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Zucchini leaves "bleaching"?


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  #1  
Old 06-04-2016, 10:09 PM
jwyckoff jwyckoff is offline
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Default Zucchini leaves "bleaching"?

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My leaves on my zucchini plans started "bleaching". (see photos)

Any thoughts on the cause?




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  #2  
Old 06-04-2016, 11:27 PM
GpsFrontier GpsFrontier is offline
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Hello jwyckoff,

1. What nutrients (and/or additives) are you using?
2. How w much are you using?
3. What is the pH?
4. How often do you change your nutrient solution?
5. What is the total water volume?
6. How much water are the plants drinking daily?
7. How old are the plants?
8. Is the condition on all of the leaves including the new leaves, or just the older leaves?
9. What does the underneath side of the leaves look like?
10, Do you see any tiny insects around the plants, especially white fly's?
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Last edited by GpsFrontier; 06-04-2016 at 11:55 PM.
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  #3  
Old 06-05-2016, 08:14 PM
jwyckoff jwyckoff is offline
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GpsFrontier,

Thanks for your reply! answers below.

(FYI: zucchini's are sharing system with tomato plants)

Quote:

1. What nutrients (and/or additives) are you using?
MaxiGro.

Quote:

2. How w much are you using?
I was around probably under 1000 PPM, and read that zuchinnis liked to be at 1200+. Recently up'ed it to 1200+

Quote:
3. What is the pH?
6.0

Quote:
4. How often do you change your nutrient solution?
2X week.

Quote:

5. What is the total water volume?
5 gallons
Quote:
6. How much water are the plants drinking daily?
hard to tell, but probably a .5 to 1 gallon a day
Quote:

7. How old are the plants?
started them in March/April
Quote:

8. Is the condition on all of the leaves including the new leaves, or just the older leaves?
just the old ones. smaller young ones look fine.

Quote:

9. What does the underneath side of the leaves look like?
"normal".

Quote:
10, Do you see any tiny insects around the plants, especially white fly's?
I have not seen any.
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  #4  
Old 06-06-2016, 12:19 AM
GpsFrontier GpsFrontier is offline
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Hello jwyckoff,

First, unfortunately I was looking for how much of the nutrients you you were mixing per gallon of water, not what PPM your nutrient solution was. The PPM doesn't tell me how much your using. MaxiGro nutrients have a feed chart so I could look up how much they recommended for full strength nutrients, but I can't compare that to what your using when I don't know how much your actually using.

Second if you have a total of five gallons of nutrient solution feeding two large plants (zucchini's and tomatos), that is going to cause nutrient stress on the plants from the nutrient concentration fluctuating as the the plants drink the water, and the water level fluctuates. The more the water level fluctuates, the more stress on the plants. With a five gallon reservoir, and plants drinking 1 gallon of that daily, that's a 20% increase in nutrient concentration in one day, 40% in two days, 60% in three days etc.. Even replacing what the plants drink with plain water every day, that's still a 20% fluctuation in nutrient concentration daily.

I can see why you would be changing the nutrient solution twice a week with such a small water volume. But if you had a reservoir that held a larger water volume that was large enough to support the plants your growing, you wouldn't have to change it so often, nor would you have so much water volume/nutrient fluctuation. And thus less stress on the plants. The plants won't be getting smaller, their only going to get bigger. That means they will only continue to drink more and more water the larger they get. The water volume is very important consider. I wrote an article about it here: What size reservoir do I need

With that said, I'm not sure the spots are a result of nutrient stress. Or at least not that alone. Water volume and nutrient concentration fluctuations can always be a problem with inadequate water volumes. But the silver looking blotches may have some other causes as well, ranging from normal (on old leaves), to powdery mildew and/or insects. Here is a list of the most common causes of silver spots on Zucchini Silvery Spots on Zucchini Leaves

However if it were powdery mildew, you should see signs of fungal growth on the bottom of the leaves. If it were white flies you would see them flying around the plant. If it were spider mites you would see tiny hair like spider webs on the leaves and stems. I have never dealt with Leafhoppers or Thrips, but it's my understanding that Leafhoppers leave trails almost like snail trails as they burrow through the leaves. And Thrips are very tiny and hide in and around the folds of new growth, and affect the new tender plant growth.
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  #5  
Old 06-12-2016, 01:50 PM
jwyckoff jwyckoff is offline
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Default Thanks

Thanks for your detailed response! It has given me a few things to consider, first being the size of the reservoir.

I appreciate your time and expertise! Thanks again.

Jason

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