Crossing land borders in S. America is easy and if you travel in South America and plan to cross borders by land there is one thing you should know which can save you a lot of money.
Most countries have restrictions from taking certain things across the border such as plants, produce, live organisms, and other items which each country may believe could threaten their eco-systems.
You may think that the banana you have could not possibly do any damage to their ecology but it will do damage to your wallet. I know of those who failed to either throw a banana away, failed to declare it on the customs form and was fined $200 US dollars, yes, you read this correctly. This fine has now been increased to $300USD as of my last crossing in 2013.
I recently did a land border crossing from Argentina to Chile in the Atacama. I had purchased some very nice blue cheese and was taking it with me. My friend I was traveling with reminded me about the fact I could not take cheese across the border. I made a bet with him I could get it across.
What I did was to make a declaration on the customs form that I had one item in the group of items which fell into the organic materials category. The cheese was in my bag. I handed the customs document to the immigration staff, they looked at it, passed me through where I placed my bag on the belt for the x-ray machine and watched it go through fully expecting the operator to pull the bag off and ask me to open it.
I was totally shocked that the bag went through and I was never asked to open the bag however, if I had been and the cheese was discovered, then I could always point to the customs document clearly stating that I was importing an item on their list of organic materials. The worst that would happen is they would confiscate (take away) my cheese but I could not be fined because I had declared the item and they failed to take it away from me.
I had also traveled this same route and there were two Americans on the bus. They asked me a question about the customs declaration and I asked if they had a deadly ham and cheese sandwich they needed to declare. Their answer was "no, we have a bag of coca leaves". I told them I should not even answer their question because we had been on the bus for many hours and they never offered to share, of course I was joking with them.
What I did tell them was that they could handle this two ways. One was to declare the coca leaves, the customs officer would then confiscate the bag but there would be no fine. The other way was to not declare the bag of leaves, try to sneak it across, the customs officer may or may not find it but if it was discovered, the bag would be confiscated, he would face a large fine and depending on drug laws at the time, it could get really bad for him. In the end he declared it, the bag was taken away from him, there was not fine or drug violation.
Therefore, when making a land border crossing, especially between Argentina and Chile as well as any other country where they make a big deal about bringing vegetation or other organic materials into their country, if it can be eaten before crossing, then eat that banana or throw it away, no one wants to pay a very expensive fine.
Travel Safe, Travel Happy