Crop | | Latham Hi-Tech Seeds

Latham Hi‑Tech Seeds

Phosphorus Deficiency in Soybeans

Credit: University of Nebraska

Phosphorus is responsible for transporting energy created during photosynthesis throughout soybean plants. This essential nutrient is critical in promoting growth, increasing water use efficiency and supporting high yields.

It can be a challenge to identify symptoms of phosphorus deficiency. Agronomists at Iowa State University confirm that phosphorus deficiency is less common in soybeans, but it can still present negative results at the end of the growing season without revealing foliar symptoms.

Scouting for Deficiency

Signs of discoloration are the best way to identify phosphorus deficiency. A dark green, blue-green, or purple-green color can be exhibited in phosphorus-deficient soybeans. Discoloration will begin on the oldest leaves and move to younger leaves.

Leaf cupping and lesions on soybean leaves are additional signs of phosphorus deficiency. The phosphorus level in the soil can also a key indicator of future phosphorus deficiency in plants.

When soils have adequate moisture, signs of deficiency may be more apparent as nutrient uptake is stimulated by moisture. Stunted growth is the most common result of phosphorus deficiency in soybeans.

Treatment Options

As phosphorus deficiency can appear to be asymptomatic, it is important to collect soil samples to capture soil nutrient levels. Once captured, you can decide if additional nutrient application is necessary.

If a deficiency appears in season, the best practice is to pull tissue samples to determine the exact cause. Take twenty leaf samples from the newest mature leaf. The leaf is usually 2nd or 3rd from the top. If plants are in early vegetative stages, send in the whole above-ground portion of the plant. Remember, always pull two samples: one from the problem area and one from a healthy area. Correcting phosphorus deficiency in–season is not typically cost effective. Once you determine phosphorus deficiency is the problem, it is best to apply phosphorus in the fall or spring before planting in dry granular form. Contact your Latham or Data Forward™ Advisor to fine tune your fertility in each field.

Latham Seeds Agronomy Team

April 1, 2019

Agronomics, Crop, Season, Soybeans, Spring
Latham Hi‑Tech Seeds

Nitrogen Deficiency in Soybeans

Credit: Michigan State University

Even as nitrogen-fixing plants, nitrogen deficiency in soybeans can be problematic for farmers. Soybeans can fix up to 50% of their own nitrogen while the other 50% is sourced from soil. Root development and soil health are key drivers of nitrogen deficiency.

A primary cause of nitrogen deficiency is poor inoculation. Rhizobia – the nitrogen-fixing bacterium responsible for prompting nodulation – cannot survive well in coarse, sandy or saturated soils. Cold and wet soils can also suppress rhizobia activity and reduce nodulation.

Soils with low pH can prevent root nodulation and reduce nitrogen absorption Flooding or highly saturated soils can also prevent nitrogen uptake, even if nodulation occurred successfully.

Scouting for Nitrogen Deficiency

Nitrogen is a mobile nutrient, moving throughout the entire plant. It moves to the newest leaves first, leaving the oldest leaves more susceptible to deficiency. In nitrogen-deficient soybeans, the lowest leaves will appear a pale shade of green or show signs of yellowing. Some leaves will also have dark green veins.

Be sure to check nitrogen levels in the soil before R1. As nodules can appear as soon as V1. Check the health of nodules by squeezing them open. If A pink color on the inside indicates that nodules are active and healthy.

Treatment and Implications

A single bushel of soybeans uses 4.2 pounds of nitrogen. Purdue University observed a 38% decrease in yield from nitrogen deficiency – a decline from 65 bu/acre to 40 bu/acre. Rhizobia population can carry over from season to season and continue to support soybean growth. We advise applying inoculant in fields where soybeans have not recently grown. The inoculant can help to stimulate rhizobia activity and promote nodulation.

It is advised to apply 20 to 40 pounds of nitrogen per acre during the R3 growth stage. However, applying nitrogen at planting – especially too much nitrogen – does not increase yield and can actually reduce nodulation. It’s important to determine the best nitrogen application and treatment plan to fit your unique needs. Contact your Data Forard™ Advisor or Latham Representative to discuss your options.

Latham Seeds Agronomy Team

April 1, 2019

Agronomics, Crop, Season, Soybeans, Spring
Latham Hi‑Tech Seeds

Iron Deficiency Chlorosis in Soybeans

Iron deficiency chlorosis (IDC) is a disorder that appears in soybeans during the early stages of the growing season. IDC can reduce yield and lead to stunting if it goes unaddressed year to year. Every year, farmers lose over $100 million to IDC and yield loss estimates range from 20-30% in severe cases.

