This spring has presented a number of challenges to agricultural producers throughout Oklahoma, and sorghum growers have been no exception.
STILLWATER, Okla. – This spring has presented a number of challenges to agricultural producers throughout Oklahoma, and sorghum growers have been no exception.
“Most crops have struggled at some point this spring,” said Josh Lofton, Oklahoma State University Extension cropping systems specialist. He fits growers into one of three categories.
First are the growers who were able to plant their crop in a timely manner, had good soil and weather conditions, and now have a crop that is growing well.
“While we would like to see this on most acres, the majority of Oklahoma’s sorghum crop has fallen into two other categories,” Lofton said. “Either growers have not been able to get into their fields and still have sorghum in bags waiting to be planted or they were able to plant but have only marginal stands.”
For growers who have yet to plant, the question has become whether or not to continue with grain sorghum planting. While there are financial considerations, growers still have the potential to establish productive fields.
Historically, OSU’s Division of Agricultural Sciences and Natural Resources has advised growers at this stage to hold off planting until late-season in order to minimize the negative effects of the traditionally challenging environmental conditions of late June and early July.
“Unfortunately, sugarcane aphids have made the success of a late-season crop more dependent on insecticide applications,” Lofton said. “If growers are willing to budget two insecticide applications and be proactive on scouting and applications, this remains a potential option.”
Other growers who have stands in the field are facing questions about whether to maintain their stands or terminate and replant.
As a general rule, if growers have between 18,000 and 20,000 active plants per acre, adequate yields still can be achieved without additional seeds planted, especially this late in the season and provided the plants are presenting consistent even stands across the field.
“If stands are spotty or skipping, growers can decide to plant certain areas of the field while maintaining others,” Lofton said. “If growers have less than 18,000 active plants per acre and decide that replanting must occur, there are instances where growers can get away with over-seeding the crop into the current stand as opposed to completely terminating and completely replanting.”
OSU recommends growers who choose to over-seed look at planting around half of the initial seeding rate.
When growers have achieved stands, both weed control and fertility issues start to emerge. If growers have made a large application on fertilizer pre-plant, especially nitrogen, then the weather patterns experienced through May likely mean a good portion of the application may already have been denitrified or leached deep into the soil profile.
“Growers will need to be proactive with side-dress applications,” said Josh Bushong, OSU Extension area agronomist for the state’s northwest district. “To trigger these, a grower’s best option is to make sure to have N-rich strips throughout their fields. If not, growers need to look for overly pale, stunted sorghum and be timely with an application.”
High levels of moisture can decrease the efficacy of many pre-plant herbicides. Thus, sorghum growers may need to make subsequent herbicide applications.
“This becomes critical as some chemicals need to be applied prior to the sorghum plant reaching 12 inches in height,” Bushong said.
The “boogeyman” of recent years is the sugarcane aphid. Numbers are growing and moving north through Texas. MyField, a scouting website, indicates populations have moved into south-central Texas.
“While there is little need for Oklahoma producers to be concerned at this point, growers do need to be aware of the aphid population movement,” Lofton said.
Currently OSU recommends treatment when an average of 100 aphids are seen per leaf blade. To scout for aphids, growers need to identify four to five locations that are representative of the field and collect five to six plants at each location.
“For each plant, growers need to look at the underside of the lowest most fully green leaf and the highest most fully developed leaf,” Bushong said.