The grass around your cuke is taking up a lot of water too. The cucumber would get more water if the grass weren't there, and if the soil was mulched. For instance, you could arrange sections of newspaper under the vines: that would kill the grass as well as help keep moisture in the soil from evaporating in the hot sun. With leaves that shade, I'd give it some fertilizer appropriate for cucurbits, ideally including iron.

oh crikey.. an engineer... lol .. watering is an art.. not a science... you tend toward scientist ... and it is warping your head.. isnt it.. lol ... you have tried to figure out your soil.. and how water works in it ... fantastic... based on said knowledge.. you have to GUESS .. what is best ... no one can really tell you otherwise ... since we cant guess as to your soil ... just do the best you can ... and wing it .. words that make a real engineer pale... lol and do note.. ALL my best friends are engineers.... so this is all tongue in cheek... but rooted in knowing the psyche of the profession ... in all those words.. i dont know how long you will be gone ... a transitory watering issue is not going to kill a plant inside a month or so ... so on some level.. i think you are over-worrying ... and lets be very clear ... YOU PLANTED 45 .... you most likely will have a loss or two ... and until that time ... you will not know your success ... heck.. with all my experience.. i would expect a failure rate ... so dont flip out and try to figure out why.. the exposure starts with not knowing how successful the dig was at inception of BB ... prepare for some loss.. and learn a happy dance.. if you win ... i dont know about your little water wand... but its better than not having any knowledge ... and you should also be inserting your finger.. under the mulch.. to teach it how to do it ... the meters eventually fail ... and finally ... i wish you would have.. wait for it.. gone with an engineered water delivery product ... crikey.. the one place you could have had the science.. instead of the art ... you went art ... little brain freeze there??? ... it would not have been a significant cost difference .... with said product.. your failure will be at distance from the spigot ... as pressure is not maintained thru the whole run... when i used such.. i would swamp the first plants.. trying to water the last plants... so put all your focus in the end of the run ... presuming you arent leaving for months on end.. i would tend.. now that the heat of summer is starting.. to err towards extra water... this is the key season to INSURE the root masses do not dry out ... and then when fall hits.. we can dry them out... for winter.. if need be ... you are not going to kill the batch... but for the worst clay soil ever .... and i dont think you have that ... you have analyzed.. and considered every variable know to the gardening world.. i hate to tell you.. you are now left to the whim of mother nature .... with decades of messing with her.. let me sum it up with.. GOOD LUCK WITH THAT ... i hope this was helpful.. and that you have some sense of humor ... i wish you luck ... ken ps: if you have failures.... talk to us then ... but in case i forget this brainstorm ... you can re-harvest some of what you have.. and place them to fill a hole .... and then plant some diverse plants where you take stock from .... lets not talk about failure right now.. but if so.. remind me about this ....

Its adapting to the lower light levels. Older lower fronds are first to go....

gle- My lawn came out ok enough....it's green, fungus gone, no weeds, over-seeded in early Sept.... My last thing to do this year is apply fertilizer late October/early November. Then starting next year, I'm going to try to follow this: http://forums2.gardenweb.com/discussions/4826669/a-yearly-guide-for-cool-season-grasses-from-rutgers to the letter and see how I make out. We're supposed to get a harsh winter in the northeast so let's see how that goes.