This article originally appeared in the fourth-quarter 2016 issue of Syngenta’s Thrive magazine. It also appears in the 2017 issue of Potato Grower.
An estimated 80 percent of plant problems start underground. Soil-borne pathogens, underground insects and nematodes all threaten healthy root structures. Hidden from the human eye, the effects of these pests and pathogens often go unnoticed until the end of the season, when damaged roots can result in significant crop damage and yield loss.
The advantages of having an uncompromised root system are many. Stronger, healthier roots take up water and nutrients more efficiently, leading to better crop development. More robust root systems also help produce stronger stems and foliage that can better withstand environmental stresses, especially in geographies where water is scarce and pests are many. Ultimately, healthier roots protect the genetic potential of the crop and lead to improved yield consistency.
“Yield starts and ends with a healthy root system,” says Dale Ireland, Seedcare technical product lead at Syngenta. “Protecting roots is crucial to reaching higher, more stable yields and overall performance.”
The Rise of Rhizoctonia
Several of the biggest threats to crop quality and yield begin with root damage caused by underground diseases. Quickly establishing itself as one of the most prominent yield-robbing soil-borne fungal pathogens, Rhizoctonia is capable of causing 20 to 40 percent yield loss and is a common soil disease in major U.S. crops, including cereals, soybeans and canola. It can also devastate yield potential in corn, cotton, potatoes and sugarbeets.
Rhizoctonia infects plants in early development stages, attacking both seeds and seedlings. It weakens plants during pre-emergence and post-emergence by infecting the root system and reducing its efficiency, causing slowed growth and damping off. Damaged root hairs reduce the plant’s ability to absorb moisture and nutrients, manage stress, and achieve maximum yield. A plant may never regain its rooting potential as a result of the disease’s significant impact on early plant vigor and development.
The Pacific Northwest is particularly vulnerable to Rhizoctonia because of the region’s soil conditions, temperatures and tillage practices, which favor disease development. “Due to soil erosion and the need for improved soil structure and organic matter, growers in the Pacific Northwest often implement direct-seed and minimum tillage practices,” says Don Drader, a Syngenta agronomy service representative in Washington State. “Unfortunately, minimum tillage often creates a soil environment where Rhizoctonia thrives.”
Protection from the Start
While completely managing Rhizoctonia once it infects a field may not be possible, growers can limit its impact. Rotating crops, using tolerant varieties and minimizing soil compaction are effective, non-invasive ways to manage the disease. To further prevent the disease from infecting their crops, growers should consider using a top-performing seed treatment.
“Rhizoctonia is a big threat in my area, but I have never had a major issue with the disease, believe it or not,” says Mike LaShaw, who grows several Rhizoctonia-susceptible crops in Rockford, Wash. “By rotating my crops and applying a seed treatment to my seeds, I’m able to manage the yield-robbing disease plus other soil-borne diseases.”
As genetics and traits continue to advance, seed is becoming increasingly valuable. But from the moment seed is planted, nematodes, insects and diseases threaten to eat away at a grower’s seed investment. The best way to protect this investment is to shield the plant early, when it matters most.
“In addition to selecting varieties with built-in disease tolerance, choosing the right fungicide seed treatment is the key to preventing Rhizoctonia,” says Ireland. “The right seed treatment can help protect the plant when it is most susceptible to damage—during that three- to four-week window after a crop is first planted.”
“Protecting roots at the earliest stages of plant development is critical for above-ground growth throughout the season,” says Kris Pauna, Seedcare product lead at Syngenta. “Seed treatments are one of the best ways we have to offer that protection, so growers can produce better-yielding, higher-quality crops.”