Organic Gardening PDF

HO-100 Organic Gardening By Krista Jacobsen, assistant professor, Horticulture, University of Kentucky. Organic gardening offers the gardener many benefits—a In this chapter:...

HO-100 Organic Gardening By Krista Jacobsen, assistant professor, Horticulture, University of Kentucky. Organic gardening offers the gardener many benefits—a In this chapter: safe, low-chemical gardening environment; produce free from synthetic pesticide residues; and gardens that can increase in Planning Your Organic Garden 01 fertility and natural pest control over time. However, reaping the benefits of organic management requires planning, observation, Organic Transplants and Seed Sources 03 and thinking about the garden as an interconnected system of Pest Management: Weeds, Insects, Diseases 04 soils, plants, pests, and beneficial organisms. Principles and Additional Resources 08 practices include: Building long-term soil fertility with composts, manures, and mulches O rganic farming and gardening have grown in popular- Rotating crops ity in recent years as consumers and producers have Using good planning practices to avoid insect, disease, and sought alternatives to synthetic fertilizers and pesti- weed pests, and using biological or mechanical controls cides in favor of biologically based management. A 2008 survey when necessary by the National Gardening Association found that 12 percent of American household gardens (12 million households) used Planning Your Organic Garden all-natural management techniques, an increase of 7 percent from 2004. Crop Rotation The U.S. Department of Agriculture (USDA) National Crop rotation is alternating crops grown in a particular bed Organic Program (NOP) defines the rules for USDA Certified or field between growing seasons. By rotating crops, you can Organic production practices. (The label used to designate avoid buildup of certain pests and also enable nutrients in the certified organic products is shown in Figure 21.1. See the soil to be used more efficiently. USDA-NOP website at http://www.ams.usda.gov/AMSv1.0/ The most popular type of rotation is alternating crops by nop for additional details). This publication provides an over- botanical family. For example, diseases that affect tomatoes can view of the principles and practices of organic agriculture for the also affect other members of the Solanaceae family, including home gardener, whether he or she wants to grow a completely peppers, potatoes, and eggplants. organic garden or adopt select practices to lower input costs Rotating crops in the Solanaceae family with crops in other and build soil fertility. The fertilizer and pest control strategies families can minimize losses from these diseases. Similarly, in this publication are consistent with spirit of the USDA-NOP rotating among crops that have different growth habits can help guidelines. However, gardeners who want to meet the “letter” of deter pests. For example, if root crops such as sweet potatoes those guidelines should explore the Organic Materials Review or carrots are planted in the same location year after year, soil- Institute (OMRI) list of NOP-approved materials at www. dwelling insect pests, such as white grubs, wireworms, and omri.org. or look for the OMRI label when purchasing garden some nematodes, may proliferate. Rotating among plants with supplies (Figure 21.2). different root architecture may prevent proliferation or help break these pest cycles. One common rotation method is based on the fertility requirements for each crop. With this method, you categorize crops by whether they “feed” on nutrients or “give” nutrients to the soil over the course of the growing season. Crops with high fertility (primarily nitrogen) requirements have been described as heavy feeders, those with moderate fertility requirements as medium or light feeders, and crops that contribute nutrients are “givers.” (See Jeavons’ book in “Additional Resources” section.) Crops are rotated in a cycle from heavy givers to light feeders to heavy feeders and back to heavy givers. Examples of crops in these categories are: Figure 21.2. OMRI label. Heavy givers: Beans (snap, pole, bush), peas, green manure Figure 21.1. USDA Certified Organic label. crops such as clovers, and field peas CHAPTER 21 Organic Gardening Light feeders: Beets, carrots, garlic, onions, sweet potatoes, Table 21.1. Common garden vegetables and their botanical families. turnips Botanical Common Heavy feeders: Broccoli, cabbage, corn, cucumbers, squash, Family Family Name Crop tomatoes Solanaceae Nightshade Tomato, pepper, potato, egg- plant, tomatillo If you plan to practice rotation, it’s important to keep records Brassicaceae Cole crop Broccoli, cauliflower, cabbage, and a year-by-year map of your garden. Flashcards also can be kale, Brussels sprouts, radish, rutabaga, turnip useful in the garden planning process. Using this technique, Cucurbitaceae Gourd