Apple researchers find Sysstem-CAL™ is compatible with plant growth regulators

Apple researchers find Sysstem-CAL™ is compatible with plant growth regulators

University and private independent research orchard trials are showing what many growers are discovering as well – that Agro-K Corporation’s calcium micronutrient Sysstem-CAL™ can be tank mixed with early-season applications of Apogee®, Promalin®, Sevin® XLR Plus and other plant growth regulators on apples without antagonism. In many trials, Sysstem-CAL enhanced PGR activity.

Peak demand for calcium in apple fruit is early in the growing season. Calcium produces fruit with stronger cell walls to better tolerate pathogens. Calcium helps reduce bitter pit and improves pack-out, storage and shelf life. Sysstem-CAL foliar calcium uses a unique, patent-pending Agro-K technology linking calcium to a highly systemic phosphite formulation for rapid absorption and translocation into the fruit where calcium is most needed.

Apogee Tank Mix Partner

Other calcium formulations can reduce the growth control of Apogee, but Sysstem-CAL does not hamper performance. In 2009 replicated field research with Cortland/M.2 apple trees, Dr. Duane Greene, University of Massachusetts, found that Apogee plus a 64-ounce rate of Sysstem-CAL reduced terminal growth the same as Apogee alone, but also increased fruit weight and reduced bitter pit.

“The weight of the fruit from trees treated with Apogee plus Sysstem-CAL were significantly larger than control fruit,” noted Dr. Greene. Dr. Greene said the increase in the weight of the Apogee plus Sysstem-Ready fruit was “worthy of note.”

“Fruit on trees that received the higher rate of calcium sprays displayed less bitter pit. But the key finding is that 64 oz/100 gallons of Sysstem-CAL in an Apogee tank mix does not reduce efficacy of the Apogee,” Dr. Greene said.

Trees in the trial block at the U. Mass. Horticulture Research Center in Belchertown were quite vigorous, with terminal growth of 50.5 cm. The application of Apogee (3 oz/100 gal) successfully reduced the final terminal growth by 50 percent to an average length of 25.2 cm. When Sysstem-CAL (64 oz/100 gal) was included in the spray with Apogee there was no reduction in the efficacy of the Apogee, and the reduction was to 24.2 cm.

Similar research at The Pennsylvania State University Fruit Research and Extension Center by Dr. James R. Schupp, Associate Professor of Pomology, also found that Apogee plus Sysstem-CAL produced equal or better shoot reduction than Apogee alone.

Similar results with Apogee and Sysstem-CAL have been seen in independent research trials at Reality Research in New York State, and among cooperators in Washington State.

W.H. “Butch” Palmer, who managed the trials in Wayne County, New York said he has been “pleasantly surprised” by the findings from two years of using Sysstem-CAL with Apogee applications to four apple varieties.

“Traditionally we do not apply calcium until summer, but now we are learning the importance of providing calcium to apple crops early in the season, at the same timing when we use Apogee,” said Palmer. “The most widely used and least expensive source has been calcium chloride. But if you mix that with Apogee, you lose some of the effectiveness of Apogee.

“With Sysstem-CAL we do not get that antagonism, and in one variety, Red Delicious, it clearly improved the performance of Apogee. And we used low 4 oz/acre rates of Apogee because a higher rate might have overcome any negative effect of the calcium. Growers are changing how they use Apogee, with lower rates in more split applications. So System-Cal is going to work perfectly for growers.

“Plus, the Sysstem-CAL formulation is easier to work with. Calcium chloride is a dry, bulky material that plugs nozzles and sometimes causes phytotoxicity. There is none of that with Sysstem-CAL. Sysstem-CAL stood out even among the newer calcium formulations, and there are a lot of them out there.”

While Sysstem-CAL can be used early in the season at timings where calcium chloride cannot, Palmer also noted that Sysstem-CAL would be a good option to replace calcium chloride in cover sprays.

Fire Blight and Apogee

Plant physiology studies show that disease tolerance is a key aspect of delivering calcium to the tree when it is most needed. By strengthening the integrity of cell walls in branches as well as the fruit, calcium helps apple trees to better tolerate disease. Because Sysstem-CAL does not interfere with the efficacy of Apogee, the PGR is able to continue its role in helping growers manage fire blight in high infection areas such as the Northeast, Michigan, and elsewhere.

Apogee inhibits gibberellin biosynthesis, which results in an early cessation of terminal growth. As Michigan State University Extension noted in a bulletin updated in 2009, “Shoots with inhibited growth are less susceptible to fire blight; therefore, the potential for the build up of fire blight during the summer is reduced significantly. Apogee only decreases host susceptibility; it does not affect the pathogen directly. Apogee is not a substitute for streptomycin during bloom for blossom blight control.”

