Just wondering, did you try a systemic insecticide? The most common cause of browning like you speak of is usually spidermites, which are easily controlled if treated with a systemic insecticide/miticide every 7-10 days, for three applications. Systemics work their way through the entire plant in order to kill the mites. You can also try a insecticidal soap/oil like Sunspray or products life Safer's.

Another helpful, less toxic treatment is to use your hose to spray down the ivy once a week. It won't effectively get rid of them all together but will prevent them from taking hold again.