Winter squash, summer squash, flashcards are made for each crop, with a copy of the flashcard melons, cucumber, pumpkin for that crop for every year in the rotation (e.g., three potato Apiaceae Carrot Carrot, parsley, celery, parsnip flashcards for three years of potatoes). You can then manipulate Chenopodiaceae Goosefoot Beet, chard, spinach the cards for a three-to-five-year timeline for the entire garden. Fabaceae Legume Pea, bean This exercise, using the botanical family as the guide to the rota- Asteraceae Sunflower Lettuce tion, is outlined in The New Organic Grower by Eliot Coleman Liliaceae Lily Onion, garlic, shallot, leek (see “Additional Resources”). Poaceae Grass Corn Common vegetables and their botanical families are listed in Table 21.1. Table 21.2. Nutrient content and release rates of organic fertilizers. Soil Fertility and Organic Fertilizers Materials N (%) P2O5 (%) K2O (%) Relative Availability A central tenet in sustainable and organic agriculture is to Medium- “feed the soil to feed the crop”—restoring and maintaining the Alfalfa meal 3.0 1.0 2.0 Slow soil organic matter that ultimately feeds crop plants. Soil organic Medium- Blood meal 12.0 1.5 0.6 matter accumulates through use of organic amendments such Rapid as composts, manures, cover crops, and mulches. Over time, Slow- Bone meal 0.7-4.0 11.0-34.0 0.0 Medium these amendments sustain fertility, relieve compaction, improve Feather meal 11.0-15.0 0.0 0.0 Slow both drainage and water-holding capacity, and improve nutrient Fertrell “Super N” 4.0 2.0 4.0 Slow retention. However, organic amendments are delivered more Fish meal 10.0 4.0 0.0 Slow slowly and less consistently than standard synthetic fertilizers Medium- because they become available as microbes and other soil Fish emulsion 5.0 1.0 2.0 Rapid organisms decompose. Greensand 0.0 1.0-2.0 5.0 Slow Table 21.2 shows the nutrient contents (N-P-K) of several Kelp1 0.9 0.5 1.0-4.0 Slow common sources of fertility in organic gardens. Manure2 (fresh) Organic fertilizers rarely contain the N-P-K ratios to match Cattle 0.25 0.15 0.25 Medium recommendation from a soil test report. However, you can use Horse 0.3 0.15 0.5 Medium the steps below to figure out how much fertilizer you need, Medium- Poultry (50% water) 2.0 2.0 1.0 Rapid whether you use the values in Table 21.2 or those listed in the Medium- nutrient analysis of a purchased amendment. Poultry (15% water) 6.0 4.0 3.0 Rapid To calculate the organic fertilizer required from several Manure2 (dry) sources, complete the following steps, based on a soil test report: Dairy 0.7 0.3 0.6 Medium 1. Calculate the nitrogen (N) recommendation first. Steer 2.0 0.5 1.9 Medium 2. Calculate the phosphorus (P205) recommendation next. Horse 0.7 0.3 0.5 Medium 3. Calculate the potassium (K2O) recommendation next. Marl 0.0 2.0 4.5 Very Slow An example of these calculations is provided in Figure 21.3. Mushroom compost 0.7 0.9 0.6 Medium Sulfate of potash Rapid- It’s fairly easy to use organic sources to meet your garden’s 0.0 0.0 22.0 magnesia (K-Mag) Medium fertility requirements, and organic fertilizers are increasingly Soybean meal 6.7 1.6 2.3 Slow accessible. However, it is important to understand that for Wood ashes3 0.0 1.0-2.0 3.0-7.0 Rapid nutrients to become available from most organic sources (other Source: Adapted from How to Convert an Inorganic Fertilizer than minerals and rock powders), they must be decomposed Recommendation to an Organic One, University of Georgia Cooperative Extension. Adapted from Boyhan, 2009. See Additional Resources. by soil organisms. Thus, it is important to understand how 1 Kelp also contains common salt, sodium carbonates, and sodium and potas- temperature, moisture, and other environmental factors affect sium sulfates. 2 Manure contents may vary with amount of straw/bedding included, feed soil organisms and the decomposition process. The effects of quality, and method of storage. (See the health and safety questions in the pH and temperature are described briefly below. For additional Cooperative Extension publication Composting (ID-192). 3 Potash content depends on the tree species burned. Wood ashes are alkaline information, Jeff Lowenfel’s book, Teaming with Microbes, is and contain approximately 32% CaO. 21-2  Organic Gardening CHAPTER 21 A soil test report recommends 2-3 lb of N, 1-2 lb of P2O5, and 3-5 lb of K2O per 1,000 square feet of garden. 1. Calculate the nitrogen (N) recommendation first. In this example, we will use blood meal for the nitrogen source (12-1.5-0.6, see Table 21.2). For the 3 lb of N recommended, the quantity of blood meal required to meet the nitrogen recommendation can be calculated as: (3 lb N ÷ 1000 ft2) x (1 lb blood meal ÷ 0.12 lb N) = (25 lb blood meal ÷ 1000 ft2) 2. Calculate the phosphorus (P205) recommendation next. Subtract the amount of P supplied by the N source (blood meal): 25 lb blood meal x (0.015 lb P2O5 ÷ 1 lb blood meal) = 0.375 lb P2O5 Use bone meal (approx. 