Can Botox Straighten my Nose?

 Dear Rachel,
When you say "straighten the tip of my nose", do you mean that you want to rotate your tip up a bit?
In either scenario, I would say that BOTOX would not be a good option.
Please let me know if I could be of further assistance to you.
Best regards.

Botox is a neurotoxin, preventing nerve and muscle fibers in a localized area from communicating.  Since the positioning of the nose at rest is not related to muscle activity, Botox will not provide any benefit in straightening a curvature.  However, as other posters have noted, the "snarling" position of the nasal tip while smiling can be improved by treating the depressor septi nasi muscles with a few units of Botox.

Botox is not used to straighten a nose but it can sometimes soften a plunging tip with animation when injected just below the columella.

No, I would not recommend Botox for use to straighten nose. Botox should not be considered a substitute for what a typical rhinoplasty (nose job) would do. 
I would recommend discussing this case with a board certified plastic surgeon, and I would not recommend Botox to straighten the nose.

It is not possible to see exactly what deviation of your nose you refer to from the photograph provided.  Regardless, Botox would not correct a nasal deviation.