Heat stress? Could be worse

Since my last report about heat and drought stress, I've noticed a few more raisins developing on clusters that are high on the vine, not as well shaded as the lower-placed fruit. 

Leaves at the top of the plants are turning brown, but what else can I expect? It's 100 every day with no rain.

Actually, the grapes mostly look really good. The yield is high, and the fruit seems to be ripening a little early. I suppose it's possible that I did not do the vines a favor by thinning only a few clusters last month. But it's hard to argue with success ...


 
... or at least signs of success so far.




I have decided to stop watering the vines. I did that a couple of times in July, but now I plan to let the sugars and acids concentrate. This is what Erv Langan at Keltoi Winery has been doing all season long — allowing the vines to stay stressed for maximum grape quality, as described in a report by Brad Douglas, KODE/KSN News, at OzarksFirst.com.

One last thing: I have made an exception for the youngest plant in the row, whose leaves are turning brown throughout, not just on top. I watered this one today:

 
 I'm wondering whether some of this damage (detail below) is black rot:

One last note: If we as a planet are now in the grip of palpable global warming — if Missouri's average high for July and August is destined to be 100 — is it worthwhile to keep growing grapes? Maybe we should switch to cacti and make tequila ...