We’ve had a fantastic stonefruit year at Terra Firma, and we’ve been harvesting lots of big, pretty, and very tasty fruit continuously since mid-April.  But in other areas of Yolo County, just 30 miles to the north, farmers have almost no crop.  Until two weeks ago, I had no idea what explained the difference.

There are a number of factors that influence the annual production of deciduous fruit and nut trees.  The first is how much “sleep” they get during the winter:  each variety and type of tree needs a certain number of hours below a certain temperature before it comes out of dormancy in the spring.  If the trees don’t get a good hibernation period, they bloom poorly or over too long a period of time, resulting in a lighter crop — or none at all.

Then there is the weather during bloom.  If you think about the weather you might want for a picnic, that would also be perfect for guaranteeing a successful crop:  sunny and warm with a gentle breeze and no rain.  Some tree crops are bee-pollinated and some are wind-pollinated, but both types enjoy the same weather.  On the other hand, heavy rain keeps beeing from flying while also washing away pollen.  Any extended periods of dampness cause the blossoms and young fruit to get molds and mildews.  A hard freeze with temperatures below 28 degrees for more than an hour or two damages or destroys flowers and developing fruit.

Until this year I was unaware of yet another vulnerability for developing blossoms:  Extreme heat.  It turns out that temperatures above 85 degrees for certain periods of time dessicate the flowers and pollen, causing a light crop or no crop at all.  March of this year featured an unprecendented early spring heatwave with multiple days in the low and mid-90s.  Anyone with peach, apricot, plum or nectarine trees blooming during that period had a near-total crop failure this year.

Luckily for us, and you, Terra Firma’s peach orchards are in a location that tends to warm up early in the spring.  Some of our peaches started blooming this year in January and the rest in February.  They had already finished polinating before the heat arrived in March.  Instead of damaging the fruit, the warm weather actually helped it.  The peaches and nectarines sized up more than usual and began ripening sooner than normal — although as a result they are also going to finish up sooner than they do most years.

But we did not completely escape this deadly-to-flowers heatwave.  Our pistachio orchard — as well as most of the other pistachios in the state — bloomed during the March heat.  There are so few nuts on the trees this year that it won’t even be worth the time to harvest them.  The event has been designated a statewide crop failure.

Historically, state and federal governments declared weather disasters only for events like tornados, hurricanes, floods, and blizzards.   Recently, untimely hard freezes occuring over large areas have been recognized as disasters for agriculture.  But to date there are no disaster declarations for heat waves, despite the fact that they are increasing in scope and severity.  Part of that is that not enough research has been done or data exists to quantify their effects.  But as they become more common and more extreme, that will likely change.

We got lucky this  year at Terra Firma with our stonefruit.  But as recently as 2023, we lost almost our entire crop due to freezing tempeatures during bloom.  And 2027 could present us with excessive wet weather as a result of the strong El Nino that is developing.  It has always been true that in farming you can do everything right and lose your whole crop in a single week.  But climate change is making it even more common.

I hope you have been enjoying the wonderful bounty of our orchards this year.  If not for the luck of geography, we might have had none at all.

Thanks,