Pins and Needles Night Ahead for Fruit Growers
The picture of an apple orchard with this blog comes thanks to Paul Fuhrmann. Paul is a commercial fruit grower in Scioto County Ohio.
So it has come down to this! All that record warmth in March and warm, dry weather in April has set the stage for a dramatic night of temperature watching for fruit tree owners and commercial growers like Paul. Will there be a killing freeze on this year’s crop?
To answer that question, I want to start out with a forecaster’s decision tree. Since weather prediction is not exact even here in the 21st century, we must learn to apply the science of meteorology to the craft of forecasting.
Specifically the afternoon and evening dew point is running in the 24 to 28 degree range. My Penn State and Drexel education tells me that valley locations will drop to 24 while hills fall to 28 at dawn under clear, calm conditions.
That hill versus dale temperature spread was well known to our native ancestors who learned to plant their fruit trees on the hills to avoid the coldest air of spring nights. Mr. Fuhrmann has been at it since the 1960s and has a careful eye on his Lucasville and Wheelersburg orchards tonight. “Last night we were 32 on the hills in Lucasville but 28 in the valley orchards in Wheelersburg. I am concerned if we get to 28 or below tonight”, Paul told me.
Paul’s orchards roam 65 luscious acres with 12 acres of peaches and nectarines and the rest apples. Paul remembers the days of 40 cent per gallon heating fuel when he would light smudge pots to keep his orchards warm. “The last time we did that was in the 1970s. It is just not economical to do it nowadays”.
That leaves Paul and his fellow apple kings the Richard Brothers in Jackson Ohio playing a waiting game. Think of it as a game of Russian Roulette with the cold air the trigger pointed right at the fruit crop.
Now what about the “art of forecasting”? How can that make my weather forecasts better? To answer those questions I call upon two wise old timer adages.
First adage….“the cloudy blustery chilly days of spring are to be most feared since they are often followed by clear, calm and frosty nights.” Check….as both those premises will be met tonight. The afternoon cloud deck has stubbornly held and kept temperatures in the 40s. As sunset occurs, those clouds will thin out and temperatures will drop like a rock. So starting at an already chilly level near 45 at sundown. It would take a mere 10-15 degree drop to produce frost and an easily doable 15-20 to produce a killing freeze.
The second adage....“when the moon shines brightly, the temperature drops more sharply at night”. Check two on this one as the waning corn planting moon (named by American Indians) will guard the heavens tonight. But fact is whether the full moon or the dark of the moon is irrelevant. Clear skies are what one looks for in order to see a cold night unfold.
Turns out the setup this April is even more primed for a killing freeze since the ground is so dry. Given the lack of rain the past 6 weeks there will be less warmth and moisture added to the air from the ground to keep the temperature up tonight.
That leaves us to hope that the wind stays up and keeps the air stirred tonight.
It appears winds will die in valley and hollow locations where I expect a low of 25 for as long as 3 hours. In the hills where the apples, peaches and pears are planted, the three hour low of 28 will likely produce a 10% fruit kill.
Keep in mind, a 25 degree low is capable of a 90% fruit kill, so it really is a matter of degrees tonight.
In the grape vineyards of Central WV, Charley and Janet Smart report the early grapes have already been zapped once (though they will come back for a second bloom) while their pear trees have already taken a hit with one third of the blooms killed off. Since fruit trees greatly overporoduce and must thin themselves anyway, losing 33% of the blooms is not an issue. But if tonight's freeze matches the first of a week ago, then the Smart's will have lost a good chunk of their crop.
Meanwhile, Gallia County extension agent Rich Stevens says so far the early strawberry crop has taken on some minimal damage. But with frosty nights ahead, "our farmers like the McCain's are covering up to prevent a killing freeze".
One final note, I am not sure I have seen such a large chunk of the USA under a freeze warning as tonight. Fully 20 states from the Mississippi River to I-95 and from Michigan to South Carolina are in loine for a frost and/or freeze tonight. Amazing !