We have no real rain in the forecast. Furthermore, our temperatures are running on May averages this April.

PNW has one of the unique climates. It is independent of the rest of USA. The differential between winter lows and summer highs is 60 degrees. That is not much an annual temperature swing.

But we have a looong spring, almost 4 months, starting from March ending in mid July.

Sey

IMO, 3 days of dark conditions will do more harm than three days of rain. For the little amount of rain that you guys get, I would embrace it, and remove the covering.

I would just use a fugicide once the rain clears. It is not the rain that does it, the fungus is most times. To each their own. Wishing you a Blessed and Abundant crop.

Nate

Lol... I just got an image of one of those SunSetter automatic roll up canopies.

Fungal issues happen more because of humidity (especially with cooler temps), which is a side effect of rainy periods, obviously, but not due only to the rain itself. Tarps and coverings can't dehumidify the air, and the lack of light under them might make the environment under there more hospitable to fungal organisms.

Perhaps one of the more experienced folks, especially someone familiar with the climate around you, can say for sure, but I suspect that, at best, you're not doing much with the tarps and, at worst, you're creating better conditions for fungus.

I could see an argument for growing tomatoes under cover that lets light through if you live somewhere where the warm season contains a rainy season of some kind--you know, constant rain for weeks--but doesn't the humidity usually dry out in short order after it rains where you are?

"It won't be sunny at all during the next three days of the forecast, so with or without The tarp I'm already screwed"

There is still a significant amount of light and energy that comes through the clouds. That's why some people can get sunburned even on a cloudy day.

"I was thinking this was a great idea because so many people are always like never water from above, don't get water on the leaves."

This is standard advice, yes, but it has to be balanced out with other things. First, your climate may not be average, therefore average advice may not apply fully to you. Second, if you keep water away from the leaves but use a method that creates a very dark environment while the air is full of moisture, you may do more harm than just letting the water hit the plants.

"But if everyone wants me to remove the tarp then I will. I hope my tomatoe plants make it."

It's your decision. You have to decide based on your research and your reasoning, not just follow the will of strangers on the Internet.

Fungal spores are usually borne on the wind or are in the soil, so I don't know how much it's worth it for someone in your climate to put up a tarp because of fear of rain. However, if you really feel the need to do so, it should probably not be a completely opaque tarp.

I agree that the now shaded plants are more susceptible to being affected by fungal spores then if left uncovered. Gorbelly explains it nicely.

Also, do not worry about watering plants while the sun is out... they will not get sunburned. I used to grow commercially in Houston Texas, and we irrigated every day overhead on thousands of varieties of plants no matter if the sun was out or not, and I never saw any indication of it burning plants.

Plants in general are tougher than most think...

If a few days of rain was a death sentence to tomato plants, I would never, ever get any tomatoes to grow where I am! Last spring seemed like straight rain until well into June. But afterwards, what great tomato weather.

We have entered into our rain-free season up here in PNW. Total average precipitation for April is 2.75".

On the temperatures department our April temps are besting May average. So it seems to be a real good tomato season .

Sey

I live in Southern California and we have a damp weekend forecast, too, but I think the tomatoes will be better off with the natural weather than under a cover. They will still get some sun in between the showers, and the problems of overhead watering are a little exaggerated. We'll be lucky if we get an inch total in the next few days.

With that mulch of hay, you really don't need to worry about disease. Most waterborne diseases aren't caused by the water, but the disease splashing up from the ground when it rains. With that mulch, little or no splashing up from the ground should happen.

Mulch may reduce disease, but will not stop it.

You're making growing tomatoes more difficult than it need be.

Orthene or Malithion are systemic and will stop the aphids for a long while. Of course, don't use systemics on edibles.

Allie Szot: Well, so far I don't see anything threatening yet, the tomatoes look happy

If it's fungal diseases you're worried about, they almost never show up overnight. In general they progress slowly, and they won't show symptoms right at the time of infection and take down your plants in a matter of hours. Sometimes, late blight can be dramatic and kill an entire plant in a matter of days, but 1) that's not usual and 2) this time of year and in your region and climate, late blight is almost certainly not a concern.