Credit: Soybean Research Information Network

What to Look For

Iron is an essential nutrient that supports key plant functions including nodulation, energy transfer and plant metabolism. Iron deficiency can reduce the absorption of other essential nutrients including nitrogen. Deficiency in iron prevents chlorophyll from forming which leads to the yellowing of leaves.

In soybeans with IDC, the youngest leaves will begin to turn yellow or white while the veins remain green. Unlike mobile nutrients such as nitrogen or potassium, iron is immobile within the plant. As a result, yellowing and signs of IDC will only be seen on newer growth. Beyond yellowing, severe cases of IDC can cause leaves to turn brown.

Causes and Implications

Upon testing, soils may have abundant levels of iron, but must be in a usable form. Wet soils, salty soils and soils with high pH (greater than 7.5) will cause IDC to occur as these factors prevent iron absorption. Calcareous or chalky soils are also favorable conditions for IDC.

IDC occurs most often in shallow areas that are wet where salts and carbonates have built-up overtime. Under these conditions, calcium particles bind to the soil, making the iron inaccessible to soybeans. Calcium carbonate neutralize acid in roots that is needed to make usable iron. For this reason, soils containing limestone with carbonate levels higher than 5% can make iron insoluble.

High nitrates can worsen IDC since absorbing nitrogen decreases the amount of usable iron. Fields with over 100 pounds of nitrogen per acre can be problematic for soybeans and lead to IDC.

Treatment

IDC cannot be managed in-season. We recommend selected a portfolio of defensive varieties to fight this in your fields. Check our line of Ironclad™ soybeans. Our Ironclad brand has been designed to fight this disorder.

Reducing stress levels for soybeans is critical for preventing IDC or worsening its impacts. Other factors including compaction, over-tillage and herbicide injuries can make soybeans more susceptible to chlorosis or lower their chances of overcoming the deficiency.

Soybean varieties that are resilient to IDC should be planted, especially if a field has produced soybeans with chlorosis in the past. In addition to selecting the right varieties, planting iron-coated seeds can be a way to combat the onset of IDC. In-furrow application of iron chelate fertilizer can also address IDC.

Rotational planting or companion cropping with oats are also solutions for preventing IDC. Intercropping soybeans with oats and wheat can reduce levels of soil nitrates that would otherwise lead to chlorosis. Contact your local Latham Representative to determine a treatment plan that meets your specific needs.

Latham Seeds Agronomy Team

April 1, 2019

Agronomics, Crop, Season, Soybeans, Spring
Latham Hi‑Tech Seeds

Armyworms and Cutworms in Soybeans

Armyworms and cutworms are known to reduce soybean stand and yield by feeding and cutting. Armyworms damage leaf tissue while cutworms clip young plants just above the soil. These worms are differentiated by their appearance.

Black Cutworm (Credit: Iowa State University)

Cutworm

Soybean cutworm species include dingy cutworm, variegated cutworm and black cutworm. Cutworms begin feeding on winter weeds before moving to soybean plants. Cutworms will burrow in the soil surrounding injured plants. Smaller larvae will feed on leaves and larger larvae will cut the plants.

Scouting and Treatment

Dingy Cutworm (Credit: Purdue University)

Begin scouting for cutworms at emergence. The most common signs of cutworm infestation are cut plants, discoloration or wilting leaves. Reduced tillage, no-till and corn on corn rotations can make cutworm infestation more likely. Legume cover crops can also attract cutworms. This protective vegetation should be removed from the soil at least two weeks before planting.

Mature soybeans are the most resilient to yield loss from cutworms. As advised by researchers from Iowa State University, insecticide treatment should also be applied if more than 20% of feeding damage is observed and larvae are smaller than ¾ inch in length.

Yellowstriped Armyworm (Oklahoma State)

Fall Armyworm (University of Tennessee)

Armyworm

The yellow-striped armyworm and fall armyworm are two popular armyworm species. Armyworms grow to be two inches long and feed on both soybean leaves and pods.

Scouting and Treatment

Typically, only one generation of armyworms can be produced in the Midwest due to their inability to overwinter in the cold. Armyworms like to seek shelter in winter annual weeds and grasses. Poorly drained fields can also be an attractive environment for armyworms to dwell.

