Today, August 3, 2010 I visited some fields in Whitley County Indiana to look at fields where annual ryegrass was not killed quite perfectly this spring. Even though the soybeans look awesome there is a problem lurking under the bean canopy. That problem is a fairly thick stand of annual ryegrass. I found ryegrass in the 2-5″ tall range. My guess is that in one field we checked that there is close to 10-15#/acre seeding rate equivalent. The grass is relatively thick in many areas. While the beans are planted in 15″ rows there is still enough sunlight hitting the ground to keep the ryegrass growing and green. The biggest problem is yet to come when the beans start to drop their leaves and the ryegrass gets more sunlight and takes off growing more quickly. On thing about annual ryegrass…it loves Nitrogen and the soybeans are providing plenty for it. I’m afraid that the ryegrass could be 2-3 feet high at harvest time…making for a “fun” harvest.
This is why it is so vital that annual ryegrass is “killed dead” in the spring. Count on two applications of glyphosate. More will come on this in a later post.