In addition, this is your first year growing in this location, correct? You shouldn't have too many fungal problems, and if you do, they were probably carried in on the plants you bought, in which case, there's not much you can do.

Also, insects can spread diseases between the plants they visit, so driving yourself crazy trying to keep your plants pristine is more energy than it's worth in that it's really impossible.

But I get it--these are your first tomato babies. That means you'll go overboard trying to do everything perfectly. Later children generally get more benign neglect, LOL.

In all cases, regular prophylactic spraying and mulching is probably the only really useful thing to do against fungal disease.

I have never heard of covering vegetables to keep rain off of them. That keeps light off of them as well as rain. What am I missing?? Fungus? It'll be much more humid under that tarp than over it. If I were a fungus, high humidity and low light is what I'd love.

I'd love 3 days of rain for my tomatoes and other veggies. Here (southern California), you hope you get a good soaking so that the ground can absorb lots of water and you can not irrigate for awhile. I'd imagine it would be the same, if not more so, in central California. IMHO, let the easy, free water work for you, you may not get the chance again for the rest of the season, and the plants really do appreciate it.

lol whats done is done at this point, no rain in the forecast for the next 10 days,

Dan, i left a great amount of space under the tarp for airflow. If you saw in my previous comments- I only covered them at night anyways where no light was even possible to get and uncovering them during the day. It was extremely windy and stuff was flying everywhere (thought the tarp was going to end up in my neighbors yard) so I'm sure they got some good airflow keeping the humidity not as warm and musty.

Humsi - water was able to penetrate all around the tomatoes plants except on the leaves themselves - i checked under the mulch and it was nice and evenly moist, I'm sure its not all bad that they didn't get all the water in the world, you never know it could encourage the roots to grow out towards where the more abundant amount of water is.

Well, OK, so you're keeping the rain off. Why? When plants get wet, they dry off. If, however, your soil doesn't drain well, and lots of rain gets it puddling and full of mud, then I guess that's a good reason to cover, but it's a better reason to fix your soil. Going back to your original post, I see the fear is "waterborne diseases". You understand that those diseases aren't falling from the sky with the rain. If you have airborne fungus that wants to start to grow in your soil, keeping rain off of it isn't going to stop it if the soil is moist anyway. You can read up on controlling fungal diseases. There are a lot of well established strategies, but I've never seen one that calls for keeping rainfall off the plants.

Allie Szot, I think people are just trying to save you some effort in favor of focusing stuff that might really do something, like spraying, etc. and trying to give you a sense of realistic risk and realistic ability to mitigate risk. Remember, even greenhouse operations have to spray to try to prevent fungal diseases. Covering outside plants with a tarp is not likely to have much of an effect.

daninthedirt: "There are a lot of well established strategies, but I've never seen one that calls for keeping rainfall off the plants."

I can see doing it if you live in a rainforest or something?

daninthedirt : "If, however, your soil doesn't drain well, and lots of rain gets it puddling and full of mud, then I guess that's a good reason to cover, but it's a better reason to fix your soil."

Would covering such a small area ultimately make that much of a difference, though? In my observation, a drainage problem means that water from a large area around the problem area is collecting there. Covering only the area where it collects or a small part of that area seems like it wouldn't do anything. My understanding is that temporary surface puddling for a few hours after a rain is, while not ideal, not the killer that flooding stress for days or more throughout the soil would be?

Allie Szot: "As for the ground being moist, you think mulching would somewhat help fungus grows since it does keep it somewhat shaded, warm and a moist environment after your water (funny how a lot of people advise other to mulch lol when your creating somewhat of a hospitable environment for disaster)!"

