Over the past few weeks, a number of alfalfa fields have been cut and preserved for later feeding. Behind corn silage, alfalfa is one of the most commonly incorporated forages in dairy cattle diets.
Foliar diseases in alfalfa can damage leaves and stems, resulting in leaf loss (defoliation), along with yield and quality losses, note University of Wisconsin Extension researchers.
Timely cuttings help to reduce these diseases, which are often not observed until three or four weeks after the previous cutting in a dairy-production system. In a 30-day cutting system, minimal defoliation may result before the next cutting.
In Wisconsin, a few strobilurin fungicide products (Headline and Quadris) were recently labeled for use on alfalfa. These strobilurin fungicides may also have an effect on plant metabolism that could result in improved yields and crop quality.
However, these products are at a high risk for fungicide resistance development by various plant pathogens. Therefore, excessive spraying might result in the product failing to control certain fungal diseases.
Research was conducted in Wisconsin, the nation's leading alfalfa-production state, to evaluate modern fungicide products on alfalfa grown under present-day practices.
Trials were conducted from 2011 to 2014 to evaluate spraying a fungicide on alfalfa in a 30-day cutting system. Treatments were replicated four to six times and fungicide was applied using a backpack sprayer calibrated to deliver 20 gallons per acre. After each of the three cuttings, fungicide was applied when six to eight inches of regrowth was present.
In total, 35 separate trials were conducted over the four-year period. Disease levels were low in the majority of trials and no significant differences were observed in foliar disease and defoliation.
Statistically, yield was greater for the fungicide-treated plots in 12 of the 35 trials. Average yield gain when applying strobilurin fungicides was 0.11and 0.05 tons of dry matter per acre per cutting (Headline and Quadris, respectively). No significant relative forage quality gains were observed.
While fungicide application could result in a slight yield bump, it may not be large enough to offset the product's application cost. The below table provides breakeven yields needed for different hay prices and fungicide application cost scenarios.
In a 30-day cutting interval, foliar diseases cause minimal damage, note the UW researchers. Coupled with the heightened risk of resistance development, application of fungicide for dairy production is not recommended unless heavy disease pressure is observed.
The author, Amanda Smith, was an associate editor and is an animal science graduate of Cornell University. Smith covers feeding, milk quality and heads up the World Dairy Expo Supplement. She grew up on a Medina, N.Y., dairy, and interned at a 1,700-cow western New York dairy, a large New York calf and heifer farm, and studied in New Zealand for one semester.
Foliar diseases in alfalfa can damage leaves and stems, resulting in leaf loss (defoliation), along with yield and quality losses, note University of Wisconsin Extension researchers.
Timely cuttings help to reduce these diseases, which are often not observed until three or four weeks after the previous cutting in a dairy-production system. In a 30-day cutting system, minimal defoliation may result before the next cutting.
In Wisconsin, a few strobilurin fungicide products (Headline and Quadris) were recently labeled for use on alfalfa. These strobilurin fungicides may also have an effect on plant metabolism that could result in improved yields and crop quality.
However, these products are at a high risk for fungicide resistance development by various plant pathogens. Therefore, excessive spraying might result in the product failing to control certain fungal diseases.
Research was conducted in Wisconsin, the nation's leading alfalfa-production state, to evaluate modern fungicide products on alfalfa grown under present-day practices.
Trials were conducted from 2011 to 2014 to evaluate spraying a fungicide on alfalfa in a 30-day cutting system. Treatments were replicated four to six times and fungicide was applied using a backpack sprayer calibrated to deliver 20 gallons per acre. After each of the three cuttings, fungicide was applied when six to eight inches of regrowth was present.
In total, 35 separate trials were conducted over the four-year period. Disease levels were low in the majority of trials and no significant differences were observed in foliar disease and defoliation.
Statistically, yield was greater for the fungicide-treated plots in 12 of the 35 trials. Average yield gain when applying strobilurin fungicides was 0.11and 0.05 tons of dry matter per acre per cutting (Headline and Quadris, respectively). No significant relative forage quality gains were observed.
While fungicide application could result in a slight yield bump, it may not be large enough to offset the product's application cost. The below table provides breakeven yields needed for different hay prices and fungicide application cost scenarios.
In a 30-day cutting interval, foliar diseases cause minimal damage, note the UW researchers. Coupled with the heightened risk of resistance development, application of fungicide for dairy production is not recommended unless heavy disease pressure is observed.
The author, Amanda Smith, was an associate editor and is an animal science graduate of Cornell University. Smith covers feeding, milk quality and heads up the World Dairy Expo Supplement. She grew up on a Medina, N.Y., dairy, and interned at a 1,700-cow western New York dairy, a large New York calf and heifer farm, and studied in New Zealand for one semester.
