What physical effects show when too much pesticide is applied?

[gssgarden]

I'm battling HUGE insect/worm problems this year and wanted to know if there are any noticable physical issues I should look for IN CASE I apply too much insecticide.
I would only use Sevin at the correct ratio. But IF I put to much on will I see:
Leaf Curl?
Deformed fruit?
Lack of fruit set?
Browning of blooming flowers?
Plant death?
Discoloration of leaves? (white spots, black spots)
Wilting?

Thanks,

Greg