1-11-0) for the phosphorus source to fulfill the remaining P requirement. 1.5 lb P2O5 – 0.375 lb P2O5 from blood meal = 1.125 lb P2O5 (1.125 lb P2O5 ÷ 1000 ft2) x (1 lb bone meal ÷ 0.11 lb P2O5) = (10 lb bone meal ÷ 1000 ft2) 3. Calculate the potassium (K20) recommendation next. The quantity of K supplied in the bone and blood meal is negligible, so the K recommendation can be calculated without subtracting the K present in the N and P sources. Using K-mag (sulfate of potash magnesia) to complete the fertility plan: (4 lb K2O ÷ 1000 ft2) x (1 lb K-Mag ÷ 0.22 lb K2O) = (18 lb K-Mag ÷ 1000ft2) Based on these calculations, meeting the soil test report fertilizer recommendations will require 25 lb blood meal, 10 lb bone meal, and 18 lb K-Mag for 1000 square feet of garden space. Figure 21.3. Example calculation to determine organic fertilizer required to meet soil test report recommendations for 1,000 square feet of garden space. an excellent gardener-friendly primer on soil ecology and the after transplant. Using healthy transplants with enough fertility activity of soil microorganisms (see “Additional Resources”). in the transplant mix to carry some nutrient forward into the garden bed will also help make up for insufficient soil nutrients pH and Liming early in the season. Garden plants typically grow best in a pH from 6.0 to 6.5, and microbial activity is restricted when pH is less than 5.5. Soil Organic Transplants and Seed Sources testing and adjusting pH according to lime recommendations Organic seedling mix can be expensive, and nutrient deliv- helps ensure that soil organisms are operating under optimal ery tends to be less consistent than with conventional seedling conditions. Calcium, the neutralizing agent in agricultural lime, mixes (though there are notable exceptions). Add fertilizer once will not spread quickly throughout the soil profile. For that the first set of true leaves appear. Typically, organic gardeners reason, it must be thoroughly incorporated before planting— use a liquid, fish emulsion-based organic fertilizer. To avoid ideally two to three months before planting—throughout the burning plants, follow dilution directions on the packaging. rooting zone, at a depth of six to eight inches. If you can’t apply The cost of organic seedling mixes increases rapidly with lime this early, it will still help if you can apply and incorporate soil or compost-based mixes, so many organic gardeners and it at least a month before seeding or transplanting. farmers make their seedling mix. Several common recipes used in organic seedling production are listed in Table 21.3. For addi- Temperature tional information on organic seedling mix ingredients, nutrient Cool temperatures in early spring also limit microbial activ- release rates, and additional recipes, see the publication Potting ity. Soils must be warm enough to stimulate microbial activity Mixes for Certified Organic Production at http://attra.ncat. in order to decompose organic fertilizers and make nutrients org/attra-pub/potmix.html. Note that one recipe is intended available to crop plants. Growth may be stunted early in the for use with soil blockers, which are hand tools designed to season if plants don’t get enough nutrients or those nutrients are form free-standing blocks of potting soil that substitute for immobilized by decomposing microbes (also known as “N rob”). peat pots, seedling flats, etc. Soil blockers have been popular To avoid stunted growth, use a readily available organic among small-scale producers, and are readily available through fertilizer such as fish emulsion or other liquid organic fertilizer some garden suppliers specializing in organic production (see when you transplant, and use it weekly for one to two weeks “Additional Resources”). 21-3 CHAPTER 21 Organic Gardening Table 21.3. Common recipes for organic potting and germination mixes. Organic substitute for Vegetable Cornell Mix Classic soil-based mix1 Soil blocking mix Organic potting mix transplant recipe ½ cu. yd sphagnum peat 1⁄3 mature compost or leaf 3 buckets2 1 part sphagnum peat Equal parts by volume of: ½ cu. yd vermiculite mold, screened brown peat 1 part peat humus (short compost, peat moss, and 10 lb bone meal 1⁄3 garden topsoil ½ cup lime (mix well) fiber) perlite or vermiculite 5 lb ground limestone 1⁄3 sharp sand 2 buckets coarse sand or 1 part compost 5 lb blood meal perlite 1 part sharp sand 3 cups base fertilizer (builder’s) (blood meal, colloidal To every 80 qt of this add: phosphate, and green 1 cup greensand sand mixed together in 1 cup colloidal phosphate equal parts) 1½ to 2 cups crabmeal, or 1 bucket soil blood meal 2 buckets compost ½ cup lime Sources: For the blocking and organic potting mixes, Coleman’s The New Organic Grower: A Master’s Manual of Tools and Techniques for the Home and Market Gardener. For the vegetable transplant recipe, Rynk’s On-Farm Composting Handbook. (See Additional Resources.) 