Comanche Extension Agent Michael Berry
Sorghums for Forage Production
Before Sugar Cane Aphids (SCA) forage sorghum, Sudan grass and hay grazers were big crops in the area. Around 2014 we started seeing considerable damage to these forage crops from the SCA- since then the acreage of these crops has dropped 90% in the area. This is unfortunate as these are good crops for our area. Forage sorghum has always been a low maintenance, drought hardy crop with good value. Before SCA, there were very few insect pests to worry about with the crop.
In the last few years there has been a lot of research done on sorghums and the SCA. The result is we now have some identified sorghum and sorghum crosses that are more tolerant to SCA. This offers you a good option if you are considering a summer annual forage crop. Here is a list of sorghum-Sudan hybrid varieties that have shown resistance to the SCA: Sweeter N Honey II Sweeter N Honey BMR both from Richardson Seed Super Sugar DM from Gayland Ward Seeds Gro-N-Graze by Warner Seed.
All Pearl Millet varieties that I have seen have also shown excellent resistance to the SCA. Your seed salesman may know of other varieties that have been tested and shown resistance.
Remember resistance is not immunity, and the SCA may still be a problem on resistant hybrids. You will still need to monitor your fields and apply an insecticide or take an early harvest if infestations increase to where leaf damage is occurring. Having the ability to harvest either hay or silage within 7 to 10 days after infestation is also important. The longer you wait the more damage and lost yield.
There are many sorghum type selections available for forage production. They include forage sorghums, Sudan grasses, sorghum-Sudan hybrids, brown midrib (BMR) hybrids, and photoperiod sensitive (PS) hybrids. Each of these have their own benefits and forage sorghum is a leafy, tall plant that typically has a late maturity. Forage sorghum silage yields can be as high or higher than corn yields, but total digestible nutrients (TDN) per acre are historically not as high. Sudan grasses have smaller stems and more slender leaves than forage sorghums. They have excellent regrowth potential and are good for grazing and multiple hay cuts, with rainfall. However, total dry matter production may be lower than other sorghum types. Sorghum-Sudan hybrids will typically have similar yields as Sudan grass in hay production. They may or may not have a sweet stalk and regrowth potential is usually intermediate. Typically, they have a lower silage yield than forage sorghums.
The BMR trait may be found in any of the above forages and refers to the plant’s brown coloration of the leaf midrib. The BMR plants usually have lower lignin content and higher digestibility. Lodging can be an issue due to the lower lignin. In county trials, BMR plants have struggled to produce near averages for non-BMR sorghums, but quality is usually better. For photoperiod sensitive (PS) plants, flowering is initiated in response to day length. Flowering is initiated when the day length drops below 12 hours and 20 minutes. The plants will usually remain vegetative from March through mid-September, grow tall, and have high dry matter production.
One good reason to consider one of these types of sorghum compared to corn is the cost. While sorghum seeds have gone up considerably the last few years it still costs a 1/3 or less than corn seeds usually cost. Nutrient demand per ton of silage is very similar to sorghum vs. corn. The biggest advantage sorghum has over corn is in water requirementssorghum generally requires 1/3 to ½ less water than corn for the same production.
Soil temperatures need to be above 60 degrees before planting any of the sorghum type forages, average between 60 and 65-degrees ideal. To help at harvest you might consider staggering planting dates if you are planting lots of acres or might have limited time at harvest. You can plant sorghum on rows from 6” to 40”- narrow rows will require higher seeding rate and will produce higher yields with adequate moisture. Irrigation capability and expected soil moisture will dictate seeding rate. For irrigated fields you would expect 75,000 to 120,00 seed per acre, dry land will be ½ the seeding rate of irrigated. Higher seeding rates do run a higher risk of lodging.