Brown Thumbs
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Will pine straw cause blight?

I'm in Mississippi and blight on tomato and pepper plants has occasionally occurred with my gardens in the past. Started a new one this year, tomatoes are 18" now. I added pine straw around each one but now worry blight, or any fungus, could start underneath it since stays moist longer. I pulled the straw about 5" away from base of plants to help, but did notice small white patches on soil surface. Watering isn't an issue so should I risk it or does pine straw harbor fungus, bugs, etc?
Brown Thumbs

Zone 8

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applestar
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Location: Zone 6, NJ (3/M)4/E ~ 10/M

Re: Will pine straw cause blight?

The way I look at it, the fungus growing in or on the pine straw is different kind of fungus from the ones that cause tomato/pepper diseases. This means the fungus (and fungal spores they produce) in the pine straw will compete for landing and living space with pest fungal spores. Sometimes fungus will actually attack each other.

So at most, they are neutral or just extra bodies, to occupy the space, but the fungus growing under the mulch could also be the symbiotic beneficial kind. I couldn't say for sure.

The mulch is supposed to keep the bad fungal spores in the soil from splashing up. So I don't think you want to pull them away so far from the stems -- an inch or two should suffice to keep the excess moisture from accumulating on the stems. In presence of excess humidity, tomatoes will form root nodules on the stem and take in moisture from the air. I think only reason to not mulch as much is if you are getting flooded with rain. Then you may want to go with thinner mulch (1-2 inches?) to enable the soil to dry out faster. But all the rain probably encourages weeds to grow too so you will have to choose.

Bugs, fungus, bacteria -- all that biological activity under the mulch helps to break down nutrients into plant-available form. Healthier plants are able to resist diseases better. Haha -- you got me thinking and more I think, more I would tend to believe the mulch will not cause blight.
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Lindsaylew82
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Re: Will pine straw cause blight?

Yes, what she said!

mulch DOES act as a barrier between the bacteria and fungus in the soil. I put pine straw right up to the stems of my plants in years past. No space needed!

Pine straw in particular will not encourage blight. Maybe if it contained blighted tomatoes before, and your tomatoes are laying on the same mulch. It acts as a splash barrier, preventing contaminated soil from splashing up onto leaves.

Here, there's really nothing I can do prevent tomato disease.... I try and try, but eventually blight, septoria, and other crap WILL take some of my plants down. Usually laaaaaate summer. Most of the time though, I get a recovery period before frost where I'll get another small crop of ripe tomatoes, and at frost, LOTS of green tomatoes. (Relish!!!!)
Lindsay
Upstate, SC
USDA Zone 7b/ Sunset Zone 31

Brown Thumbs
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Location: South US

Re: Will pine straw cause blight?

Thanks for the info. What I'm calling "blight" is when the plants all of a sudden start wilting bad and if I pulled them up, they would have some spider web looking stuff on the roots. It seemed to occur once temperatures got hot in the summer and when the soul was moist. Tomatoes and peppers were the only things it happened to. Hope to avoid problems this year. I've never tried pine straw until now...it goes around our flowers though with no harmful effects. Thanks again.
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imafan26
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Re: Will pine straw cause blight?

Blights are common problems on tomatoes.
Healthy plants are the best defense

Use a drip watering system or water at the base of the plants and avoid wetting the leaves as much as possible
Wet humid conditions encourage fungal issues. If you cannot control the environment, use preventive anti fungal sprays when humid conditions are present

Space the plants well, crowding limits air circulation and encourages fungal issues

Mulch is a good thing, so is removing the lower leaves.

If you have had problems with fungal disease before, good sanitation is a requirement. Pull diseased plants so they don't spread the spores, burn the debris and make sure your hands, clothes and tools are sanitized so you don't move the problem around.

If you have a moderate to severe pest or disease problem, rotate your crops and do not plant members of the same family in that area for 3 years.

You can try solarizing in summer to try to kill soil pathogens in beds you have had problems with. Follow up with a crop that is not susceptible.
https://www.ipm.ucdavis.edu/PMG/PESTNOTES/pn74145.html
Happy gardening in Hawaii. Gardens are where people grow.

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Lindsaylew82
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Re: Will pine straw cause blight?

Would likely need a pic of said roots to say with any moderation a certainty, buuuuuuut....

There are beneficial fungi in the soil that interact with the plants. Spiderwebby stuff around the roots? Like waaaay down? I'd say that's prolly hair roots or beneficial fungus. Prolly still not from the mulch. Maybe it's nematodes.... If not, fusarium wilt can take a plant out VERY quickly. Lots of things can cause wilting, but I wouldn't attribute any of them to mulch.
Lindsay
Upstate, SC
USDA Zone 7b/ Sunset Zone 31

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