1 This mix is heavier than modern peat mixes but still has good drainage. Compost promotes a healthy soil mix that can reduce root diseases. Vermiculite or perlite can be used instead of sand. Organic fertilizer may be added to this base. 2 Standard 10-qt bucket. Pest Management: Weeds, Insects, Diseases Crops and cover crops planted in tight succession compete with weeds for light, nutrients, and water. The more these One of the main differences between organic gardening resources are in use by crop plants, the less available they are and conventional gardening is the use of pesticides. Organic for weeds. gardeners choose not to use any synthetic chemicals to control In addition, planting vigorous transplants on relatively weeds, insects, or diseases. Instead, they use a combination tight spacing closes the plant canopy rapidly, helping crop of cultural, physical, and biological controls. The philosophy plants out-compete weeds for light, water, and available nutri- behind organic pest control is that using “many little hammers” ents. Techniques such as French biointensive gardening and allows the organic gardener to beat back pests to a manageable square-foot gardening (described in more detail in books by threshold even though these techniques lack the chemical John Jeavons and Mel Bartholomew, respectively, listed in the strength of many conventional garden inputs. “Additional Resources” section) emphasize close plant spacing Cultural controls, used to prevent pests from ever becoming and arranging plants by vertical size to produce a dense canopy a threat, are the first line of defense in the garden. They include that maximizes crop production and minimizes weed pressure. proper plant selection, fertility management, crop rotation, and physical exclusion. Physical or mechanical controls manually Mulches and Other Physical Barriers remove pests from the garden. Biological controls, which can be Physical barriers such as mulches, plastic, landscape fabric, organic pesticides or beneficial organisms, are used to manage and even cardboard block light to germinating weeds. They an existing insect or disease problem. It is a common miscon- greatly reduce weed emergence and also conserve water. When ception that organic gardening prohibits the use of pesticides in these barriers are plant-based, they add organic matter to the any form. A number of pesticides that are derived directly from soil as well. Typically, a one-to-two-inch layer of straw or hay biological or mineral sources are organically approved. They mulch, with some additional hand weeding, will suppress weeds may be highly toxic, but they typically break down much more for much of the season. More mulch can lead to outbreaks of quickly in the environment than their synthetic counterparts. fungal and bacterial disease in warm, wet years. To minimize Organic management of weeds, insects, and diseases integrat- diseases, keep mulches off crop plant stems. Also, on long- ing cultural, physical/mechanical, and biological controls is season, disease-sensitive crops such as tomatoes and peppers, discussed below. remove lower leaves touching the mulch. Direct-seeded crops such as root vegetables and lettuces can be planted through a Weeds thin layer of mulch and still emerge. To promote crop emer- gence while minimizing weeds between the crop rows, you also Cultural controls for preventing weeds include the follow- can mulch with a thicker layer around the planting furrow and ing strategies: leave the furrow exposed. crop rotation and spacing Straw mulch is commonly used in home gardens, and it physical barriers on the soil is effective in controlling weeds and conserving moisture. bringing into the garden only materials that you know to be However, if it’s not clean, straw may import weed seeds and cre- free of weed seed ate more weeds than it reduces. Mulches and hay and manures not allowing existing weeds to go to seed from animals eating them can contain herbicide residue, but 21-4  Organic Gardening CHAPTER 21 most herbicides break down rapidly in the environment. grub hoe However, picloram, clopyralid, and aminopyralid do not break down quickly, and, in concentrations as low as one ppb (parts per billion), they can be lethal to sensitive garden plants such as peas, beans, lettuce, spinach, tomatoes, and potatoes. These herbicides are used to control broadleaf, persistent weeds such as Canada thistle in pastures, under power transmission lines, and in hay and wheat crops. They are used because they are collinear hoe stirrup hoe long-lived, effective, and low in toxicity to humans and other Figure 21.4. Specialty garden hoes. animals. They can, however, persist in the garden for several years. If you are buying hay or straw mulch from a local farm, you can avoid bringing in contaminated mulches by asking garden hoe, the head of a stirrup hoe has a limited