(Lambda-cyhalothrin) insec- ticide in the spring will control all types of aphids and impede the spread of BYDV. Detrimental Diseases The key diseases in cereal crops – and specifically winter wheat – are Fusarium, Rhizoctonia and Pythium. Three elements are needed to have disease pressure in a field: a host, the pathogen and an environment. Obviously, there are many other bunts and smuts that may occur in different geographies. Pythium is a killer and likes cool, wet conditions. It will kill crops. It’s a huge disease in cereals and also in corn and soybeans. Pythium is a prob- lem in areas where growers are pushing the envelope to get their crops planted, when the soil temperature is not quite ideal. “We had a wet spring in some areas in 2018,” Kelley says. “Growers were really putting their seeds in very moist, saturated ground, and we heard of Pythium issues popping up.” On the flip side, Rhizoctonia favors a warmer, drier environment but won’t kill crops. In 2018, Kelley saw instances of huge Rhizoctonia pressure early in the season. The crop survived but at harvest the disease made a significant impact. Fusarium also favors dry conditions and attacks the plant’s root hairs. “You don’t know in advance what the planting season will bring,” says Kelley. “You may have warm, dry weather or you may have a cool planting season. A seed treatment will provide protec- tion, regardless of what the environment throws at you.” Research and Response North Dakota State University researchers have accumu- lated 14 years of seed treat- ment data going back to 2003 for hard red spring wheat (HRSW) stand and yield response to fungicide seed treatments. These trials are primarily conducted near Fargo, which is located near the North Dakota-Minnesota border, and Dickinson, which is nearly 300 miles west of Fargo and within 60 miles of the North Dakota-Montana border. These two seed treat- ment trial locations are in very different types of production systems with very different yield environments. Of the 41 experiments rep- resented by the data set, 135 treatments were conducted in the Fargo region with a non- treated check mean yield of 69.6 bushels per acre. Across all trials in the western region near Dickinson, 75 treatments had a non-treated check mean yield of 36.1 bushels per acre. “Production in the western half of North Dakota is pre- dominantly no-till with small grains being a focal point in production,” says Andrew Friskop, North Dakota State University Extension cereal crop pathologist. “Western trials are all conducted in growers’ fields. Whereas, production in the eastern half of the state, including Fargo, is predominantly conventional till. More than 95 percent of the eastern North Dakota trials have been challenged with Fusarium or Cochliobolus.” Since 2013, Friskop has overseen these trials. “The primary use of fungi- cide seed treatments in North Dakota is to control both seed- borne and soil-borne diseases,” he says. “The one seed-borne disease that we most com- monly encounter is loose smut in our small grains.” Loose smut is found in spring wheat, winter wheat and spring durum wheat. To a lesser extent, Friskop finds some common bunt. He says due to growers’ widespread use of fungicide seed treat- ments and certified seed, there are generally few issues with seed-borne diseases causing yield reductions in North Dakota. The other way that seed treatments are used is to sup- press soil-borne root rots. “When we think of root rots, there are several ways they can attack the plant. For example, with Fusarium, we can have some crown rot issues,” Friskop says. “We can also have some sloughing-off of roots, or we can have some lesions that start early and girdle the stem throughout the season.” Regardless, there is no shortage of root rots or seed decay that can potentially occur. In the past five years, he says the three diseases that seem to pop up most frequently are Fusarium crown rot, common root rot and Pythium root rot. Although some of these diseases prefer different environments and different conditions, they often occur in a complex. Because of that, when thinking of seed treatments from a fungicide perspec- tive, one of the first words that come to Friskop’s mind is “broad-spectrum.” “When it comes to the importance of fungicide selection, it depends on the disease,” he says. Interpreting the Data Since Friskop started in 2013, he has conducted several seed treatment trials and created a huge data set to give a summary of the results. This data encompasses 41 experiments with more than 210 replicated treatments. “For the replicated treat- ment, think of it as a fungicide or a combination of fungi- cides’ effects on the improve- ment of stand and yield,” Friskop says. “We have done several studies, and we know what type of active ingredi- ents can be effective on the specific pathogens that we’re studying, but more impor- tantly, what type of active ingredients can be effective across an entire field.” Friskop notes that it’s diffi- cult in trials to correlate a seed treatment with yield. “A seed treatment’s big- gest effect occurs early in OCTOBER 2018 SEEDWORLD.COM / 37