This tutorial will show how to map an object without causing texture streaks. 
We will be using two mapping channels in the uvw modifier, TL Unwrap and a mask to accomplish this.

We start with a simple mesh, a bread-loafish looking thingymabob. We assign a uvw modifier to this mesh which will have the default map channel of 1.

You ugly thing! Let's unwrap it using the unwrapper of your choice. I used Texporter to get a template to make an award-winning texture

If mapped onto the model and rendered, this is what you get

Some nasty streaking there. Lets do something about it by using a cylindrical mapping around the loaf and set it to map channel 2



Now put TL unwrap on the top of the modifier stack. Set Mapping Channel to 2, switch off all Trims and set Mesh Material ID to any number other than 1. That's to prevent TL Unwrap from showing faces on top of the render. Since mine's longer than yours I of course put it to 99 too.
Now set your texture to 100% self illumination and unwrap. The reason is that we don't want any shading on the unwrapped render. The resulting map will look like below.

Because you set Mapping Channel to 2, TL Unwrap has cylindrically unwrapped the loaf but shows what texture was assigned before (channel 1).
Bring this into Photoshop and paint a mask covering all parts that streak. I resized this map since resolution isn't that important.



Use this mask and delete the streaking stuff from your texture. Then paint an unstreaked version using the (unstreaked) edges as a guide to get this

Now assign this map to your object using a mix material with texture1 (uvw1) in one slot, texture2 (uvw2) in the other and the mask as the mixer using uvw channel 2. It should look like this.


For novelty's sake, this is how the loaf would have looked like with only a cylindrical mapping. Streaking at the poles. Here's also how the mask looks like when placed. Oops forgot to make it seamless on top. Well, it won't show.

And THIS is how it looks like when all three work together! No streaking and a seamless transition from one texture to the other, hooray!
The ugly loaf now grandly looks like...an ugly loaf with a bad texture.