Seed and Seedling Diseases

Part 2, Section 2: Corn Pest Management

Corn Pest Management

DISEASE 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. Essentially, 100 percent of commercially 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 a new 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.