Applying insecticide is recommended when armyworms are less than one inch. Once armyworms mature and exceed 1 ¼ inches in size, they will stop feeding so it is unnecessary to apply insecticide. Contact your local Latham Representative to assess the best options for treating armyworm and cutworm infestation in your soybeans.

Latham Seeds Agronomy Team

April 1, 2019

Agronomics, Crop, Insects, Season, Soybeans, Spring
Latham Hi‑Tech Seeds

Fall Frost Damage in Corn and Soybeans

Frost damage occurs in corn and soybeans when plants are exposed to freezing or below-freezing temperatures. Damage can occur to the plants above and below the soil when temperatures range from 28 to 32°F and colder. Corn and soybean plants exposed to air temperatures below 28°F are often lethal and prevent plants from undergoing full recovery from injuries. The key in assessing frost damage is waiting five days to allow for any potential growth recovery or rehabilitation to occur.

Credit: Michigan State University

Fall Frost in Soybeans

Once soybeans begin maturity and already have developed pods, they are most often immune from frost injury. Soybeans placed in narrow rows can have more protection from freezing air temperatures in being covered by leaf canopies. Pods growing on the lower portion of the plant are less vulnerable to frost damage than those on the top part of the canopy. Injured soybeans exhibit elongated pods that shrink to smaller than normal sizes upon drying. Most yield loss occurs during the full seed maturity stage.

Soybeans damaged by frost should be dried at a temperature no higher than 130°F and may have lower oil content. Both frost damaged corn and soybeans may also have delayed dry down.

Credit: University of Minnesota

Fall Frost in Corn

Frost-damaged corn can exhibit softened kernels prone to breakage and should be dried at temperatures below 160°F and be stored at a moisture level no higher than 14%. The storage life for frost-damaged corn will be cut in half and damaged corn should be handled separately from uninjured corn.

Latham Seeds Agronomy Team

April 1, 2019

Agronomics, Corn, Crop, Fall, Frost, Season, Soybeans, Weather
Latham Hi‑Tech Seeds

Nitrogen Deficiency in Corn

Photo credit: University of Minnesota Extension

Nitrogen is an essential nutrient and its depletion can lead to severe yield loss. Nitrogen deficiency can be difficult to spot as different hybrids exhibit different symptoms. Most corn plants deficient in nitrogen will exhibit pale-yellowish leaves with a spindled appearance.

Nitrogen is a mobile nutrient and moves to the newest leaves first, leaving the oldest leaves more susceptible to deficiency. By moving from the oldest to youngest leaves, signs of yellowing will often form a “V” pattern on the plant leaf.

Causes of Nitrogen Deficiency

Cold or saturated soils are the primary causes of nitrogen deficiency in corn. Periods of heavy rainfall increase nitrogen leaching, depleting saturated soils of the vital nutrient. Aside from soil leaching, nitrogen can be lost through denitrification – where the nutrient is converted to a gas form and lost in the atmosphere.

When soil conditions are dry, sandy or poorly fertilized, early-applied nitrogen fails to be absorbed by plants. Insect diseases that injure root systems can further prevent proper absorption of nitrogen and lead to deficiency.

Other unavoidable circumstances happen later in the growing season when the increase in plant height and density can block sunlight absorption and reduce photosynthesis. This leads corn to use nutrient reserves within the plant, which will weaken stalks.

Implications

60% of the nitrogen needed to support corn growth is built-up between V4 and pollination, making this an important time to monitor for deficiency. Scouting for nitrogen deficiency should also take place after episodes of heavy rainfall.

While having negative implications on yield potential and crop quality, nitrogen deficiency can also contribute to other corn disorders including tip-dieback and kernel abortion. Plants that are nitrogen deficient will cannibalize their stalks to compensate for the nutrient loss. This makes stalks more vulnerable to lodging and pinching.

Management Options

Tissue sampling can provide insight into how severe deficiency is. When testing for nitrogen deficiency in corn, gather samples from different areas of the field to compare nitrogen levels in deficient corn with healthy plants.

Nitrogen deficient corn should be harvested early in order to prevent additional yield loss from stalk lodging. When planning for next year’s crop, avoid planting hybrids with a history of poor nitrogen uptake. Some hybrids also demand a higher level of nitrogen during grain fill than others, so it is important to consider when planning for the next crop.

Be sure to consult with your local Latham representative to determine the best plan for managing nitrogen deficiency in corn.

