When it comes to fruit trees, I have always put disease-resistance as a top priority. Here are two peach trees planted four metres apart.
The left-hand one is not particularly disease-resistant. I think it was given to us four years ago and I cannot recall the variety. You can see it is suffering from curly leaf, which reduces photosynthesis and overall vigour.
The right-hand one is a Black Boy peach. We have grown them for eight years and have never had curly leaf. When growing organically, it helps to have cultivars that are less vulnerable to plant diseases.
Plums, like the one pictured below, seem to be highly disease-resistant.
We have eight different varieties and have never had any problem with disease.
Plums are nice, but I do like peaches more. We have about 30 Black Boy peach trees in the ground that produce deep purple fruits.
We propagate them from the stones and sell them locally to those interested in low-maintenance, beautiful peaches.
We also grow disease-resistant apples. Apple varieties reported to have higher resistance include: Liberty, Monty’s Surprise, Belle de Boskoop, Peasgood Nonsuch, Priscilla, Akane, Captain Kidd, Lobo, and Reinette du Thorn.
Avocados are another story entirely. They are known to resent wet feet and suffer from phytophthora root rot. Soil conditions and/or mounding and drainage seem to be the most important factors for preventing stress in avos. Those shown below are stressed from being in pots to two years (a long story), but you can see the new growth forming at the tips. We planted them last autumn in a area with free draining soil, but also added small mounds and drains to be extra safe.
The avos below come from the same order three years ago but went in the ground straight away.