Matt Hanson

UW-Extension Dodge County

GH Alfalfa Yield and Efficacy Protocol

Purpose:

Compare yield of late-generation glandular-haired alfalfa varieties and a grower selected susceptible variety under high potato leafhopper populations in a sprayed and unsprayed plots. 

Materials:

• Seed of one GH alfalfa varieties will be supplied to grower cooperator.
• Susceptible variety will be the grower’s choice and supplied by the grower.

Methods:

Plots are to be seeded in spring of 2004 next to a susceptible variety planted at the same time or the previous year.  No data to be taken during the seeding year, however field should be scouted and PLH controlled if threshold is exceeded.  In the first production year, the PLH-susceptible variety is to be swept for potato leafhoppers at weekly intervals starting with the second crop regrowth.  If leafhopper populations do not build to established threshold then yield data is not required for that cutting.  If potato leafhopper populations build to the established economic threshold in the susceptible variety then an insecticide application should be applied across both varieties, leaving an untreated block at least 100 feet square. 

Yield data is required from the sprayed and unsprayed plots of both varieties.  Yield can be taken by weighing alfalfa from a 10 ft windrow.  Select an “average” windrow portion from two places in each plot, clip ends square with, and weigh (eight total weights).  One grab sample of alfalfa should be taken for moisture determination from each of the four plots.

Results

Dry Matter yield data and PLH counts should be sent to Bryan Jensen.  Results of all plots will be made available to each cooperator.  Final results will be used for State and County Extension meetings.

SUGGESTED PLOT LAYOUT