Fungicide applications under Saskatchewan irrigation
By Donna Fleury
Under high irrigation management for cereals in Saskatchewan, diseases that impact yields have been increasing steadily over the past few years. Some of the major fungal diseases, such as Fusarium head blight (FHB), Septoria glume blotch, tan spot and spot blotch thrive in this moist environment.
Growers and researchers wanted to determine if fungicide applications to control cereal diseases could improve yields and increase profitability. In collaboration with industry co-operators, the Irrigation Crop Diversification Corporation (ICDC) implemented several demonstration projects from 2009 to 2012 to compare the efficacy of fungicide application to prevent FHB and control other diseases in high yielding wheat.
“We established the demonstrations for preventing diseases in three wheat types with local grower co-operators under field scale conditions on their farms,” explains Rory Cranston, regional crops specialist with the Saskatchewan Ministry of Agriculture in Outlook, Sask. “We have implemented nine projects since 2009, using 40-acre treatment plots and a 10-acre untreated check plot at each demonstration site. Hard red spring, soft white spring and durum irrigated wheat were used in this demonstration, with fungicide treatments of Folicur, Proline, Prosaro, Caramba and Quilt.”
The demonstrations focused mainly on preventing FHB with fungicides, but also compared fungicide applications at the flag leaf stage to control leaf diseases combined with an application at flowering to control FHB. Because the timing of a fungicide application to control FHB is later than the timing to control leaf disease, there is no protection for late-season leaf disease infection in the area treated earlier to control early leaf disease infection. Bayer CropScience, BASF and Syngenta donated some of the fungicide products, and the rest was purchased with funding provided by the Agricultural Demonstration of Practices and Technologies (ADOPT) program.
“For each demonstration site, the crop progress was monitored throughout the growing season,” says Cranston. Soil moisture was monitored throughout the year with the use of Watermark sensors installed at 12- and 22-inch depths. Rainfall and irrigation were recorded with the use of rain gauges and WeatherBug stations in the area.
“Leaf samples were collected in early August from each treatment plot and compared to the untreated check. Yield, grade, and FHB infection were determined for each of the treatments and compared to an untreated area,” says Cranston. “At harvest at each demonstration site, five-acre samples were collected and measured in a weigh wagon, which gave us a very accurate representation of yields. Three grain samples were collected from each treated and untreated plot at each site and were also analyzed for comparison.”
Overall, the results from the demonstration projects conducted from 2009 to 2012 showed that the yield benefits from using fungicide on durum and soft white wheat were significant. Yield data from 2012 was not included as the plots were hailed out in late August, preventing collection of harvest and yield data. However, from the first three years, the yield benefits in durum and soft white wheat ranged from a 21 bushel per acre advantage from a Prosaro application to a 9 bu/ac advantage from applying Folicur. There was a small yield benefit demonstrated in the hard wheat sites. The yield benefit in hard wheat ranged from 17 bushels per acre to 3 bushels per acre.
“Based on these results, we encourage growers who are growing cereals under irrigation and in areas with FHB or other diseases, to pencil in a fungicide application for disease prevention,” notes Cranston. “The high yielding irrigation management provides a nice moisture environment conducive to disease, and with the right temperature conditions, a severe infection can result. The timing of application is different for FHB and other leaf diseases. However, in the demonstrations, the highest return on investment occurred when a single fungicide application was made at the timing to control FHB.”
An increased return on investment also resulted from the combination of an early application of a fungicide to control leaf disease and a second application to control FHB. This combination treatment has the potential to provide a high return on investment in those years when disease pressure is high in late June. However, in most years, the greatest agronomic and economic benefit will occur when there is a single application of fungicide at flowering to control FHB.
Cranston recommends growers also pay attention to water management at the timing of fungicide application. “A good strategy is to fill up the soil profile to field capacity prior to making a fungicide application for FHB. After application, reduce water levels just to keep up with crop demand, as too much water creates a more conducive environment to infection. Although irrigation will still be required for growth, reducing the amount is important.” He also encourages growers to follow proper fungicide application practices and pay particular attention to nozzles, water volumes and other critical factors affecting application.
“The results of the demonstrations have shown that a fungicide application can significantly increase yields in durum and soft white wheat under irrigation, and growers should consider applying fungicides when growing these two types of wheat,” says Cranston. “Although fungicides have also shown some yield benefits in hard wheat, growers should take a careful look at the economics and the environment. If the weather looks like it will create an environment favourable for disease infection, then a fungicide application can provide an economic benefit. Preventing FHB and controlling leaf diseases in cereals will help growers increase yields and profitability under high irrigation management conditions.”