USA
April 8, 2015
Last year, growers in several sugarbeet-growing regions across the U.S. experienced significant disease pressure from one of the most destructive sugarbeet diseases – Rhizoctonia. This soilborne fungal disease is capable of causing significant yield loss by reducing tonnage and sugar content, as well as affecting quality in storage piles. The battle against Rhizoctonia is fought with proactive and timely management practices beginning at seed selection time.
Rhizoctonia, caused by the fungus Rhizoctonia solani, thrives in warm, wet conditions and can begin early in the season causing seedling death, but can also show up later in the season as crown and root rot. Late August or early September or before harvest is an excellent time to evaluate potential yield, quality and income losses from this disease.
Symptoms & Management Tools
Typically visible during scouting late in the growing season or during final cultivation, growers may see several symptoms of Rhizoctonia, including:
- Bright and/or wilted leaves
- Stunted root growth or rotted off roots
- Large numbers of lateral roots emerging from the main taproot
- Small, dark roots
- Abnormally large rot area around the crown
- Blacken petioles on stem next to crown
According to Steven Poindexter, senior sugarbeet extension educator at Michigan State University Extension, if the disease impact is greater than desired, then your management plan may need to be altered.
“This may include either a T-band in-furrow and/or an early foliar-banded application of Quadris® fungicide, if you are not applying Quadris already,” Poindexter said. “Switching to a variety more tolerant to Rhizoctonia, in combination with a Quadris spray program, will typically yield very good results, particularly under heavy disease pressure. Select varieties carefully as some of the more tolerant varieties may genetically not produce the highest yields or be the most tolerant to nematodes.”
Hilleshög® brand varieties from Syngenta are leaders in disease tolerance packages. Many varieties offer enhanced Rhizoctonia protection, which plays a critical role in season-long management. Rhizoctonia tolerance kicks in during the critical time when the plant is focused on maximizing sugar content and yield.
In addition to choosing tolerant varieties, Michigan State University Extension Sugarbeet Advancement recommends growers be proactive and evaluate every sugarbeet field for its level of Rhizoctonia. This will help in determining the effectiveness of the grower’s management plan. This is also a good tool to predict Rhizoctonia levels the next time beets are grown in that field. It’s recommended to randomly flag 100 feet of row in at least six locations in each field and count the dead and dying beets in each location. The dead beet carcasses are easy to determine and often leave holes in the ground. Dying beets are typically very yellow with roots either partially or completely covered with rot. These dying plants can normally be wiggled in the soil or can be easily kicked out of the ground. Some beets can also have some Rhizoctonia spots on the roots, but still have a normal foliar appearance. Detecting those plants visually is nearly impossible and should not be included in the counts.
Rhizoctonia can develop relatively early and throughout the entire growing season, depending on the environmental conditions. Syngenta agronomists recommend the following tips for the upcoming sugarbeet season:
- Use tillage and fertilization to promote crop growth
- Plant cultivars with Rhizoctonia tolerance
- Ensure adequate soil drainage
- Make timely fungicide applications early rather than late
- Avoid cultivation that dumps soil into the crown of young plants
- In the future, consider longer rotations and planting non-host crops such as wheat or barley as the previous crop to sugarbeets
Help stop Rhizoctonia before it starts
Choosing the right seed treatment is another key to preventing Rhizoctonia. CruiserMaxx® Sugarbeets insecticide/fungicide seed treatment, a combination of separately registered products, plays a critical role in developing a strong and robust stand. CruiserMaxx Sugarbeets protects against both seedling diseases and insects, enhances vigor, improves stand establishment and increases yield potential by protecting the sugarbeet plant as the seed germinates and develops. Additionally, Syngenta anticipates registration for Vibrance® seed treatment fungicide for sugarbeets, another tool to combat Rhizoctonia, for the 2016 season.
Choosing an early disease management plan, best variety, and seed treatment to steer clear of Rhizoctonia will provide growers with the best chance for success. Following best practices, monitoring fields, and speaking with area crop consultants, co-op agronomists and retailers can help growers make sound decisions that enable them to grow more sugar.
©2015 Syngenta. Important: Always read and follow label instructions. Some crop protection products may not be registered for sale or use in all states or counties. Vibrance is not registered for sale or use on sugarbeets and is not being offered for sale. Please check with your local extension service to ensure registration status. CruiserMaxx Sugarbeets is an on-seed application of Cruiser 5FS insecticide and Apron XL, and Maxim 4FS fungicides. Dynasty seed treatment fungicide is available as an optional fourth component. Apron XL®, Cruiser®, CruiserMaxx®, Dynasty®, Maxim®, Quadris®, Vibrance® and the Syngenta logo are trademarks of a Syngenta Group Company.
Topics
Species
