Since we wrote to you about spraying the tomatoes with copper to save them from the late blight, we have received quite a few emails asking us about what that means and if we spray other crops with other products. We also had a visit from a French agriculturalist who asked about the American organic certification and whether we participate. We explained that, because of the CSA relationship of trust and open communication about our farming practices, we don’t feel the need to be certified. In addition, certification would cost us quite a bit of money and it doesn’t make sense to pass that cost on to the CSA members. In order for you to feel comfortable with our farming practices, we thought we should share with you the products we spray, what crops we spray, and why we spray.
Copper: One of the products that organic growers can use is NuCop 50 WP. It is a blue powder that we mix with water and spray on the tomatoes as a fungicide. The copper is absorbed by the spore of the oomycete pathogen and kills the spore. The oomycete that has already developed on the plant cannot be killed. Organic growers have to use the spray as a protectant and apply it before the pathogen appears on the crop. Once the oomycete has established itself on the crop, the copper can be sprayed to control the spread of the spores, but the copper will not destroy the pathogen itself. We use copper to control early and late blight in the tomatoes. For early blight, we spray when the plants are young and, once they begin to have fruit, we quit spraying. The late blight infection we have now requires that we spray until the end of the harvest. If we quit spraying copper, you would have only one or two more weeks of tomatoes at best.
We handle this product carefully and we do not go into the tomatoes for 24 hours after copper is applied. As we stated before, you should wash your tomatoes before you eat them. The copper product is only on the surface of the tomato and easily washes off. Copper is a trace mineral in the soil and, because we rotate our crops every year, this one season of a heavier-than-normal use of copper will not affect the soil life or soil health. Copper does not leach into ground water. We are careful to spray only when there is no wind so that the copper does not drift into other areas of the farm or into other crops.
Entrust: This is a product we use to control European Corn Borer in sweet corn and peppers. We also use it when the flea beetle infestation is especially heavy in greens like arugula or in eggplant. With the addition of the parasitic wasps (trichogramma ostrinae) we also use to control the corn borer, we have almost no worm damage in the corn. We have more damage in the peppers this year because we didn’t control the worms early enough. The larvae from the corn borer moth eat holes in the tops of the peppers. Then, when it rains, the peppers fill with water and rot on the plant. If not controlled, the larvae can do a lot of damage very quickly in a pepper crop. We spray the corn because most people do not enjoy finding worms in their corn ears.
Enrust is created from bacteria called spinosa that are found in the soil. It works best on pests that eat the sprayed leaves. Entrust can have some effect on the pests and beneficial insects when it has just been sprayed. Once the product dries, it is not harmful to insects that are not ingesting the sprayed leaves. It is not considered to be toxic to humans. We are careful to spray so that it does not drift (blow in the wind to places we do not want it). Insects can build up a resistance to Entrust, so we do not spray it more than two or three times on a crop per season. We use about two ounces per acre per application and the product is broken down in the soil.
Bt: This product comes from the bacteria Bacillus thuringiensis. We use the product called DiPel DF. There are many different strains of Bt, but we use this one to control cabbage loopers (the worms found in your cabbage and broccoli). It works only by digestion and causes the larvae of the looper moth to quit eating. We sometimes use it to control corn earworm in the corn by spraying it directly on the silks of the ears. We only do this if our scouting (carefully surveying the crop for evidence of a pest) shows that we have a high level of corn earworm moths in the corn field. DiPel DF is not toxic to humans or other animals. It only affects the larvae that eat the plant leaves.
All three products are aided by what is called a spreader sticker and, in our case, that is Nu-Film P, another OMRI approved material. Nu-Film improves the material’s effectiveness by protecting it against early UV degradation, by making it stick to the leaves of the plant, and by lowering the surface tension of the water which creates a smaller droplet and therefore better coverage.
Biodynamic Preparations: The biodynamic preparations are used in addition to good farming practices to increase the health of the soil and plants on the farm. They are similar to the homeopathic remedies we use to benefit human and animal health. We use horn-manure preparation to increase the humus formation in the soil (the stable soil aggregates that increase organic matter) and to increase the rooting of the plants. Horn manure is made by filling cow horns with cow manure from animals raised on grass. The filled horns are then buried in the ground over the winter. When the horns are dug up in the spring the manure has fermented into a compost-like substance. After we dig it up we insert the six compost preparations and store it in a stone urn immersed in peat moss to maintain its freshness. The compost preparations are made from fermented medicinal herbs: dandelion, chamomile, valerian, yarrow, stinging nettle, and oak bark. We also put very small quantities of each in the compost piles. We also apply both horn-silica and (on a trial basis) the horn-clay preparation, which are both made in a way similar to the horn-manure. We use very small amounts of these preparations and stir them in warm water for one hour. Horn-manure and horn clay are sprayed on the soil and horn silica is sprayed on the leaves of the plants.
When we are making a decision about whether or not to use a certain product, we carefully weigh the pros and cons. We have increased the use of spraying because we felt that you wanted a less damaged product. We heard from you that you don’t want to find worms in your broccoli or corn. We understand, and we do our best to deliver that. We do not use products that are not on the OMRI list (OMRI is the organization that decides if a product can be used in certified organic production). If you have further questions about what we use to protect the crops so that we can deliver a better product to you, please send us an email at firstname.lastname@example.org. This continued discussion is how we determine your needs and how to best meet them. It is important that, even though we have had this relationship for almost 20 years, the lines of communication stay open. We thank you for your questions and input.
For more information on Entrust, DiPel DF, and NuCop WP50 we recommend that you read the Resource Guide for Organic Insect and Disease Management published by Cornell University. You can find it on their website: http://www.nysaes.cornell.edu/pp/resourceguide/index.php
For an article on the Biodynamic Preparations we suggest the article on the ATTRA (The National Sustainable Agriculture Information Service) website: http://attra.ncat.org/attra-pub/PDF/biodynam.pdf and at the Biodynamic Association’s website: http://biodynamics.com/node/111