swivel joint whether the field in which the crop was grown has been sprayed at the top that allows the blade to remove weeds by pushing with picloram, clopyralid, or aminopyralid in the past two to and pulling the hoe without having to lift the hoe. The ability three years. These herbicides are sold under the following trade to move the hoe back and forth without having to lift the hoe names: has also led to stirrup hoes also being called “scuffle hoes.” The Picloram: Tordon, Access, Surmount, Grazon, and Pathway stirrup hoe can work the soil deeper than a garden hoe in loose Clopyralid: Curtail, Confront, Clopyr AG, Lontrel, Stinger, and light soils. To chop out larger or deeply rooted weeds, a Millennium Ultra, Millenium Ultra Plus, Reclaim, Redeem, chop or grub hoe is an aggressive tool that quickly unearths Transline weeds. Although grub hoes are effective, they can be heavy Aminopyralid: Milestone, Forefront, Pharaoh, Banish. and physically demanding to operate. Mechanical cultivation—Mechanical cultivation is generally Weeding techniques used in large gardens that have wide spacing between rows. On Once weed pressure begins to mount—and it generally a large scale, it can be much faster than hand weeding. Garden does—physically removing weeds is the organic gardener’s only tillers are set at as shallow a depth as possible so nearby crop option. No consistently effective, approved organic herbicides plants won’t be damaged and soil disturbance at deeper depths are available at this time. The following methods are most will be minimized. Extensive, regular mechanical cultivation commonly used. destroys soil structure and leads to increased breakdown of soil Hand weeding—The oldest method of weed control is hand organic matter and organic amendments such as composts and weeding, and it is still the most effective for commonly occur- manures. Mechanical cultivation should be conducted under ring weed species in Kentucky. Hand weeding is particularly proper soil moisture conditions to help minimize damage to soil effective for removing annual weeds with shallow root systems. structure. Soils that are too wet will stick to tillage implements, With hand weeding, you can remove weeds growing in the row “smear” the soil, and create compacted conditions when the without harming growing crop plants. If you regularly hand- soil dries. In general, soil moisture can be estimated by taking weed while performing other gardening tasks, you can do so a handful of soil and forming a ball by gently squeezing it. If rapidly and keep weed pressure low. Hand-weeding is also the ball readily holds its shape, it may be too wet to till. Soils the easiest method to use when weeding in garden beds with that crumble gently but still have some tangible moisture are mulches. However, if you’re weeding on a large scale or have in better condition for tillage. high weed pressure, you may need to use tools. Hoeing—Hoeing can be both efficient and effective for Insects removing small weeds or chopping out larger ones. It is most Insect control in the organic garden begins with growing effective for weeding between rows of crop plants that have a healthy plants. Weak plants, which have nutrient deficiencies, wide spacing between plants so the crop plants won’t be dam- tend to be the first to succumb to insect pressure. Nutrient aged. Hoe shallowly near plants so you do not damage their excesses (particularly nitrogen) can lead to outbreaks of insects roots; hoe deeply when you need to unearth roots of persistent such as aphids. Soil testing and proper fertility management can weeds such as curly dock, Johnsongrass, nut sedges, etc. A help minimize both nutrient deficiencies and excesses. sharp hoe makes hoeing much easier, as does having the right Timing is also important. For pests that increase through- hoe for the job (Figure 21.4). For light weeding in tight garden out the season, such as corn earworms, tobacco hornworms, spaces or in fine seed beds, use a collinear hoe. It is a small, light cucumber beetles, etc., early plantings can minimize pest tool that is dragged along the soil surface or slightly below it to pressure. For pests such as flea beetles that subside with onset kill weeds. For larger weeds or larger areas, a standard garden of summer heat, delaying plantings of eggplant and other hoe is most commonly used. A stirrup hoe, or “hula hoe,” is an summer crops that are sensitive to flea beetles can minimize alternative to the garden hoe. It has a spring-steel blade that their damage. cuts in both directions for high efficiency. Unlike a fixed-blade 21-5 CHAPTER 21 Organic Gardening Table 21.4. Guide to insects as biocontrols. are used as traps for cucumber beetles, which feed on a variety Beneficial Insect Pest Insect Controlled of cucurbit crops. Insect pests on the trap crop can either be left Green lacewing (Chrysoperla Aphids, mealybugs, immature scales alone or destroyed