Italian Ryegrass as a Nurse Crop for Alfalfa
        There seemed to be a vast love affair with Italian ryegrass this spring as a source of fast growing, high quality forage to replace damaged alfalfa stands.  It was seeded alone, as filler in thin alfalfa stands, and as a nurse crop for new alfalfa seedings.  It’s the latter use that demands a fairly high level of management because of the competitive nature of Italian ryegrass.  If seeded too heavy, it can out compete the slower growing alfalfa seedlings.  Further, if too much growth remains in the fall, alfalfa stands can be “smothered out” during the winter.  Much of the preliminary work with Italian ryegrass has been done in Minnesota.  Based on their results and experiences, here are their recommendations for using and managing Italian ryegrass as a nurse crop: 

·    Try it on a small acreage.  We still have much to learn about the best ways to make this concept work.

·    Seed no more than 5 lb/ac of Italian ryegrass.  More may work, but be conservative to ensure that there isn’t too much competition for the perennial(s).

·    Plan to take an October cutting, so use only with perennial forage species and varieties that can handle a seeding-year fall cutting.  This shouldn’t be an issue with modern, winter-hardy alfalfa varieties in fertile, well-drained soils.

·    Avoid seeding techniques that place the ryegrass seed right next to the perennial forage seed. Broadcasting both or at least one of the seeds should help reduce the competitive effect of Italian ryegrass on the slower-establishing perennial.  Italian ryegrass can probably tolerate a broader range of seeding depths (1/4 to 1”) than small-seeded perennials.

·    Use 30-40 lb N/ac at establishment.

·    Plan to cut often in the seeding year; first 50-60 days after emergence, and about every 30 days thereafter including a mid- to late October cut.  Cut as close as you can at each cutting to slow the initial rate of Italian ryegrass regrowth and thus reduce its competitiveness.

·    Plan to make haylage, baleage, or graze.  Ryegrass is difficult to get dry enough for hay; it can be done, but it’s difficult. If the under-seeded perennial is grass, a tedder may be effective in getting it dry enough to bale without significant DM and quality loss. 

For more details on the Minnesota Italian ryegrass research see:
http://www.extension.umn.edu/cropenews/2005/05MNCN14.htm

Shifting Hybrid Maturities for Late Planted Corn for Silage
        Joe Lauer, UW Extension Corn Agronomist, reminds farmers selecting corn hybrids for silage to first consider planting the latest relative maturity of corn that will reach harvest maturity by frost.  Higher yields are produced with hybrids that mature slightly later than those adapted for grain production – perhaps 5 to 10 relative maturity units later.  These hybrids will result in the highest yield of high quality forage.

        When planting is delayed beyond May 20, earlier maturity hybrids should be planted to reach harvest maturity by frost.  However there comes a point (about June 1 in northern Wisconsin and June 20 in southern Wisconsin) where planting is delayed to the extent that even shorter maturity hybrids will not reach harvest maturity by frost. At this point it is preferable to plant later maturity hybrids so they reach pollination at frost, and then allow drying after frost to get the hybrid to low enough moisture content for ensiling. 

        The recommendation to switch back to later maturity hybrids for late planted corn silage is made because corn has two peaks in forage quality: one at pollination and one at harvest maturity.  The early peak in forage quality at pollination is high in quality but too wet for ensiling unless frost can dry the corn down. For late planted corn, aiming for a hybrid that will be at pollination at frost becomes a better choice than planting a short season hybrid that will not reach harvest maturity. 

Aphanomyces Race 2 Found Throughout State
        Aphanomyces (APH) is an important root disease of alfalfa in the Midwest.  It’s a soil borne fungus that infects roots and is often found in conjunction with other root diseases such as Phytophthora root rot and Fusarium root rot.  One problem with APH is that it is very difficult to diagnose in the field.  Further, at least two races exist and while many varieties are resistant to race 1, few are resistant to race 2.  The race 2 strain was originally thought to be primarily confined to the southwest corner of the state.  Last summer, Dan Wiersma (Pioneer Hi-Bred Agronomist in north central WI) conducted soil bioassays from samples taken throughout the state to identify the where APH 2 was present.  His results showed that APH 2 was distributed widely across central and southern areas of Wisconsin (Figure 1).  Growers who experience problems with alfalfa establishment need to consider APH 2 as a potential cause if seedlings seem to establish but and then die soon after emergence (or appear unthrifty). 

Figure 1.  Distribution of Aphanomyces Race 2 in Wisconsin from a total of 51 samples tested.  (Wiersma, 2004)