Evaluating Your Crops After Tough Spring Weather
Scout your fields, manage weeds proactively and provide timely applications of nutrients if you want to reach or exceed your yield goals this year.
Fortunately, the cold winter left the soil in ideal conditions for planting. But this was followed by a frost that took out some of the early-planted soybeans and dinged alfalfa, corn and pastures.
We know that damaged corn will come back because the growing point is below ground until the V6 leaf stage, but for soybeans the growing point is located at the top of the plant and, once damaged, the seedling is lost.
For most growers across the Corn Belt it’s been a tough spring, with delayed planting and slow crop development. Some areas have been cold and wet and other areas cold and dry. Some farmers had to replant and others are taking preventative planting.
Replant or late-plant decisions aren’t complex. Generally you should stick with the same corn hybrid until late May, or wait until June to switch to soybeans.
Buying a shorter-season corn hybrid comes with less yield potential and it may not even be adapted to your area.
As for soybeans, stick with the same maturity group regardless of planting date — unless you’re in the northern Corn Belt, where you should cut maturity by half a unit.
Once your crops emerge, remember to scout your fields and observe what’s happening. Here are some tips on what to look for:
Stands Are Key. During the first scouting pass, look at emergence and stands. Are they close to your target population?
Focus on either thin stands or irregular plant distribution. If gaps exist, look for reasons why this happened. If patterns are repeatable, it’s probably related to the planter. If patterns appear random, it’s probably related to the soil.
Insects And Diseases. The second factor is to look for signs of insect feeding, and the third is to look at stems for symptoms of disease or discoloration.
Yellowish or purplish discoloration indicates that seedlings were under stress during emergence but probably will recover once temperatures get warm and the plants establish a root system.
Don’t Forget Weeds. Scout for weeds, paying special attention to problem glyphosate-resistant weeds like waterhemp, Palmer amaranth and giant ragweed. With the planting that remains this spring, remember to start with clean fields, applying a pre-emergence residual herbicide and a complimentary tankmix for post applications.
Once you identify weeds, plan to incorporate multiple chemistries into your post-emergence spraying program and spray weeds when small — under 4 inches.
The key is incorporating multiple modes of action into your weed-control program and making timely applications using the best procedures.
Benchmark Nutrients. If you applied nitrogen last fall, or early this spring before planting and had a number of big rain events, your corn may run out of nitrogen.
University of Illinois agronomist Fred Below says the success of fall-applied nitrogen depends on the weather from mid-March through May. If April is wet, growers will have to change their nitrogen plans.
“Roughly 30 pounds per acre will be lost if rainfall is 1 inch above average, and 60 pounds if 2 inches above average,” he says.
If rainfall is above average in the spring, Below suggests applying nitrogen with herbicide or a sidedress application. You can always measure available nitrogen by pulling a soil sample from 0 to 12 and 13 to 24 inches deep, and have it analyzed for nitrate and pounds of available nitrogen.
Will Foliar Apps Work? If the spring weather has taken a toll on your plants or held them back a bit, a foliar application of nutrients, sugar, biologicals or growth stimulants along with your pesticides could be an option.
One key to making this practice work is knowing whether foliar feeding is effective. But if you don’t do your own strip trials, it’s hard to know that. You can look for deficiency symptoms in crops, but by the time you get this information the deficiency might be too far along to correct.
You can run soil tests to see which nutrients might be lacking, but soil tests for micronutrients aren’t always reliable. Tissue tests are the most reliable way to measure if nutrient levels are deficient or sufficient.
The biggest challenge isn’t so much the cost, but the wealth of products available to choose from and deciding which product or analysis is best.
Stimulating Plants. When it comes to foliar feeding, you can’t provide enough nutrients through the foliage and meet all the plant’s needs. But as an agronomist I believe foliar feeding makes nutrients immediately available to the plant, which increases photosynthesis and other metabolic processes.
This, in turn, stimulates the plant and roots to be more active, pulling in more nutrients and water and synthesizing more growth-regulator compounds. And maybe that’s enough to get the roots pulling more nutrients out of the soil.
So what are your spring crop-management plans?