Pre-Harvest Crop Management
BY Agronomy Team
TOP DIEBACK AND STALK ROTS ENCOURAGE SCOUTING FOR STALK INTEGRETY
With corn harvest soon upon us it is especially important this year that we spend time scouting our corn fields and prioritizing which fields need to be harvested first and which ones can wait. In walking corn fields, we are seeing a fair amount of top dieback and some stalk rots.
Top dieback is when leaves begin to die or senesce from the top down, earlier than normal. The most common stresses that cause top dieback are drought, insect damage or disease. Top dieback caused by drought or hybrid specific top senesce will be fairly uniform across a field. Top dieback caused by insect damage or disease will be more random across the field. Damage from tunneling insects like corn borer are less common today due to the wide use of Bt traits.
Anthracnose is a fungal disease that commonly causes top dieback. Symptoms of anthracnose include black lesions that are visible on the outer stalk tissue behind the leaf sheaths. If you split the stalk the pith will be discolored or rotted in the upper nodes. Conditions favorable for infection include cloudy days with high humidity and plant stress following pollination. The picture below shows top dieback from anthracnose.
Other common stalk rots to be on the lookout for include:
Fusarium Stalk Rot causes salmon/pink discoloration of the stalk and disintegrated pith.
Physoderma Stalk Rot which in most instances is a leaf disease but can cause stalks rots. Physoderma is associated with a brown or black ring around one or several of the lower nodes on the stalk.
Diplodia Stalk Rot can be found in both the stalk and the ear or kernels. The stalk has brown/black fungal structures embedded in the rind and the pith is disintegrated with vascular bundles still intact.
Gibberella Stalk Rot is very similar in appearance to Fusarium and is tough to discern since both cause pink/red or salmon colors. The stalk will have small, black fungal structures that scrape off easily.
In areas where stalk rots are showing up, it is a good idea to evaluate stalk integrity. The common procedure to follow is to check fields that were planted in “less than ideal conditions” as well as shorter day hybrids first. Walk across a portion of the field and perform Pinch, Push, Shove and Slash tests along the way looking at both green healthy plants and also plants that are yellow/tan and or stunted:
- Pinch the stalks 4 to 8 inches off the soil level. If it collapses, you have a crown or stalk rot, or both.
- Push the stalks so the top of the plant touches the row across from it. If it buckles under that pressure, odds are you have a stalk rot.
- Shove a few stalks down the row and see how much pressure it takes to break them. The less pressure it takes to break them, increases the probability of standability issues.
- Slash or cut the stalk 10 to 12 inches above the soil line with a sharp knife down to or through the roots (Remember to be safe and cut away from yourself). It is a good idea to dig up the plant first before cutting. The crown and stalk should be a white or creamy color. The photo below shows a healthy stalk and root on the left, whereas, the stalk and root on the right is not healthy. If it is not, that plant has a crown or stalk rot.
The more plants that fail these tests, increases the odds that you will need to harvest that field early or move it up in the harvest schedule. Remember that these affected plants will be more susceptible to wind damage, the longer the harvest window gets. Having and following a harvest order decreases the likelihood of harvesting down corn, and increases the likelihood of capturing more yield but also having a safer and less stressful harvest season.
WEED CONTROL FOR NEXT SEASON CAN BEGIN NOW
The Agronomy Team published an article last week that listed topics to consider as harvest draws near or has begun for some. One topic discussed last week was weed escapes. Making note of what worked or what fell short of expectations as far as weed control this year can aid in our decision making for our plan of attack on weeds next year.
One weed control measure to consider that can be accomplished this fall is a burn down to control winter annuals. Early control of fall germinating, winter annuals such as marestail, field pennycress, chickweed and others can allow for a clean start to weed control in the spring especially in no-till systems. Winter annuals can be heartier if allowed to overwinter which can make them more difficult to control in the spring.
Considerations for fall burndown applications.
- Common herbicides used are dicamba, 2-4,D or a combination of these two products. Common names for combination products are WeedMaster® and Brash®, among others. Follow label recommendations on rates and adjuvant for these products.
- Temperature ranges to keep in mind for application. Control is best achieved when daytime temperatures are 50 degrees F or greater and nighttime temperatures are 40 degrees F or greater.
- In fields with past weed issues a residual herbicide can be used this fall to aid in keeping those fields cleaner longer. There are several options for fall residuals be sure to consult the label for plant back restrictions for possible spring crops.
If you have questions on specific products or weed identification, contact your Dairyland Seed DSM or Regional Agronomist.
SAFETY
With the 2021 harvest season upon us, remember to take time to think about the safe way to work or do a job. During harvest season we may be running on less sleep, running on less than ideal nutrition and pushing hard to get a crop in before inclement weather hits and stops us, we need to remind ourselves our family and employees amidst all these stresses to do the job the safe way.
We have all done many of the jobs that need to be done ahead of, during, or after harvest, numerous times. We all know the best, safe way to do a job, and then we also know a short cut or two that is quick and we have done it that “quick way” countless times. The issue is the “quick way” may not always be the safest way. 99% of the time the “quick way” works, however that 1% of the time could lead to an accident or worse.
Lastly, remember by doing it safely you are setting an example of how to do a job correctly, others may watch how you do things, it could be your spouse, your children, your grandchildren or an employee. Set a good example and do it safely.
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| Brian Weller Western Region 507.456.3034 |
Dan Ritter Central Region 219.863.0583 |
Branden Furseth Northern Region 608.513.4265 |
Mark Gibson Eastern Region 260.330.8968 |
Amanda Goffnett Eastern Region 989.400.3793 |