Raccoons or possums?

I have a big garden in town. Something destroyed a big patch of sweetcorn last summer pretty much in one night. The stalks were mostly pulled down. I had a small, late summer patch that also got destroyed. It was inside a privacy fence. I though it was raccoons. I’ve live trapped two possums in the last few weeks. Do possums damage corn like raccoons do?

Something carried off a chicken too. I think it either ate it all inside a 6’ privacy fence or ate some then carried it over the fence. I don’t think a possum could climb a fence with a chicken. Maybe a group of possums ate everything but the feathers? I saw two possums with chickens in their mouths a few years ago.

I think I’ve probably got both animals?

Would a tall variety of corn help much next year?

I’m planning to keep trapping.

Trapping is a stop gap only - in that it will only temporarily solve your issue. The fact that you have not even identified the culprit, and are just randomly trapping and eliminating anything that "might" have done the damage is unwise.

First and foremost, both raccoons and possums have territories and perform huge pest control duties (coons insects and rodents/possies insects). Elimination of them allows the smaller "predators" to proliferate and simply creates a "vacuum" or vacant territory that will swiftly be replaced by another raccoon or opossum. You will never get a permanent solution, just an ongoing, frustrating, battle.

I highly recommend looking at a barrier method (metal roofing as fence, electric netting) or consider a guardian dog to protect your crops and "own" the territory.

At the very least, identify the "predator" before arbitrarily trapping animals that were likely, not guilty, in the first case (there are a host of others from humans to bear to deer and more, depending on where you live and the species that reside there), and perhaps take the time to learn the benefits our natural wildlife offer, such as rodent, grub, slug and snail (just to name a few) eradication which would be potentially FAR more helpful, in the long run.

The city would never let me build a metal fence.  I’m pretty sure there is a code against electric fences, but I might try that.

I’ve had a garden here for 12 years with only minor problems, so there are clearly more of these animals here than normal. They destroyed about a hundred ears of corn in a couple nights. It’s not like I’m encroaching in their territory. The yard was bare dirt when I moved here. I planted every tree and even the grass.  I’m not going to give up on gardening because the possum population increased. I did give away my chickens for their safety.

Crop protection is just that, crop protection. It is not about blame (on either side), encroachment, or "rights", it is about the best way to ensure your hard work is protected. The mere presence of a family dog would likely go a long way, but only if a family pet is desired.

The metal/electric fencing would strictly be around the planted area, within your property, not to replace the existing fencing.
None of these methods will work if predators are digging/sneaking under existing fencing or if able to access plot by circumventing exclusions methods by using roofs (sheds, pergola's, houses) or vegetation (trees, shrubs, trellises).

The garden oasis you created has also changed the environment, creating habitat that attracts these various forms of wildlife. With protective measures not in place, it was only a matter of time before it was discovered.

It is the same with the installation of a pool, pond, fountain, compost, etc. If not properly secured, all these "good" things can lead to attracting problems. The key is being proactive, and layering your protections BEFORE your "oasis" is discovered and exploited. It can still be done after the fact, but is more difficult - once a food source is identified it is hard to give it up.

Metal is unclimbable and chewproof which excludes all (squirrel, rat, raccoon, rabbit, possum, dog, cat, deer, human etc.) but flighted predators, especially when embedded (trenched) into the ground 12-24 inches to guard against digging predators.

Electric fencing is a "conditioning" or deterrence method that makes accessing the plot undesirable.

Electric strands MAY be allowable/acceptable atop the existing fence (assuming they are scaling and not digging in) and would be the least expensive method. Installing a couple of strands on insulators hooked up to a charge unit shouldn't cost more than $150.  

The electric netting is just 3 feet high and installed on step in stakes around the specific area requiring protection. It is super easy to install, move, or relocate as needed. It can be deployed temporarily or permanently and has the advantage of being relatively easy to step over.  Cost is slightly higher than single strand, and dependent on size, but, again, would be a one time cost.

In your circumstance, with what sounds like a smaller plot, I would most likely suggest taking a good look at the electric netting. It could be deployed for short periods, as crops near maturity (if this is when the predation occurs) or seasonally (if the predation is throughout the growing season), then stored the rest of the year. Cost is not prohibitive ($150 for 150 feet of netting plus $100 for charge unit) and would protect against all predators under 3 feet tall that cannot fly or dig beneath the netting.

Electric netting would not be useful or effective against humans, deer, bear or flighted predators.

If you don't want to own a dog, wolf urine spread around the fence line will deter most raccoons and opossum out on patrol.
While the live animal is a sure thing, the wolf urine is something that usually works pretty well, however, should the pest animals ever figure out that there isn't really a wolf around, they will comeback.

A game camera or two will definitely identify the culprit(s) and don't forget ground hogs, they can do serious vegetative damage too.

I have had raccoons kill chickens a number of times.  I've never had a possum kill one.  Just two weeks ago I got home from work late and went to shut the chickens up and chased a possum out of the chicken coop.  I have had them get in and eat eggs before, but never kill a chicken.  That isn't to say they won't, I just haven't seen it.  I have seen possums eat a chicken that was already dead a number of times.

As far as your corn goes, my money would be on the raccoons but I'm not sure.  I'd second the notion of the dog if you have time for one.