Latham Seeds Agronomy Team

April 1, 2019

Agronomics, Corn, Crop, Fertility, Growth Stages
Latham Hi‑Tech Seeds

Anthracnose Leaf Blight

Photo Credit: University of Minnesota

Colletotrichum graminicola is a fungal pathogen that causes anthracnose leaf blight. Anthracnose leaf blight is a foliar disease that appears in the early and late stages of growth in corn plants. The fungus survives in infected corn residue that remains in the field over the winter. The disease creates elongated lesions with a dried, brown appearance across the length of the leaf blade and is bordered by a darker reddish-brown color.

In the earliest part of the season, leaf blight will impact the lower leaves of the plant and expand toward the top of the plant by late season. The upper part of the plant will begin to exhibit early senescence while the lowest part of the corn plant will remain green and healthy.  This is a characteristic of the Top Dieback part of this disease.

Disease Causes

Anthracnose leaf blight develops predominately from the infected residue left behind in the field. No-till, reduced till and corn on corn rotations can increase the likelihood of the disease to emerge. Though no-till and reduced-till methods are critical for preventing erosion and other corn disorders, it can lead to the accumulation of corn debris that is conducive for housing the fungal pathogen.

The fungus thrives in a warm and wet environment. Moisture from rainfall will often create black specks that appear across the lesions. Wind can also act as a transportation method for the fungus as spores can travel by air or water.

Implications and Treatment

The disease will infect at the seedling stage, causing foliar damage, and end at the growing season, causing stalk rot. Although anthracnose leaf blight has the potential to occur later in the growing season, early signs of the infection do not guarantee that it will resurface closer to harvest. Iowa State University researchers state that because of the early-season nature of the leaf blight, impacts on yield are rarely demonstrated. The late season stalk rot phase of the disease tends to be more detrimental on yield and harvestability.

Crop rotation and the use of resistant hybrids are the best ways to combat leaf blight. Fungicides can keep anthracnose leaf blight in control, but it likely will not be effective for combatting the stalk rot phase. Further, corn hybrids that provide resistance against the earliest stages of leaf blight are not often effective for preventing the onset of late-season stalk rot.

If tillage is used, methods that bury infected corn residue can prevent leaf blight from emerging again during the next season. Crop rotation has also been deemed as an effective way to prevent the continued onset of anthracnose leaf blight. For corn that has perpetually been impacted by leaf blight, two-year rotations away from corn are also advised.

Latham Seeds Agronomy Team

April 1, 2019

Agronomics, Corn, Crop, Disease
Latham Hi‑Tech Seeds

Imbibitional Chilling

Causes of Imbibitional Chilling

Imbibitional chilling occurs during the process by which crops absorb water prior to germinating, a phase known as imbibition. Under optimal conditions, seeds should be planted when soil temperatures are above 55°F. When seeds are planted in soils below optimal temperature, the uptake of cold water can damage cells and cause seeds to rupture. This can lead seeds to become shriveled and cause seedlings to emerge late, in a corkscrew shape, or not at all.

If an injured seed eventually develops into an emerged seedling, it can become more vulnerable to disease or damage from herbicides. The risk of imbibitional chilling especially increases when soil temperatures fall below 50°F. Imbibitional chilling or cold injury can occur within 24 to 36 hours of planting, making the relationship between planting timing and soil temperature critical.

Preventing Chilling Injury

As the injury to seedlings occurs after planting, there is little preventive action that can be taken aside from planting when soil temperature is optimal. In the best case, if enough time is afforded between planting and the drop in soil temperature, a seed is less likely to undergo chilling if it is able to absorb warm water. There are ways to determine if imbibitional chilling has occurred after planting. When scouting, look for signs of inconsistent emergence. If a plant looks to be missing, dig into the soil around the area to see if a seedling can be found. If it has a corkscrew shape, underwent leaf emergence below ground, or is missing parts, these are also signs of imbibitional chilling. Delayed emergence of a seed can be the result of reduced seed vigor that can result from imbibitional chilling.

Soil temperatures should be monitored and averaged for the week preceding the projected planting date. To determine the soil temperature on the chosen planting day, take the temperature of the soil just after sunrise – the coldest part of the subsequent 24-hour period. Soil temperature changes more slowly than air temperature, but air temperature can still be a strong indicator for what to expect with soil temperature. If it is projected that soil temperature will remain above 50°F for 24 to 48 hours after planting, imbibitional chilling can be avoided.

