Covering tomatoes against blight?

[Vanisle_BC]

I don't see many people on the forum growing tomatoes under cover? I lost a whole season's crop many years ago, to what I assumed to be late blight. Then I heard a garden guru say on radio that for blight to get established, foliage must stay wet for 24 hours. Ever since, I have had a roof (not enclosure) over my tomato beds. Do others find this unnecessary, perhaps because of drier climate - or is this a piece of dubious garden lore?

[applestar]

Was the advice specifically about late blight? Fortunately, I haven’t experienced late blight except that one year when it had been spread all over the country due to infected plants sold by big box stores.

I had not heard of this particular concept to protect tomatoes from overhead rainfall, etc. with physical roof. (I can’t imagine building such a thing though — what about the 6 ft plus cherry and indeterminate varieties? What about the gusty winds from hurricane and tropical storm remnants?)


Early blight is common and I more-or-less accept it as something that takes over the tomatoes along with septoria. It’s just a question of how long they can withstand it and grow ahead of it. It’s more important that there is sufficient air movement/airflow as preventive.

Overhead watering is commonly discouraged for fungal disease susceptible crop like tomatoes and cucurbits. But I admit to ignoring that since it’s easiest for me to water with overhead sprinklers in conjunction with soakerhoses laid out for specific beds in order to reach all the plants that needs it.

Here, the excessive humidity in combination with day/night temperature fluctuations results in heavy morning dew anyway, so not keeping the foliage wet/keeping the foliage dry is near impossible. That plus yearly drought/lack of ANY rainfall during at least part of the summer months means spot watering is insufficient and artificial thorough overhead watering and showering to wash OFF the fungal spores is also what is needed, as well as to moisten the parched ground of the entire area, not just the garden beds.

[rainbowgardener]

Does your roof not block the sun and rain from your tomato plants?

If you are going to do all that, you might as well grow them in a greenhouse.

[Vanisle_BC]

Does your roof not block the sun and rain from your tomato plants?
If you are going to do all that, you might as well grow them in a greenhouse.

Well, no .

The roof is poly on a wood frame abt 6ft high (ridged so the height varies); plants trained up strings to the roof framing, more or less like Steve Solomon's system in 'Growing Vegetables West of the Cascades'. Greenhouse is flimsy 8x8 with sloped walls & center walkway; not much room left for plants like tomatoes so I wouldn't consider it; strictly for seedlings or potted things. Tomato bed is 20 x 3.5, accessed from alongside(s). Watering has been 'manually' by hose at ground level and more recently automatic drip-tape. We don't get much wind and it's never been a problem. Neither is lack of light. I've had to deal with sunscald at times.

The 'blight' incident may have been something else; it was long ago with the details forgotten. The advice - also long ago - was specific to late blight and was not about keeping the plants dry but about not letting them be wet for 24 hours at a time. So I followed it and yes the roof keeps the rain off them. That's the point of having it. Either it's kept blight etc. at bay or I've just been lucky all these years - obviously I don't know which. Just wondered if others have relevant information.

[applestar]

So in your area — “Pacific Northwest” region — lots of rain, right? So maybe it does make sense?

Corollary to what I was describing — drought and relatively tiny garden bed, which would be sucked dry of moisture by the surrounding thirsty soil if it was the only spot irrigated — is that the rain doesn’t have to fall ON the plants or the bed, if the entire rest of the grounds is wet from rain.

[Vanisle_BC]

Dunno, Applestar; In this valley we do get waterlogged winter soil, but often have hot, dry, 'baking' summers; by which I mean knocking on 100F. My beds are raised 12" and more; in early spring cold, damp, compacted soil is more of an issue than actual saturation. In summer, before I installed the drip tape, I've traditionally done serious soil-level soaking with an open-ended hose; even poking it right down into the ground around the tomato plants. That has worked well for me.

I guess the more I experience & the more I read, the more I see that one size doesn't fit all. At times I feel that if something works for us maybe we shouldn't bother analyzing it too much. If it doesn't work that's another story.

I'll be reluctant to drop the habit of giving rain protection to my tomats unless I become convinced that it's useless or has negative consequences. I already use that superstructure to train the plants. Making a roof out of it's not much extra trouble.

By the way, for many years all my tomatoes were grown in the same bed, with no problems other than that one isolated case of ?blight. After I roofed it there was no recurrence. Maybe simple coincidence; maybe not?

This year I'm growing, 2 of each:
Ailsa Craig
Black Vernissage
Camp Joy (Chadwick's Cherry)
Cherokee Purple
Feuerwerke *
Jaune Flamme
Latah
Longkeeper
"Mystery Keeper" - claimed to last even longer
Principe Borghese
Sweetie

* Only Feuerwerke (a single plant) seems to be less than robust.

[rainbowgardener]

Yes, indeed. I always say all gardening is local. Sometimes people write in here with some garden question, but give us no clue even what continent they are on. How are we supposed to be able to answer. And clearly what works in hot, rainy TN doesn't work in hot, dry TX and so on.

[Gary350]

One thing I know about blight it comes in cycles, so does the weather. Blight is known to come for 3 to 5 years then be gone for 5 or 6 years, weather pattern does the same thing. Tennessee weather is very high humidity even in summer, non stop rain 3 months in fall, some summers very little rain for 3 months then fall rain or maybe too much summer rain.

I have learned if my tomatoes plants are in full sun and planted 3 ft apart to get good air flow and plenty of sun on the whole plant I have less chance of getting blight. Blight seems to start low near the soil then work its way up the plant. I have tried many things to stop blight but it seems once blights gets started it can not be stopped. If my tomatoes get blight it is usually about July 15 and plants are pretty much dead 3 to 4 weeks later.

My goal every year is to put 100 pints and 20 quarts Mason Jars of tomatoes in the pantry quick as possible only way to do that is get 200 lbs of ripe tomatoes in 2 weeks before blight kills the plants. After that all we need is 2 nice ripe tomatoes for dinner every evening.

I have experimented with lots of ideas, planting tomatoes on east side of a large tree so they get early morning sun then shade after lunch until dark keeps plants alive in 100 degree weather but that increases the chances of blight and bugs.

Plants in full sun all day makes sun burn tomatoes, plants suffer very bad in the heat, tomato crop stops and sometimes plants manage to live until cool weather then produce a few more tomatoes.

What really works best for me it to plant 6 different varieties of tomatoes, no matter what weather does some plants do better than others. Also plant tomatoes in several places around the garden, some in full sun all day, some with morning sun then shade until dark, some with lots of shade no matter what weather does some plants do better than others.

Cherry tomatoes are hot weather tomatoes they do much better in full sun and 100 degrees all day than larger tomatoes.

I have noticed once plants reach a certain age they get blight while younger plants have not get blight yet. I save seeds to plant the following year, I always have new plants growing in random places all over the garden anywhere there is a place to plant something. If I have at least 1 new plant producing tomatoes every 2 weeks and blight kills 1 plant every 2 weeks I still have a few tomatoes all summer for the kitchen table.

Another thing that seems to help blight is, do not put nitrogen on tomatoes unless soil is very low in nitrogen, fertilize with P & K plus calcium. K is the best it makes strong plants and lots of fruit. I fertilize mostly with wood ash every 2 weeks all summer from wood that I burn it is loaded with K, lots of minerals and lime. Wood ash on tomato plants all summer works wonders for my tomato plants.

We like to have a few tomatoes on the dinner table for Christmas it is nice to have several plants loaded with 50 green tomatoes when cold weather kills the plants. We keep green tomatoes in the kitchen and eat them as they get ripe.