It’s time to scout soybeans!! Tune in for a 10 minute soybean blitz on what to look for in the field.
| Insects: Japanese Beetles | 1:55 |
| Insects: Gall Midge | 2:35 |
| Insects: Aphids | 3:55 |
| Diseases: Sudden Death Syndrome | 4:45 |
| Diseases: Frog Eye | 6:10 |
| Diseases: Soybean Cyst Nematode | 7:14 |
| Disorders: Iron Deficiency Chlorosis | 8:22 |
| Disorders: Root Development | 9:33 |
| Disorders: Herbicide Injury | 10:55 |
If you’re fortunate to be done with planting your crops, it’s time to get back out there and check your stands. This year I’m especially concerned with soybean stands for three main reasons:
Walking fields right after emergence gives you the most time to make corrections or to replant. Stand reductions rarely occur evenly across a field. That’s why I recommend taking 10 stand counts in the area where the problem is the worst, as well as taking 10 counts in an area that was not affected or is slightly affected. Most university researchers recommend keeping a final stand of at least 100,000 plants per acre.
University trials also indicate that planting soybeans on or before June 1 in northern Iowa and southern Minnesota gives 95% of expected yield. It is usually June 15 before soybean yields drop below 85% of what is expected. Over the years, we have seen decent soybean yields when soybeans were planted around the 4th of July.
Scouting early and often is the best advice I can give, so you can remedy the situation as soon as possible. Different insects, diseases and pests may be present due to weather conditions and stage of crop development. Scout diligently all growing season long!
Will your planted fields be affected by imbibitional chilling? Tune in the hear symptoms of the chilling effect.
Each day we turn the calendar, I receive more calls from Latham® dealers and farmers asking whether they should change maturities. Keep in mind, the object is to achieve maximum yield potential for this crop. When you switch maturities, you forfeit maximum potential and have essentially decided to lower your yield expectations!
Based on my experiences over the past 40 years – as well as research findings from many Midwest land grant institutions – I can tell you with confidence that full-season hybrids and varieties outperform early maturing hybrids and varieties. Most people jump the gun and make the switch way too soon. Corn planted in mid-June can make decent yields, and there’s no need to switch from corn to soybeans until after that.
There becomes a point in time where the advantages of planting a full-season hybrid diminishes to the point where shifting to a shorter-season hybrid or variety will generally result in drier corn and higher yields come fall. Below is a summary of factors to consider when deciding whether to switch corn or soybean maturities.
I’ll use northern Iowa and southern Minnesota as an example. If your maturity range is 98- to 109-days (which is what I use for the Latham Research Farm), then you should generally not deviate from those maturities until at least May 25. If all you have left to plant is your 98-day hybrids, then you can safely extend your planting window to about June 7-10. On the other hand, if you only have your 109-day hybrids left to plant, you’ll probably be better off switching to 95- or 99-day products.
That brings us to the next subject… if you must switch, how early of a hybrid is needed? You don’t need to take it to extreme and switch from 109 RM to an 85-day hybrid or something equally silly! Research has proven that it pays to stay closer to your “normal” maturity. Switch to hybrids that are about 5 to 7 relative maturity units earlier than full season for the region. Yields in this scenario will be greatly improved if northern Iowa and southern Minnesota farmers (from the example above) move toward a 92- to 95-day hybrid that is more closely adapted to the area.
The decision to switch maturity with delayed corn planting is difficult because of so many variables including: available GDUs, first frost date and fall drying conditions. With this in mind, here are some general guidelines for Iowa farmers:
| Location within Iowa |
Full Season RM | Switch to on May 25 |
Switch to on June 10 |
| South of U.S. 92 | 114-117 | 108-111 | 105-109 |
| Central | 108-115 | 104-110 | 100-106 |
| North of U.S. 20 | 100-109 | 96-105 | 94-100 |
For your convenience, below are few links to related articles: Adjust this information depending on where you farm, but make your decision is based on sound research and not “coffee shop facts.” Just because your neighbor is switching doesn’t mean it’s the best decision. Conduct a little research of your own before deciding what might be best for your operation.