Everything in gardening (and in life, really) is about tradeoffs and context. Principles in gardening are not necessarily in opposition just because they are contradictory. Which one is right at what time often depends on the back and forth between all the factors that affect your garden. Seemingly contradictory principles can both be true depending.

Mulch could harbor bad microorganisms, sure. It can also provide a hiding place for pests that can chow down on your tomatoes. However, soil, if it has been well cared for, is biologically very active (lots of competing, complementary, etc. organisms keeping one another in check and keeping conditions healthy) and there is much less risk of something harmful growing out of control in it vs. the very likely risk of unnecessary stress on your plants if lack of mulch causes weeds, soil temperature fluctuations, and soil moisture fluctuations. In addition, the above-ground tomato plant is not the wonderland of microorganisms that the soil is, and destructive organisms can propagate out of control much more easily up there. That's why mulch on the ground as temperature/moisture/weed control and as barrier between organisms in the soil and the above-ground tomato plant is almost always a good practice.

Could this be the time that mulching is the bad thing to do? Sure. Freak events, unlikely events, happen in the world. All we can do is try for best practices and try to balance risks and rewards in our favor. And sometimes, our choices will have been the wrong thing to do in hindsight but still a sound decision at that time, with what was possible to know at the time.

It looks to me like the person being hard on you is yourself. Are you depending on your tomato crop to survive nutritionally or financially? If not, then maybe try to have fun and just enjoy the learning process. As someone who likes to geek out with her hobbies, I try to enjoy my failures as much as my successes because it all teaches me interesting stuff. I don't consider it a waste of money if it means that I come back next year with more wisdom. There are no guarantees. But the consensus of the experienced gardeners on here is a good guideline for now. And for those topics where everyone, no matter how experienced, has a different philosophy or for issues that are highly dependent on the individual characteristics of everyone's microclimate and garden conditions, you get to have the fun of experimenting to work that out yourself. For those topics where there is strong consensus from more experienced gardener, consider the consensus seriously.

Allie Szot: "For the anti fungal spray - does anyone have any suggestions"

You might find this thread helpful

It is not possible to keep tomato foliage 100% dry unless you grow them in high tunnel or greenhouse.

But you can do things so that the foliage gets dry quicker by PRUNING lower leaves and some within. So that air can pass thru and evaporate the water. Also, never water plants in the evening. Then the wet environment will be a good environment for bacterial growth. Instead water them in the morning. Most fungi / bacteria need a moist environment where the air is stagnant (not moving).

On the Mulch :

Mulch is more suitable for hot and dry/arid environment. then there are different kinds of Mulch and how thick you apply them. For example , I apply a thin layer of small pine bark nuggets. This is just to prevent splash. Otherwise our weather is not hot . Also, if you have pruned the lower leaves high enough and you have good air flow, enough sun .. you should not have fungi growth problem because of mulch.

There is no "one size fits all" way of doing things.

Sey

OP, Use fungal sprays as a preventative, not a curative. Once every 10 days or after a long rain event. A lot of people use Daconil, Mancozeb and copper on a rotational basis. Spray them in the early morning, so the sun does not burn the leaves.

Allie, when looking at advice for growing things, you also need to consider the climate that the advice is coming from. It's probably not a good idea to overhead water tomatoes - as in every time you water - in areas where it's naturally humid. I'm assuming (and I could be wrong) that where you live in central CA is not a naturally humid area, as I know where I live in southern CA is not naturally humid. Any moisture you get on your plants will normally dry in a very short time, except during rainy periods, which is acceptable. Where I am (and again, you are probably similar other than being hotter in the summer, and again, I could be wrong), fungal diseases aren't generally the biggest issue we should face. My biggest issues are insect problems and dry, hot wind later in the season. Mulching well (which, for us, is to keep moisture in the ground so you don't end up evaporating everything you just put into it, and to keep the soil temperature cooler than a preheated oven in the summer) and pruning even just the lowest foliage so that it's not dragging on the ground should pretty much leave you free of fungal problems. I don't even preventatively spray anything for fungus, it's just not normally an issue where I am.

