source: Joe Gardener
Have you heard of the disease triangle? It represents the three elements which must be in place before a disease becomes active: a host, a pathogen and the right conditions. Remove any one of those three elements, and disease won’t affect the plants in your garden. Period. Sounds easy, right. Well, it’s not, but many of the preventative measures are.
The first and best thing you can do is to keep as many diseases out of your garden as possible, and that starts with plant selection.
Never buy a seedling that shows any sign of disease – like withering, dark or yellowing spots, or discolored foliage. The lowest set of leaves may have naturally reached the end of their lifecycle and turned pale or yellow, but other yellowing is a red flag.
Look for disease-resistant tomato varieties. Resistance doesn’t mean bullet-proof. It just means those plants will put up a stronger fight against that type of pathogen.
While some diseases are transmitted through the seed; they are more commonly transmitted through the air, from the soil on water droplets, or by insects.
Bacterial diseases must penetrate the surface of the plant through a cut, a wound or some natural opening. Pathogens are tiny, so they only require a very small opening. In fact, even a broken tomato hair creates an opportunity.
Does that seem discouraging? Take heart. Bacterial diseases are not the most common enemy.
Viral diseases are also less common, but those are the real killers. They attack the entire plant system. You can’t remove a stem or two affected by viral disease. Once it’s in the plant, that plant has to go. More on that in a minute.
Fungal diseases are the most common. Fortunately, they are also the easiest to treat. These pathogens affect the plant from the its surface, and they grow when the foliage is moist – from rain, irrigation or humidity.
Whenever possible, keep water off the foliage and direct it efficiently into the soil for ready access by the plant roots.
Are you a smoker? Tobacco products are often tainted with Tobacco Mosaic Virus. All it takes is for you or a tobacco-using visitor to make contact with a tomato leaf after handling a tobacco product, and you might soon have to remove a virally-infected plant. So if you smoke or chew, be sure to wash your hands thoroughly or wear gloves before handling tomato foliage.
Proper support is another worthwhile disease prevention step. When the plant is kept up off the ground, soil-borne disease has much less opportunity to make contact with foliage. Good air circulation also reduces infection from fungal disease. Although the fungi may blow onto foliage, the continual movement of air can prevent it from growing.
A well-supported plant will also be easier to monitor for signs of disease, so you can get a jump on removal when necessary. That’s a very good thing, because in spite of all these proactive steps, disease will take hold.
check out this video from New Leaf Community Garden for tips on pruning your tomatoes for healthy disease free tomatoes: https://fb.watch/v/-PDypkCe/