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Utah

I'd like to see a little technical discussion on why our plants wilt, and if this is bad or not.
in my younger years i always thought my plants wilted because it got hot outside and they weren't watered enough. and that it was always a bad thing.
now i'm not so sure.
the last four days i have noticed that all of my plants have wilted during the day. friday and saturday were both sunny and warm temps in the high 70's. both days i watered mid day to see if it helped any. from what i could see it didn't. but yesterday and today it is only in the mid 50's outside- still sunny- so it's not hot but they still wilted. so full sun cause wilt ? is wilt bad ? also my western most plant gets shaded 2 hours before the others. and it perks right up when it gets in the shade.
time to break out the shade cloth for all my plants from 9am to 4pm or 6pm ?
thanks for your thoughts.
gordon

5/19/2003 5:35:06 PM

Liverpool , England

The leaves wilt when the roots are not big enough to absorb enough water to keep the leaves from drying out in the heat.

Alun

5/19/2003 7:21:11 PM

Montoursville, PA

I am at the three leaf stage, tender and just starting one week under cold frames. Up to 95 degrees with no wilt. Have tried to stay under 90 degrees. In any event there has been no wilt yet. Could this be individual plant differences?

5/19/2003 10:29:27 PM

Montoursville, PA

OOPS.....State of Utah could be extremely dry??? Better talk to other North Western Growers if at all possible.

5/19/2003 11:01:17 PM

Menomonie, WI ([email protected])

I know it has to do with transpiration, one of these biology majors will have to teach us more on this. The plants ability to take up water is less then the plants release of water. This causes the wilting, the plant also at this time goes into some kind of dormacy, shutting its pores to stop the loss of water. Try a wind break to decrease the flow of air around the plant, which will decrease the transpiration. The warmer the air the more water it will hold, so maybe misting cools the air, and increase the water in the air, reducing the evaporation. My 801.5 stelts clone wilts now and it is only 70 degrees, boy its not going to like 90 degrees. Shannon

5/19/2003 11:41:08 PM

Caceres, mid west of Spain

Definitely wilting is a stress sign, but it is a protection strategy as well. A wilty plant is not photosintezing at the best rate, and so, not producing so much as she could do with tender leaves, but is surviving.

Some plants do not wilt because they shut the stomes to avoid dehidratation. Hadn't those plants hard skins on the leaves, they would get burnt, and that occurs some times in cucurbitacea family.

The problem is concerned with the balance between root water absorbtion and leaves evaporation. Absorbtion depends on soil water content and pressure, root system volume and roots health and vigour. Evaporation depends on leaves skin and total surface of leaves for the plant side; the temp air, the sun intensity, the air humidity and wind speed for the environment side. The light is very important but for the increase of the temp on the surfaces where it lies.

We can help the plant with a good soil health program (trichoderma and endomiccorrhyza), good watering and soil aireation, working the soil in the best moments, and more phosphorus than nitrogen in the first month; Besides that, windbreaks, misting and shading (low percentage) in the sunniest moments.

Don

Some moments of the plant growth are worse than others, because a inbalance is produced (leaves grow faster than roots). After a while, less help is required because the tendency is to look for that balance.

5/20/2003 12:55:12 AM

Puyallup, WA

Last year, my plants wilted in late May because of too much nitrogen. I quit using the fertilizer and they bounced back
in 7-10 days.

5/20/2003 1:18:25 AM

porterville,california usa

Gordon; check out the pics in my diary. i have 2 plants that wilt at night as well as daytime, the Whittier and my 618 Derosiers. i took pics early in the morning when the temp was 65* and late in the afternoon with temp at 82*. i saw no change after wetting the leaves. i did a soil test and found very low P and very low K, both are needed for good root development. my prognosis is insufficient P and K caused the root systems to be underdeveloped. i`m piling on the P&K now to see if it`s too late for the plant to grow roots at a faster rate. i`m sure the plant has been stunted somewhat because of this. i`ll play with it for a while to see if it can catch up with the others.

