We're spending a great deal of time right now watering - but only hazels (or other) that were planted THIS year. Anything planted last year, for us, is not stressed - yet. Though it might be. Anything planted 2 years ago; we consider safe and not in need of supplemental water except perhaps in extreme circumstances (or on sandy soils, maybe).
But; yes; this kind of extreme heat and dry weather can kill tubelings planted this year; they're still tiny. Get them watered if you have ANY doubts about it.
Our friend Hank Roberts made this comment on the last post:
"I know you're too busy to be blogging these days, just thinking about y'all while watching the weather. I know a tiny bit about heat stress on corn and soy (both the limits during critical periods and the overall degree days, I think?), but nothing at all about what factors combine to affect success with your woody crops."
Yah, busy, but it takes a while for the pickup water tank to fill; 450 gallons-
We're expecting this to be a year when the hazel crop really shines- so far, the hazel crop is in no danger at all; not even stressed; while the prices of corn and soybeans go up every day it doesn't rain-
Take a look here to get an excellent idea of how heat and drought affect the corn crop: and note that's from August of last year. The corn this year; having been planted earlier, may actually be more at risk.
Very quickly; the hazels share almost none of those risks. The crop pollinated and the nuts were set in March and April. Currently they are sizing, and filling. Yes, it's known that some hazels may suffer decreased size, or even abort the embryo, if exposed to high heat at the wrong time. But- our hybrids include genetics that appear to be immune to those problems. So far. Hazels are C3 plants, not C4 like corn- which we can and do argue is a great advantage (twice the Growing Degree Days in the same locations); but precise effects of heat are not well studied.
What is known about heat stress in hazels is only on a cultivar by cultivar basis- and our populations of diverse hybrids confound the desire to make broad sweeping statements.
One thing for growers to do- keep an eye on your hazels! Those that come through this summer with good solid crops- are going to be important for future of food, as the climate warms.