Seed and Seedling Diseases
Part 2, Section 2: Corn Pest Management
Corn Pest Management
Seed and Seedling Diseases
Corn planted into cold, wet soils can be in the ground for several weeks before emergence. Under these conditions, seeds and newly emerged seedlings are quite susceptible to attack by soilborne pathogens. The use of conservation tillage practices, particularly no-till, also results in seed being placed into cooler soils. As growers move to earlier planting dates and increase no-till planting, the use of fungicide seed treatments on corn has increased.Mostcommercially sold corn seed is treated with a fungicide or mixture of fungicides to aid in the control of early season diseases. With the reduced use of Captan as a seed treatment, the two primary products used are ApronXL (mefenoxam) and MaximXL (fludioxonil). ApronXL is a narrow-spectrum fungicide with excellent activity against Pythium and Phytophthora. Maxim XL is a broad-spectrum fungicide that is very effective against many soil fungi but is not effective against Pythium or Phytophthora. This pair of fungicides offers good protection against most seed and early season diseases.
In addition to ApronXL and MaximXL, the strobilurins and triazoles are two new families of fungicides used as seed treatments. The strobilurin family of fungicides is marketed as a broad- spectrum, systemic product with some activity against Pythium and Phytophthora. Dynasty (azoxystrobin) has the same active ingredient as Abound or Quadris. Stamina (pyraclostrobin) has the same active ingredient as Headline. Although the strobilurins are noted to have some activity against Pythium and Phytophthora, the seed treatment should include ApronXL for adequate protection.
Vortex (ipconazole) is a triazole that has systemic, broad-spectrum activity but little or no activity against Pythium or Phytophthora. In this case, the manufacturer recommends using Allegiance-FL (metalaxyl), a chemical similar to ApronXL, to provide adequate seed protection.
Poncho/VOTiVO is an insecticide and biological seed treatment on corn and soybeans that is labeled to control early season insects and provide early season protection from plant pathogenic nematodes. The active ingredient for nematode protection is a Bacillus bacteria species. Many Bacillus species have been used as biological controls, but the impact of nematodes on Pennsylvania corn yields has not yet been determined.
Monsanto has developed the Acceleron Seed Treatment, which may include metalaxyl (Allegiance-FL), ipconazole (Vortex), pyraclostrobin (Stamina), and/or trifloxystrobin as fungicides along with clothianidin or imidacloprid for insect protection. The combinations available of this product should offer thorough protection to seed and seedling diseases.
Syngenta has created the Avicta-Complete Corn 500 package, which includes six chemicals targeting insects, nematodes, and fungal diseases. Avicta Complete contains thiamethoxam (neonicotinoid insecticide), abamectin (nematicide), thiabendazole (Fusarium-targeted fungicide), fludioxonil (Maxim XL), mefenoxam (Apron XL), and azoxystrobin (Dynasty). With both Apron XL and Maxim XL along with thiabendazole, this treatment again should adequately protect seed corn from plating through emergence.
With this very abridged list of seed treatments, it is important to realize that technology is driving the use of new protection products on corn seed. Again, multiple modes of action are important to protect against both diseases and insects that can lead to disease issues.