Residue management has the greatest potential for maintaining productivity of a continuous corn system. Due to improved genetics and management practices, farmers are achieving higher yields which consequently results in greater levels of corn residue. This increase in residue can hinder the emergence, standability, and yield potential of the next crop.
Corn residue can also cause issues during planting. For example, surface residue and root balls can interfere with desired seed placement, resulting in skips and uneven emergence. Moreover, residue can result in cooler and wetter soils at planting, which can cause delayed emergence, slower seedling growth rates, and increase the risk for soil compaction.
Management Tip: Combine attachments or post-harvest stalk shredding should be considered to complement fall tillage and spring tillage. Managing residue effectively can require intense tillage or the use of strip-till practices to facilitate the burial, removal, and decomposition of residue.
In most cases, continuous corn should be pursued on well-drained and highly productive soils as nitrogen availability can be compromised in a continuous corn system by less carryover from the previous crop (soybean, alfalfa), N tied up in residue decomposition, less efficient N use by slower growing seedlings, or untimely N application.
Management Tip: It may be advantageous to make multiple N applications throughout the season (fall, spring pre-plant, and a sidedress in-crop application). Also, a balanced starter fertilizer is more likely to produce a positive response in a continuous corn system because early growth conditions may be more stressful in continuous corn. Maintaining both P and K at optimum levels is important for stand establishment and to help minimize problems with stalk strength and stalk rots.
Weed management options can be reduced in a continuous corn system. Using pre-plant (PP) or pre-emergence (PRE) herbicides is critical to help protect corn yield potential and facilitate timely postemergence (POST) herbicide applications. Corn is sensitive to early weed competition, which requires that a POST herbicide application be made by the V3 stage of growth to help protect corn yield potential.
Herbicide-resistant volunteer corn can be a challenge; however, volunteer corn is less competitive in corn than in dry beans, sugar beets, and soybean. Lodged plants, insect-induced or genetic ear drop, exceptionally low harvest grain moisture content, poor harvest conditions, and improper combine adjustments can cause grain loss and increase the potential for volunteer corn the next spring. Herbicide options are limited and cultivation may be the best option for volunteer corn control in corn.
Management Tip: Integrating PP or PRE herbicides into the continuous corn system provides the option to use multiple herbicide modes of action to manage weed shifts or resistant biotypes. Additional information for weed control can be found at www.roundupreadyPLUS.com.
Several diseases including anthracnose, northern corn leaf blight, gray leaf spot, Goss’s wilt, and Diplodia ear rot can survive on non-decomposed corn residue. Selecting corn products with a disease resistance package matched to the history of disease problems in the field can help provide yield potential protection and help reduce the opportunity for disease-induced stalk lodging.
Corn products that have high ratings for emergence, vigor, and early growth are less susceptible to seedling diseases, such as Pythium and Fusarium. Seed treatments can also help protect seedlings from these pathogens, as well as insects such as wireworms, seed corn maggots, and grubs. Continuous corn fields can have a higher incidence of corn nematode damage, which can be reduced by additional seed treatment.
Management Tip: Herbicide- and insect-resistant trait technologies should be considered to help protect yield potential from insect and weed infestations, which can be more prevalent in a continuous corn system. Selecting corn products with multiple modes of action against corn rootworm damage as well as broad-spectrum protection for above-ground insects can help reduce potential yield losses.
Increased disease potential in a continuous corn system may benefit from the application of fungicides. Fields should be scouted weekly to determine if a fungicide should be considered. Late-season fungicide applications can be an important tool to help limit potential yield losses. It is important to create a record of disease history to help determine susceptibility to disease for subsequent growing seasons.
Management Tip: A fungicide application near or during silking can help reduce incidence of disease later in the season.
Fields should be scouted prior to harvest to identify fields with stalk and ear rot problems. Identified problem fields should be considered for an early harvest to reduce the potential for harvest losses.
Management Tip: Consider harvesting problem fields early to reduce the potential for harvest losses.
Contact your local Illinois DEKALB® brand representative to help recommend the best products and insect trait protection for your field and to help identify best management practices for a continuous corn system.