Latham Seeds Agronomy Team

April 1, 2019

Agronomics, Corn, Crop, Emergence, Soybeans, Spring
Latham Hi‑Tech Seeds

Rootless Corn Syndrome

Credit: Iowa State University

Rootless corn syndrome is a disorder, often a result of hot and dry soil surfaces and planting into dry soil. With rootless corn syndrome, the nodal roots will fail to attach to the soil. Nodal roots are essential conduits for transporting water and nutrients to corn plants. Their absence is highly consequential for the quality of stand and overall yield outcomes.

Dry soils warm more rapidly than moist soils, and combined with conventional tilling, corn plants can become susceptible to failed nodal root development. Heavy rainfall and planting when the soil is too wet can compact the soil, preventing nodal roots from extending downward.

The erosive effects of rainfall and wind combined with shallow planting depth are the primary drivers of rootless corn syndrome. In addition to weather-related causes, when corn is planted at a depth less than 1 inch below the surface, nodal root development can take place at a depth shallower than what is needed for having access to moist soil. Nodal roots should form between 1 to 1.5 inches below the surface.

What to Look for

Nodal roots first appear around the V1 and V2 stage. Rootless corn occurs in plants with poorly developed root systems and is usually observed in plants from about V3 to V8. When rootless corn syndrome is suspected, look for signs of lodged and collapsed corn plants. Corn plants may still be standing but later on they will lose vigor and fall over. Test plants in the area of concern by tugging on them to determine whether nodal roots are established and growing down.

Preventative Action

Rootless corn can largely be prevented by ensuring that seeds are planted at least 1.5 to 2 inches below the soil surface. For corn plants whose nodal roots fail to grow, the prospects for survival are bleak. Corn nutrient and water uptake hinges on having a developed nodal root system. For plants that do survive, poor stands and low vigor will be exhibited.

Moving soil to cover roots may allow them to recover – but if an operation is following a no-till plan, this may not be viable. Further, row cultivation for bringing soil around nodal roots will be ineffective if the soil below the surface lacks moisture for supporting recovery. Adequate rainfall and the absence of drought conditions will support optimal nodal root development and prevent rootless corn syndrome.

Latham Seeds Agronomy Team

April 1, 2019

Agronomics, Corn, Crop, Disease, Drought, Emergence
Latham Hi‑Tech Seeds

Corn Rootworm

Left to Right: Southern, Western and Northern Rootworm. (Credit: Iowa State University).

Corn rootworm causes negative impacts for farmers every year. On average, corn rootworm costs farmers $1 billion annually, with costs equating to $800 million in lost yield and $200 million in treatment expenses.

The Western, Northern and Southern corn rootworms are three variations of this insect. They grow to be ¼ of an inch long when fully mature. The larvae appear white in color with a dark brown head. After mating in the late summer months, rootworm eggs overwinter and eventually hatch in May or June of the following year.

Rootworm Causes

Rootworms develop across four stages – egg, larvae, pupa and adult. The larvae feed on roots which leads to lodging and overall poor plant stand. Adult rootworms feed primarily on corn silks which can interfere with pollination, leading to lost yield.

Rootworm Larvae (Credit: Iowa State University)

The greatest impacts on yield and quality of stand are larvae feeding on the nodal roots. Mature rootworms tunnel throughout the root system and cause significant damage or death to corn plants. Root feeding and tunneling alone can lead to a loss in yield of up to 50 percent.

While rootworms primarily feed on corn, weeds are also a food source for larvae and mature beetles. Moist soil conditions with high organic matter content create favorable conditions for females to lay their eggs.

Scouting and Treatment Options

When scouting in the spring and early summer, dig up corn plants and check for damage on the root system.  Look for signs of tunneling or larvae actively feeding on roots. Placing the roots of a corn plant along with attached soil in water and waiting for larvae to float to the surface is another strategy to use. In the later stages of summer, watch for beetles feeding on corn ears and silks.

North Dakota State University found that complete loss or severe damage to a single root node can lead to a yield loss of 15 to 18 percent. Crop rotation is considered the best method for combatting continued infestation.

Below is a chart to help guide your insecticide application decision.

We have Latham® hybrids equipped with resistance to rootworm have been deemed an effective method for staving off infestation. Contact your local Latham® representative to determine which hybrids will work best for combatting corn rootworm.

Latham Seeds Agronomy Team

April 1, 2019

Agronomics, Corn, Crop, Insects