weeg,

from my humble inexperience, plant will survive up to 105-112 for weeks without shade cloth, and actually look healthy. If mulched enogh you shouldn't need to water at least for 5 days between deep waterings. The real question is what is the point in keeping them alive other than harvest the fruits they are bearing. Sure, you might have a few hold over plants but watering tomato trees with no flowers is no fun. Basically all tomato production will cease at those temps, unless you got varieties like early girl or heat wave, which have set fruit for me even in those temps. Shade cloth could prevent sunscald if it is a problem for you, but is most useful for starting tender mater seedlings mid summer for a fall crop. This is the only time I would use the stuff or if I had a sunscald problem. Cheers.

Vince

Hi weeg - I keep 60% shade cloth on my greenhouse and use 60% over a lettuce patch I keep going that is also in tree shade but it is only good for 15 degrees of temp change. Works somewhat here for me as my high temps are +or- 105 but still doesn't allow for fruit set on tomatoes and the greenhouse still breaks 90 degrees regularly unless I open all the sides too. I can't see it doing enough for tomatoes given your temps there. My brother lives in AZ and 105 sounds cool based on temps he has reported to me.;)

On the other hand, I have a neighbor who uses burlap feed bags over his tomatoes and swears he still gets fruit set so using the max shade cloth you can get like 80+ might be worth a try. Also consider some of the varieties that are more heat tolerant - Heatwave did well for me. Not a great tomato but beats the supermarket ones hands down. There is also Solar Fire, Sunmaster, and Solar Chaser. No personal experience with them. Good luck.