Powdery Mildew mycelium Before & After

LITERATURE REVIEW OF DISEASES THAT HAVE BEEN SUCCESSFULLY TARGETED WITH POTASSIUM BICARBONATE SPRAYS.
Alternaria leaf spot, Black spot Helminthosporium, Powdery mildew, Anthracnose, Cercospora leaf spot, Phoma Septoria leaf spot, Botrytis, Downy mildew, Phomopsis blight, Dollar spot, Botrytis blight, Fusarium leaf spot, Phytophthora (leaf)

AGRICULTURAL APPLICATIONS

Floraculture / Gardens (ROSES)
4gm/L or 4kg/ha
Apply at first sign of disease. For best protection, apply every 7-10 days until conditions are no longer favorable for disease. Apply to run-off with Eco-Oil@ 2 ½ ml/L every second spray.


Grape vines
4-5 kg/ha
Apply on a regular basis every 14 days and every 7 days when disease pressure is high. Apply with Eco-Oil or Synertrol Horti Oil@ 250ml/100L. Thorough coverage is essential. Do not apply at less than 7 day intervals.

APPLICATION TIMING
Start applying at first sign of disease. For best protection, repeat at one to two week intervals until conditions are no longer favorable for disease development. Shorten interval during rainy and humid weather when leaf surface remains wet for extended lengths of time.

ECOCARB RESEARCH UPDATE
by Sallyann Roberts Moore

"Powdery mildew samples observed under a microscope began reacting within seconds of contact with the bicarbonate solution, Ken says, and were dead within minutes."

Bicarbonates offer
Effective disease control

A bicarbonate formulation has proven effective in eliminating powdery mildew in roses, ornamentals, vegetables and fruit crops, and offers potential for control of other diseases in a broad range of environments. The new product was developed at Cornell University and H&I Agritech, Inc., in co-operation with Church & Dwight Co.Inc. .R.Kenneth Horst, a Cornell University professor specializing in biocompatible control of pests and diseases, began testing bicarbonates in an effort to find an environmentally friendly method of eliminating common plant diseases.

Though bicarbonates have proven to be effective disease control agents, Ken says growers who spray their crops with baking soda, perhaps the most familiar bicarbonate, will be disappointed. That's because baking soda alone fails to cling to and spread over the leaf surface, resulting in ineffective disease control. In addition, types of bicarbonates other than sodium, the basis of baking soda, may prove to be more effective against specific pests or diseases.

To improve the ability of bicarbonates to cling and spread, Ken includes a surfactant (spreader-sticker) in his formulation. The surfactant causes the bicarbonate formulation to adhere to the targeted area and spread uniformly across the leaf surface, significantly improving the effectiveness of the spray. Ken and his staff tested more than 350 surfactants before selecting the safest, most effective additive for his bicarbonate mixtures.

But in addition to the improved properties provided by a surfactant, selecting the correct bicarbonate is essential. During his bicarbonate studies, Ken's group found that ammonium bicarbonate had the greatest effect on some diseases, while potassium and sodium bicarbonates work best against others. In his work on powdery mildew, for example, Ken found potassium bicarbonate offered the greatest benefit.

"Sodium bicarbonate is okay, but it's not as good", Ken says. "And ammonium bicarbonate doesn't do the job on powdery mildew." Ken says Church & Dwight, the Princeton, New Jersey, company that markets Arm & Hammer products, had developed both a potassium and sodium bicarbonate product. According to M.Stephen Lajoie, Church & Dwight's director of research and development, the company expects to receive a commercial label for both products during the first quarter of 1996. Final marketing plans for the product, to be released as part of the Armicarb pesticide line, haven't been completed. However, Church & Dwight expects the product will become available to growers sometime this year.

Most chemicals for powdery mildew control currently available are preventives, Ken says. But bicarbonates both eliminate the disease after it appears on the crop - provided the infection isn't too severe - and act to prevent rapid recurrence of the problem. Last summer, ornamentals growing outside Cornell's Plant and Soil Science building developed powdery mildew. Two or three applications of the bicarbonate formulation eliminated the problem, and no further occurrence of the disease was observed during the growing season, Ken says.

Ken has observed similar results in roses. In one trial, several rose plants were grown without bicarbonate treatment. When the test concluded, the untreated plants, which had developed high mildew levels, were sprayed with bicarbonate. Not only did the spray eliminate powdery mildew, but Ken says that nearly a month later the mildew remained at levels almost too low to begin new tests. The only damage associated with bicarbonates is foliar burning when application rates exceed recommended concentrations.

Flower development on roses grown with bicarbonate sprays is normal, Ken says, and testing confirmed that sodium bicarbonate doesn't increase the level of sodium in plant tissues, soil or run-off water.
The precise method by which bicarbonates work is unknown; however Ken says they seem to damage the cell wall membrane in powdery mildew spores.

This leads to dehydration and death of the cells. Ken also believes pH to be factor in bicarbonate effectiveness. Bicarbonate solutions have a pH of 8.2 compared to a neutral pH of 7.0. Regardless of how they work, bicarbonates act quickly to eliminate disease. Powdery mildew samples observed under a microscope began reacting within seconds of contact with the bicarbonate solution, Ken says, and were dead within minutes.

In addition to their effectiveness on powdery mildew, bicarbonates have potential for controlling black spot on roses, rust, dollar spot and pythium blight in turf, late blight in potatoes, mildew and rust in wheat and diseases of alfalfa. peanuts and bananas. Moreover, Ken says his tests of bicarbonate for control of other diseases appear promising, though further research is needed in the area of insect control. "
Sallyann Roberts Moore is a freelance writer from Ann Arbor, Michigan.