by hand picking or with an organic insec- rufilabris)1 and whiteflies, thrips, spider mites ticide. if you have to use pesticide to get rid insect pests, trap Lady beetle Aphids, Colorado potato beetles (egg cropping helps limit how much you have to spray in addition stage), and other insect pests to protecting crop plants. Beneficial nematodes (vari- Root knot nematodes, flea larvae, ous species) grubs Beneficial Insects Praying mantis (Tenodera Foliar-feeding insects Beneficial insects, or “natural enemies,” are used in the aridifolia sinensis)1 Mealybug destroyer Mealybug larvae organic garden to control pests biologically. A number of spe- (Cryptolaemus montrouzieri) cies of beetles, parasitic wasps, flies, and nematodes are preda- Trichogramma wasp Over 200 species of moth eggs, includ- tors or parasitoids of pest insects. (Parasitoids are organisms ing tomato hornworm, loopers, etc. that lay their eggs or larvae in the body of a host [pest] organism. Spined soldier bug (Podisus Larvae of Mexican bean beetle, The immature parasitoid feeds on the body fluids and organs maculiventris)1 European corn borer, corn earworm, of the host and eventually emerges and kills the host.) A num- cabbage looper, cabbageworm, Colorado potato beetle, and flea ber of beneficial insects are available commercially. Sources beetles. can be found online and in the UK Cooperative Extension publication Vendors of Beneficial Organisms in North America 1 These beneficial insects are general predators, shown with the pest insects against which they are particularly effective. (ENTFACT-125) at http://www.ca.uky.edu/entomology/ent- facts/ef125.asp. Common, commercially available beneficial Row covers of lightweight fabric can be used as insect bar- insects and the insect pests they control are listed in Table 21.4. riers to exclude insect pests from crop plants. When using row In general, you can expect a delay between the time of ben- covers in the summer, the fabric should be of “insect-barrier” eficial insects’ release and effective control of the pest. Effective thickness so that temperatures under the fabric don’t get too control can be difficult if you release them after you notice a hot and maximum light penetrates the fabric. The fabric can be major pest outbreak, because a sufficient population has to removed after the threat of pest damage has passed. For crops build up to control the outbreak. You should release a large that bear fruit, the insect barrier should be removed during number of them at the first sight of the pests. Most importantly, flowering to allow for pollination. Row covers are particularly you should create a habitat in which the beneficial insects can effective in preventing imported cabbageworms and cabbage overwinter and persist in your garden or yard. Ideally, a year- looper moths from laying their eggs on Brassica crops. Use round habitat for beneficial populations will limit outbreaks of wire hoops, which are available commercially, or homemade pest insects. Typically, perennial vegetation, woody shrubs, crop PVC frames to support row covers during the summer. Both residues, and even boards will provide overwintering habitat hoops and frames will allow air to circulate around the plants. for beneficial insects and their offspring. These supports can also be used with thicker fabrics and/or The most reliable way to control insect pests is to physically plastic to extend the growing season into spring or fall. Avoid remove them from the plant by hand and drop them into a pinning plants to plastic mulches, where they can be damaged container of soapy water. Adding a squirt of dish soap to an by excessive heat. empty quart jar, then adding water, creates a solution that A wide variety of traps can be made or purchased. For exam- effectively traps insects placed in the jar. The soap breaks the ple, slugs and snails can be attracted to a shallow container filled surface tension of the water, which prevents the insects from with beer and buried level with the soil. The slugs and snails gaining traction and climbing out of the jar. This method works drown in the beer. (The beer must be changed every several particularly well for beetles and caterpillars, which can generally days, as the trap fills and/or becomes foul.) Prepared sticky traps be controlled at the garden scale by daily scouting and removal are available in garden shops for whiteflies and other insects but while you take care of other garden tasks. Physical removal is are best used for monitoring for insect pressure, not control. less effective for small or fast-moving insects, which will likely Japanese beetle traps, which rely on a synthetic lure or a sex require some of the other techniques explained above. pheromone to attract the beetles, are also available in garden Although organic insecticides, which are derived from shops. These traps are highly effective, even from long distances. botanical