No one can argue our weather has been boring in 2013. Many find these spring reminders of winter unusual to say the least. The area and most of Kansas has experienced two hard freezes combined with freezing precipitation over the last two weeks. This stands in sharp contrast with the winter/spring seasons common during much of the 2000s. The K-State weather station at the US 281 and US 50 junction reported a high temperature of 4l° F and a low of 34° on Thursday April 18. Friday, April 19, had a low in the mid-20s.
These temperatures combined with the hard freezes of the previous week at the very least have resulted in cosmetic damage to the wheat leaves in almost all fields. Reports of damage to the growing point and some stems on jointed wheat are reported but overall the area is in better shape than other parts of the state and certainly areas in Oklahoma and Texas. This year having wheat development behind schedule is a good thing. The true extent of damage will unfold over the next several weeks. One question comes to mind regarding our weather, what is normal?
· When speaking of weather “averages”, the term normally means a 30 year average. Now, the averages are for the period from 1981 to 2010. The averages at the start of each new decade. Next an average can be deceiving since meteorologists simply take the high and low, add them together, and divide by two. So the average when the high and low temperatures are 20 and 70, the average is the same for 30 and 60. So averages are quick and dirty but not always very useful.
· In spite of what we think, the typical average date of the last frost, temperatures under 32°, is April 15 or this past Monday. The 95% frost-free date here is actually May 10. So in reality, temperatures under freezing now aren’t all that unusual.
· There is a difference between a “frost” and a “hard-freeze.” A hard freeze is when temperatures into or below the mid-20s and stay there for several hours. Crops like wheat typically tolerate a “freeze” well. The problem as development progresses is a “hard-freeze.”
· One last weather related item is helpful. Air temperatures you see reported are normally reported at meteorological screen height which is 1.5m or 5 feet. Temperature increases near the ground so a freezing temperature at 5 feet may be above freezing at the soil surface where the plant is.
This is corn planting season and some has been planted. Corn planted today treated with fungicides and insecticides can remain in the ground during weather like this, germinate and emerge when the weather improves and be just fine. On April 18, the 4 inch soil temperatures from the weather station mentioned above were 49° for the high and 46° for the low. Temperatures at the two inch depth were lower but will also increase more rapidly as conditions improve. Fifty degree minimum temperatures are recommended for corn planting so the forecasted weather this weekend should get soil temperatures there rapidly. And fortunately, we are in prime planting season right now.