Agronomy Update: Scout Those Fields! Should I Cut My Alfalfa?
BY DAIRYLAND SEED AGRONOMY TEAM
Seed and Seedling Diseases
We are finding some seedling diseases and are keeping an eye on further development. These diseases are often referred to as seedling blights, and include pythium, phytophthora, fusarium, rhizoctonia, etc.
These diseases are each unique. However, they are mostly fungal diseases, generally worse in “heavy” – higher clay content soils, can attack both corn and soybeans, and can result in weakened or killed seedlings.
Conditions favoring seedling blights include soils that tend to hold water, resulting in low soil oxygen levels. These diseases thrive in lower oxygen conditions, such as those that occur in saturated soils. Too much rainfall, poor drainage, and/or soil compaction all result in conditions for infection.
Seed treatments include fungicides which are quite effective in preventing most seedling blights for a couple of weeks after planting. However, much of the crop this year was planted into cold soils and seeds and seedlings have been in the soil three weeks or more before emergence. Coupled with the heavy rainfall in some areas, conditions are favorable for disease development.
If you are in these conditions, or suspect seedling diseases, dig seedling and examine roots and underground stems (the mesocotyl in corn or hypocotyl in soybeans). Roots and stems should be white and firm. Brown and/or slimy or mushy roots and stems may indicate seedling blight. Above ground symptoms include yellowing, stunting, and overall poor growth.
As you scout, make sure to dig seedling and examine the underground plant structures. If you need help identifying seedling blights, let us know.
Post Herbicide Applications and Stressed Crops and Weeds - Notice
Many herbicide labels recommend avoiding applying herbicides if the crop or weeds are stressed. Stressed crops lose their ability to detoxify or metabolize herbicides into a non-toxic compound. Healthy vigorous crops shake off the herbicide and continue normally. Stressed weeds normally fail to take in enough herbicide to get a lethal dose and may result with less than adequate weed control.
The concern for this growing season is that many growers have had crops planted anywhere from four weeks plus before emergence. Most of the delay was caused by cold/wet weather. Recently, heavy rainfall in some geographies has caused crusting on heavier soils. For some growers, a triple whammy, cold/wet and now crusting!
After emergence, if the crop displays yellowing, lack of vigor, slow growth and less-than-ideal root systems from root disease, suffocation or insect feeding, consideration should be given into delaying herbicide applications, if possible, until the crop looks like it’s recovering from stress.
If a post herbicide application is imminent, try to follow the pesticide label for those often-overlooked precautions.
Alfalfa: Calendar Says Go and Plants Say No
After a tough winter on alfalfa in 2018-2019, the winter of 2019-2020 seemed to be a little kinder to our alfalfa stands. Well, it isn’t agriculture unless there is a challenge.
This year we rolled into early spring with alfalfa moving right along developmentally. Then growth seemed to slow considerably in late April and early May. Many folks typically plan on hay harvest this week and, in many cases, it’s just not quite there from a tonnage standpoint. The colder temperatures have really reduced the yield potential on many stands. Sara Hagen, Dairyland Seed Forage Leader, indicates, “The challenge is do we wait another week to ten days and perhaps jeopardize getting that last harvest later this growing season? Or sacrifice tonnage, but stay on a cutting schedule to safely access that last cutting.”
Much depends on the individuals’ outlook for what growing conditions will be like for the balance of the summer.
- If we have favorable conditions the rest of the season, one may consider harvesting now and relying on more favorable weather to get growth back on schedule. Another consideration would be alfalfa weevil larvae feeding levels.
- If levels are at or nearing threshold one may consider taking the cutting now and forego other treatment options. This option would put us back on harvest schedule and aid in alfalfa weevil larvae control.
- Yet another consideration is the present forage supply.
As always there seems to be several factors to weigh into the equation of making the agronomic decision.
Corteva Technology Use Agreements
All growers with orders for any Corteva Agriscience brand seed product, regardless of crop or trait (including non-GM products) need to have a signed Corteva Technology Use Agreement in place by September 1. Growers should sign the Corteva Technology Use Agreement electronically at www.agcelerate.com. Signing electronically is preferable, however, paper copies are available at www.traitstewardship.com.
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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 |
Rod King Eastern Region 574.596.6721 |
Terry Jones Eastern Region 419.630.3115 |