Now is the time to scout your alfalfa for potato leafhopper.
The potato leafhopper is the most destructive insect to alfalfa in Pennsylvania, causing average annual losses of approximately $15 million.
It reduces yields, quality (especially by lowering protein content) and stand longevity. The stress leafhoppers trigger has increased root rot and stand failures.
Extension agronomist Sarah Frame explains this damage is especially evident in new seedings.
Potato leafhoppers usually arrive in Pennsylvania in early June, but this year their arrival was delayed by a lack of rain storms coming from Southern states that usually blow potato leafhoppers north from their overwintering sites.
Now that they have arrived, it is good to recognize that potato leafhoppers are perennially the most damaging pest of alfalfa in Pennsylvania, but they can also cause economic damage in other legume forages and some vegetable crops.
Potato leafhoppers can be frustrating given the sporadic nature of their infestations. Even in bad leafhopper years, many fields escape damage.
Once potato leafhoppers colonize alfalfa fields, adults deposit eggs into stems and leaf veins. In warm weather, these eggs will develop into adults in about three weeks, so populations can increase quickly.
Potato leafhoppers have strawlike mouthparts and extract plant juices. Heavy feeding disrupts nutrient flow within plants, causing yellow triangles to form at the leaflet tips (“hopper burn”). This evidence of damage does not develop until seven to 10 days after feeding begins.
As feeding continues, damage gets worse and the chlorotic areas spread toward the base of the leaflet. Once hopper burn is evident, economic loss has occurred.
For nonchemical control, resistant varieties of alfalfa are valuable. These varieties are covered with fine hairs (technically glandular trichomes), which decrease leafhopper feeding.
Obviously this option needs to be pursued before establishment.
Another option is to mix other forages in with alfalfa. Alfalfa/orchardgrass stands (or other combinations) appear much better at tolerating leafhopper damage than pure stands of alfalfa.
Spiders and other natural enemies kill potato leafhoppers, so using integrated pest management and spraying insecticides only when economic populations develop will help maintain these allies in pest control.
In fact, we have growers in Pennsylvania who do not treat their alfalfa fields with insecticides and claim they do not see potato leafhopper damage; natural enemies would be the best explanation for this lack of damage.
If damaging populations develop, early harvest or insecticides are often the only choices.
Source: lancasterfarming.com
Photo Credit: gettyimages-0shut0
Categories: Pennsylvania, Crops, Alfalfa