Alfalfa weevil larvae across the state spent the past week in the peak growing degree days (GDD) ranges for feeding and development. As we get nearer to first cutting it is important to keep an eye on these pests before they can build up to economically damaging levels.
The following table indicates the average alfalfa height and alfalfa weevil population for the couple of fields scouted in each county for the week of April 30th-May 6th.
|
County |
Alfalfa Height (inches) |
Average Larvae Count per Stem |
|
Allen |
17-26 |
0.3 |
|
Defiance |
14-17 |
0.8 |
|
Mercer |
18-26 |
0.3 |
|
Putnam |
15-23 |
0 |
|
Ross |
14-24 |
1 |
|
Wayne |
12-24 |
0.2 |
|
Wood |
16-24 |
0.2 |
None of the fields across the state scouted are above the economic threshold for control. The average larvae count per stem has decreased in many counties as more and more fields have been sprayed to lower alfalfa weevil pressure. For fields that have been or are going to be sprayed as a control method it is important to remember to consider the pre-harvest interval required. As alfalfa continues to mature early or a timely first cutting become a more common control method. If harvesting a field with a high alfalfa weevil population, it is best to scout for alfalfa weevil pressure one week after harvest to lower pest impact into the second cutting.
Scouting for alfalfa is a quick and easy process. To get started, reference the article written earlier this year “Scouting Early Alfalfa Weevil Activity” and this 5-minute forage team video “Alfalfa Weevil Scouting”. If you have any questions reach out an author or your local extension office.