Battle for the Belt: Season 2, Episode 18- Planting Date and Weed Control Interactions

Champion Belt for Battle for the Belt in corn

Article is taken from https://agcrops.osu.edu/newsletter/corn-newsletter/2024-25/battle-belt-season-2-episode-18-planting-date-and-weed-control by Taylor Dill, Osler Ortez, Laura Lindsey, Alyssa Essman

Episode 18 of Battle for the Belt is now available: https://www.youtube.com/watch?v=xbf-dlV-jmc

In Episode 18, we are with Dr. Alyssa Essman, Weed Control Extension State Specialist, at the Western Agricultural Research Station in South Charleston, Ohio talking about weed management considerations for different planting dates.

Weed Control Considerations
The critical period for weed control is the first four to six weeks after crop planting. This period is when the young plants are most sensitive to competition with weeds for resources such as moisture and sunlight. Timely weed management, especially within this window, will reduce yield loss potential from the presence of weeds. In situations where soybean or corn are planted, but inclement weather prevents us from being able to get back into the field in a timely manner, it is very important to refer to herbicide labels and the weed control guide to evaluate management options. In areas that have had dry weather, the use of adjuvants becomes especially important, as plants develop a thicker cuticle and the herbicide has a harder time getting into the plant.

Weed Control in Corn – Western Site
The fifth planting date (June 17) of Battle for the Belt has more weed competition than the other planting dates at this time, as the plants were not tall enough yet to fully canopy, and the weather had not allowed a post emergence application. The height of weeds, growing past the top of the corn, shows that the weeds have a competitive advantage. In these plots, the plants near the weeds are about a leaf in growth stage behind the plants that are further from the weeds. In earlier planting dates, there is greater canopy closure and fewer weeds.

Weed Control in Soybean – Western Site
In general, there are less options for chemical weed control in soybeans compared to corn. When soybeans are planted earlier, they tend to flower earlier, and this pushes pre- and post-emergence herbicide applications earlier as well. The first planting date occurred on March 25^th and soybean plants were flowering on May 28^th. Application of many post-emergence herbicides is restricted at the R1 growth stage. In the later planting dates, canopy closure is delayed and weeds are in competition with soybean plants. Weed species present in the field may change based on planting date, where the early planted soybean may compete with early emerging weed species, and later planted soybean may compete more with later emerging weed species. At the Western Agricultural Research Station in South Charleston, Ohio, soybeans planted at every planting date compete with giant ragweed. In the first (March 25^th), second (April 16^th), third (May 6^th), and fourth (May 24^th) planting date, the soybean plants are further along in growth stage and canopy closure (Figure 1), which helps to prevent weeds issues in the field.

Figure 1. Canopy closure differences from left to right in planting date one (March 25), planting date two (April 16), planting date three (May 6), planting date four (May 24), and planting date five (June 17).

If you have more questions about weed identification and weed control contact Dr. Alyssa Essman at essman.42@osu.edu or check out the weeds website, u.osu.edu/osuweeds.

What’s happening in the field?
At the Western location, every planting date of corn is in the reproductive phase of growth except for planting date five which is still in its mid vegetative stages. Disease and insect pressure are still very low in corn. For soybean, all planting dates have reached reproductive stages except planting date five. The first two planting dates have been in R4 for a few weeks as the crop continues to grow vegetatively. There is low disease pressure at this location, with no frogeye leaf spot found.

At the Northwest location, the first planting date (May 16) of corn just reached R1; however, Northwest received rain after every planting date that has left some plots flooded, so about a quarter of the planting date one plots are behind in development because of the water damage. The rest are in vegetative stages and have had no signs of tar spot. Soybeans planted during the first planting date reached R3, and there is low disease pressure.

Finally, at the Wooster location, planting date one corn is at R3, with planting date two at R1. In the third planting date, the 100-day hybrid is at R1 but the 107, 111, and 115-day hybrids are still in vegetative stages. There is very low disease pressure present at this location. The soybeans are all in reproductive stages except for planting date five. The insect and disease presence here is also low.