or mineral sources, do not persist as long as their con- However, beetles may linger and feed on crop plants, doing ventional counterparts, a number of them are used in organic more damage than would have occurred without the traps. For gardening. In general, an organic insecticide requires that the that reason, these traps are not widely recommended. Instead, pest insect ingest it directly or at least come in contact with it. you might consider removing beetles and other insects by hand. For example, organic gardeners can use Bacillus thuringiensis Trap crops are grown to lure pests away from more desirable (Bt) to control caterpillars. It should be applied as a spray or crop plants. For example, flea beetles will feed on giant mustard powder every three to five days as needed during periods of over kales and other Brassica crops, and blue hubbard squashes caterpillar pressure. 21-6  Organic Gardening CHAPTER 21 Table 21.5. Insecticides approved for use in organic production. Active Ingredient Origin of Active Ingredient Pest Insects Controlled Bacillus thuringiensis (Bt) A toxin produced by the soil bacterium Bacillus Caterpillars, such as cabbage looper, hornworm, imported thuringiensis cabbageworm, corn ear worm, etc. Diatomaceous earth Fossilized remains of diatoms, algae with a silica-based Particularly effective on soft-bodied insects but also hard shell deters beetle, flea, and ant activity on plants Insecticidal soaps Salts of fatty acids derived from coconut and other oils Soft-bodied insects such as aphids, thrips, whiteflies, etc. Kaolin clay A naturally occurring clay mineralogy ground into a fine Numerous. Kaolin clay is sprayed on crop plants, deterring powder pests from landing, feeding, and depositing eggs. Neem The neem tree (Azadirachta indica), an evergreen native to Gypsy moths, leaf miners, whiteflies, thrips, loop- the Indian subcontinent ers, caterpillars, and mealybugs (disrupts feeding and development) Pyrethrins Chrysanthemum (Dendranthema grandiflora) flowers Numerous. Pyrethrins are general insecticides and affect beetles, caterpillars, and various sucking insects. Sabadilla Seeds of a tropical lily plant Schoenocaulon officinale, Sap-feeding insects, caterpillars, and thrips1 native to Central and South America Spinosads Soil actinomycete, Saccharopolyspora spinosa Numerous. Disrupts neurotransmittors and feeding pat- terns in moths, caterpillars, leaf miners, thrips, Colorado potato beetles, and fire ants Sulfur The mineral sulfur Spider mites, psyllids, and thrips 1 Highly toxic to honey bees, so application at sunset is recommended. Several general insecticides, such as pyrethins, are approved plants when leaves are dry and place them in sealed plastic bags. for organic production. These insecticides should be sprayed This practice will help prevent bacteria or fungal spores spread- just before sunset, when pest insects are active but pollinators ing to healthy plants. To minimize disease transfer between are not, in order to prevent contact with bees and other pol- plants, avoid harvesting or pruning tomato plants while the linators. Examples of insecticides approved for organic produc- leaves are wet. Use a bleach-treated cloth to wipe down prun- tion and the organisms they control are listed in Table 21.5. ers between working tomato or tree crops, which will also help Organically approved insecticides are available at some garden minimize disease spread. supply stores but are also available online in home garden Many diseases spread by insect vectors—insects transporting quantities from commercial organic nursery and horticultural disease from plant to plant as they feed. In Kentucky, bacterial suppliers (see “Additional Resources”). wilt of cucurbits is a classic example of this method of disease spread. Spotted and striped cucumber beetles carry bacterial Diseases wilt of cucurbits between cucumbers and other cucurbit plants as they feed. Therefore, this disease is controlled through the Cultural controls are the best way to prevent disease in beetle vector, not the bacteria (Erwinia tracheophila) that causes organic gardening, since few options exist for biological con- the disease. This example highlights an important principle for trol of diseases. Gardeners can best control diseases from the the organic gardener: knowing the root cause of a disease or outset through cultural practices that deter buildup of disease other problem in the garden requires understanding the entire organisms. Crop rotation is especially important in controlling garden as a system. One might view the disease as the problem diseases of Solanaceous crops (tomato, pepper, potato, etc.) as because it may be the final fatal blow to the plant. However, if bacterial and fungal diseases are particularly problematic when the root cause is insect or soil related, treating the disease is these crops are produced organically. It is also best to avoid