Can I avoid falling in the rain on a corner? I was riding in the rain a few months ago and fell turning a 90° corner. Here are the details:


Riding on a road bike with new 25mm smooth tires inflated to 100 psi (Cannondale Synapse with Continental Gatorskins inflated to 690 kilopascal)
It had been raining for at least an hour, but was not raining hard at the time of the fall
There was no obvious oil or other liquids around, no dirt or other substances
There was no strong wind and the temperature was well above freezing
I was coasting at about 10 mph (16 km/h) around a corner on smooth asphalt
I weigh 210 lbs (95 kg)
I fell to my inside, right side
The fall was immediate with no dramatic skidding or sliding


Here is a photo of the corner, with a red square where I slipped: 



I was surprised to discover that the smooth tires are not particularly the culprit in my fall, as bicycle tires for on-road use have no need of any sort of tread features; in fact, the best road tires are perfectly smooth, with no tread at all. 

(Edit: Per multiple comments and answers, the above link is not specific to wet surfaces and the assertion that no tread is optimal does not apply here. It appears treads should help with wet surfaces.)

I live in a desert climate so I haven't had much experience with slippery roads, and none since that accident. Is there anything I could have done to avoid falling, or do I simply need to avoid any wet, asphalt surfaces?
16 km/h is so slow that even the worst tyres should keep you up, unless something like oil spills were involved.

If something is so slippy that you fall without warning at such low speeds there is not much one could do. If you have a hunch this might happen tripodding corners or getting off the bike may help.

The first drizzle after a long dry spell can leave a very slippy mix of wet dirt on the tarmac. It sometimes feels almost like soap. More intense rain washes it off quickly.

Some surfaces (eg metal or road markings) can get slippy when wet. Avoid anything that looks smooth and wet. edit: The smooth tar of the patched cracks visible in your photo are also example for such treacherous surfaces.

If temperatures are closer to zero black ice may form spontaneously. It is nearly impossible to distinguish from wet road and is extremely slippy.