I've had trouble keeping my tomatoes fungus free (black spot, mostly... black spots then yellow leaves, then dead leaves). It usually starts from the bottom so this year I've removed all branches that threaten to touch the ground. Does anyone know anything good or bad about this practice?
I bet this has been discussed before. The reason I didn't find it in this forum is at the posting to DG below.
Usually tomatoes get discussed til everyone quits saying anything real- they cant remember what hasnt been said I think. None of my forum searches ever went where I needed anyway, so the mess isnt affecting me as bad as many.
My guess is you are having far too wet and cold a summer this year. I will shoot ya a few names and let you research this tho. Root Knot nematodes, fungus like fusarium wilt, anthracnose, over watering. Branch removal is a choice used to increase tomato production by many- I thin, but a tomato is a vine and gets air roots to help the vine gather nutrition as it grows along, removing branches that will not bear fruits again simply redirects the plant growth to the producing parts of the plant. Wet years I train the vines up, dry years I allow to lay along the ground for the rooting.
I trim the bottom leaves as well. It helps with air circulation. Also, the lower leaves a lot of the time will start touching the ground if I don't trim them, which breeds fungus and disease, so I like to trim them. I also cut off any that turn yellow or die off.
one of the most common disease that affects the lower leaves of tomatoes is early blight. Also nitrogen difficiency can cause the tomato to translocate nitrogen from the older leaves to the new growth. Nitrogen dificiency can occur where large amounts of unrotted organic matter is added to the soil. This causes the microbes that are decomposing the organic matter to consume the nitrogen faster than it is releasing it by the decomposition of the organic matter. Also as the tomato plant gets larger it blocks light and its normal for a few of the lower branches to die back or senesce. I usually do not trim mine back unless they are yellowing and are unsightly or i see disease.
One culture method that I've read about involves removing all leaves below the first set of blossoms. Since it keeps the foliage from touching the ground that's how I prune mine, as well as taking off all suckers. I grow mine in tripods and tie each one up to its bamboo pole with the green velcro strips.
I've grown my tomatoes in containers, in the ground, and in hanging topsy-turvy bags. They have fewer disease problems in the latter since they are not touching the ground or any soil. It takes quite awhile for the fungal diseases to find their way to them when they are hanging. But they eventually do here in the humid south. I try for the most disease-resistant varieties I can find and don't do overhead watering, but sometimes even those acquire a fungal problem. I do cut off yellow and spotted leaves as the season goes along.
Gowing tomatoes with a plastic mulch also helps reduce chances of disease. I have also used weed block landscape fabric. You can either fasten it down or bury the edges...and just poke holes for the transplants. Lets water penetrate in and prevents weeds from growing. You don't get any splash up and it also warms the soil.
I discovered red plastic sheeting this year. I will never grow tomatoes without it. Major weed preventer, great for warming the soil (badly needed this Spring), and I believe that it discourages fungus, the way mine are growing. I just use those metal garden staples, and make a basic square or round area with the tomato in the middle.
Oh, this Spring, I hauled out my saved plastic bird seed bags, and wrapped them around the base of my tomato cages, to help with warmth and also wind. Worked beautifully!
Again, I used those metal garden staples to kinda staple them together. I believe that this helped my tomatoes very much this Spring.
I am harvesting my heirloom tomatoes now - Brandywine Yellow, and German Pink. I was given a striped heirloom variety but it has not ripened yet. They tower over me, and I am 5'10" tall.