There is absolutely no reason to start switching soybean maturities until at least mid-June. I use June 20 as our cutoff here in North Central Iowa, but again, it depends on what you were planning to plant in the first place. In this area, bean maturities range from 1.8 to 2.7. L 2482 R2’s are still good to plant in this region until mid-June as we’ve done it before with great results.
Soybeans have even more resiliency when it comes to maturity stretch. Because soybeans are more “photo period” sensitive, they actually adjust based on the length of the nighttime. A planting date of June 20 in southern Wisconsin and June 15 in northern Wisconsin, using early maturing varieties, was considered to be the latest practical date by the University of Wisconsin. Soybeans can be planted in our area as late as the Fourth of July with decent yield results as long as we don’t go into a dry period.
The 2019 planting season will certainly test our patience! It’s tough to turn pages off the calendar without putting any seed in the ground, but it’s better to wait a few more days than to mud seed into the ground. Experts warn that compaction and/or inadequate seed-to-soil contact from planting in wet conditions cause yield reductions for soybean farmers. During a wet year, it’s even more important for soybean growers to pay close attention to machinery. Avoiding soil compaction and obtaining good soil closure over seeds will help increase yields. For more soybean planting tips to boost yields, click here.
In 2018, the EPA extended the registration for over-the-top use of select dicamba products to control weeds in soybean and cotton fields that are genetically engineered to resist dicamba. This registration included label updates which add certain measures to further minimize the potential of off-target damage. This registration will automatically expire on December 20, 2020, unless the EPA extends it further. Listed below are some of the FEDERAL updates now in effect:
Minnesota: Must not apply dicamba herbicides after June 20th. There will be no temperature restriction for 2019.
North Dakota: Must not apply dicamba after June 30th. Keeping records of dicamba applications is required and will be strictly enforced.
South Dakota: Must not apply dicamba after June 30th, 45 days after planting or the R1 (beginning bloom) stage of soybeans, whichever comes first. Applicators must also pass a short exam after training is completed.
Illinois: Must not apply dicamba after June 30th. Do not apply when the wind is blowing toward adjacent residential areas. Before spraying, the applicator must consult the FieldWatch sensitive crop registry. Further restrictions apply when spraying near the downfield edge of any Illinois Nature Preserves Commission Site.
These are just some of the new requirements for the application of dicamba over-the-top of soybeans in 2019. There may be additional restrictions from the states not mentioned above or from local authorities. If you will be applying any of the dicamba products in 2019, make certain you attend the required ANNUAL training and conform to what the label requires. Please make these restrictions a high priority so we can continue to use this valuable tool in the fight against weed resistance!
Join us this morning on #AskTheAgronomist as we discuss pertinent planting tips with the recent addition of snow in the forecast. #LathamSeeds
Rotting of soybean stem and root tissue, or “damping off,” can jeopardize stand quality and reduce yield. The Phytophthora fungi can impact seedlings both before and after emergence. Even if seedlings successfully emerge above the soil, they will have poor vigor and slow early growth.
Poor stand is one of the primary consequences of damping off, though replanting may be possible. North Dakota State University research cites that Phytophthora-related yield loss has reached up to 30% in states throughout the Midwest.
Cool weather is a major cause of damping off as it slows germination and stifles growth. Phytophthora thrives in soil temperatures between 70 and 77°F but can also survive in extremely cold temperatures. Warm temperatures, poor drainage and/or clay soils create a susceptible environment for damping off.
Before seedlings emerge, the fungi can cause seeds to rot. Rotten seeds will appear to be caked in soil with discolored roots. Roots may not be fully developed or even exist.
Wilting can occur in emerged seedlings as the cotyledons will appear brown and saturated. Plants that developed leaves before showing signs of damping off will begin to turn a grayish color before turning brown.
Damping off can sometimes be confused with herbicide injury. Whereas fields impacted by herbicide injury will have uniform damage, damping off will create inconsistent patches of impacted crops.
With the overwintering nature of the Phytophthora fungi, controlling the amount of field residue can make the environment less conducive for fungal growth. Also, when planting early or in fields with poor drainage consider using fungicide seed treatments to protect seedlings.
Varieties equipped with genes resistant to Phytophthora will protect plants after they emerge and later in the season as well. Contact your local Latham® representative to determine which varieties will work best for your needs.
