less humidity.
  • Use a supplier of seed, not grain. Professional seed suppliers procure seed from agronomically sound producers trusted to bring quality, weed- and disease-free seed into the market.

To meet the demand for quality assured, ultra clean seed, we offer Guardian™ Fall Rye. This brand is carefully selected and screened to ensure the cleanest and purest cereal rye for cover cropping, higher than industry standards.

10 Steps for Successful Cover Cropping

While cover crops won’t be seeded for several months, the cover crop key decision season is upon us.  Make sure you keep these steps in mind to ensure success:

  1. Have a Goal. Ask: “What do I want to accomplish by planting a cover crop and what benefits do I want to work toward?”
  2. Select the Right Cover Crops to reach your goals. There are many species on the market and each has a distinct set of characteristics to achieve different outcomes. Wrong choices lead to more problems.
  3. Have a Plan. Think about changes that may be needed to your current farming system to allow for correct establishment (and management):
    • Modifying crop rotation (perhaps adding another crop to your rotation creates a wider window in fall)
    • Altering previous crop’s harvest slightly for more timing flexibility
    • Adjusting herbicide program for timely cover crop seeding
    • Additional pass in fall and/or spring for planting and spring termination
  4. Select a Field or Areas of Your Farm that will benefit most from a cover crop
  5. Think Small Acres starting out. Consider new management concepts needed when first trying cover crops.
  6. Get Seed Ordered Soon. It may take longer than you think for less-traditional seed to arrive. Good, clean seed is the most demanded too (seed, not grain. Seed is professionally grown and maintained for good quality and germination).
  7. Allocate Labor and Equipment. Depending on your seeding plan, you may need extra help for prompt seeding after cash crop harvest. If the plan includes custom seeding, communicate plans early to ensure timely application.
  8. Consider Leaving a Check Strip for Comparison. How better to determine progress than by seeing uncovered ground side-by-side?
  9. Balance Goals and Spring Management Wisely. Even the perfect cover crop not managed or terminated correctly in spring can lead to setbacks for your subsequent cash crop.
  10. Make a Commitment. Some goals are easily noticed and well defined, but improving soil health is a journey, not a destination. It takes time to regenerate soil and demands producers consider long term expectations, no matter the initial goal or objective.

LINK™ Inoculant – Year One Lessons

Last year we introduced LINK™ Cover Crop Inoculant, a peat-based product designed to inoculate all legumes in one convenient package. We knew it’d be a hit for several reasons. What we learned this fall wasn’t surprising, but we want to share with you our findings:

  • After several presentations on the importance of inoculants, it surprised us how many questions arose on how long pre-inoculants survive on seed prior to planting. Remember, in many cases (aside from red clover and alfalfa), rhizobium that nodulate cover crop legumes are fragile and susceptible to desiccation.Depending on the strain, they won’t survive on seed beyond 24 hours. In contrast, rhizobium that nodulate alfalfa can survive on seed 2+ years. Beware of pre-inoculated cover crop seed. In most cases, there won’t be any surviving rhizobia.
  • Anytime you work with dry peat products you may run across a challenge or two at planting, largely due to moisture in planting equipment (humidity, dew, etc.). We didn’t uncover any issues with this, largely because LINK™ has a low use rate. It’s important to state again the correct procedure for mixing the product with seed:Mixing LINK™ and the seed thoroughly is important and even layering the seed and inoculant can improve this more. We also saw that slurry mixing worked especially well, but planting needs to commence as soon as the “coated” seed is dry.
Other Points to Keep in Mind:

  • Each legume requires a certain strain to nodulate properly. For example, the strain that nodulates red clover will not nodulate crimson clover, and peas and vetches require their own specific strains. Likewise, any leftover soybean or alfalfa inoculant will not work with cover crops.
  • LINK™ is designed to apply to the entire seed mix for ease of use and convenience. The advantage of applying inoculant to the entire mix is that the non-legume seed components “carry” inoculant into the soil, where the legume seeds are nearby. This provides more complete nodulation of the legume and enhanced nitrogen fixation than if the inoculant was applied only to the legume seed. Remember, inoculants are for the soil, not the seed!
  • LINK™ is included with Soil First™ cover crop legume mix orders of 500 pounds or more and can also be purchased as a standalone product
  • LINK™ can be used effectively on over 50 legumes making it a convenient option for forage plantings too
Other Frequently Asked Questions: 

  • How long will LINK™ stay viable after it’s been applied to the seed? 24 hours
  • Is LINK™ a GMO product? No. There are no ingredients of LINK™ that would render it a GMO.
  • Can I apply LINK™ at the same rate on straight legumes too, and are there enough rhizobium to handle a mono-culture legume seeding? Yes. With LINK’s high rhizobia counts there are sufficient numbers of rhizobia present to nodulate each straight legume on the label.

For more information, please review the LINK Technical Sheet, or contact us to learn more.

About The Dirt

The Dirt is a periodic email series with timely cover crop tips from the agronomic experts at Soil First and La Crosse Seed. If you have a question you’d like us to answer, contact us here.