Is it too early to talk about this? I'm sure I could do a ton of research and find good answers but I am so impressed with everyone's knowledge here that I thought I would cut to the chase...
Last year I was hit with blight mid-season. I treated with some fungicide (supposedly organic) and managed to salvage some tomatoes.
Are there preventative measures to take at the beginning of the season to keep your plants as healthy and disease-free as possible rather than wait for something to attack?
I'm not sure there's a whole lot a person can do. One thing is not to grow your tomato plants in the same spot every year, to avoid soil borne diseases. Not everyone ascribes to that practice, although I do.
I remember a discussion we had a year or two ago, about the infectious agent that causes blight being able to overwinter on tomato cages and stakes, and whether it was important to disinfect them each spring. I use wood stakes and don't do anything to disinfect them.
You can make sure the pH of your soil is correct, so that the roots are able to absorb sufficient nutrients, and provide the plants with plenty of calcium, to prevent blossom-end rot.
Unfortunately, seeds and starts sometimes come pre-infected with various diseases, and there is really nothing you can do about that. There's no way to tell, until the plant develops symptoms.
Some diseases are spread by wind currents, and there isn't a lot you can do about that. One thing is to keep areas around your property free of weedy overgrowth, because some plant diseases overwinter in weeds. Cool, damp weather can allow certain fungal diseases to flourish, but there isn't much you can do to control the weather, either.
Overall, just keep a close eye on your plants for early signs of disease or pests, so you can treat them before too much harm is done. Sometimes, that means removing and destroying plants that show signs of a disease for which there is no treatment, to prevent its spread to your other plants.
As preventative measure, it may sound silly, but keeping the garden clean, and weed free as much as possible helps.
Thinning out/pruning tomato plants to a degree, so an adequate airflow is provided helps... Beneficial flowers and herbs to attract beneficial insect helps to control the population of other nasty bugs that spread diseases.
Keeping leafs from tomato plants off the ground and preventing splash-up on to the leafs helps to prevent some soil born diseases from affecting the plants.
As for blight, no real answer there, one of the most devastating diseases. After the rain, I try to spray plants with 10% fat free milk solution. If threads of blight are detected in the nearby areas, I may apply a copper based spray, but no more than maybe 2-3 times per season.
I'm sure others will chime in as well. Brows through [url=https://www.helpfulgardener.com/forum/viewforum.php?f=39]Organic Insect and Plant Disease Control[/url] section for more ideas too
The past 2 years the whole country has been hit with blight. I lost my 2009 tomato plants 2 weeks after picking enough tomatoes to can 100 pints and 10 quarts in mason jars that was late July. All my tomato plants were dead by the end of July.
Last year 2010 my tomato plants had blight again. I did some research and found if you mix 1 tablespoon of copper sulfate and 3 tablespoons of lime with 1 gallon water and spray your plants it will kill blight. When I started spraying my plants some had blight worse than others. I managed to save about half of my 30 plants but later in the summer I lost a couple more plants. I had ripe tomatoes until the last week of October.
I have a 2 gallon pump type sprayer I was putting 2 tablespoons of copper sulfate and 6 tablespoons of the white power lime called called hydrated lime in 2 gallons of water. I sprayed the whole plants top and under side of all the leaves every day. Some of the plants were too far gone to recover.
Everything I read says history shows blight stays in the soil 5 to 6 years. Planting in a different location in uninfected soil sometimes helps with the problem I tried that last year is did not work. This year I plan to start spraying my plants the first day they are planted. I am going to spray the soil around the plant too.
Put corn meal around the stems of your new plants to keep away cut worms. If the corm meal becomes hard from dew or rain put down more corn meal. When plants become larger and strong with tough stems about 3 to 4 weeks corn meal it no longer needed.
Howard Garrett talks about using row cover in one of his books to protect the plants from disease spread via the wind and insects. Here is a picture. Some row cover allows 90% light penetration. I bought some of this row cover, but did not install it yet. I am going to try wrapping a couple as a test to see how if I can tell a difference.
I have had really good luck fighting fungal infections using cornmeal. My pumpkins developed a fungus last fall so I soaked 1 cup of cornmeal in a gallon of water. Then I strained it and sprayed them. The fungus cleared up in about 3 days. I also had some mushroom compost that was growing mold so I mixed some cornmeal in with it and the mold died off. This year I am going to try it on my tomatoes if anything starts to develop.
