Source: Byers, R.A., C.C. Bahler, W.L. Stout, K.L. Leath, and L.D Hoffman. 1999. The establishment of alfalfa into different maize residues by conservation-tillage and its effect on insect infestation. Grass Forage Sci. 54:77-86.

Efficient establishment of forage crops is essential to maximize yields and to protect the soil from erosion. Using conservation tillage to sow alfalfa is the most efficient way of protecting the soil from erosion, but it requires special attention for adequately preparing the field. When using conservation tillage, alfalfa is often planted in grass sod or small grain stubble. These environments harbor many pests including slugs (Deroceras reticulatum, D. laeve, and Arion fasciatus). It has been shown that alfalfa sown into fields covered with maize residue has a better chance of establishment because of the disruption of the slug's natural environment. Earlier studies did not address whether there is any subsequent increase in insect damage to alfalfa seedlings grown under the maize residue technique. This follow-up study examined the effect of insect infestation on alfalfa establishment grown under three types of maize residues: (1) silage, (2) silage plus winter rye cover, or (3) grain. The alfalfa was sown at three times, early April, late April, and late May, for three consecutive years. The pesticide, carbofuran, and the molluscicide, methiocarb bait, were used on half of the plots. Net sweeps of the test plots were conducted one month after sowing to assess the population counts of various known alfalfa and general pest insects. These insects include the tarnished plant bug (Lygus lineolaris), the plant bug (Plagiognathus politus), pea aphids (Acyrthosiphon pisum), and the meadow spittle bug (Philaenus leucophthalmus spumarius). It was shown that silage plus winter rye cover maintained the lowest number of insects when compared to the other maize residue treatments. Rye that was not killed by early herbicide treatment competed with the alfalfa during the growing season. Although the silage plus winter rye cover never yielded the greatest amount of alfalfa, when combined with the aberrant rye growth, the two yielded the greatest amount of total forage. In all cases, alfalfa planted in early April had the greatest yield. In conclusion, the authors state that the silage plus winter rye cover is the best system because it harbors the fewest number of pests and it yields the greatest amount of total forage. This system exemplifies some of the best practices for sustainability of forage systems.

Abstract author: Jude Maul, 27 November 2000.

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