Pest and disease management. I prefer to go organic on pest management because the plants are in my living space. If only a few plants are infested, I take the plants to the sink and rinse them every day for 3 days, then once a week for a couple of weeks to get any eggs which have hatched into plant feeders. If there is a higher population, the simplest, and usually quite effective spray for soft bodied insects, is simply 1 tsp of dish soap to 1 quart of water. By soft bodied insects, I mean aphids, mealy bugs, and mites. I do not have any pictures of such insects at this time, but if you google images you will find plenty of pictures. The dish soap is safe to apply, safe to be around, and often smells pleasant. The soap must contact the insect in order to kill so it is important to spray under the leaves as well. There are a few plants which are sensitive to soap so it is wise to try it on one plant of a species before spraying all of them. I found the following plants to be sensitive to soap: lemon verbena, pepper plants, and sweet peas.
Mites are sometimes controlled with the soap, but I find it much more effective if other ingredients are added. You need a blender, one quart of water, 1 tablespoon of red hot pepper, 1 tablespoon of vinegar, 1 clove garlic and whir that around to tiny bits. Let it sit overnight and then strain through a coffee filter. Put the strained liquid in a 1 quart spray bottle and add 1 tsp of soap. Do not add the soap to the blender. What a mess if you do. This mix is good to control thrips as well. If you have access to fresh tobacco leaves (do not use commercial dried tobacco because there is a possibility infecting plants with disease…especially tomatoes) add a fresh leaf of tobacco to the blender. Nicotine is a deadly poison and is quite effective added to the mix.
Another safe spray is neem oil and soap. This has become my favorite method of control. Neem oil is the oil from the seed of the neem tree. In India, neem has hundreds of uses from food to medicine. It is not recommended to eat the oil, but it is safe for people, pets, and usually beneficial insects. It’s mode of action is manifold. There is a physical mode of action. The oil sprayed on the insect clogs it’s breathing pores and it suffocates. Second, there is a chemical that causes insects to stop feeding and reproducing when neem coated plants are fed on. This is where neem protects beneficial insects because they do not feed on the plants. Being directly sprayed will kill them, but they do not feed on the plants so are safe. Not only do the pests stop feeding, but they are unable to enter the next stage of their life. Eggs do not hatch, larvae or nymphs do not become adults, adults do not mate and lay eggs. There is also some residual protection for about a week. And it is said if the plants are watered with this solution, not only will soil insects be killed, but neem is taken up into the plant and will have some systemic protection as well. I’m not sure about this last one because I’ve only seen claims and not any science behind it. Lastly, neem oil will control powdery mildew, a common affliction of African violets. Neem oil can be purchased on line. Make sure you get pure neem oil because if there is any water present, neem breaks down rapidly and will not perform as expected. The spray mix for this is 1 and a half teaspoons of neem oil and 1 and a half teaspoons of dish soap (soap aids in kill as well as acts as an emulsifier for the neem) to 1 quart of water. Use all of the spray within a couple of hours because the water will start breaking down the active ingredient in neem. There are precautions when using neem. It will damage flower buds and open flowers. It also should not be applied to water stressed plants or it will cause damage. All plants that are sprayed with it should not be in full sun for a few hours after spraying. The oil intensifies the sun and will cause burning.
OK, what does it smell like? The closest thing I can describe is it smells like garlic. Could be offensive to some but I don’t find it so and the smell only lasts about a day.
Disease control. The best way of controlling disease is to discard the plant unless it is something like powdery mildew. Powdery mildew looks like whitish dust on the surface of the leaves and will not wash or brush off. It can kill the leaf and spread to other susceptible plants. A good control is the neem and another is milk. Yes, milk. I use half skim milk and half water making sure to coat the leaf surface. Spray all susceptible plants whether or not they show signs of the disease...almost all plants are susceptible.
As for other diseases, spots and lesions, you can try copper soap. This is a product sold in garden centers as an organic disease control.
Root rot is usually caused by over watering or poor drainage. You can try to save the plant by knocking it out of the pot, trimming off brown, decaying roots, cutting back the top growth to match the amount of root left and re-potting it in very well drained soil. Careful watering must be observed to allow the plant to recover. Water the plant sparingly to allow new roots to grow. Crown and stem rots, are usually caused by bacteria getting into wounds and often is incurable so the easiest thing to do is to discard the plant to protect the others.
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