As a rose gardener, I will attest to the following statement: if a product is advertised to prevent diseases, I'll try it. However, I am typically disappointed with less than satisfactory results from these expensive products. Now we are being bombarded with alluring names such as organic, bio-something and organic solutions for plant problems. First let's define organic. The definition goes something like this: "of, like or derived from living organisms". Organic products may also cost you more and you may have to use more of the product per application. More importantly, do they really do the job that they were intended for?

If the product was lab-tested under strict optimum conditions you cannot expect the same results in the field. In the field there are many variables to consider, such as rain, temperature, sun exposure, etc. At the Institute of Ecosystem Studies, we try many new products and advise gardeners as to which products will give the best desired results. With serious health and environmental issues surrounding many chemical fungicides used to control Black spot (Diplocarpon rosae), we wanted to see how effective an organic fungicide would be. We decided to set up a field test and conduct a comparative spray program where treatments and visual observations would be made throughout the growing season.

The Test: We decided to replicate five groups of roses selected with medium overall ratings, averaging 7.3. We chose a hybrid tea, floribunda, shrub and Austin (English) roses. To induce fungal diseases, roses were planted too close together and poor watering techniques were used. A control plot, which received no disease-preventing treatment, was included for comparison. All roses were fertilized with Rose-Tone® in May, June and July. Each rose plot received a different treatment intended to suppress fungal diseases: a bacillus-based product, a harpin protein product, a compost tea and a popular chemical fungicide. One set of roses was kept as a control site. Individual hand sprayers were used to prevent contamination from other products.

The Products: Since we wanted to test a broad range of pesticides, we selected the following; Spectricide, Immunox® Plus, a conventional pesticide with both insecticidal and fungicidal action. Immunox® Plus utilizes myclobutinal and permethrin as its active ingredients. Precautions must be used when mixing and using this product. Messenger®, marketed by Edin-Bioscience, which uses the harpin protein to induce a plants' immune system to fight off diseases. This response is known as SAR, (systemic acquired resistance). This product is actually a bio-chemical, as the DNA of the bacterium Escherichia coli is chemically altered to produce harpin proteins on a commercial scale. E. coli strain K-12 is considered very safe to use. The next product, we used during the 2004 season with significant results, was Serenade® Solutions^TM, manufactured by Agri-Quest, Inc., was used at IES during the 2004 growing season with good results prompting us to try it for this comparative demonstration. This product relies on the bacterium Bacillus subtilis to compete with disease pathogens for food and growing space. The Bacillus fungi attach themselves to the disease microbes which weakens them, all while triggering a SAR response in the rose. Listed as a bio-pesticide it is very safe to use. View the EPA's (www.epa.gov.) web site for more information on these products. The last and most important was the use of a compost tea. Using a digester we incorporated air into a mix of water and a filter bag of worm compost. The addition of an activator (molasses) provided simple sugars as food for a population of fungal, bacterial, microarthopods and beneficial nematodes which leached out into the liquid tea or soup. Used as a spray or drench, the tea produces optimum soil conditions for nutrient retention and recycling. Also the organisms from the tea which land on a leaf surfaces will compete for spatial niches and literally push harmful pathogens out. For more information on compost tea see the following; www.soilsoup.com and www.soilfoodweb.com by Dr. E. Ingham and the site www.agroforestry.net. Because any insecticide would have killed all beneficial organisms in our plots, we did not use them for controlling insect pests. It was interesting to note that Immunox® Plus, which contains an insecticide did not significantly reduce pest insects compared to plots whose products id not include conventional insecticides.

The Results: No significant results were observed in any of the plots for the first few weeks of the growing season. Three weeks into the trial we did note a significant increase in growth and vigor in the compost tea plot. Foliage on the compost tea- maintained roses was lush and rich in color. Since the roses were planted close, this set actually grew together. The blooms were many and twice the size of the roses in the Immunox® Plus plot. Success in this trial was based upon the amount of leaf retention. The best results in suppressing Diplocarpon rosae was obtained by Messenger® and the compost tea. The two products were practically equal in suppressing blackspot with an average 10 percent defoliation in the roses. One potential drawback connected with the use of Messenger® was an increase in cane and foliage growth late into the growing season. This may not allow for the season maturation process to progress uniformly and may lead winter dieback of this late growth and impact winter survival. The growth and characteristics of the compost tea-grown roses, with exuberant early-season growth should overwinter well. Roses in the Serenade® Solutions^TM plot retained 75 percent of their leaves. However, this product leaves an unsightly white residue on blooms and leaves. Surprisingly, Immunox® Plus defoliated the roses, regardless if leaves were infected black spot. Immunox® Plus-sprayed leaves were found to be dry and leathery. These roses did refoliate in late summer. There could be a winter survival issue in these roses as well.

Conclusions: Do organic products work as well as conventional fungicides? From the results of our trials it seems they do and at times even perform better. Realize you need to research and follow all of the instructions per label directions. We recommend incorporating compost tea into your garden practices. One advantage with compost tea is you can actually concoct your own tailored-made spray or drench. In addition to all the benefits compost tea will provide the existing soil microbial population and related plant benefits, you can gear you tea to combat fungal and/or bacterial pathogens. You can also adjust your tea ingredients to perform optimally under differing soil types. Be sure to check with local extensions or agencies that can help you make the best choice.