A southern California Pawpaw patch

So what seems to be doing best in California?

N-pHuric is not right for my situation,
so please stop pushing your products on me!

About once per year I recalibrate our fertigation dosages. The pH of our municipal water has been creeping up lately, now at 8 - a poor situation for our local soils. To adjust the municipal water pH, I add 1/4 ml of N-pHuric per gallon of water to achieve pH 6.3 for many of the plants, and 1/2 ml per gallon to produce pH 5.3 for the acid-loving varieties.


Here is Agrium’s published lab results for their N-pHuric product. I have added ml / gallon conversion to the scale along the bottom of the graph and the chart for Colorado river water dosages of the 15/49 product I use.

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In response to the chart:

  1. Thanks
  2. Anyone in a warm long season climate should consider “11-13”, which is a BEF53 seedling & sibling of Susquehanna & Potomac.
    It has large fruit size of superior quality & is higher yielding than Susquehanna.
    The reason it was not selected for release is because it sets 3 to 4 fruits per cluster, the fruits ripen up to 5 weeks apart & it is the latest ripening of all cultivars at KSU.
    Repeated fruit checking & squeezing was required to pick at the right time in Kentucky.
    However, conditions should be very different in hotter long season environments.
    I had considered hybridization of “11-13” with the early ripening cultivars NC-1 & selecting elongated seeds, because that is an anecdotal trait of elevated gibberellin hormone levels.
    Your thoughts?

A requirement for 400 chill hours may be less of an issue for Richard in Vista California, than it would be for someone else in a different environment.
@Richard is using Urea Sulfate for pH balancing, which slightly inhibits dormancy, by increasing thiol, needed for Zinc Finger Proteins which are used for temperature sensory & keeps them in a hyper active false positive spring status.
Many but not species often falsely assume that it’s spring during the fall, with many water soluble Sulfur products.
The high levels of Chloride due to being close to the Ocean can facilitate psuedo chill hours effect too.
Having lived in Imperial Beach & Encinitas, I can personally vouch for this effect on at least 70% of the species I grew.
Pawpaw could be different.
This article is about seed germination, however auxiliary nodes breaking dormancy fall under similar hormone & enzyme control.
Essentially the false spring stimulus from Thiol combined with artificial chill hours via Chloride resulting in blooming both at bud break with limited chill, plus also immediately after summer dormancy during rain or dense cloud cover.
Urea Sulfate is a good for many low chill environments for that reason, but use within 60 days of a hard freeze, is highly problematic!

N-pHuric is not Urea Sulfate. Although N-pHuric is in the CAS Urea Sulfate category, the similarity ends there. They have different stoichiometry and different states of matter at room temperature.

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Really, what is your evidence?
Would be nice for you to publicly admit when you are wrong on topic.
Would also be nice to hear “Thank You”, when someone gives you valuable information, which you didn’t know, about products you are using.
This is mine:
Urea Sulfate, aka Monocarbamide dihydrogensulfate, aka MonoUreaSulfuric, aka Uronium hydrogen sulphate


Pawpaws on parade!


Looking very good so far.
Let’s hope for continued success!
Urea Sulfate is an awesome choice for your environment.
I suggest in keeping all nutrients balenced & at about 15% above deficiency.
6.3 pH sounds optimal to me too.
You shouldn’t have any Sulfhydryl toxicity or Ammonium burn using this form of Sulfur.
If you get any Xanthomonas or other gram-negative bacterial infection on leaf perimeters it is due to Molybdenum deficiency.
N-pHuric or Urea Sulfate is going to increase the need or Molybdenum.
Hoping for your success.
Feel free to ask for assistance if you have any issues.
Lower pH might reduce the water solubility of Vista California’s 10ppm Molybdenum.
Optimal (Rhizobium bacteria & Mycorrhizae) Molybdenum storage is approximately 100ppm, required for optimal microbe health, function & division, as every time they divide resources are reduced by 50%.
Sulfate increase that division, plus FeMo-Cofactor enzyme production contains Molybdenum.
Increased FeMo-Cofactor means more Ammonium, which increases pH & helps keep Molybdenum water soluble.
If Manganese is too high in the soil, symbiotic microbes which create an external biofilm over the top of Nitrogen fixating bacteria will turn their Ammonium into Nitric acid reducing pH & precipitating Molybdenum.
So best to know (Iron, Manganese & Molybdenum) levels of soil or potting mix, plus monitor soil pH even though feeding perfectly balanced 6.3pH solutions.
Molybdenum is also needed in the leaves to (store & retrieve) Nitrogen in leaf perimeters.
The will be an increased demand in the leaf for Molybdenum, for Nitrogen (storage & retrieval) functions.
If pH gets too low, Urea might build up in leaf perimeters increasing susceptibility to Fungi & gram-negative bacteria.
While I have not used N-pHuric brand name of Urea Sulfate, nor the company’s blends, I have used Urea Sulfate before as a bulk dry 33% nitrogen product.
I’m very familiar with both advantages & disadvantages in multiple environments.
Feel free to ask questions if you run into problems.
I’m very certain that you won’t have issues in Vista,
however, realize that the product can cause problems in environments with too much Nickel or Copper.
And if soil is too saturated with Calcium Carbonate, osmotic pressure will go too high before soil pH is neutralized.
Best wishes for success!!!
I’m honestly here for assistance if you desire.

I read your modified thread post.
Modified mine as well.
Will research your product further.
Please read me modified response.
If you run into problems, feel free to PM contact me or thread tag me either one.

In the prior century I earned undergraduate and graduate degrees in math and physics and completed several minors, including chemistry and geology. In the period 2003 to 2016 I owned a licensed horticultural consulting business and among other things sold Grow More products nationwide. I also designed a few fertilizer products for them, the most successful being Fruit Fuel 16-8-24. There are others here on GrowingFruit with similar if not more advanced credentials. Please stop pestering me with matters you feel need correction and offers of assistance.

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Okay, I totally understand.
Good luck.

N-pHuric CH4N2O4S


Urea sulfate CH6N2O5S

Urea sulfate

Over the past three weeks the saplings have sent new branches under and around the shade cloth into the direct sun. So today I removed the cloth and we’ll see how well they fare.


The potted Pawpaws have been exposed to full sun for week now. So far just 2 of the 12 are showing brown spots and the remainder are thriving.


I grafted a Pawpaw cutting this spring onto a small sucker I dug up. It’s doing fine without shading.

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The sun in New York is probably not as intense as Southern California.

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Also my section of NY has many cloudy days. We had a long stretch of cool cloudy and rainy weather is late spring when vigorous growth was happening. When weather changed to sunny some plants had some leaf damage but I didn’t notice any on the Pawpaw.

I can understand soil type being a problem but how would heat and humidity be a problem? Ive lived in Florida my whole life and consider the heat and humidity to be much more intense in north central Florida, Georgia ,Alabama and South Carolina! South Florida has more mild winters but also more breezes off the ocean! For example it might be 96f 89% humidity in north inland Florida but on the same day Miami or Naples is usually 5 to 10 degrees cooler with 10% less humidity . This only applies to summer months. I thought chill hours would be a problem but you proved that wrong! It may be the very high lime content south Florida or tge hurricanes actually destroyed them!