thanks but there is no roundup in my direct neighborhood, i checked the roots on one of them and noticed nothing particular. for sure i think of a fungus / bacteria or even a virus maybe...
Last year too? Then the problem may be environmental.
I doubt the problem is overfeeding because the plants aren't dark green, no tip scorch, etc.
Just a hunch ... have you got termites in yr garden? In any case pull one of those plants and look at the roots. You may see chewed roots.
It may also be Nematodes which can be fixed by watering thru Molasses at One table spoon per gallon (4.5 litres). Nematode affected roots have lumps on them.
Possible chemical spray drift. Roundup sprayed next door on an unfriendly breeze will do this.