Early blight is caused by the fungus, Alternaria solani, which survives in soil, but its spores are also airborne so mulch is only a limited type of control. Late blight is a potentially serious disease of potato and tomato, caused by the fungus Phytophthora infestans and has the same modes of travel - wind, water, soil. The only true prevention is weekly using anti-fungal sprays on the plants from the day of planting out. Daconil is the most commonly recommended one. But use of chemicals does not appeal to many. Many claim that using compost tea as a foliar feed/spray can also help control both EB and LB. It works for me but it is a control only, not a preventative.

There are no known truly resistant varieties - wouldn't the commercial tomato industry love it if there were - so that they wouldn't lose millions annually to the problem!

The issue comes up for discussion frequently on the Tomato forum and there are a few blight tolerant varieties suggested now and then. Legend is one of them. Sadly, the hybrids that have been bred for tolerance and marketability aren't taste ravers.

Any tomato can be used for canning. You are not limited to plum/paste tomatoes in any way. Indeed many much prefer using the larger rounds, beefsteaks, and oxhearts etc. for cooking and canning because of the greatly improved flavor of the sauce made. Plus they have greater tolerance to many of the other tomato problems that plum and paste types are prone to such as BER and blossom drop. Again, this is often up for discussion on the Tomato forum.

For me, given the chronic problems of EB and LB, it boils down to planting extra plants of multiple types of varieties to insure that we will have enough tomatoes - of all types - to meet our canning needs. But if paste is what you want to limit yourself to then San Marzano and San Marzano Redorta and Opalka are some of the best. Seeds for them are readily available fro the main suppliers: tomatogrowers.com, SSE, tomatofest.com, etc.

Dave

greenhouser, Are you planting your tomatoes in the same place every year?

No, we rotate them from one place to another in the gardens and from one end of the gardens to the other. They seldom are planted in the same place more often than 3 or even 4 years. Next spring, now that I'm canning again, we're increasing the size of two of the gardens.

Dave: I once tried compost tea and even putting it through a fine kitchen strainer it wouldn't go through the nozzle of my sprayer. It kept clogging. I'll pick up some Dacinol next trip to town. I plan to grow a much larger number of types of toms (and peppers) next year also. Have you had any problems with whitefly or other insect pests on your toms and other crops?

If you make your compost tea using a tea bag you don't have to worry about straining it. There are many different things that folks use for the tea bags - old pillow case, tube socks, nylon stockings, multiple layers of cheese cloth, etc.

Always dilute it to the color of weak iced tea before applying and never spray it in the heat of the day.

Daconil is just one of the brand names available. Ortho Garden Disease Control is another. But to work it must be applied weekly exactly per label instructions. It coats the leaves so that the fungus spores can't take hold on the leaves. It will not "cure", it will only prevent and/or slow progression of blights is already infected.

Dave

I learned a valuable lesson about disease control in tomatoes this year. I grew about 200 plants total, give or take a few.

I planted half of them in my regular garden space, which has been in continuous cultivation for about 50 years.

I planted the other half in a brand new bed I made just this year by simply mowing the grass extremely short, sprinkling the lawn with fertilizer, and covering with black plastic.

This past spring and early summer were exceptionally wet and cool to cold, with over 9 inches of rain between Memorial Day and the 4th of July, so conditions were perfect for diseases to develop.

The plants in the original garden were (and still are) just covered with various leaf blight and spot type diseases, despite my spraying them every three or four days with various fungicides, including Daconil, Mancozeb, Sulfur, and something called "Organicide." It rained so much the fungicides were constantly being washed off, so weren't helping all that much.

The plants in the new ground developed far, far less disease, and looked/still look much cleaner and prettier. They received the same fungicide treatments as the other lot of tomatoes.

I can't attribute this difference to variety, either, as both spaces contain many of the same varieties (I'm growing about 25 kinds this year).

So, the lesson I'm taking away from this is to rotate as much as possible onto clean ground in the future. I have a couple of acres and plenty of lawn which can die to make new beds as needed. I realize this may not be as practical for people without the space to do this, but if you can do this, it seems to make a big difference.

Dennis
SE Michigan

Dennis: Thanks Dennis. I have over an acre but most is not suitable for gardening due to limestone rock right near the surface or large trees/shade/roots. I have no more than 2000 sq. ft suitable for veggies. Oddly enough only the Roma's suffer from blight. By the time I see it on the other toms the season is over and frost due anytime. All those veggies in the tom family are burned and not composted. So it's not disease but insect pests doing all the damage this year. It started in one garden that was used one time, then laid fallow for 2 years. Reclaimed forest land. It started with whitefly, then spider mites moved in and wiped out every squash, water melon, tomato and pepper plant. I tried organic pesticides and they did nothing! I tried what our Ag Agent suggested and these 2 pests are totally immune to everything, from Malathion to Ortho-MAX. When we took leaves there for examination he said it was the worst infestation he had ever seen... and he's not a young man. Now they've spread to the east garden. It's like a nightmare that wont end. Our collards are being destroyed by WF and spider mites are killing the chard and spreading to the other veggies. So in my case the problem started in the new garden, then spread to the old garden. The south garden is also going down to these pests. They spread a virus to the string beans, turning them yellow, then brown... then they dry up and die. The south garden was a flower bed at one time and reclaimed for veggies this year. Oh, and the WF also carry silverleaf virus for squash. A search on the net shows WF carry and spread as many as 60 plant diseases. They're Typhoid Marys of the garden world.