I have planted green beans three times because I have an
annual problem of the leaves either being completely chopped off or they
appear lacy and nearly gone. I have seen slug slime, so that may be some
of the problem, but what does the lacy leaf indicate? I also have a lot
of “potato bugs” or “sow bugs,” could that be the problem?
According to The Organic Gardener’s Handbook of Natural Insect and
Disease Control edited by Barbara Ellis (Rodale, 1996), lacy leaves on
your bean plants might be the work of Mexican bean beetles. Parasitic
wasps (Pediobius foveolatus) can be used to control the Mexican bean
beetle. As a last resort, you can spray or dust your plants with
pyrethrin. See links here:
From the Connecticut Agricultural Experiment Station
From the University of California
Large holes in the leaves may be caused by other beetles as well, such as
the cucumber beetle, which can be managed by protecting your plants with
row cover like Reemay. If damage is severe, you can use pyrethrin or neem
spray.
Small holes in the leaves may be the work of flea beetles, and the
management is the same as above.
The chopping off at ground level sounds like it could be the slugs eating
shoots as they emerge, or climbing up the plant and eating it down to the
ground. It could also be the result of cutworms. Look for these at dusk, and look during the day at or just below the soil surface. I manage these
pests by looking for them frequently, and squishing them or cutting them
in half with my pruning shears.
I had never heard of sow or pill or potato bugs (isopods) being a
vegetable pest, but apparently they do have that potential if the
population is large enough. See the discussion among gardeners on Houzz.
You might try fooling the pests by planting your beans in a different
location, especially a raised bed.
I have grown runner beans in the center of England for
several years, with good crops and healthy plants, but this year my
plants have some sort of disease. The leaves have brown spots which seem
to spread along the leaf veins and then over the whole leaf. Some plants
are still producing healthy beans, but on some plants the beans have shrivelled
and turned yellow. I don’t know if these are the same plants with the
worst leaf problems as the plants are tangled together too much. I have
looked at various websites, but am not sure that any diseases shown
correctly match my problem. I would be very grateful if you have any
idea as to what it is and how to deal with it.
While I cannot diagnose the problem remotely, your description does sound
quite a bit like anthracnose, which is a fungal disease. According to The
Organic Gardener’s Handbook of Natural Insect and Disease Control by
Barbara Ellis (Rodale Press, 1996), this disease thrives in wet, humid
conditions. You would see leaves with dark streaks, and black petioles
and veins on the underside of the leaves. If this is indeed the problem,
plants may be sprayed with sulfur, or you can seek out resistant
cultivars next time around (‘Espada,’ ‘Marbel,’ Morgane,’ and ‘Rocdor’
are a few).
On the other hand, the yellowing of the seed pods sounds more like
bacterial blight, also encouraged by warm, damp weather. If your plants
are not forming any new pods, remove and destroy them. Next time you
plant, be sure there is adequate space between plants, and perhaps
rotating the crop to a different location might help.
Just to give you some basis of comparison, here are links to sites with
information about diseases affecting beans:
Cornell University Vegetable MD Online
University of California, Davis Integrated Pest Management
Royal Horticultural Society lists several problems affecting runner beans. There is a fungal disease of broad beans called chocolate spot which sounds a little like what you describe.