Theme 2-2: Forage Production and Utilization--Poster Sessions
Description
The bermudagrass stem maggot, Atherigona reversura Villeneuve, was first reported damaging bermudagrass Cynodon dactylon (L.) Pers grown for forage in 2010 in the southeastern US. Damage results from individual larvae feeding internally on the vascular tissue just above the terminal node of the grass stem. Damage slows plant growth and reduces forage accumulation. To address the need for economic guidelines to manage this new pest, the relationship between the percent of stems damaged by bermudagrass stem maggot and forage yield was measured in commercial bermudagrass hay fields in northcentral Texas during 2016 and 2017. The slope of the linear regression, representing the yield loss per percent stem damage, was used to calculate economic injury levels for a range of hay market values and control costs. The impact of stem damage on protein content, energy and digestibility of bermudagrass hay was also investigated. In this study, percent ADF was positively correlated with bermudagrass stem damage, suggesting that stem damage was associated with increased fiber and reduced digestible energy. TDN was significantly and negatively correlated with increasing bermudagrass stem maggot damage. These results suggest a trend of declining crude protein and energy and an increase in fiber content associated with increasing bermudagrass stem maggot damage. This apparent loss of forage quality is consistent with the observed leaf death and cessation of new growth resulting from bermudagrass stem maggot feeding. However, the R2 value for the relationship between each of these forage quality attributes and stem damage was very low, ranging from 0.03-0.07, and therefor the impact of stem maggot feeding on forage quality remains unclear and additional studies are needed.
Included in
Economic Injury Level for Bermudagrass Stem Maggot (Diptera: Muscidae) in Bermudagrass Forage Production in Texas
The bermudagrass stem maggot, Atherigona reversura Villeneuve, was first reported damaging bermudagrass Cynodon dactylon (L.) Pers grown for forage in 2010 in the southeastern US. Damage results from individual larvae feeding internally on the vascular tissue just above the terminal node of the grass stem. Damage slows plant growth and reduces forage accumulation. To address the need for economic guidelines to manage this new pest, the relationship between the percent of stems damaged by bermudagrass stem maggot and forage yield was measured in commercial bermudagrass hay fields in northcentral Texas during 2016 and 2017. The slope of the linear regression, representing the yield loss per percent stem damage, was used to calculate economic injury levels for a range of hay market values and control costs. The impact of stem damage on protein content, energy and digestibility of bermudagrass hay was also investigated. In this study, percent ADF was positively correlated with bermudagrass stem damage, suggesting that stem damage was associated with increased fiber and reduced digestible energy. TDN was significantly and negatively correlated with increasing bermudagrass stem maggot damage. These results suggest a trend of declining crude protein and energy and an increase in fiber content associated with increasing bermudagrass stem maggot damage. This apparent loss of forage quality is consistent with the observed leaf death and cessation of new growth resulting from bermudagrass stem maggot feeding. However, the R2 value for the relationship between each of these forage quality attributes and stem damage was very low, ranging from 0.03-0.07, and therefor the impact of stem maggot feeding on forage quality remains unclear and additional studies are needed.