Growers should consult their state’s Extension pomologists for Apogee rates and timings if used for fire blight.

Sysstem-CAL Works Well with Promalin

In working with a block of mature Early Red One Delicious/Mark 63 trees in 2009, Dr. Greene also found better results, including an increase in fruit weight, when Sysstem-CAL was used with Promalin. He said there were indications that Promalin plus Sysstem-CAL produces greater L/D ratio changes, possibly through an effect at the molecular level that helps the Promalin effect fruit shape.

“Promalin treatments increased the L/D ratio, and the trees that received Promalin plus Sysstem-CAL were generally slightly more desirable fruit type (greater L/D ratio),” Dr. Greene reported. “The only treatment that increased the L/D ratio more than Promalin alone contained 2 pints per acre of Promalin plus 2 quarts of Sysstem-CAL. There appeared to be no phytotoxicity following application.”

Dr. Greene tested various combinations of Promalin at either 1 pt/acre or 2 pt/acre alone or with 2 qt/acre or 4 qt/acre of Sysstem-CAL. The applications were made according to Promalin label directions when most of the king flowers were open on May 15.

“There were both favorable and unfavorable temperatures following application, which may explain why the L/D response to Promalin was not great,” said Dr. Greene. “While these data do not conclusively show that Sysstem-CAL does enhance the response of Delicious apples to Promalin, the numbers are suggestive of this.

Fruit Thinning PGRs also compatible with Sysstem-CAL

Orchard trials by Reality Research found that Sysstem-CAL improved thinning programs using Sevin XLR Plus, MaxCel®, and Fruitone® N. Sysstem-CAL had no phytotoxicity or handling issues and “definitely improved fruit thinning” of Gala, Fuji and Red Delicious varieties, said W.H. “Butch” Palmer, who managed the trials.

“Gala and Fuji are two varieties that are difficult to thin each year,” noted Palmer. “We wanted to determine whether adding Sysstem-CAL to treatments of the PGRs would improve thinning. We applied two applications of the three PGRs, some with and some without Sysstem-CAL. These were on May 23 at petal fall and on June 2 at 10-13 mm.

“In the Gala trial, the addition of Sysstem-CAL to the Sevin and MaxCel petal fall treatments gave somewhat better thinning than the products alone. Plus, a higher percentage of the fruit was sizes 2.75 inches and larger.

“In the Fuji trial, all the applications with Sysstem-CAL significantly impacted fruit set. The highest percent fruit thinning was where Sysstem-CAL was tank mixed with Sevin at petal fall, followed by a tank mix with Fruitone N at first cover.

“The Fuji treatments where Sysstem-CAL was with Sevin at petal fall and with MaxCel at first cover showed the highest significant percentage of the largest fruit – three inches or better in diameter. While this treatment did not have the highest amount of thinning, it produced significantly firmer fruit.

“We were not sure going into these trials what effect adding Sysstem-CAL may have on a thinning program. We knew the calcium would be good for the crop, but would it interfere with thinning? So we were being cautious in this approach. The answer was that Sysstem-CAL definitely improved the performance of the thinning PGRs. We saw a typical response to the PGRs, not an adverse one.”

The Findings Show a Fit for Sysstem-CAL

In apples, growers no longer have to choose between the benefits of plant growth regulators and addressing the fruit’s peak demand for calcium between bloom and the end of cell division. Whether the PGR is for shoot reduction, shaping the apples, or thinning the potential crop, Sysstem-CAL doesn’t just deliver the calcium when and where it is most needed within the tree and developing crop.

Sysstem-CAL isn’t just for early season crop development. Applications of Sysstem-CAL after cell division is complete will continue to support the tree’s needs so calcium is not pulled from the fruit, thereby maximizing fruit calcium levels, which will reduce bitter pit and improve storability of the fruit.

Growers of other crops also are using Sysstem-CAL to maximize fruit quality and minimize calcium deficiency problems such as blossom end rot in tomatoes and internal cell breakdown in stone fruit.

Use of Sysstem-Cal as a spray adjuvant with PGRs is not registered in California.

For more information about Sysstem-CAL and other Agro-K products and research, phone 800-328-2418 or email

© 2010 Agro-K Corporation. Sysstem-Cal is a trademark of Agro-K Corporation. Sevin is a registered trademark of Bayer, Fruitone is a registered trademark of  AMVAC. MaxCel and Promalin are registered trademarks of Valent. Apogee is a registered trademark of BASF.

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