There are multiple crop plants that are perennial in certain climates but treated (by necessity) as annuals further north. If I recall, tomatoes and runner beans both fit this category.
As perennials, these plants would clearly not be rotated, at least not in the short term. As such, I would assume their susceptibility to disease would be sufficiently low to allow them to continue productivity without the the-sky-is-falling-because-you-didn't-allow-X-years-between-crops thing.
So I'm wondering, then, to what degree these "perennial" plants can be grown as annuals in the same soil without regular rotation. Why is this practice so frowned upon? Why do the same plants we are warned to rotate do (apparently) fine when grown as perennials in warmer climates?
How warm is your climate? I would guess rotation is recommended to confuse pests. Ive grown the same tomatos for 5 years in the same spot. Not perrenial, some fall to ground and resprout. I just let it happen.
Horn worms are the only invasion i have gotten, but its easy enough to deal with. Just pick them off.
There are numerous resons in conventional farming to rotate crops. The reasons being mostly nutrient, pest and disease related. Conventionl crops that don't get rotated like perennials, often have some high cost high maintenence systems in place to reduce those pest pressures. Conventional farming goes against nature, therfore goes against natures way of creating available fertility, and the plants natural defense against pest or disease. Plants have been documented to literally use chemical cues, to call in a species spacific preditor insect, to eliminate a pest that is attacking it. That means the plant must identify the insect thats attacking it, and have a pre-established species spacific symbiotic communication with the preditor, and the plant does all that in a matter of minutes. These chemical cues are like the chemical cues that occur in the synapses of mammalian brains, and it's crossing species and kingdom boundaries.
Some studies have found that when you break away from conventional farming methods, and create a healthy soil biome. The nutrients that become available to plants through the symbiotic relationships plants have with bacteria and fungi. Creates a strong immune system within the plant, that resist pests and disease to an unfathomable degree. Think of pests, like the wolf. The wolf goes for the sick, dieseased, and dying. Well some studies suggest when plants are truly healthy, as in nutrient dense healthy. Pests aren't even attracted to them, because pests are attracted to the stress signals and chemistry of unhealthy plants, brought on by a weak immune system, from nutrient deficiency and malnutrition. The plants immune system becomes so strong, disease doesn't even really phase it, and the plant recovers quickly if even becoming symptomatic. Plants have relationships with micro flora and fauna in the soil, just like humans have the same relationships with the probiotics in their gut. Without those microscopic bacteria and fungi in our guts, we could eat all day, but litteraly die from disease and malnutrition, because those microscopic organisms are what make the majority of our food biologically available to our systems. The same thing that occurs in our digestive tracts, is happening all around the roots of healthy plants, including networks that span over ten times the plants root structure, modesty speaking.. Tilling the land destroys much of that mycorrhizal network, and creates an inhospitable environment for those healthy plant probiotics, that often need living roots to feed them sugar for long term survival. So once you step away from natures way of doing things. You creat more problems that have no true solutions, and that's what I call a long row to hoe...