ineffective if the underlying condition or cause is not resolved. composting residue of diseased plants of any Solanaceous crops Very few sprays are designed to control diseases organi- so that disease organisms won’t build up in the compost pile. cally. Copper-based products are considered synthetic but are Instead, dispose of residue of diseased plants or any Solanaceous allowed in USDA-certified organic production with certain crops in sealed garbage bags and burn it or throw it away with restrictions. These products are restricted because they can municipal garbage. accumulate in soil and create copper toxicity problems; are It’s also important to select disease-resistant cultivars. There highly toxic to fish; and can also harm bees, beneficial soil bac- are a number of sources for high-quality, untreated, and/or teria and fungi, and earthworms. Copper-based products have organic seed. Knowing disease issues that are problematic in been shown to be somewhat effective in controlling downy and your garden and in your region is key to proper cultivar selec- powdery mildews, bean anthracnose, and tomato early blight. tion. It should be noted that treated and/or genetically modified Bordeaux mix (a blend of copper sulfate mixed with hydrated seeds are prohibited in USDA-certified organic production. lime) is considered a synthetic substance and is restricted in Disease organisms are spread by moving infected materials organic production due to its long residual activity and high from plant to plant. To help avoid such spread, remove diseased toxicity to bees. Sulfur that is mined (elemental sulfur) rather 21-7 CHAPTER 21 Organic Gardening than extracted through manufacturing/power generation can Kuepper, George. Potting Mixes for Certified Organic Production. be used in certified organic production. In addition to serving 2010 (reviewed edition). ATTRA Publication #IP112. as a trace mineral, sulfur has fungicidal effects. National Sustainable Agriculture Information Service, Research and development of organically approved disease Butte, MT. 20 pp. https://attra.ncat.org/publication/ controls is occurring rapidly. Up-to-date information and new potting-mixes-for-certified-organic-production/ products can be found at Extension’s eOrganic website (https:// Lowenfels. Jeff, and Wayne Lewis. 2006. Teaming with Microbes: eorganic.info/) as well as Caldwell’s Resource Guide for Organic A Gardener’s Guide to the Soil Food Web. Timber Press, Insect and Disease Management, listed in the “Additional Portland, OR. 196 pp. Resources” section.. National Sustainable Agriculture Information Service (also known as ATTRA). An excellent source of information on all kinds of sustainable and organic agricultural practices, Additional Resources marketing, etc. www.attra.org. Bartholomew, Mel. 2005. Square Foot Gardening: A New Way to Online Information Service for Non-Chemical Pest Garden in Less Space with Less Work. Rodale Press, Emmaus, Management in the Tropics. Trap Cropping. Hamburg, PA. 352 pp. Germany. http://www.oisat.org/control_methods/cul- Boyhan, George. E. 2009. Growing Vegetables Organically. tural__practices/trap_cropping.html University of Georgia Cooperative Extension Bulletin 1011. Oregon State University Extension Service. Organic Gardening Athens, GA. 10 pp. https://secure.caes.uga.edu/extension/ Fundamentals. 10-Minute University Series. publications/files/pdf/B%201011_4.PDF Organic Gardening Magazine. Published by Rodale Press since Caldwell, Brian. 2005. Resource Guide for Organic Insect the 1940s. and Disease Management. New York State Agricultural Organic Materials Review Institute. www.omri.org. Experiment Station, Geneva, NY. 169 pp. https://www.sare. Riotte, Louise. 1998. Carrots Love Tomatoes: Secrets of org/wp-content/uploads/Resource-Guide-for-Organic- Companion Planting for Successful Gardening. Storey Books, Insect-and-Disease-Management.pdf North Adams, MA. 224 pp. Coleman, Eliot. 1989. The New Organic Grower: A Master’s Rynk, Robert. 1992. On-Farm Composting Handbook. Natural Manual of Tools and Techniques for the Home and Market Resource, Agriculture and Engineering Service. Gardener. Chelsea Green Publishing, White River Junction, Stephens, James M. 2003. Organic Vegetable Gardening. Florida VT. 340 pp. Cooperative Extension Service Circular 375. University of Gershuny, Grace, and Deborah L. Martin (eds). 1992 (Revised Florida, Gainesville, FL. 12 p. Edition). The Rodale Book of Composting: Easy Methods for United States Department of Agriculture Agricultural Every Gardener. Rodale Press, Emmaus, PA. 278 pp. Marketing Service. The National Organic Program. Jeavons, John. 2004 (Sixth Edition). How to Grow More http://www.ams.usda.gov/AMSv1.0/nop. Last modified: Vegetables (and Fruits, Nuts, Berries, Grains and Other Crops 11/09/2010. than You Ever Thought Possible on Less Land than You Can Imagine). Ten Speed Press, Berkeley, CA. 240 pp. Revised 01-2024