Dormant Sprays Now Can Bolster Citrus Crops Later

"TKO" Phosphite and Nitro-22 SRN

Do you ever watch those home repair, do-it-yourself shows?

Old-timers knew that giving a citrus tree a good whack with a broomstick often increased blooms and fruit. They didn't know the science behind it -- that wounds cause a plant to produce the hormone traumatin, which in turn increases flowering.

What does beating trees with broomsticks have to do with the dormant sprays that today's savvy citrus growers are planning for January? A lot, as turns out...

Dormant Sprays - A Better Approach

Citrus trees in fact need a fair amount of stress to produce high yields. That stress comes in part from winter chill hours - generally 600 to 800 chill hours below 68 degrees Fahrenheit are required to have a good crop. Citrus growers have traditionally augmented chill hour stress by "shock sprays" of phosphite and urea.

Phosphite is a water soluble form of phosphorus, and when sprayed on dormant plants it is quickly absorbed by twigs and branches. Once in a plant, it is extremely mobile, moving in both xylem and phloem. In addition to its nutrient properties, phosphite has noticeable and proven biostimulant properties such as increasing bud formation, increasing blossom set, increasing fruit set, and increasing yield and crop quality. A dormant spray of phosphite provides the "good stress" that citrus groves need. Growth Product's "TKO" Phosphite, a clear liquid solution, is especially easy to use and agronomically effective.

Stresses like drought, heat, disease, pH and salinity.

The urea spray can be more problematic. This year especially, with nearly all groves in the Florida citrus belt having experienced severe leaf drop in early November, and with the ubiquitous stress of greening disease, I worry that a urea spray might be too much of a stress and could damage trees beyond their ability to recover.

Because of this, my colleagues and I recommend a January dormant spray of 2 quarts "TKO" Phosphite with 1 to 2 gallons of Nitro-22 SRN, at a rate of 50 to 125 gallons per acre. Growth Product's Nitro-22 with 40% Slow Release Nitrogen, 4% sulfur, and neutral pH will provide all the benefits of a urea spray, without the possible negatives.

The combo spray of "TKO Phosphite" and Nitro-22 SRN will effectively increase bud induction and flowering, by providing just the right amount of stress and by providing all the additional beneficial properties of phosphite and slow-release nitrogen such as better rooting and improved disease resistance.

But Wait! There's More....

The other key aspect of January dormant sprays is disease control. That's never been more relevant than now, with the presence of Asian citrus psyllid and Huanglongbing (HLB/greening disease) in Florida.

Tank-mixing or otherwise combining the TKO Phosphite and Nitro-22 spray with an organophosphate or pyrethroid insecticide is a key part of suppressing psyllid and other insect levels all year long. Coordinated efforts among growers are the most effective method of control, and benefit all citrus professionals in the state.

The University of Florida's Citrus Health Management Areas's (CHMA's) website provides excellent on both coordination and timing of sprays. Timing varies slightly from year to year, and this year the spray window may be a little earlier due to some earlier than normal cooler temperatures we've had in Florida.

Give us a call

This is a lot to digest, but a dormant spray is essential to having good citrus production next year. We would be glad to talk with you and to help tailor a spray program that is best for your particular grove. Just give us a call at 800-648-7626 or email us at