No one is trying to pile on or confuse you, as someone else already said, everyone is just trying to save you some effort in areas where it won't help and direct your efforts in a more useful direction.

Location, location, location. We’ve heard that phrase used in business, but it also holds true for gardening.

My location is in the San Gabriel Valley, just east of Los Angeles and I’ve been a very successful tomato grower for over 30 years now.

Those cages are 6 foot tall. Pictures were taken in July.

Location not only applies on where to plant a certain plant, but also how you care for them. Certain practices that work very well in one part of the country, do not necessarily work in other parts of the country.

One of these is the “‘don’t let the leaves of your tomato plants get wet” rule. In most of the country, that’s true. Most of the fungal/bacterial diseases love hot, humid conditions.

However, where it’s hot and dry (like here in SoCal), we can ignore that rule. Any water that gets on the leaves will generally dry in a short time.

I once met Steve Goto, a commercial heirloom grower, at a tasting event. He urged us to not be afraid of getting the leaves wet. In fact, he encouraged us to water overhead. He said it cleans the leaves and washes off any airborne fungal spores before they can get started. Of course, that’s assuming you have a mulch down.

I regularly hose down my plants during the hot, dry months and I haven’t had any problems with disease. Been doing that for at least 10 years now (maybe more).

Naturally, I would not give that advice to someone in, say, Chicago (where I used to live). I know Chicago has hot, humid summers at times. I can remember hearing on the radio "It's 9 PM, 90 degrees and 90% humidity". Or to someone anywhere else

outside my experience with their weather.

Same with watering while I'm on my soapbox. We have to water a lot here. Other parts of the country don't have to water anywhere near as much as we do. If we don't water almost every day, our soil turns into one, big adobe block! Even with mulch.

We’ve just had those 3 days of rain and my plants look wonderful. Natural rainfall does something to plants that doesn’t seem to happen with water from the tap.

"We’ve just had those 3 days of rain and my plants look wonderful. Natural rainfall does something to plants that doesn’t seem to happen with water from the tap."

I have always thought this was true from my experience. Even well water coming from my irrigation seems to do more damage than water from the heavens.

Powdery Mildew in its very early stage can also be controlled by dousing it with a forceful spray of water.

Allie
Szot, did it rain for 3 days in a row ?

Personally,
I don’t trust very much the weather forecast.

Let me
give you an example:

Monday
May 12, 2014, the forecast said that the ENTIRE WEEK will rain !

I was
very skeptic looking at the radar map, but…

[ Those
green - rain - clouds were going to... Canada. ]

Now, out
of the 8 CONSECUTIVE days of raining - according to the weather forecast - only
ONE DAY it rained: Friday. One day out of eight, is not exactly a reliable
forecast, imho...

So what I do now - as I always did - is checking the radar map.

I see where
the are clouds are moving, and I know better what kind of weather will be.

I don't know where those weather people saw so much clouds to rain for 8 days in a row...

My weather forecast only mentions the percent of probability. That is smart way out : For example today it said there is 80% of rain. Haha. It didn't even rain 1/16" . But it sure did rain .LOL

Anyway, I am glad that our rain season coming to an end. Total average rainfall for April is about 2.5". July is our driest month.

Sey

I use Weather Underground to find out past temperatures, rainfall, etc. Through WU, you can pinpoint a 'personal weather station' in your specific area. One of the stations is just a few blocks from my home, so I'm confident that it gives true measurements for me.

The National Weather Service website has the information also, but it's harder to find. And the NWS version only gives data from a few places. None of which are close to my home.

We had

0.18 in on Apr 8

0.34 in on Apr 9

0.12 in on Apr 10

Not a lot of rain, but it did rain.

I was once told that the percentage that you get in the weather forecast isn't the probability of rain. It means that under similar weather conditions in the past, it rained X% of the time. I find that interesting, if true.