Root rot?

I used this forum last summer but forgot my old username :-) But now I'm back.

My garden was doing great until just recently. I took a green bean plant and a pea plant to our local extension agent and she expects root rot due to either over watering or a fungus. My plants seem to grow fine for the first 4 or 5 weeks and then they start dying from the bottom up. Wilting and turning brown. I can submit pictures tomorrow.

Anyone else experience anything like this?

What a bummer, has it been really rainy lately, do your beds have good drainage?

Sorry we have had company the last few days.

We have not had very much rain at all. I water with a wand sprinkler every morning just until the soil is wet. Each morning the boxes are dry.

My boxes are on a concrete slab and have a sheet of 4x8 sheet of plywood on the bottom. The plywood has holes drilled in the bottom for drainage.

This is just my suggestion.

I think the culprit is the plywood bottom on top of the cement, along with watering.  The plywood  and concrete are probably constantly wet.  Have you checked the condition of the plywood bottom by digging down to the plywood. Stick it with a screw driver.  Is it rotting before its time?  Do you use MM or a soil combination?  Constant wetness + wood = dry rot.  Do you mulch the top?  Mulching = less watering= moist but not soggy mix.  If the mix is dry each morning, then it sounds like you aren't mulching.

I know Mel states you can add plywood with drilled holes to the bottom but it is so you can move it around or make table tops.  Plywood on the bottom of table tops has air circulation under the plywood.  If you aren't moving it, then it doesn't need the plywood.

I would rebuild it.  Remove the plywood bottom.  Place a sheet of plastic on the concrete to keep the concrete from discoloring.  Place the box on the plastic.  Line the bottom and up the insides a bit with weed screen to keep the Mel's Mix in place.  (So is doesn't wash away)  Replace mix.  Plant.  And, Mulch the top so you don't have to water as much.

Well, if the extension agent doesn't know?
Without pics it's hard to tell. In the morning, before watering, dig all the way to bottom, to be sure it's dry.
If it is really dry and draining well, it may be a fungus.
What do the plants look like, yellow, spotty, or green, looking good, then falling over?
Do you have anything else planted?
What is your weather like? Hot yet?
Do not water more that about an inch per week unless it's very hot. Let it dry out some and get a fungicide to use.
Jo