Winter Kill in Alfalfa & Wet Soil Management

Well, last weeks rain, rain go away article had very little effect on the sky, but temps are rising and in some parts of the state, soil temps are roughly just under 60F. Field prep has slowed or come to a halt, and concern is rising about getting crops in the ground on time. Remember that studies show that full season hybrids can be planted until about May 26th. When thinking about switching to shorter season hybrids, remember this. Switching to an early maturity hybrid prior to that point in May most likely won’t be beneficial and may result in reduced profit. Stay positive, stay patient, and stay SAFE! On these warm days like this past Monday, remember that safety comes first – even in a hurry. A prosperous planting season is a SAFE planting season.

There seems to be a misunderstanding with last weeks article – by all means, Do Not Plant TOO Shallow. When an agronomist suggests planting shallower, they’re suggesting adjusting planting depth slightly depending on the soil moisture. Different textured soils respond to moisture differently, so make sure you consider texture when adjusting the planting depth.

Wet, cold soils can do a number on a corn plant, such as inhibiting root growth, leaf area expansion, and photosynthesis. When roots are drowning, the lack of oxygen slows important mechanisms down and reduces growth. Several resources, including the Penn State Agronomy Guide, state the importance of seed contact with moist soil. “Plant 1.5 inches when soil is cold and/or moist; plant deeper when soil is warm and/or dry. Plant 1.5 inches in heavy soils or when soil crusting is anticipated.” But, make sure you’re not planting too shallow or too deep. Poor seed coverage, uneven emergence, and variable plant stands are some risks of planting too shallow. Not to mention the other consequences from planting too shallow. When in doubt, contact your trusted crop advisor with questions or concerns.

Now, on to alfalfa. We’ve seen winter kill this year across the state. With the heavy fall rains and heavy snow cover this past winter, it is no surprise that alfalfa has died or isn’t looking too promising this spring. Estimating yield potential is essential to your decision making. Take a look at the below Alfalfa Stem Count vs. Yield Potential Chart.

Check on the health of the plants, and don’t forget about the roots! Dig up plants and examine crowns for size, symmetry, and number of shoots. Cut the root and look for discoloration. Healthy stands have fewer than 30% of plants in category 3 or 4.

Scouting alfalfa will allow you to make any management decisions. Fields with good stem densities and a healthy root may have suffered some loss, but may be able to yield well. Check the stand density chart above for recommendations on management. If less than 40 stems per square foot, you may want to consider replacing the stand and planting corn.

As always, keep an eye on the stand throughout the summer for pests. Keep track of southern winds for Potato Leafhopper pressure, and check stands for Alfalfa Weevil before 1st cut (and after, too). If an insecticide is necessary, consider including a foliar to give the alfalfa that extra boost it may need for a yield advantage.

Next week we’ll focus on early season pests – cutworm, armyworm, wireworm etc – stay tuned!