How much stress can soybeans handle? Phil Long discusses important early season soybeans stresses and their impact on yield. #AskTheAgronomist
1:00 — Scouting Tips: Staging soybeans
3:45 — Post-emergence weed control
6:20 — Yield impact with early season stresses
9:12 — Soybean nodules
10:15 — Final thoughts
What role does sulfur play in your soybeans? Phil Long discusses the importance of available sulfur and feasibility of in-season application.
Early season field scouting is essential to detect potential issues like weed and insect pressure, as well as to monitor the effectiveness of your fertility program. One great tool to try and discover fertility problems is a plant tissue analysis. To assure good results from the lab, you must collect the proper part of the plant for the current growth stage of the crop.
For the most effective tissue sample, consider following these four steps:
A proper method to collecting early season corn tissue samples is to gather 15 or more plants to complete a single sample. This method is best when the corn is up to 12 inches tall, which is approximately the first three weeks following emergence because much of the nutrients come from the tissues within the seed at this stage.
One example of how a tissue sample can help determine a cause is the case of a purple-colored corn plant. This could be the result of phosphorous deficiency, or it could be because nighttime temperatures were too low.
Plant tissue analysis is a proven diagnostic tool that compares nutritional variances between normal and abnormal zones in the field. No matter the crop, plant tissue analysis is worthwhile to help determine nutrient needs. Don’t make fertilizer decisions based on plant tissue samples alone. To create a nutrient plan, combine tissue sampling with soil test results, records of lime and nutrient applications, cropping history and recent crop protectant applications.
Wait until V2 growth stage, which is three to four weeks after emergence before taking tissue samples of soybeans.
Accurate tissue testing begins with proper sample collection and handling. Collect the proper part of the plant for the correct growth stage of the crop. Also make sure to collect the proper number to have an accurate complete sample. Try to package samples in paper bags. If it will take a while before you get the samples shipped, store samples in a cool environment but do not freeze the sample. In addition, never include roots with the plant samples.
If you’re interested in learning more about how to conduct your own tissue samples, call your Latham Precision Agronomy Advisor. We can help download your Latham Data Forward app, so you can use the no-cost tissue sampling function to collect your samples!
Soybeans are a common host of thistle caterpillars – an insect that is able to feed on over 300 different plants. Damage from the thistle caterpillar can be minor leaf feeding or in large infestations, total defoliation. In higher infestations action may be needed, but typically thistle caterpillars don’t cause enough damage to reduce yield or warrant chemical control.
In adult form, thistle caterpillars are known as painted lady butterflies and have a wingspan of 2 to 3 inches. The wings are orange, pink or brown with four eyespots near the tips of the wings. Caterpillars have a yellow stripe that runs the length of the body. Their spiky hairs make the insect distinguishable from other look-a-like insects.
The insect is typically unable to overwinter in the Midwest. Butterflies migrate from southern portions of North America to the Midwest and lay their eggs in June. The eggs are lime green and oblong with a ribbed texture.
Thistle caterpillars can produce one to two generations per year and feed primarily during July and August. Caterpillar feeding takes place over the course of 2 to 6 weeks until the insects reach pupation. The second generation of the insect is known to feed at the topmost layer of the canopy and causes leaves to stick together from excreting silk.
Thistle caterpillars are known to cause the most harm to soybeans during V3 and V4. When scouting for signs of caterpillar feeding, examine leaves from each level of the soybean plant. Select 100 different plants from across the field and check for feeding injuries at the top, middle and bottom third of the plant.
Treatment is advised when defoliation is exhibited in 30% of plants during vegetation or 20% in plants undergoing reproduction. Insecticide application can be used to control the insect’s population. Be sure to consult with your local Latham representative to determine the best treatment plan for managing thistle caterpillars.
