So you’ve decided to go ahead with your urban farm and now face growing pains? Hopefully you’ve followed guidelines in How to Grow? and are ready to dig deeper now!

WATERING SCHEDULES

DISEASE & PEST CONTROL

Despite all preventive organic care, some problems will occur given global warming, environmental decay, plant epidemics and vector-related issues. In fact, as soon as you start your urban farm, you would be unknowingly inviting an assortment of mites, ants, worms, bees, butterflies, birds and even rodents who will joyously arrive to gatecrash the party. These are folks of varied types, and it is important to differentiate between the harmless and the harmful ones.

Foliage, especially of fruiting veggies and sweet leaf veggies (lettuce, spinach) are often targets of leaf-eating worms and aphids that feast on foliage and fruit. Growing foliage intensive plants during the high humidity months in Mumbai is also an invitation for fungal attacks. I have found that regular use of Neem Oil Foliar spray can deter harmful worms, and aphids, and inhibit the spread of fungus. In my experience, regular dusting of wood/coconut shell ash on diseased foliage is even more effective. And of course, when disease is widespread, or irrevocable as with verticilium blight, the best you can do is uproot and destroy the diseased plant and quarantine the soil for some time. If the foliage is healthy but being feasted on by gluttonous leaf-eaters, try locating the culprit worms and evict them from your farm (or better still, squish them dead).

Soil, especially manure-rich soil, is often home to worms, and it is the black and white ones that are generally harmful (not the dark red ones). In the case of worm-ridden soil of the wrong variety, I would isolate the container and/or empty it and dry out the soil in hot sunlight for a couple of weeks.

Ants are usually not problematic, except when assisting aphids, and can be tolerated in the farm as they also help to transport pollen. Butterflies and bees are the unqualified stalwarts to any farm and need to be encouraged. Most birds won’t bother you except if you are growing fruit. Rodents can be destructive and you can hang up your gardener boots once neighborhood rats discover the delights of your sugarcane, ginger and potatoes. For these goons I have have an aggressive, closed-door, mouse-trap policy. I was recently surprised by the visit of a squirrel, a flock of parrots and a bunch of unruly monkeys on my high-rise (Monkeys in Mumbai – OMG!!!). My solution is to tie netting around growing gourds/fruit or, more simply, just eat my produce before they do!

Solution 1: Insecticidal Soap Sprays

Here’s an easy way to make and use your own natural insecticidal soap:

1. Combine one cup of oil, any variety, such as vegetable, peanut, corn, soybean, etc. with one tablespoon of dishwash liquid or other “pure” soap. Avoid any dishwash liquid that contains degreaser/bleach/synthetic fragrances.
2. Mix two teaspoons of this mixture to a cup of warm water and put into a spray bottle. Mix only what is needed for a one-day application.
3. Add a teaspoon of ground red pepper or garlic to repel harmful insects and/or a teaspoon of vinegar to prevent powdery mildew.

Maintain a schedule of regular applications in the mornings/evenings. Avoid spraying your plants in extreme heat conditions as phytotoxicity may occur.

Solution 2: Foliar Sprays

Foliar spray, although not a substitute for healthy soil, can be beneficial when a plant is suffering from certain nutrient deficiencies. Foliar plant spray involves applying fertilizer directly to a plant’s leaves as opposed to putting it in the soil. Foliar feeding is similar to humans putting an aspirin under their tongue; the aspirin is more readily absorbed into the body than it would be if it were swallowed. A plant takes nutrients through the leaf much quicker than it does through the root and stem.

Foliar sprays are generally less concentrated than fertilizers. Common natural materials used are kelp, compost tea, weed tea, herbal team fish emulsion, baking soda, phosphate and silica salt sprays. Foliar sprays should be applied on the tops and undersides of leaves, and preferably in the morning – to prevent excessive evaporation in noonday sun and to optimize absorption during the day’s photosynthesis.

Solution 3: Oil Sprays

Petroleum-based horticultural oils (mineral oils), essential plant oils, neem oil, vegetable seed oils, and even fatty acids can be used effectively not just to fight insect pests, but to control pathogenic fungi as well. Oil sprays protect against fungi by helping to repel the water that is needed for fungal growth. Rotation of oil types minimizes possible environmental accumulation of one kind. Petroleum is the most persistent; vegetable and neem oils are the more easily biodegradable.

