DRY BEAN UPDATE: NEW - 08/08/06

Bacterial Disease Alert:

There are limited reports of bacterial diseases, including Common Blight, Halo Blight and Brown Spot in eastern Colorado. Maintain a rigorous scouting program, and consider copper-based bactericides such as Kocide, Champ, NuCop, Cuprofix, Nordox, or TopCop, applied according to label directions.

Scout all fields for signs of infection (lesions, chlorosis, sporulation) by fungal diseases such as Rust and White Mold; most of our acreage is planted to rust-susceptible varieties. In fields with a history of white mold, vine-type varieties, and moderate to heavy fertility and water, consider application of a protectant fungicide spray with Topsin M or Endura (Boscalid) at 100% to full bloom. These products are very effective if applied to blossoms so that the fungus cannot colonize the treated flowers and initiate disease on stems and pods. The disease can also be slowed down by extending intervals between irrigations late in the season.

Pesticide options are listed in the Bean Pesticide Summary and the Pest Summary.

White Mold Alert:

In fields with a history of white mold, vine-type varieties, and moderate to heavy fertility and water, consider application of a protectant fungicide spray with Topsin M or Endura (Boscalid) at 100% to full bloom. These products are very effective if applied to blossoms so that the fungus cannot colonize the treated flowers and initiate disease on stems and pods. The disease can also be slowed down by extending intervals between irrigations late in the season.

Bean Rust Alert:

Last fall, we scouted areas in western Nebraska with confirmed reports of bean rust in 2003 and 2004. The potential exists in 2005 for new rust outbreaks on susceptible varieties of beans growing in eastern Colorado if the sexual stage of rust is completed in other production areas and spores are blown into our area. So aggressively scout new-crop beans before flowering and if confirmed in the field or nearby area, apply protective and systemic fungicides (Maneb/Manex, Bravo/Terranil, Quadris, Headline, Endura). Always check label for rates, intervals and pre-harvest interval.

Bean Rust Life Cycle:

Pycnia (yellow to tan spots) develop on the leaves as a result of infection from overwintering teliospores (black rust) that resulted from rust infected bean plants during the latter part of the previous growing season. When pycnia are fertilized by spores from other compatible pycnia, snowy white aecial horns will develop on the lower surface of the leaf below the pycnia. Spores released from the white aecial horns can then infect new dry bean leaves, erupting in the (reddish-orange) uredinial dry bean rust that can travel long distances and infect other bean fields. This uredinial rust stage can infect new plants, and release new spores in repeating cycles several times during the growing season. At the end of the growing season, as bean plants begin to change color, rust infected plants begin producing teliospores, which can overwinter in bean debris, and initiate the cycle again the following spring.