Why, in Israel, do they get rid of ותן טל ומתר in barech aleinu but then add מוריד הטל in ata gibor? If it's the end of the season for טל (which, maybe i'm wrong, but I don't think there an end to that one) then stop saying טל. If it's not the end then leave it in both places. I know they get rid of "מטר" because it's the end of the rainy season, but why can't they still say "ותן טל לברכה..."?
Tzlosa D'Avraham (by R. Avraham of Chechanov) suggests the following:
The Ashkenazic minhag, to not mention dew at all, is based on an analysis of Taanis 3b, where it is implied that only after the fact do we not make a person repeat Shemoneh Esreh if he said it during the summer, but that ideally one should not do so. The reason behind this is that, as the Gemara notes on the previous amud, "dew never ceases" and therefore it is inappropriate to praise Hashem as its provider. [What that means - on the contrary, I would think that this should make us praise Him for it all the more? - I don't know.]
However, this creates a potential problem during the winter, because if one forgot משיב הרוח ומוריד הגשם and also didn't say מוריד הטל, he'll have to repeat Shemoneh Esreh.
The compromise, then, is to indeed say the latter during the summer (so that even during the winter a person will be apt to say one or the other phrase), but to punctuate the tes with a kamatz so as to make it effectively the end of the sentence, thus making it refer back to the previous phrase - מחיה מתים אתה רב להושיע - and hence not to the daily dew but to the special dew that Hashem will use to resurrect the dead.