1. Petroleum-based oils: These oils have a long history of use in horticulture. Before the 1970s when lighter formulations were developed, orchardists sprayed their trees in the spring, while the trees were still dormant, with heavy (“dormant”) oils to protect against insect pests. You can now purchase refined horticultural oils such as a product named SunSpray, which is effective against powdery mildew and sometimes against black spot. You can also purchase mineral oil at a drugstore and use it to make your own, less expensive, spray. Horticultural oils should not be used on drought-stressed plants or those weakened by disease, and they should not be used when temperatures exceed 85°F. With repeated use petroleum-based sprays can also build up in your soil.
2. Vegetable oil sprays: Cooking and salad oils are more readily available than most other oils and are probably less disruptive to the environment. Vegetable oils are biodegradable and shouldn’t cause any long-term problems in the garden. Emulsified vegetable oil sprays of sunflower, olive, canola, peanut, soybean, corn, grapeseed, or safflower can control powdery mildew on apple trees, roses, and possibly other plants, and cottonseed oil has considerable protective value against powdery mildew. However, emulsified vegetable oil can leave a greasy film on leaves, which you might find objectionable. Check for plant damage before general use, and be especially careful of blooms.
3. Herbal oil sprays: Essential oils such as those made from basil, fenugreek, cumin, mint, clove, and eucalyptus may be effective against a number of fungal pathogens. For instance, solutions of cumin or clove oil completely inhibit sugarcane rot, and basil oil can inhibit growth of soilborne pathogens. A commercial formulation of mint oil (Funga-Stop) is available to help control soilborne pathogens. However, these essential oils need to be researched further before they become prevalent in horticulture.
4. Neem oil: Neem is derived from the neem tree, a native of Myanmar (the former Burma) and India. Extracts of neem seeds are used as insecticides; they kill insects as they molt or hatch. Recently, fungicides made with neem oil have become available commercially. Neem oil appears to have better fungicidal properties than many of the oils described above, perhaps because neem contains sulfur compounds, which have their own fungicidal properties, as well as other natural pesticides. A neem-oil formulation called Trilogy has been approved by the EPA for use on foods, while Rose Defense and Triact (for control of powdery mildew, rust, black spot, Botrytis, downy mildew, and other common diseases) are designed for use on ornamentals. Make sure you buy neem with fungicidal rather than insecticidal properties.

Solution 4: Soap Sprays

Like many other methods outlined here, soaps have been used for many years by organic gardeners, particularly as insecticides. Commercial formulations now include soap solutions with fungicidal properties, which show some control of powdery mildew, black spot, canker, leaf spot, and rust. You can also make your own version. All soaps can damage plants when applied improperly. Test before you spray widely.

Solution 5: Botanical Amendments

Plant preparations have been used for centuries in medicine and pest control. For example, opium from the opium poppy was one of the first pain killers. Farmers in India use neem leaves to protect their stored grain from insects. Herbs and spices, such as basil and clove, have been used by many cultures to protect food from spoilage, as both have antimicrobial properties. Sprays made from aqueous garlic extracts have antibiotic and antifungal properties and will suppress a number of plant diseases, including powdery mildew on cucumbers and, to some extent, black spot on roses.

Solution 6: Using Beneficial Organisms

Beneficial fungi or bacteria can control garden diseases by competing with disease-causing organisms for nutrients and space, by producing antibiotics, by preying on pathogens (a process called hyperparasitism), or by inducing resistance in the host plant. Antagonists do not persist in the environment, are non-toxic, and in some cases are as effective as chemical fungicides. Beneficial fungi are effective only when humidity is high (usually 60 to 80 percent), so they would work very well in Mumbai.

Hyperparasites

Ampelomyces quisqualis is a powdery mildew hyperparasite first described in the mid-nineteenth century. The fungus attacks a wide range of powdery mildew species and genera; it spreads naturally through the air, and acts quickly. The commercially available strain, AQ-10, can provide some control of powdery mildew on cucumber, grapes, roses, and possibly other plants. Research has shown that better results are obtained when AQ-10 is mixed with a horticultural-oil solution before spraying.

Compost Tea

Water extracts of fermented compost, or “compost teas,” are full of antibiotics, microbial products, and beneficial microbes that compete with pathogens, such as those that are responsible for powdery mildew, Botrytis gray mold, and leaf blight. The “tea” can be used as a foliar spray to help suppress plant disease. Undiluted compost may also benefit a plant’s roots, and stem, as well as the soil when applied as a thin layer of mulch around the plant.

***Combine Your Solutions

You may have greater success combating plant diseases when you combine control treatments instead of employing a single control strategy. For example, baking soda is usually more effective when used with oil because both have antifungal properties. The oil may also help provide an even distribution of baking soda on plant leaves. Pathogens can also develop resistance to ingredients that are applied frequently, so a rotation of active ingredients can reduce the likelihood of pathogen resistance.

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