Sclerotinia stem rot – also known as White Mold –can lead to significant yield loss in soybeans. Yield loss from white mold is attributed to the damage it causes to leaves, pods and stems. Research from the University of Wisconsin estimates the disease has costed growers in the U.S. and Canada 101 million bushels of soybeans – equal to $1.2 billion.
White mold is caused by the fungus Sclerotinia sclerotiorum and overwinters in the soil for a number of years. After the fungus emerges from the soil, mushroom shaped structures known as apothecia will form on the soil surface. The apothecia, ranging between ¼ and ½ an inch wide, will first infect through soybean flowers before it reaches the stem.
While the fungus primarily spreads through the air via spores, moisture is required for infection to take place. As a result, cool and wet weather along with high humidity are the main causes of white mold.
While Sclerotinia sclerotiorum is often confused with other fungal pathogens, the sclerotia distinguishes white mold from other look-alike diseases. Symptoms of white mold will be most prevalent between R3 and R6. Infected plants will exhibit white fuzzy growth on the lower stem.
Soybean blossoms are the first area of the plant to exhibit signs of infection and neighboring stems and pods may appear water-saturated. After infecting blossoms and pods, white mold may eventually spread through the entire stem causing it to turn tan or bleached of color. As the mold growth becomes thicker, black spots will begin to surface throughout the fuzzy white surface.
White mold also creates foliar symptoms, causing leaves to completely die while still attached to the stem. In infected soybeans, the tissue area between the leaf veins will turn gray and cause leaves to become wilted and curled.
Due to the overwintering nature of the sclerotia, a two to three-year rotation away from soybeans is advised. When it comes to genetics, some soybean varieties are more resistant to white mold than others. Varieties with resistance to the fungus may recover better than others. It is also important to consider planting practices that cause white mold growth. Shade created from high plant density and growing canopies can lead to the fungal disease. Increasing row width and reducing planting populations are the best methods to improve airflow through the canopy and reduce infection from white mold.
In addition, broadleaf weeds are notorious for hosting white mold and herbicides should be used to control weeds. Fungicides are a viable method for treating white mold and can reduce the negative impacts incurred by soybeans. However, they are most effective when applied just before infection takes place. Be sure to consult with your local Latham representative to determine the best treatment plan for white mold.
Japanese beetles cause damage to corn by interfering with pollination and lead to defoliation in soybeans. Their distinct metallic-green heads and bronze wings make them distinguishable from other look-alike beetles. The insect undergoes one life cycle per year with adults reaching 5/16 inches in length.
Eggs are laid during July and August and overwinter until temperatures rise in the spring. For both corn and soybeans, adults migrate from grass and begin feeding in late May or early June. The peak emergence for Japanese beetles occurs 4 to 5 weeks after feeding begins.
Japanese beetles tend to feed in concentrated areas and in groups. After the female burrows into the soil, she will lay 1 to 4 eggs at a time for several weeks. Adult grubs feed on turf grass in late summer and early spring before emerging to feed on crops.
Corn In corn, Japanese beetles can feed on silks and interfere with pollination. Though leaf feeding in corn is possible, a majority of the economic impacts are attributed to silk feeding. Plants should be treated if there are three or more beetles per ear.
Research from the University of Tennessee found that repeated clipping of silks did not always lead to yield loss. More importantly, the environment has a stronger influence on the damage Japanese beetles can cause. Higher yield loss in infested corn plants that were under drought stress as opposed to plants that were not.
In soybeans, the beetle strictly feeds on the soft tissue bordering leaf veins, leaving them skeletonized. Soybeans growing in sandy soils are even more susceptible to defoliation from Japanese beetles. Though yield loss from Japanese beetles has not been quantified, figures from North Dakota State University (see table) point to the general yield impacts from defoliation.
Research from the University of Nebraska advises treatment when damage reaches 30% defoliation before bloom or 20% defoliation during flowering. As long as beetles appear to be actively feeding, insecticide application is advised.
Japanese beetles are easily confused with other species of beetles, including masked chafers and May or June beetles. Be sure to consult with your local Latham representative to confirm suspected Japanese beetle infestations and determine the right treatment plan.
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Photo Credit: Purdue University