yes it is heart breaking to see such promising plants get the blight, one thing to try might be just grow some real short season ones,,rocket or sub arctic maxi, out here in blight country I never grow tomaotes without a clear plastic roof to lessen the odds of blight. why not plant one or two plants, remember, that is one of those things money just can't buy, true love and home grown tomatoes.

I was actually growing subarctic last season, and they got hit with blight before I got any ripe tomatoes out of them.

The fungus-like oomycete that causes Late Blight (p. infestans) requires living tissue to survive. So if it was Late Blight and assuming the gardens were cleaned out well before winter the odds of it recurring are no greater than usual. Since the filaments can also be air borne re-infection is always possible IF the weather conditions allow.

Although we can often go fro several years with no signs of LB, it is a risk we all take as gardeners and while the risk is probably higher in a community garden than in the average home garden it still boils down to if we want tomatoes we plant and then cross our fingers.

Just as with the other fungus-caused diseases the regular use of fungicides from the day of plant out can push the odds of success into our favor.

Dave

Thanks, Dave.

My issue is I'm not sure the gardens were cleaned out well enough, so that's part of my worry.

I was recommended copper fungicide to help prevent it, but I found out that there's no way drop copper levels in the soil. I'm also not sure if it would be allowed in my community garden since they're organic.

I have been trying the new late blight resistant varieties for a couple of years, and they are a great way to make sure you have a few sure things in your tomato patch. Mountain Magic (red cherry) doesn't seem to know what disease is, same with Plum Regal (paste). Haven't tried Defiant or Iron Lady, both slicers, but I plan to.

Maybe you should post on the Tomato Forum.

By all means post on the Tomato Forum. digdirt is one of the gurus there; he knows what he's talking about.

One way LB can survive from year to year is when potato growers don't clean out their beds thoroughly in the fall. If their plants had LB last year and they didn't harvest all the potatoes, and then don't clear them out when those old tubers sprout the next spring, the disease is apt to reappear in those potatoes ... and spread to tomatoes in the neighborhood.

Here's Cornell's Late Blight page:
http://www.longislandhort.cornell.edu/vegpath/photos/lateblight_tomato.htm

Be sure to look at "Late Blight FAQ" and "Late Blight: Correction of Misinformation" in the right-hand column.

Try Serenade.
After I started to use it every 2 weeks my tomatoes survive at lease a month longer then before. It is not toxic, can be used the day of harvest, but does have some smell...
If you decide to try it buy concentrate, not diluted spray and start spraying as soon as you transplant your plants, at least once in 2 weeks, better if once a week.

Here is a link that might be useful: serenade

Yep, I'm definitely worried about late blight coming back. We usually have a large plot just for potatoes, and they were all affected. I have no guarantee that all the potatoes were dug up, though I don't remember surprise potato plants ever popping up from previously left-in potatoes. I would have to talk to the guy who usually handles that plot.

That Serenade looks really good. I'll have to see if I can find it in Canada. I just wish it listed its ingredients, since I'm wary of using any copper fungicide.

I think I'm going to risk it. A huge reason why I love to garden is tomatoes, and I think as long as I'm careful with watering and very observant, I hope it will be OK.

This post was edited by moiraine on Thu, Feb 5, 15 at 10:24

May I ask why you are wary of using copper fungicides? Most any 'organic approved' fungicide will be copper based or at least contain some copper. The only other organic alternatives are to use Neem or one of the oil based mixes as used on fruit trees and are far less effective or use some sort of row covers so the airborne pathogens can't attach to the leaves in the first place.

Dave

I personally am not using copper unless I am desperate... I don't think copper is any safer than most non-organic fungicides, to prophylactically spray your crops, including to the environment (it is toxic to marine life and has effects on soil)... sometimes it seems to me the organic label is arbitrary. If you say, well, you need to consume tons of copper to have a serious negative effect, the same is true of most chemical-based fungicides (copper is also, by definition, a chemical.)

Sorry don't mean to drag the topic on a tangent :)

Why not try some resistant varieties.... it's not like they are bad.

Here is a link that might be useful: Copper Toxicity

Copper is a mineral, a natural component of all soil and needed by plants to survive. Anything used in excess can be toxic but the actual amount of copper contained in most all the fungicide sprays is quite low - less than 0.5% in most while the rest is a marginal amount of sulfates in some form and 99% inert ingredients. So exposure due to fungicide spraying is minimal unless one bathes in it.

I am not pushing the use of copper-based fungicides and their effectiveness, especially when compared to the performance of some of the synthetic brands, is very debatable. But given the amount of tomato fungus diseases, the use of some form of fungicide is often required IF one wants any tomato crop at all. In those situations many would advocate using copper as it is somewhat effective and the least toxic of what is available.

Of course we always have the option of using nothing at all and accepting the poor end results or giving up on growing tomatoes.

Dave

Serenade is not copper based - it is bacterial. Serenade Garden Disease Control contains a unique, patented strain (QST 713) of Bacillus subtilis(bacterias) which controls diseases such as Fire Blight, Botrytis, Sour Rot, Rust, Sclerotinia, Powdery Mildew, Bacterial Spot and White Mold. Apply Serenade Garden Disease Control to roses, vegetables, fruits, flowering plants, trees and shrubs at 2-4 oz/gal water.

I read that there's nothing you can do to reduce copper levels in the soil once you use copper fungicide, and I'm worried about too-high levels. I'll admit, it's more my ignorance keeping me from using it, since I don't know how much copper fungicide would need to be used to actually show a noticeable difference of copper levels in the soil. I'm part of a community garden, so I don't want to do anything to the plot that will prevent future gardeners from growing things.

If it would take an astronomical amount of copper to make enough of a difference that it would start harming the soil, then I certainly don't mind using it (like you said Dave, anything I can do to prevent disease). However, I just don't know what that amount would be.