Agronomy Update: Delayed Planting Concerns

Across the Dairyland Seed marketing area, we are dealing with delayed planting scenarios. The degree of severity, however, varies from region to region. As of Monday, May 13, planting estimates from the agronomy team range from 5 percent to as high as 35 percent corn planted. Drier weather is forecasted for some areas while planting prospects for others look slim.

Given this information, serious questions are beginning to arise relating to planting dates and hybrid maturities. As a generality, we still have about two weeks before that really needs to occur. Again, opinions vary among agronomists. In the northwestern marketing region, May 20 may be the date to consider changing maturities. As we move to the east, June 1 seems to be the date where changing maturities needs to occur. Calendar date is only one consideration. Growers need to evaluate their own operations. Some geographical areas and operators may have been pushing their maturities by design to the full end before weather delays. That situation now needs to be examined closely. Conversely, perhaps a grain operation typically plants earlier hybrids for their given growing area. That gives them the option of sticking with what they planned for a longer period.

Drying corn may also be a concern. Can the operation dry corn? If so, what is the drying capacity? We have little idea of what harvest moistures will be this fall. We obviously should plan on wet corn. However, we can make up a lot of lost heat units given the right growing season. A September with plenty of sun and heat can speed drying and maturity. Data proves that staying with the best adapted hybrid until the end of May or early June is typically the best choice.

From a corn physiological stand point, agronomists know that hybrids planted late “adjust” their maturity. A hybrid planted on May 1 and also planted two weeks later in mid-May, mature at the same time. The common number assigned to this adjustment is about 6 to 7 GDD per day. For example, a hybrid planted May 20 will require 60 to 70 less GDDs to mature than one planted May 10. So roughly it requires 2 to 3 less calendar days to mature. Should you need to change maturities, drop about 5 RM days from your usual plan.

Communicate with your Dairyland Seed supplier and keep them informed of your planting delays. This assists in making sure we can meet your needs should the situation arise that we need to change seeding intentions. Feel free to consult with them about your operation and what may work best for you in this delayed planting season.

In summary:
• Stay on plan through the last week of May
• Consider switching hybrids June 1 for most scenarios
• Drop back 5 RM days each week past June 1
• Hybrids adjust about 7GDD per day of late planting
• Stay in communication with your Dairyland Seed supplier and agronomy team

FEAR NO WEEVIL – ALFALFA WEEVIL

As we roll through the month of May and hay harvest continues to be delayed, it is a good time to monitor for alfalfa weevil. Alfalfa weevil scouting activity should be monitored when we have received 250-300 heat units using a base of 48 degrees F after January 1. In many areas we have obtained that level or exceeded it and are beginning to see larval feeding activity.

Scouting for weevils involves collecting 25 to 30 stems randomly across the field. If 25 to 50 percent of the leaf tips have severe feeding and there are three larvae or more per stem control measures need to be enacted. This may include an insecticide application or a timely early harvest. If weather permits, harvesting will eliminate food source and hiding areas for the larvae. After first harvest, continue to monitor fields as alfalfa weevil could continue to feed on stubble and cause issue especially if regrowth is limited.