Opinion by Slade Franklin
Take the Time Now to Make Grasshopper Management Decisions
By Slade Franklin, Weed and Pest Coordinator, Wyoming Department of Agriculture
Predicting Mother Nature proves to be impractical time and time again, yet we never seem to give up on our efforts in trying.
Two years ago when higher than normal grasshopper numbers were expected in Wyoming and throughout the West, many grasshopper experts expected the peak hatch of pest species to start at the beginning of June, as is typical. Due to the cooler temperatures and above normal moisture, hatches began two to three weeks later than usual, forcing most of the Weed and Pest Control Districts to alter the timing of their management programs. This year, above normal spring temperatures and a lack of moisture has the grasshoppers emerging three to four weeks earlier than the average. Reports of new hatches are coming in daily from many of the county Weed and Pest Control Districts, along with survey personnel from the USDA-APHIS-Plant Protection Quarantine (PPQ).
The fact that grasshoppers may be a problematic in certain areas this year comes as no surprise. Near the end of each summer, USDA-APHIS-PPQ staff monitor densities of adult grasshoppers throughout the state. Last year’s survey indicated various areas throughout the state were still susceptible to damaging infestations in 2012. The survey results have proven over the years to be a reliable tool for the Wyoming Weed and Pest Control Districts, the Emergency Insect Management Committee and their federal and state partners when making their preliminary plans leading into the next summer.
Comparing adult survey counts from 2009, 2010 and 2011 indicates that grasshopper outbreaks are on a downward trend in Wyoming. However, climate conditions in some areas this past year favored grasshopper reproduction and may not follow the trend. The long, warm fall favored increased grasshopper egg production and the current early, warm spring weather means a higher probability of hatching grasshoppers surviving. Therefore, many of the Weed and Pest Control Districts have applied for and received funding through the Emergency Insect Management grant program to assist with funding grasshopper control programs. The funding provided by the grant will help offset the financial burden Wyoming’s private landowners experience in managing grasshoppers on their property. Additionally, in 2011 as well as in 2012, the grant program will cover the costs of managing grasshoppers on state-owned lands. The Emergency Insect Management Committee prioritized the funding based on counties where adult surveys indicated the highest potential for sever grasshopper densities.
Although grants play a critical role in the implementation of the programs, as does the coordination the Weed and Pest Control Districts provide, the key to the program still rests with the landowners. Natural resource management is often based on reaction and not prevention. In the past, grasshoppers were often managed reactively, and progress on grasshopper management has been made since the major outbreak the state suffered during the mid-1980s. At that time, the Wyoming Department of Agriculture and USDA relied heavily on blanket treatment of large swaths of rangeland with broad spectrum pesticides, done typically after the rangeland and cropland damage was extensive.
With the help of UW and new chemistry, the preferred management system has adopted a more preventative approach. Instead of relying heavily on older broad spectrum pesticides such as carbaryl and malathion, we now have Diflubenzuron and Rynaxypyr, which help us target grasshoppers in their early life stages with minimum impact to non-target insects. These insecticides have little contact activity that reduces the impact treatment has on beneficial insects. Dimilin insecticide disrupts the immature grasshoppers’ normal molting process. Rynaxypyr interferes with insect muscle function, causing them to cease feeding shortly after they consume vegetation treated with it. These products do not always translate to immediate mortality, but with a little patience 90 percent mortality can be obtained.
One hundred percent control is not the goal, as grasshoppers that survive help to maintain the predator populations that normally keep grasshopper populations in check. This helps to maintain long-term natural control of the following year’s populations.
UW Extension has also developed the Reduced Agent and Area Treatments (RAATs) strategy to help minimize the costs of grasshopper control through a process of alternating treated and untreated swaths. This treatment approach was developed to take advantage of the grasshopper’s mobility, allowing land managers to nearly double their treatment area without increasing the amount of pesticide used and reducing the impact on less mobile beneficial insects.
This preventative management approach was certainly put to the test in 2010 and 2011 throughout Wyoming with repetitive success. An example of this success was with Campbell County, where the local Weed and Pest Control District, USDA-APHIS-PPQ, and the cooperating landowners used the approach to protect over 1.6 million acres in 2010, representing over half of the county land area. Due to the success of the program, the district supervisor did not need to implement a program in 2011.
The difficulty landowners will face this year is determining whether or not they should sign-up for the county spray programs and what the economic benefit will be. Because grasshopper outbreak predictions are not as widespread as 2010, and will be sporadic within the individual counties, there may be a tendency to avoid making a decision to enroll until it’s too late. Setting up treatment blocks, along with contracting aerial applicators, weather and monitoring grasshopper life stages can be a daunting task, and is can be even more challenging if all the cooperators are not at the table early. Recently, history has shown that a preventative approach is effective, and this is why many of the Weed and Pest Control Districts are requiring early landowner signup. This early enrollment will assist the districts in organizing immediate response to high densities through program implementation, not program organization. Therefore, take the time…and take the time soon, because Mother Nature isn’t waiting, to contact your local Weed and Pest District to discuss management program options.