I am certainly no tomato expert but did have the problem with yellowing lower leaves a few years back. I tried an anti-fungal spray and that seemed to help a little.

A friend came over and I pointed out the problem. She said my plants were too close together. Air needed to circulate to help alleviate the fungus-producing environment.

My beefsteaks have never been prolific producers. Always producing less than the "average" tomato.

Good luck!

Mark

Would it be possible to post a picture? From your description it could be anything from excess watering to one of the systemic viral diseases. You can eliminate some of the possibilities by cutting off a bigger stem and slicing it open to check for brown discoloration or sludge.

On the Tomato Pests & Diseases forum there is a long thread call "Problem Solver 2". It contains many links to sites with photos and information you can use to diagnose the problem. Check it out and see if it can help you narrow down the possibilities.

Dave

Here is a link that might be useful: Common Tomato Problems

They have enough room for air to circulate, I wish I had a way to post a pic. I think I will cut into a stem and see what I find. I hope it isn't sludge, sludge sounds really kind of gross! Debating on pulling up these plants and setting out new ones, but with the heat I don't know how they would do. Betsy

Fusarium Wilt: Yellowing of the leaves occurs in tomatoes infected with Fusarium Wilt. This yellowing spreads upward from the base of the plant as the disease progresses. It may occur ononly one side of a leaf midrib or one one side of a plant. The leaves wilt noticeably before they die, and the whole plant eventually dies. Fungicides are not effective..prevent fusarium by planting resitant varietes and follwoing sanitary garden practices. Resistant Varietes: Ace 55, Beefeater hybrid, Beefmaster, Better Boy, Better Girl, Burpee's Big Girl, Campbell's 17, Floradel, Homestead, H1350, KC 146, Kokomo Manluce, Manapal, Marion, and Supersonic.

Big Beef Tomato is a VFFNTA Hybrid which should be resistant to Fusarium Wilt.

She could have a wilt the tomato isn't resistant to however.

If indeed it is the fungus there isn't much that can be done.
From my reading (& my garden has it):
Mulch heavy, it is thought that it is active in warmer soil temps, but a close relative is active in lower soil temps!
It is a race against time, fruit may set at reduced yields, some say taste is diminished though.
It is believed that this fungi has no ill effects on humans, but the control fungicide is very suspect and not ozone friendly.
There is a little promise that a fungus strain/bacterium combo will control somewhat, but again at reduced yields.
To make matters worse, there are various strains (races). Hence you may see VF1, VF2 & VF12 to be resistant to race 1 &/or 2.
Unfortunately it doesnÂt seem that homemade compost introduces any micro critter predators to control.
As if all that weren't enough, the fungi also uses "host" plants (some mints are one example) and they show no ill effects.
Seeds can be infected as well. Spores can survive many years in soil.
Fusarium has quite the winning strategy.

Up here in Central New York State, (Finger Lakes Region),
it is called "Blight", which I believe is just another
name for Fusarium Wilt. I have it quite often in my
garden, but it doesn't usually hit until the plants
are at the top of their cages and quite a bit of the fruit
is set. I've tried all sorts of measures, including pinching off the leaves that turn yellow. Eventually
the entire plant is infected. Most of the time, the
very top leaves stay green and are enough to keep the
vine providing nutrients to the established fruit and
I get 'some' tomatoes off each plant. Do a Google on
"tomato blight" and you will find volumes written,
but no known solution to the problem.

I think I am going to pull them out while there is still time to replace them. I bought some "Black Prince" tomatoes yesterday. Thanks everyone....Betsy