I have been receiving a few calls on producers considering reseeding poor barley stands, or concerned about their cereal crops in general. So I thought I would take this chance to review some key points producers and agronomists should think about if considering reseeding their cereal acres. A lot of the information is derived from a great article by North Dakota State University staff titled “Replanting or Late Planting Crops” (Publication A-934; Revised). I have included some of that information and added Manitoba-specific data and comments.
Why are some cereal fields impacted? Many producers were able to start seeding their cereal crops early in 2015. However, slow and/or uneven emergence was noted in many fields due to cool soil temperatures, dry soil conditions (in some areas of the province) and below normal temperatures following emergence. The slow growth was further complicated by excessive rainfall, wind, snow and frost over May Long weekend, and then another frost event on May 30. Not only do these conditions bring with it concern for erratic crop emergence and poor plant stand establishment, it can also promote a number of seeding diseases and root rots.
The Main Question to Answer. At the end of the day, producers must try and answer the question “Will which result in greater net return – keeping the original stand or replanting to the same/different crop?”.
The final decision should be backed by sound agronomic and economic information as well as taking into consideration AgriInsurance coverage and contracts. Agronomic information to consider should include: level of injury, crop uniformity and overall plant health of the original stand, alternate crop choices if reseeding, and management practices related to crop growth and development for either the original stand or the replanted crop. Producers and their agronomists should accurately assess all these factors in order to make an informed decision. I realize that is a lot of information to gather. Perhaps it is easy to think of it in a few steps.
Step 1: Evaluate original crop stand and yield potential. The best possible evaluation of the surviving stand is needed because the critical yield comparison ultimately will be between the original stand versus the replanted stand with a later than optimum planting date. Remember, you need to allow time for crop to recover from injury prior to assessing plant stands!
To accurately evaluate the existing stand, stand counts should be taken at random from several areas of the field. For more information read the article “Doing Plant Stand Counts in Your Cereals”: http://cropchatter.com/doing-plant-counts-in-your-cereals/. Typically for cereals, minimum stand levels that should be considered acceptable before reseeding is done ranges from 8 to 14 plants per square foot (NDSU). During early growth stages, most cereal crops can sustain some stand loss without experiencing significant yield reduction due to increased tillering. Keep in mind barley and oats typically tiller more than spring wheat.
However, the minimum stands stated is assuming plant stands are relatively uniform in distribution; what can complicate this assessment is the damage in fields can be distributed randomly throughout the field.
In addition to the direct effect of stand reduction, indirect effects of crop injury, such as increased weed competition and increased disease potential, should be considered. Damaged crops usually grow slowly until they have recovered, which provides the potential for greater weed competition.
Step 2: Evaluate yield potential & agronomics of replanted crop options. Crops replanted later in the season almost always will yield less than those planted at an optimum time. Figure 1 shows the yield potential of various crop types as seeding moves into June in Manitoba.
Figure 1: Percent Average Yield from 2005-2013 for Manitoba Crops Planted in Week/Month as Reported to MASC
Not only yield potential should be considered however. A short growing season increases risk of damage by fall frost affecting both yield and quality of the replanted crop. Increased risk of high daytime temperatures can also affect crop development. For example, there is increased risk of the crop flowering when daytime temperatures are high which can increase probability of floret abortion.
Delayed seeding may also increase potential of yield loss due to disease and insects. MAFRD articles Crop Choices in a Late Planting Scenario and Mitigating Risks Associated with Delayed Seeding will provide additional information to producers.
Step 3: Determine Reseeding Costs. Comparison of the estimated yield of the original stand with expected yield of the replanted crop minus any costs associated with reseeding must be considered.
The decision to reseed ultimately must be made by comparing the economics of the original plant stand with that of a replanted crop. This can be subjective and each case must be considered individually in terms of time of year, alternate crop choices, previous herbicide use, crop economics, AgriInsurance coverage and contracts, and other related factors. If a producer has AgriInsurance, it is recommended they contact their MASC agent prior to terminating a field and replanting.
Once again, I’d like to acknowledge information from NDSU’s article “Replanting or Late Planting Crops” (Publication A-934; Revised).
Submitted by: Pam de Rocquigny, Provincial Cereal Crops Specialist