Potato leafhoppers (LH) migrate into New York each year and can be a serious threat to second and later harvest of alfalfa, negatively affecting crop yield, forage quality and stand longevity if not controlled.
J. Hansen, D. Viands, and J. Lawrence from Cornell University, School of Integrative Plant Science, Plant Breeding and Genetics Section and Cornell CALS PRO-DAIRY have released a Leafhopper Resistant Alfalfa Varieties fact sheet.
Control measures include:
- spraying with a labeled insecticide,
- harvesting early,
- and planting a potato leafhopper-resistant (LH-R) alfalfa variety.
Potato leafhopper resistant alfalfa varieties were first commercially available in 1998. Since then improvements in yield and LH-R levels have been made by plant breeders.
A LH-R alfalfa variety should have resistance to LH yellowing and LH stem stunting. However, some varieties have more resistance to LH stem stunting than to LH yellowing. Also, LH-R alfalfa varieties have 85+% resistance to LH, but the resistance is not in 100% of the plants in a field. Thus, some symptoms of damage will be apparent in every field, but the LH-R varieties will have significantly less yellowing and be taller than conventional alfalfa.
Generally, LH-R alfalfa will not need to be sprayed with insecticide, even in the seeding year. In 2011, K. Waldron sampled one replication of a trial planted in 2010. In this trial there were 4 LHR varieties and 7 conventional varieties.
On the conventional alfalfa varieties, the LH laid many eggs that hatched into nymphs and the nymphal feeding damage severely stunted the plants.
For more information about PRO-DAIRY, visit prodairy.cals.cornell.edu.