5/20/2003 3:25:08 AM

Deer Park, WI

Transpiration is the method by which plants cool themselves. Pores on the underside of the leaf surface, called stomata, open up and release water molecules. The evaporative effects of water serve to cool the plant. Water gives the leaves the normal, unwilted structure you normally see. THis is called "turgidity". It kind of acts like air in a tire. WHen the water is lost through transpiration, the leaves lose turgidity, and wilt. To demonstrate the significance of transpiration, an acre of corn can transpire up to 4000 gallons of water a day. And a mature oak tree up to 100 gallons per day. THats a lot of water!

Plants can also wilt due to the disease, bacterial wilt. This phenomenon is quite similar to wilt caused by heat, except the plants do not recover when the temp goes down or moisture goes up. I'd rule this out before trying anything else. Discoloration of the leaves and stunted growth also accompany this disease.

5/20/2003 8:59:52 AM

Mineral Virginia

Joze,
So if I read your post right, shouldn't we devise a method for misting the bottom of the leaves rather than the top? Sounds like the pores open on the bottoms, release water, there by weakening the structure of the leaf, causing wilt.

5/20/2003 9:13:07 AM

Utah

thanks guys-
I appreciate all the input. it's not bacterial wilt.

The plants are quite young and small ... so they don't have big root systems. they are getting enough water and fertilizer. (10-32-10) i'm assuming the P and K are fine. it was generally overcast for about a week then full sun, which i'm sure shocked the plants some. It is VERY dry in Utah, which contributes to transpiration more that other wise would. and i'm at a fairly high elevation. which makes for thin air intense sunshine, hot days and cool nights. also my soil is clay based. so that's the summary.
I was wondering if it was worth it to try something... like a little shade structres. I think I'll do that.
the forcast calls for the mid 80's later this week... and I had frost this morning, 2nd day in a row !
thanks again for the input.
gordon

5/20/2003 9:22:35 AM

Utah

- so that's why it is so humid in the mid-west... all that corn transpiration-
:)

5/20/2003 9:43:27 AM

San Diego

I had this problem last year with a young seedling plant, it wilted even in 60 degree sunlight. The plant stopped growing after 3 weeks and I dug it up. The roots on it did a "root ball thing", very short and no good roots anywhere. I started over and the problem was solved with a better plant. Jim

5/20/2003 1:24:45 PM

Cornwall UK.(50N 5W)300ft.

I've noticed in the past with other types of plant that those in pots of peat based compost wilt quicker than those in pots of soil based when grown side by side.
Last year when I did some germination experiments I found that pumpkin seedlings in peat had a compact very fine fibrous root system whilst those grown in soil had fewer roots that were much thicker and longer(thats why I don't think dirt is dirt)
Gordon,I don't know what your starter mix is but if it doesn't contain soil maybe the roots are reluctant to leave the medium they were started in,just a theory I haven't tried to prove.
Mark.

5/20/2003 5:15:35 PM

Kuna, Id.

OK, here I go and please remember I was told this and am still a little lost about the subject. I was told that potash helps build bigger and stronger cells in a plant. And it also helps the plant take up water and with bigger cells holds more water thus wilts less if any. If anyone can explain this as being true or false would help me a lot. The soil guys had me add another 200 lbs of potash to the patch which puts me way over the high side. My soil test doesnt show potash unless it's one of those letters I dont understand.
Ken

5/21/2003 12:00:57 AM

Deer Park, WI

Funnydad- I dont see any real benefit to misting on the bottom, plants will not take in any appreciable amount of water thru the stomata, its an out door only. As long as the area around the leaf surface is cool, the mist is doing its job. Leaves are quite thin, which means the temperature is probably the same on top as bottom.

Ken- Potash is a form of Potassium, which is designated as a "K" on your soil test report. The "P" stands for phosphorous.

g1t- I read somewhere that transpiration is responsible for something like 10% of the moisture in the atmoshphere...so you might not be too far off base with that comment there...:)

5/21/2003 8:55:33 AM

Phoenix Az

Here in az its 105 deg!!! Mine are willting a bit.

5/21/2003 2:58:01 PM

Kuna, Id.

Thanks Joe,So if my Potassium is already 279 ppm I wonder why they wanted me to add another 200 lbs to the patch. By the way the patch is around 10,000 sq, or is 279 low to some of you?
Ken

5/22/2003 10:54:44 AM