Soil Drench for Tomatoes

This year I decided to try a new (to me) technique to prevent or reduce the chance of soil-borne diseases affecting my tomatoes and peppers. In catalogs I have read about natural products like Actinovate (containing the bacteria Streptomycin lydicus) that can populate the rhizosphere and attack fungal infections such as Fusarium and Pythium in the soil before they infect the plant.  It sounded like an interesting idea, maybe worth trying.

A little searching on the internet showed these types of biological products are considered safe and effective and are used by commercial growers. Actinovate is used by landscapers to treat fungal infections in lawns such as brown patch and dollar spot. Actinovate is also OMRI-listed and is being used by gardeners to treat vegetable crops. Renee of Renee’s Garden uses Actinovate as a preventive spray on her garlic fields to ward off garlic rust. There is a lot of discussion on the Tomatoville garden forum worth reading and one of the more interesting threads describes the use of a mix of Actinovate and other products to create a soil drench to be used before planting out tomatoes and peppers. I decided to try my own slight variation of Ami Deutch’s formula from the Tomatoville forum.

The basic idea is to create a soil drench solution in which the beneficial organisms are dissolved. The tomatoes, still in their pots, will be soaked in the solution and then drained before planting in soil. This inoculates the root zone with the beneficial organisms. They colonize the area and promote healthy plant growth and help the plant resist attacks by fungal diseases. You could use just a single product/organism such as Actinovate, but why not make a comprehensive soil drench, since the biggest effort here is in mixing the solution and drenching the plants.

 
The three components of Ami’s mix are Actinovate, Biota Max, and Myco-Grow (for which I substituted Great White). What are these? Actinovate identifies itself as a fungicide for organic gardening. Since it gets used for lawn problems, it is widely available at garden centers as well as from online sellers and Amazon. If  you buy locally, be sure to check the use by date sticker. The stuff at my garden center was 18 months past the use by date. Actinovate contains a single ingredient, a patented strain of the bacteria Streptomyces lydicus, strain WYEC 108. It colonizes the root zone of the plant, setting up a symbiotic relationship with the plant. It feeds off exudates of the plant while excreting by-products beneficial to and protective of the plant and attacking some disease organisms. Soil diseases suppressed include the soil borne fungi Fusarium, Verticillium, Rhizoctonia, Pythium, and Phytophthora. Actinovate can also be used as a foliar spray and is effective against powdery and downy mildew, grey mold, fire blight, rust, and black spot.

The next major component of the mix is the Myco-Grow or Great White. These are water soluble mycorrhizae inoculants and contain roughly equivalent organisms, both fungal and bacterial. Rather than include the whole list, you can view a comparison I did of the composition of several products here. Both are a bit pricey and you want to get the smallest size, about an ounce, so you can use it up in one season. Myco-Grow has to be bought from the supplier while Great White is widely available from hydroponics stores and from mail-order suppliers and Amazon.

The third component is Biota-Max,  which is described as a Soil Probiotic. I consider it optional if you have trouble obtaining it since it adds just a few new microbes to the mix, but I chose to use it. You have to source it online direct from Custom Biologicals. What you get in your package is a single lozenge, somewhat like an Alka-Seltzer tablet. Ami calls for it to be cut in quarters, with one quarter used in each gallon batch of drench.

To make the drench, dissolve one quarter tablet of Biota-Max in a gallon of pure (chlorine-free) water. Be careful using city water if it is treated because it will kill all your expensive microbes. Then add 2 teaspoons (10 cc) of Actinovate and 2 teaspoons (10 cc) of Great White to the water and mix thoroughly. I used a gallon milk jug to mix and carry the water to the garden. For the dipping container, I cut an opening in an empty gallon cider jug.

After I prepared the planting hole and added all the supplements, I submerged the plant in the drench in its container so the soil mass did not dissolve in the drench. After about 5 seconds when the bubbling stopped, I lifted the plant and let the excess drench drain back into the container and then planted it. The gallon was more than enough to treat 14 tomatoes in Solo cups plus a couple in packs. The left over solution can be poured around the base of the plants. I would like to be able to say that the plants are exuberant and rapidly growing today, but shortly after being planted we started three days of rain with daytime temperatures in the 50s and nighttime temps in the 40s, so the plants are actually looking a little shell shocked. The inoculant is not going to be active at these temperatures, but I am looking at long term results and disease resistance, so it will be awhile before I can decide if this was successful.