Roda, A. 1996. Effects of growing alfalfa with perennial grasses upon potato leafhopper Homoptera Cicadellidae and alfalfa weevils Coleoptera Curculionidae. Thesis, Michigan State University, East Lansing, Michigan, USA.

Intercropping forage grasses with alfalfa may decrease populations and damage of potato leafhoppers, Empoasca fabae (Harris), and alfalfa weevils, Hypera postica (Gyllenhall). In field bioassays, more leafhoppers left treatments when orchardgrass plants were interspersed among the alfalfa compared to equal densities of orchardgrass planted in a discrete patch. Leafhoppers probed bromegrass, orchardgrass and alfalfa, although the frequency and duration of probing differed between plants. Leafhoppers placed on bromegrass or orchardgrass remained longer than those placed on alfalfa. In a laboratory behavioral bioassay, leafhoppers showed increased emigration from pure and mixed grass treatments. Grass volatiles alone did not elicit emigration, but stimuli obtained from contact increased emigration.

In 1995 field studies, the number of alfalfa weevil larvae, number of damaged tips and intensity of weevil feeding were reduced in alfalfa-forage grass mixtures containing either bromegrass, orchardgrass, timothy or Kentucky bluegrass in the first but not second year after establishment. These experiments indicate the potential role of intercropping a forage grass with alfalfa for both potato leafhopper and alfalfa weevil management

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