I think I read somewhere not to use a foliar spray when the tree has open flowers on it. It is time for me to start my spring fertilizer program, and I used to spray with a micro nutrient spray each spring, but now I am wondering if this would harm developing buds, flowers, or young fruit.

Any suggestions?

It is really better to apply KNO3 about a month before bloom time as a foliar spray --it is suppose to support bloom formation.

Tolumnia, let me give you an "unclear" answer. I cannot say from experience about spraying trace elements per Se during bloom, as I normally spray Potassium Nitrate/trace mineral about 4-6 months prior to the expected bloom date. However, I will add that I do spray during bloom with Gibberellic Acid to set the fruit, and I have sprayed Sevin insecticide to control aphid outbreaks, with no damage of any kind to the blooms, even open blooms. I don't think I would recommend spraying horticulture oil during bloom, but personally, I would not be afraid of spraying trace minerals during bloom. However, it CERTAINLY all depends on the intensity of the sprayer you use. If your sprayer puts out a forceful spray, the booms might get damaged due to the pressure from the sprayer. I don't *THINK* that the trace minerals themselves would cause any problem. However, you should first spray just a portion of one your trees, and wait for a day or two to ascertain the results. - Millet

poor bees!

Bees in Colorado in the middle of winter????? It still snowing in Colorado. - Millet

Commercial growers in Florida, South Africa (where this was discovered) and Brazil often use a high-purity foliar spray of urea in January. That can dramatically increase bloom and fruit set in mid- to late-March for us. Always urea, never nitrate. I'm not sure why. I seem to recall reports of up to 20% increase in yield.

While root systems cannot absorb or use urea directly, leaves of citrus do. So there is no ammonification or nitrification involved.

Malcolm

Foliar spray of urea in january is really interesting.
Is there any detailed information on this subject, any web article?

Thanks,

I have been using a 2% solution of KNO3--what is the recommended concentration of urea?

I suspect spraying urea is a lot less expensive than spraying potassium nitrate. A secondary, benefit from spraying KNO3, as reported in the proceedings of the Florida State Horticultural Society, is that additionally, KNO3 applications produces a greater number of larger sized fruit. The study showed that trees receiving the KNO3 applications had over 30% more size 100 and larger fruit, and generally averaged $5.00 more per tree due to fruit size increase. - Millet

Spraying during bloom with anything is risky, and normally not done. KNO3 is sprayed 2 months prior to bloom. I do not know for sure, but spraying KNO3 at this time might not give you all the added benefits, of an earlier spray, because the bloom are already here. But like I say I am not sure. - Millet

Here are a couple links on the application of urea.

http://www.actahort.org/books/632/632_21.htm

http://www.fluidfertilizer.com/PastArt/pdf/34P8-11.pdf

Thanks for the information and the links