High nighttime temperatures during the reproductive growth (at or after flowering) can reduce kernel number, and if later in the season, kernel weight. This effect can be explained as an increase in the rate of respiration, increasing the demand for sugar for energy and diminishing its availability for supplying the growing kernels.
In addition, as experienced in many parts of our state, high night temperatures tend to accelerate plant phenology, running more quickly but with overall lower plant efficiency in using available resources. This situation has been documented in many parts of the state as an earlier-than-usual (close to 2 weeks) flowering time. For example, a corn planted during the first week of May was flowering around the first or second week of July in 2017 (depending on the maturity) and a similar corn hybrid this year was reaching the same stage around the last week of June.
The effect of high night temperatures will be exacerbated as corn is entering into the most critical growth period (a few days before flowering to grain filling). The consequence of high night temperatures will be reflected in reductions in kernel number (if timing of the stress was around flowering) and/or kernel weight (if timing of stress was coincided with the grain filling period). In summary, high night temperatures will be impacting corn yields, but the final yield reduction is yet to be determined, clearly depending on the timing of the stress (duration) and the area of the state affected.
While scouting your corn fields after these rains are sure to be on the lookout for leaf diseases. If you don’t catch the diseases in time in can hurt your yields dramatically. These are some of the common corn leaf diseases to be watching for.
It is typically less serious in Kansas than the other leaf diseases. Symptoms are small, round to elongated pustules that start out golden brown then turn darker later in the season. Common rust pustules commonly form on both sides of the leaf and are sparser than those of southern rust. This disease can occur wherever corn is grown. Infection is favored by moderate temperatures (60 to 77 degrees) and high relative humidity (greater than 95 percent for at least six hours).
Common rust is easily controlled by using resistant hybrids. Fungicides are not recommended for this disease alone since common rust causes only minimal yield loss. Continue reading “Corn Leaf Diseases”
K-State Research and Extension is partnering with Kansas Corn to host three regional K-State Corn Production Management Schools to be held in January in western, central and eastern Kansas. These will provide in-depth training targeted for corn producers. These sessions are free for producers to attend and we will work to ensure CCA credits are available. Schools will be followed by a tour.
The one-day schools will cover up-to-date and specific corn topics: corn management, high-yielding corn factors, weed control, soil fertility, price and market perspectives. After lunch, participants will have the opportunity to participate in discussions and information specific to their region. Continue reading “2018 K-State Corn Schools Slated for January”
I helped with the Harvey County tillage survey this week and saw evidence of insect damage across the county.
Be on the lookout for corn earworms Continue reading “On the Lookout for Corn, Milo and Soybean Insect Damage”