DES MOINES, Iowa- Selecting the right hybrid, modifying planting practices and choosing a suitable planting date can help improve stand establishment in high-residue fields, say experts from Pioneer Hi-Bred, a DuPont business.
While many factors come into play, Pioneer experts say early-planted, high-residue, corn-on-corn field environments tend to experience considerable emergence stress especially in cold, wet springs.
"For corn-on-corn situations, there's a lot of disease potential, especially in no-till or minimum-till environments," says Scott Heuchelin, Pioneer research scientist and field pathologist. "The source of disease often resides in the previous season's crop debris on the soil surface. When moisture and warmer temperatures increase in the spring, fungi have the opportunity to further colonize crop debris and release more spores into the field environment."
"For growers planting into high-residue environments, hybrids with strong high-residue suitability ratings and high stress emergence scores provide a good starting point for maximizing productivity," says Imad Saab, Pioneer research scientist.
The company's high-residue suitability ratings factor in hybrid performance on several key traits, including stress emergence scores, northern leaf blight, anthracnose, gray leaf spot and Diplodia ear mold. Ratings may vary by geography, depending on the relative importance of these traits in target environments.
"Regional input plays an important role in assigning and characterizing trait scores," Saab says. "The majority of Pioneer®brand hybrids are rated as suitable (S) or highly suitable (HS). Pioneer actively selects against traits that contribute to poorly suited ratings (X)."
Incorporating residue through tillage can help minimize disease potential, especially for seedling, stalk and foliar pathogens, Heuchelin says. Once incorporated into the soil, residue begins to break down as mites, arthropods, bacteria, nematodes and other fungi degrade and consume it as well as the pathogen's means of reproduction. The exceptions are the corn rusts, which have nothing to do with residue. Their spores typically blow in from growing regions to the south.
"Rotation is a key strategy to manage disease from one season to another," Heuchelin says. "Many growers may be moving fields out of rotation because of commodity prices, but the risk for disease in corn-on-corn fields is much higher. During a two-year rotational cycle, spores in residue tend to lose viability between host crops due to degradation. Growers who choose not to rotate and use no-till or minimum-tillage should consider high-residue suitability ratings in their hybrid selection process."
Excess residue also influences soil temperature and can keep soils from warming quickly. Saab encourages growers to pay close attention to near-term weather forecasts and avoid planting ahead of cold weather events that would cause seed to remain in saturated cold soils for extended periods before emergence. High-residue fields could suffer adverse effects due to compounding factors from cold, wet springs during and after emergence.
Modifying planting practices may be another viable solution to manage residue. Saab says row cleaners, for example, can help growers sow healthier stands.
"In the spring, the ground needs as much sun as possible to warm up," Saab says. "Residue can hold water and prevent warming of the soil, thereby slowing emergence. Planting when the soil is too wet also can result in compaction, which we know can cause stand loss and non-uniform emergence. A properly working row cleaner helps the soil warm faster and removes physical barriers such as residue clumps."
Poor residue management can jeopardize yields. Pioneer has data showing that extremely high-residue situations, if left unmanaged, affect both the number and uniformity of emerged plants.
"Uniformity tends to lend itself to higher yields," Saab says. "From our experience, if a plant is one leaf stage behind its neighbors when the corn is knee-high or below, it can lose a third or more yield at harvest depending on growing season conditions."
Once a seedling lags behind, Saab says overshadowing occurs from neighboring plants, which can result in a runt plant.
"It won't capture as much sunlight to photosynthesize," he says. "It'll be shorter, thinner and the ear likely will be much smaller and with fewer kernels. Uniformity has become a more important concern as more growers place hybrids into stressful conditions early in the season and other factors - like residue - add more challenge to emerging plants."